maintenance manual.pdf

1 Precautions and Basic Operations of Equipment Maintenance 1-1..............

1.1 Precautions of Maintenance Operations 1-1................................................1.1.1 Precautions for Laser Safety 1-1..........................................................1.1.2 Precautions for Electrical Safety 1-2....................................................1.1.3 Precautions for Mechanical Safety 1-4................................................1.1.4 Precautions for Network Management System Maintenance 1-4........1.1.5 Precautions for Service Grooming 1-4.................................................

1.2 Maintenance Operations 1-5........................................................................1.2.1 Using the Orderwire Telephone 1-5.....................................................1.2.2 Cleaning the Fan 1-5............................................................................1.2.3 Swapping and Replacing the Board 1-6...............................................1.2.4 Switching On/ Off the Equipment 1-8...................................................1.2.5 Cutting Off the Alarm Sound 1-10..........................................................1.2.6 Resetting the SCB Board 1-10...............................................................1.2.7 SCB Board DIP Switches 1-11...............................................................1.2.8 Operations of Loopback 1-12.................................................................1.2.9 Testing the Receiving Optical Power and Transmitting OpticalPower 1-15......................................................................................................1.2.10 Testing Bit Errors 1-16.........................................................................1.2.11 Preparing the Ethernet Cable of NM Computer 1-17...........................1.2.12 Testing Trunk Cables with a Multimeter 1-18.......................................1.2.13 Definition of East and West 1-19..........................................................

2 Regular Maintenance 2-1....................................................................................

2.1 Maintenance Overview 2-1...........................................................................2.1.1 Classification of Maintenance 2-1........................................................2.1.2 Basic Principles of Regular Maintenance 2-2......................................2.1.3 Maintenance Considerations For the OptiX 155/622H 2-2..................

2.2 Regular Maintenance Items 2-3...................................................................2.2.1 Checking the Audio Alarm of the Equipment 2-3.................................2.2.2 Viewing the Indicators 2-3....................................................................2.2.3 Checking Temperature of the Equipment 2-4......................................2.2.4 Checking and Regularly Cleaning the Fan 2-5....................................2.2.5 Checking Orderwire Telephone 2-5.....................................................2.2.6 Checking Performance of ATM Layer 2-6............................................2.2.7 Checking Service --Bit Error Test 2-7..................................................

2.3 Regular Maintenance Items of NMS 2-8......................................................

3 Basic Thoughts and Methods 3-1......................................................................

3.1 Requirements for Maintenance Staff 3-1......................................................3.1.1 Professional Skills 3-1..........................................................................

3.1.2 Aware of Network Layout 3-3...............................................................3.1.3 Collecting and Storing On-site Data 3-3...............................................

3.2 Basic Principles of Fault Locating 3-4..........................................................3.3 Common Methods of Fault Locating 3-4......................................................

3.3.1 Alarm and Performance Analysis 3-5...................................................3.3.2 Loopback 3-9.......................................................................................3.3.3 Replacement 3-15..................................................................................3.3.4 Configuration Data Analysis 3-16...........................................................3.3.5 Configuration Modification 3-17.............................................................3.3.6 Meter Test 3-18......................................................................................3.3.7 Experience of Maintenance 3-18...........................................................3.3.8 Comparison of Fault Locating Methods 3-18.........................................

3.4 Classified Fauts & Troubleshooting 3-20........................................................3.4.1 External Faults Handling 3-20................................................................3.4.2 Localizing Fault to a Single Station 3-22................................................3.4.3 Localizing Fault to the Board 3-23.........................................................

3.5 Contact Huawei for Assistance 3-24..............................................................3.6 Obtaining the Latest Technical Documentation 3-24......................................

4 Common Faults Treatment 4-1..........................................................................

4.1 Payload Interruption 4-2...............................................................................4.1.1 Common Cause Analysis 4-2...............................................................4.1.2 Common Treatment Methods 4-2........................................................4.1.3 Fault Treatment Procedures 4-2..........................................................4.1.4 How to Remove Some Payload-Interruption Faults in TypicalNetwork 4-4...................................................................................................

4.2 Bit Errors 4-8................................................................................................4.2.1 Common Cause Analysis 4-8...............................................................4.2.2 Common Treatment Methods 4-8........................................................4.2.3 Fault Treatment procedures 4-9...........................................................4.2.4 Cases of Typical Faults 4-10..................................................................

4.3 Pointer Justification 4-12................................................................................4.3.1 Common Cause Analysis 4-12...............................................................4.3.2 Common Treatment Methods 4-12........................................................4.3.3 Fault Treatment procedures 4-12...........................................................4.3.4 Treatment of Pointer Justification Problems in Two TypicalCases 4-12......................................................................................................4.3.5 Examples of Typical Faults 4-15............................................................

4.4 ECC Fault 4-17...............................................................................................4.4.1 Introduction to ECC 4-17........................................................................4.4.2 Common Causes of ECC Faults 4-17....................................................4.4.3 Common Treatment Methods 4-18........................................................

4.4.4 Fault Treatment procedures 4-18...........................................................4.4.5 Removal of Typical ECC Faults 4-18.....................................................4.4.6 Tips for ECC Fault Location 4-20...........................................................

4.5 Orderwire Fault 4-22.......................................................................................4.5.1 Introduction to Overhead Processing Unit 4-22.....................................4.5.2 Common Cause Analysis 4-22...............................................................4.5.3 Common Treatment Methods 4-22........................................................4.5.4 Fault Treatment procedures 4-22...........................................................4.5.5 Common Orderwire Problems 4-23.......................................................4.5.6 Removal of Typical Orderwire Faults 4-24.............................................

4.6 Equipment Interconnection Fault 4-25............................................................4.6.1 Common Cause Analysis 4-25...............................................................4.6.2 Common Treatment Methods 4-25........................................................4.6.3 Fault Treatment Steps 4-25...................................................................4.6.4 About STM-N Optical (Electrical) Interface Interconnection 4-31..........4.6.5 Typical Case of Equipment Interconnection 4-32..................................

4.7 Ethernet Interconnection Fault 4-34...............................................................4.7.1 Ethernet Interface Board and Configuration 4-34..................................4.7.2 Common Faults and Causes 4-38.........................................................4.7.3 Common Methods for Fault Localizatio 4-39.........................................4.7.4 Procedures 4-40.....................................................................................4.7.5 Classified Fault Localization and Handling 4-43....................................4.7.6 Common Troubleshooting Cases 4-46..................................................

5 Alarm Generation Principles of OptiX Equipment 5-1.....................................

5.1 Alarm Generation Principles of the System 5-2............................................5.1.1 System Signal Flow 5-2.......................................................................5.1.2 System Alarm Flow 5-3........................................................................5.1.3 Analysis and Explanation of Alarm Principles 5-5................................

5.2 Generation and Detection of Alarm and Performance Signals in theHigher Order Signal Flow 5-7.............................................................................

5.2.1 Down Signal Flow 5-8..........................................................................5.2.2 Up Signal Flow 5-11...............................................................................

5.3 Generation of Alarm and Performance Signals in the Lower OrderService Signal Flow 5-13......................................................................................

5.3.1 Down Signal Flow 5-13..........................................................................5.3.2 Up Signal Flow Path 5-16......................................................................

5.4 Suppression Relations between Alarm Signals 5-17......................................5.5 Examples of Locating a Fault According to the Signal Flow 5-19..................

5.5.1 Bit Error Problems 5-19..........................................................................5.5.2 Alarm Specific Problems 5-20................................................................5.5.3 Summary 5-22........................................................................................

5.6 Generation and Detection of ATM Service Alarms 5-23.................................5.6.1 Logic Diagram of Board 5-23.................................................................5.6.2 ATM Signal Flow 5-24............................................................................5.6.3 Detection of ATM Alarms and Performances 5-25.................................

5.7 Alarms and Signal Flows of Ethernet Service 5-27........................................5.7.1 Logic Diagram of ET1O Board 5-27.......................................................5.7.2 Generation and Detection of Alarms 5-28..............................................

6 Flow of Serious Fault Handling 6-1...................................................................

6.1 Flowchart of Handling Serious Fault 6-1......................................................6.2 Flowchart Description 6-3.............................................................................6.3 Recommendations 6-4.................................................................................

A Alarm Signal Flow A-1........................................................................................

B List of Alarms and Performance B-1.................................................................

B.1 Common Alarms B-1....................................................................................AU_AIS B-1...................................................................................................AU_LOP B-3..................................................................................................B1_EXC B-4..................................................................................................B2_EXC B-5..................................................................................................B3_EXC B-6..................................................................................................DOWN_E1_AIS B-6......................................................................................ETH_LOS B-7................................................................................................FAN_FAIL B-7...............................................................................................HP_LOM B-8.................................................................................................HP_RDI B-9...................................................................................................HP_REI B-10...................................................................................................HP_SLM B-11..................................................................................................HP_TIM B-12...................................................................................................HP_UNEQ B-12...............................................................................................ILL_SQ_VC12 B-13.........................................................................................ILL_SQ_VC3 B-13...........................................................................................ILL_ MFI _VC12 B-14......................................................................................ILL_ MFI _VC3 B-14........................................................................................LCAS_BAND_DECREASED B-15..................................................................LP_RDI B-15...................................................................................................LP_SLM B-16..................................................................................................LP_TIM B-17...................................................................................................LP_UNEQ B-18...............................................................................................LTI B-19...........................................................................................................MS_AIS B-20...................................................................................................

MS_RDI B-21..................................................................................................MS_REI B-22...................................................................................................POWER_FAIL B-22.........................................................................................PS B-23...........................................................................................................R_LOF B-24....................................................................................................R_LOS B-25....................................................................................................R_OOF B-26....................................................................................................SYNC_C_LOS B-27........................................................................................SYN_BAD B-27...............................................................................................TU_AIS B-28...................................................................................................TU_LOP B-29..................................................................................................T_ALOS B-30..................................................................................................T_DLOS B-31..................................................................................................UP_E1_AIS B-32.............................................................................................VC_DELAY_TL B-32.......................................................................................

B.2 Category of System Performance B-33..........................................................RS (Regenerator Section) Performance Events B-33.....................................MS (Multiplex Section) Performance Events B-33..........................................MSA (Multiplex Section Adaptation) Performance Events B-34......................HP (Higher Order Path) Performance Events B-34.........................................HPA (Higher Order Path Adaptation) Performance Events B-34....................LP (Lower Order Path) Performance Events B-35..........................................PS (Protection Switching) Performance Events B-35......................................Framing Performance Events B-35.................................................................

C Guidance for OptiX Routine Maintena nce and Record C-1...........................

C.1 Daily Maintenance Recommendations C-1..................................................C.2 Explanation of SDH Daily Maintenance Record and Guidance forSDH Daily Maintenance C-3...............................................................................C.3 Guidance for SDH Daily Maintenance C-4...................................................C.4 Guidance for SDH Monthly Maintenance C-7..............................................C.5 Guidance for SDH Quarterly Maintenance C-8............................................C.6 Guidance for SDH Yearly Maintenance C-8.................................................C.7 SDH Daily Maintenance Duty Log C-9.........................................................C.8 SDH Monthly (Quarterly) Maintenance Record C-11.....................................C.9 SDH Yearly Maintenance Record C-12..........................................................C.10 SDH Outburst Problems and Solutions Record C-13...................................C.11 Board Replacement Record C-14................................................................C.12 Data Modification Record C-15....................................................................

D Abbreviations and Acronyms D-1.....................................................................

Index .................................................................................................................

Huawei Technologies Proprietary

HUAWEI

OptiX 155/622H(Metro1000) STM-1/STM-4 MSTP Optical Transmission System Maintenance Manual

V200R006


OptiX 155/622H(Metro1000) STM-1/STM-4 MSTP Optical Transmission System Maintenance Manual Manual Version T2-040399-20041130-C-2.60

Product Version V200R006

BOM 31033599

Huawei Technologies Co., Ltd. provides customers with comprehensive technical support and service. Please feel free to contact our local office or company headquarters.

Huawei Technologies Co., Ltd. Address: Administration Building, Huawei Technologies Co., Ltd., Bantian, Longgang District, Shenzhen, P. R. China Postal Code: 518129 Website: http://www.huawei.com Email: [email protected]


Copyright © 2004 Huawei Technologies Co., Ltd.

All Rights Reserved No part of this document may be reproduced or transmitted in any form or by any means without prior written consent of Huawei Technologies Co., Ltd. Trademarks

, HUAWEI, C&C08, EAST8000, HONET, , ViewPoint, INtess, ETS, DMC, TELLIN, InfoLink, Netkey, Quidway, SYNLOCK, Radium, M900/M1800, TELESIGHT, Quidview, Musa, Airbridge, Tellwin, Inmedia, VRP, DOPRA, iTELLIN, HUAWEIOptiX, C&C08 iNET, NETENGINE, OptiX, iSite, U-SYS, iMUSE, OpenEye, Lansway, SmartAX, infoX, TopEng are trademarks of Huawei Technologies Co., Ltd. All other trademarks and trade names mentioned in this manual are the property of their respective holders. Notice The information in this document is subject to change without notice. Every effort has been made in the preparation of this document to ensure accuracy of the contents, but all statements, information, and recommendations in this document do not constitute the warranty of any kind, express or implied.


Summary of Updates

This section provides the update history of this manual and introduces the contents of subsequent updates.

Update History

Manual Version Notes

T2-040399-20041130-C-2.60 Compared with V2.50 version, this version supplements alarms for EFT board.

Updates of Contents

Updates between document versions are cumulative. Therefore, the latest document version contains all updates made to previous versions.

Updates in Manual Version 2.60

Appendix B List of Alarms and Performance Alarms for EFT board are added.

OptiX 155/622H(Metro1000) Maintenance Manual Contents


i

Contents

1 Precautions and Basic Operations of Equipment Maintenance 1-1

1.1 Precautions of Maintenance Operations 1-1

1.1.1 Precautions for Laser Safety 1-1

1.1.2 Precautions for Electrical Safety 1-2

1.1.3 Precautions for Mechanical Safety 1-4

1.1.4 Precautions for Network Management System Maintenance 1-4

1.1.5 Precautions for Service Grooming 1-4

1.2 Maintenance Operations 1-5

1.2.1 Using the Orderwire Telephone 1-5

1.2.2 Cleaning the Fan 1-5

1.2.3 Swapping and Replacing the Board 1-6

1.2.4 Switching On/Off the Equipment 1-8

1.2.5 Cutting Off the Alarm Sound 1-10

1.2.6 Resetting the SCB Board 1-10

1.2.7 SCB Board DIP Switches 1-11

1.2.8 Operations of Loopback 1-12

1.2.9 Testing the Receiving Optical Power and Transmitting Optical Power 1-15

1.2.10 Testing Bit Errors 1-16

1.2.11 Preparing the Ethernet Cable of NM Computer 1-17

1.2.12 Testing Trunk Cables with a Multimeter 1-18

1.2.13 Definition of East and West 1-19

2 Regular Maintenance 2-1

2.1 Maintenance Overview 2-1

2.1.1 Classification of Maintenance 2-1

2.1.2 Basic Principles of Regular Maintenance 2-2

2.1.3 Maintenance Considerations For the OptiX 155/622H 2-2



ii

2.2 Regular Maintenance Items 2-3

2.2.1 Checking the Audio Alarm of the Equipment 2-3

2.2.2 Viewing the Indicators 2-3

2.2.3 Checking Temperature of the Equipment 2-4

2.2.4 Checking and Regularly Cleaning the Fan 2-5

2.2.5 Checking Orderwire Telephone 2-5

2.2.6 Checking Performance of ATM Layer 2-6

2.2.7 Checking Service --Bit Error Test 2-7

2.3 Regular Maintenance Items of NMS 2-8

3 Basic Thoughts and Methods 3-1

3.1 Requirements for Maintenance Staff 3-1

3.1.1 Professional Skills 3-1

3.1.2 Aware of Network Layout 3-3

3.1.3 Collecting and Storing On-site Data 3-3

3.2 Basic Principles of Fault Locating 3-4

3.3 Common Methods of Fault Locating 3-4

3.3.1 Alarm and Performance Analysis 3-5

3.3.2 Loopback 3-9

3.3.3 Replacement 3-15

3.3.4 Configuration Data Analysis 3-16

3.3.5 Configuration Modification 3-17

3.3.6 Meter Test 3-18

3.3.7 Experience of Maintenance 3-18

3.3.8 Comparison of Fault Locating Methods 3-18

3.4 Classified Fauts & Troubleshooting 3-20

3.4.1 External Faults Handling 3-20

3.4.2 Localizing Fault to a Single Station 3-22

3.4.3 Localizing Fault to the Board 3-23

3.5 Contact Huawei for Assistance 3-24

3.6 Obtaining the Latest Technical Documentation 3-24

4 Common Faults Treatment 4-1

4.1 Payload Interruption 4-2

4.1.1 Common Cause Analysis 4-2

4.1.2 Common Treatment Methods 4-2

4.1.3 Fault Treatment Procedures 4-2

4.1.4 How to Remove Some Payload-Interruption Faults in Typical Network 4-4



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4.2 Bit Errors 4-8



4.2.3 Fault Treatment procedures 4-9

4.2.4 Cases of Typical Faults 4-10

4.3 Pointer Justification 4-12




4.3.4 Treatment of Pointer Justification Problems in Two Typical Cases 4-12

4.3.5 Examples of Typical Faults 4-15

4.4 ECC Fault 4-17

4.4.1 Introduction to ECC 4-17

4.4.2 Common Causes of ECC Faults 4-17



4.4.5 Removal of Typical ECC Faults 4-18

4.4.6 Tips for ECC Fault Location 4-20

4.5 Orderwire Fault 4-22

4.5.1 Introduction to Overhead Processing Unit 4-22




4.5.5 Common Orderwire Problems 4-23

4.5.6 Removal of Typical Orderwire Faults 4-24

4.6 Equipment Interconnection Fault 4-25



4.6.3 Fault Treatment Steps 4-25

4.6.4 About STM-N Optical (Electrical) Interface Interconnection 4-31

4.6.5 Typical Case of Equipment Interconnection 4-32

4.7 Ethernet Interconnection Fault 4-34

4.7.1 Ethernet Interface Board and Configuration 4-34

4.7.2 Common Faults and Causes 4-38

4.7.3 Common Methods for Fault Localizatio 4-39

4.7.4 Procedures 4-40

4.7.5 Classified Fault Localization and Handling 4-43



iv

4.7.6 Common Troubleshooting Cases 4-46

5 Alarm Generation Principles of OptiX Equipment 5-1

5.1 Alarm Generation Principles of the System 5-2

5.1.1 System Signal Flow 5-2

5.1.2 System Alarm Flow 5-3

5.1.3 Analysis and Explanation of Alarm Principles 5-5

5.2 Generation and Detection of Alarm and Performance Signals in the Higher Order Signal Flow 5-7

5.2.1 Down Signal Flow 5-8

5.2.2 Up Signal Flow 5-11

5.3 Generation of Alarm and Performance Signals in the Lower Order Service Signal Flow 5-13

5.3.1 Down Signal Flow 5-13

5.3.2 Up Signal Flow Path 5-16

5.4 Suppression Relations between Alarm Signals 5-17

5.5 Examples of Locating a Fault According to the Signal Flow 5-19

5.5.1 Bit Error Problems 5-19

5.5.2 Alarm Specific Problems 5-20

5.5.3 Summary 5-22

5.6 Generation and Detection of ATM Service Alarms 5-23

5.6.1 Logic Diagram of Board 5-23

5.6.2 ATM Signal Flow 5-24

5.6.3 Detection of ATM Alarms and Performances 5-25

5.7 Alarms and Signal Flows of Ethernet Service 5-27

5.7.1 Logic Diagram of ET1O Board 5-27

5.7.2 Generation and Detection of Alarms 5-28

6 Flow of Serious Fault Handling 6-1

6.1 Flowchart of Handling Serious Fault 6-1

6.2 Flowchart Description 6-3

6.3 Recommendations 6-4

A Alarm Signal Flow A-1

B List of Alarms and Performance B-1

B.1 Common Alarms B-1

AU_AIS B-1

AU_LOP B-3

B1_EXC B-4

B2_EXC B-5



v

B3_EXC B-6

DOWN_E1_AIS B-6

ETH_LOS B-7

FAN_FAIL B-7

HP_LOM B-8

HP_RDI B-9

HP_REI B-10

HP_SLM B-11

HP_TIM B-12

HP_UNEQ B-12

ILL_SQ_VC12 B-13

ILL_SQ_VC3 B-13

ILL_ MFI _VC12 B-14

ILL_ MFI _VC3 B-14

LCAS_BAND_DECREASED B-15

LP_RDI B-15

LP_SLM B-16

LP_TIM B-17

LP_UNEQ B-18

LTI B-19

MS_AIS B-20

MS_RDI B-21

MS_REI B-22

POWER_FAIL B-22

PS B-23

R_LOF B-24

R_LOS B-25

R_OOF B-26

SYNC_C_LOS B-27

SYN_BAD B-27

TU_AIS B-28

TU_LOP B-29

T_ALOS B-30

T_DLOS B-31

UP_E1_AIS B-32

VC_DELAY_TL B-32

B.2 Category of System Performance B-33



vi

RS (Regenerator Section) Performance Events B-33

MS (Multiplex Section) Performance Events B-33

MSA (Multiplex Section Adaptation) Performance Events B-34

HP (Higher Order Path) Performance Events B-34

HPA (Higher Order Path Adaptation) Performance Events B-34

LP (Lower Order Path) Performance Events B-35

PS (Protection Switching) Performance Events B-35

Framing Performance Events B-35

C Guidance for OptiX Routine Maintenance and Record C-1

C.1 Daily Maintenance Recommendations C-1

C.2 Explanation of SDH Daily Maintenance Record and Guidance for SDH Daily Maintenance C-3

C.3 Guidance for SDH Daily Maintenance C-4

C.4 Guidance for SDH Monthly Maintenance C-7

C.5 Guidance for SDH Quarterly Maintenance C-8

C.6 Guidance for SDH Yearly Maintenance C-8

C.7 SDH Daily Maintenance Duty Log C-9

C.8 SDH Monthly (Quarterly) Maintenance Record C-11

C.9 SDH Yearly Maintenance Record C-12

C.10 SDH Outburst Problems and Solutions Record C-13

C.11 Board Replacement Record C-14

C.12 Data Modification Record C-15

D Abbreviations and Acronyms D-1

Index i-1

OptiX 155/622H(Metro1000) Maintenance Manual Figures


vii

Figures

Figure 1-1 Wearing an ESD wrist strap 1-3

Figure 1-2 Schematic diagram of the OptiX 155/622H (rear view) 1-5

Figure 1-3 Inserting a board 1-7

Figure 1-4 The OptiX 155/622H power switch 1-9

Figure 1-5 Schematic diagram of equipment interface of the OptiX 155/622H 1-11

Figure 1-6 Schematic diagram of the SCB DIP switches 1-12

Figure 1-7 Inloop and outloop of SDH interface 1-14

Figure 1-8 Chain network 1-14

Figure 1-9 Inloop and outloop of the PDH interface 1-15

Figure 1-10 Illustration of transmitting power test 1-16

Figure 1-11 Connection for bit error test 1-17

Figure 1-12 Ethernet cable and RJ-45 connector 1-17

Figure 1-13 Definition of the west line and the east line of single-optical-interface board 1-19

Figure 1-14 Definition of the west line and the east line of dual- optical- interface board 1-19

Figure 1-15 Connection of the optical fibers between stations in the ring network 1-20

Figure 1-16 Connection of the optical fibers between stations in the chain network 1-20

Figure 3-1 The chain network 3-6

Figure 3-2 Effect on the ECC communication caused by the software loopback 3-11

Figure 3-3 Timeslot allocation diagram 3-13

Figure 3-4 Loopback path from NE 1 to NE 3 3-14

Figure 3-5 Looping back the PDH interface 3-20

Figure 4-1 Unprotected chain network 4-4

Figure 4-2 Path protection ring 4-7

Figure 4-3 Chain network 4-10

Figure 4-4 Unidirectional path protection ring 4-11

Figure 4-5 Ideal networking system (1) 4-13

OptiX 155/622H(Metro1000) Maintenance Manual Figures


viii

Figure 4-6 Ideal networking system (2) 4-14

Figure 4-7 Path protection ring 4-15

Figure 4-8 Clock tracing direction after changed 4-16

Figure 4-9 ECC problem in the chain network 4-18

Figure 4-10 ECC problem in the ring network 4-21

Figure 4-11 Networking system of typical case of orderwire problem 4-24

Figure 4-12 Networking system 4-32

Figure 4-13 Connection method for ping test 4-40

Figure 4-14 Troubleshooting for Ethernet service unavailability 4-41

Figure 4-15 Troubleshooting for Ethernet service abnormity 4-42

Figure 4-16 Networking diagram 4-46

Figure 4-17 Networking topology 4-48

Figure 5-1 Signal flow of OptiX 155/622H system 5-2

Figure 5-2 The alarm signal flow of OptiX 155/622H system 5-4

Figure 5-3 Service alarm signal flow of OptiX 155/622H system 5-4

Figure 5-4 Flow chart of alarm signal generation between SDH interface and the cross-connect unit 5-7

Figure 5-5 Flow chart of alarm signal generation between 2M PDH interface and the cross-connect unit 5-13

Figure 5-6 Structure of V5 byte 5-14

Figure 5-7 Suppression tree of some major alarms 5-17

Figure 5-8 Networking diagram 5-19

Figure 5-9 Networking Diagram 5-21

Figure 5-10 Logic diagram of AIU 5-23

Figure 5-11 Equipment networking diagram 5-24

Figure 5-12 OptiX 155/622H alarm check flow chart 5-25

Figure 5-13 Logic diagram of ET1O board 5-27

Figure 6-1 Flowchart of serious fault handling 6-2

Figure A-1 SDH alarm signal flow A-1

Figure A-2 ATM alarm signal flow A-2

OptiX 155/622H(Metro1000) Maintenance Manual Tables


ix

Tables

Table 1-1 Connection of the straight-through cable 1-17

Table 1-2 Connection of the crossover cable 1-18

Table 2-1 Colors and meanings of the indicators 2-3

Table 2-2 Requirements for the temperature of equipment 2-4

Table 3-1 Common faults handling 3-5

Table 3-2 Description of cabinet indicators 3-7

Table 3-3 A comparison between maintenance through the NMS and through board indicators 3-9

Table 3-4 Software loopback offered by the OptiX 155/622H 3-10

Table 3-5 Comparison between various fault locating methods 3-19

Table 3-6 Troubleshooting procedures and methods 3-23

Table 4-1 Monitor positions and functions of alarm and performance events for bit error threshold crossing 4-9

Table 4-2 2M time slot assignment table 4-15

Table 4-3 Common cause for equipment interconnection fault 4-38

Table 4-4 Performance events and causes 4-43

Table 4-5 Configuration items and requirements 4-44

OptiX 155/622H(Metro1000) Maintenance Manual About This Manual


x

About This Manual

Related Manuals

The related manuals are listed in the following table. Document Usage

OptiX 155/622H(Metro1000) STM-1/STM-4 MSTP Optical Transmission System Technical Manual

Introduces the functionality, structure, performance, specifications, and theory of the product.

OptiX 155/622H(Metro1000) STM-1/STM-4 MSTP Optical Transmission System Hardware Description Manual

Introduces the hardware of the product, including box, power, fan, board, and a variety of interfaces.

OptiX 155/622H(Metro1000) STM-1/STM-4 MSTP Optical Transmission System Installation Manual

Guides the on-site installation of the product and provides the information of the structural parts.

OptiX 155/622H(Metro1000) STM-1/STM-4 MSTP Optical Transmission System Maintenance Manual

Guides the analysis and troubleshooting of common faults.

OptiX 155/622H(Metro1000) STM-1/STM-4 MSTP Optical Transmission System Service Configuration Guide

Guides you through the configuration of data services on the T2000 network management system.

OptiX 155/622H(Metro1000) STM-1/STM-4 MSTP Optical Transmission System Electronic Documentation (CD)

Contains all the above manuals in CD format, readable with Acrobat Reader.



xi

Organization

The manual is organized as follows: Chapter Description

Chapter 1 Precautions and Basic Operations of Equipment Maintenance

Describes environment requirements for the OptiX 155/622H(Metro 1000), maintenance precautions and maintenance operations that should be grasped by maintenance personnel.

Chapter 2 Regular Maintenance Discusses operation objectives and methods during daily maintenance of the OptiX 155/622H(Metro 1000).

Chapter 3 Basic Thoughts and Methods

Focuses on common fault locating methods and handling procedures, which is the key of maintenance.

Chapter 4 Common Faults Treatment

Analyzes several common faults and gives the corresponding treatments.

Chapter 5 Alarm Generation Principles of OptiX Equipment

Details the generation of alarms and performance events and their relationships. This section helps you to troubleshoot through alarm/performance analysis.

Chapter 6 Flow of Serious Fault Handling

Guides the users how to handle the situation after major fault.

Appendix A ~ Appendix D Lists frequently-used information about the equipment for the convenience of the readers, including alarm signal flow, common alarms list, guide for routine maintenance operation and record table, and abbreviations used in this manual.

Intended Audience

This document is for: Maintenance engineer



xii

Conventions

The manual uses the following conventions. Symbol Description

Means reader be careful. In this situation, you might do something that could result in equipment damage or loss of data.

Means reader be careful. The equipment is static-sensitive.

Means reader be careful. In this situation, the high voltage could result in harm to yourself or others.

Means reader be careful. In this situation, the strong laser beam could result in harm to yourself or others.

Means reader take note. Notes contain helpful suggestions or useful background information.

Environmental Protection

This product has been designed to comply with the requirements on environmental protection. For the proper storage, use and disposal of this product, national laws and regulations must be observed.

OptiX 155/622H(Metro1000) Maintenance Manual 1 Precautions and Basic Operations of Equipment Maintenance


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1 Precautions and Basic Operations of Equipment Maintenance

1.1 Precautions of Maintenance Operations

To ensure the safety of the maintenance personnel and that of the equipment, basic rules must be followed during equipment maintenance.

1.1.1 Precautions for Laser Safety

Warning:

The laser emitted by the optical interface board is invisible infrared ray, which may cause permanent damage to human eyes.

During operations in which the eyes may be exposed to laser irradiation, the operator should wear infrared ray filtering protective glasses to prevent possible harms to the eyes. It is forbidden to look directly at the laser emitting ports and the optical connectors on the optical interface boards without protective glasses.

The user is required to prepare the protective glasses.

1. Disposal of Fiber Interfaces

Optical interfaces on the optical interface boards and fiber jumpers must be covered with optical caps no matter whether they are in use or not.

This action can:



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Prevent the invisible laser ray from irradiating the human eyes.

Protect from dirt to eliminate the loss of fiber interface or fiber jumpers caused by dirt contamination.

2. Cleaning Optical Fiber Interfaces and Optical Fiber Jumpers

Always clean the high-power laser interfaces by using special cleaning tools and materials, which are generally available from the fiber and cable manufacturers. For low-power laser interfaces, pure anhydrous alcohol can be used instead if special cleaning tools and materials are unavailable.

Prior to cleaning optical interfaces, pull out optical fibers on the optical interface board and then pull out the board first. It is recommended that this work be done or supervised by the engineers of the customer service center of Technical Support Department of Huawei to avoid damage to the optical interface board due to mis-operation.

Warning:

It is forbidden to use any unsuitable cleaning tools and materials for the cleaning of optical fiber connectors and optical interfaces on the optical interface board!

Using unqualified tools and materials will destroy optical connectors and optical interfaces.

3. Looping Back Optical Interface Board

During hardware loopback test of the optical interface with fiber jumpers, an attenuator must be used to avoid the over strong receiving optical power from saturating or even damaging the optical receiving module.

4. Replacing Optical Interface Board

When replacing an optical interface board, always pull out optical fibers from the board first, and then pull out the board. Never swap the board with optical fibers on it.

Replace the optical interface board only when it is necessary. Thus, mismatch between the parameters and actual use can be avoided.

1.1.2 Precautions for Electrical Safety

1. ESD Precautions

Prior to equipment maintenance, ESD measures must be taken as per the stipulations in this section, to avoid damage to the equipment.

In case of body movement, clothes friction, friction between shoes and ground, and



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holding plastics in the hand, human body will generate static electromagnetic field and store it for a long time. Before touching the equipment, boards or IC chips, the maintenance personnel must wear an ESD wrist strap and the wrist strap is well grounded, thus avoiding damages to the ESD-sensitive components, as shown in Figure 1-1.

Figure 1-1 Wearing an ESD wrist strap

Warning:

The static electricity produced by human body can damage the ESD-sensitive components on the circuit board, such as large scale integrated circuit.

2. Precautions for Board Electrical Safety

The unused board should be kept in the ESD protection bag. Wear an ESD wrist strap and make sure the wrist is well grounded before touching the board.

Moisture-proof treatment of the board.

For the storage of spare circuit boards, attention must be paid to the influence of the temperature and humidity of the environment. Desiccant should be placed inside the ESD protection bag to absorb the moisture in the bag and keep the bag dry.

When the circuit board encapsulated in an ESD protection enclosure is taken from a cool, dry place to a hot, humid place, wait for at least 30 minutes before opening it. Otherwise, the moisture will condense on the surface of the circuit board and may damage the elements.



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3. Precautions for Power Supply Maintenance

Never install and remove the equipment power cable with the power on.

Note: At the moment when the power cable touches the conductor, electric sparks or arcs will be produced, which can cause fire or injury to the personnel.

Before installing or removing the power cable, be sure to switch off the power supply.

Before connecting the cables, make sure that the cables and cable labels conform to the actual installation.

1.1.3 Precautions for Mechanical Safety

Avoid shocks during board transportation, which may cause damage to the boards.

When replacing a board, swap the board with care and strictly follow procedures.

There are plenty of pins in each slot on the equipment backplane. If some of them are crooked or pressed down due to inadvertent operation, it will affect the performance of the whole system, even cause short circuit and system breakdown, or damage the equipment. Refer to Swapping and Replacing the Board for detailed operation steps of swapping the board.

1.1.4 Precautions for Network Management System Maintenance

Do not quit the network management system when its software is working normally. Although quitting the network management system will not interrupt the service on the network, it will disable the network management's ability to monitor the equipment during the shutdown period and jeopardize the continuity of the equipment monitoring.

It is strictly forbidden to run programs irrelevant to the equipment maintenance on the network management computer, especially PC games. It is also forbidden to copy files or programs that have not been virus checked onto the network management computer. Kill viruses regularly with the latest virus killing software to prevent the computer virus from infecting the network management system and damaging the system.

1.1.5 Precautions for Service Grooming

Do not groom the service configuration during the traffic peak. Choose the hour of minimum traffic, such as deep in the night, to do it.



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1.2 Maintenance Operations

1.2.1 Using the Orderwire Telephone

The connector of the phone line of orderwire telephone should be connected to the "PHONE" interface in the SCB board on the back panel of the OptiX 155/622H, which is represented as “8” in Figure 1-4.

Ensure the ringing switch on the left side of the orderwire telephone set is put to the "ON" position, lest the telephone should not ring when an incoming call arises. The dialing mode switch should be put to the "T" position to select the DTMF dialing mode.

Dialing a call: Take down the orderwire telephone, press the "TALK" button on the front of the set. As a result, the red indictor is lit on the upper right corner of the front of the set, with the dial tone sounding. If the orderwire telephone is under off-hook condition, you can dial a number.

Receiving a call: When the orderwire telephone rings and in the meantime a red indicator on the back of the set flashes, take down the orderwire telephone, and press the "TALK" button. As a result, the red indictor is lit on the upper right corner of the front of the set. In this case, you can begin to talk.

After conversation, be sure to press the "TALK" button to turn off the indicator on the upper right corner of the telephone set. Otherwise, the orderwire telephone will remain under off-hook condition and the incoming calls not be dialed in.

1.2.2 Cleaning the Fan

Effective heat dissipation plays an essential role in ensuring normal operation of the equipment. It is therefore of vital importance to check the operation and ventilation of the fan. Cleaning of the air filter is a very important job when cleaning the fan.

As shown in Figure 1-2, in the OptiX 155/622H B stands for the fan board and the right part of A for the air filter. Equipped with the ear on the panel, the air filter can be removed when unscrewed.

IU1IU2IU3

IU4

SCB

FANPower filter unit and air filter

B A

Figure 1-2 Schematic diagram of the OptiX 155/622H (rear view)



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Warning:

In the Figure 1-2, the left part of A in the OptiX 155/622H equipment is the power unit. Removing it will switch off or even damage the equipment.

Check if the fan operates properly every day. If the environment of the equipment room can not satisfy the requirements for cleanness, the air filter of the fan will be easily blocked, giving rise to poor ventilation. Thus, the fan should be cleaned twice a month at least.

Cleaning the air filter: Drag the ear on the panel out and remove the air filter. You can take the air filter outdoors to clean it with water, wipe it clean with rag and dry it in a well-ventilated place. After cleaning, push the air filter along the guide rail to its original position. Do not push it in forcibly.

Warning:

After cleaning the air filter, you should not insert it into the equipment until it is dry enough, so that water-drop of it will not result in any short circuit in the equipment and thus damage the equipment.

1.2.3 Swapping and Replacing the Board

The board of the OptiX 155/622H employs the horizontal structure. Make sure you plug/unplug the board properly. Otherwise, the equipment may be damaged.

Warning:

The static electricity the human body generates may damage the static sensitive components on the PCB. Always wear the ESD wrist strap before touching a board. Note that the two ejector levers on the front panel are insulative.

1. Inserting a Board

(1) To begin with, make sure the slot for the board to be plugged in is the correct one.

(2) Push the board with moderate force along the left and right guide rails to the



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bottom of the guide rails, and align the notches in the left and right levers of the front panel with the left and right grooves. At this time, the board is under floating insertion.

(3) Check the sockets on the backplane. Make sure the board connector aligns with the backplane socket. Then, push the board front panel slightly harder to engage the board in the backplane.

If obstruction occurs, do not insert the board forcibly while inserting the board. In this case, pull the board out, and check whether pins on the backplane are normal. If there are pins bent or fallen, please contact engineers in Customer Service Center of Huawei Technical Support Department to have them handled. If pins on the template are normal, try inserting again after adjusting the board position. If the board insertion still fails when nothing is found abnormal, please contact engineers in Customer Service Center of Huawei Technical Support Department.

(4) When the board connector is well fit in with the backplane, push inward the left and right levers of the front panel (the left lever to the right, and the right lever to the left), until the board is completely inserted. Then, tighten the lock screws.

The method of inserting the board is shown in Figure 1-3.

Figure 1-3 Inserting a board

Never insert the board in a forcible manner. When inserting the board, remove them if there exist the blank panels obstructing your view and then install them again.

Warning:

Forcibly inserting a board in an improper position will cause permanent damage to the equipment.



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2. Pulling out a Board

As shown below, the operation sequence of pulling out a board is the reverse of inserting the board:

Unscrew the lock screws on both sides of the board. Push simultaneously the board levers outwards with two thumbs (the left lever to the left and the right lever to the right) to separate the board from the backplane. And then take out the board carefully. The operations are similar to those in Figure 1-3, except that the two thumbs push the levers outward instead of inwards.

Do not touch the board components with your hand when plugging/unplugging the board. The board should be kept in an anti-static bag when being taken out.

3. Replacing a Board

Warning:

When you are replacing an SCB board, be aware that this board is not hot swappable.

When replacing a board, make sure that the board to be plugged and that to be unplugged are of the same model.

Most boards of the same name and different models are interchangeable. However, it is recommended that you consult with local technicians from Huawei Technologies Co., Ltd. in case of accident. For example, the model of an optical board is usually related to its transmission distance and a short-distance optical board differs from a long-distance one in transmission capacity. A substitution of a short-distance optical board for a long-distance one will result in a blocked optical path.

1.2.4 Switching On/Off the Equipment

Press the power switch (POWER key) to the “ON” or “OFF” position to switch on or switch off the OptiX 155/622H. The POWER key is in red and located on the right side of the back panel of the OptiX 155/622H. Refer to "10" in Figure 1-4.



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Figure 1-4 The OptiX 155/622H power switch

Follow the correct steps when switching on/off the equipment.

1. Sequence of Switching on the Equipment

(1) Make sure that the hardware items of the OptiX 155/622H are properly installed, cables are properly distributed and its input power meets the requirement. Test the resistance between the connectors of power supply and ground with a multimeter to assure that no short circuit exists in the equipment.

(2) Make sure the power switch is in the "OFF" position. Connect the power line which is connected to the primary power supply (or battery, and so on).

(3) Press the power switch to the “ON” position.

Then, the equipment is switched on.

With the equipment powered on, the running indicators on the boards should begin to flash (some board may begin to flash in 5–6 seconds). In case of any abnormality, such as sparkling, smoking, smelling of burn, you should switch off the power immediately and locate the fault.

2. Sequence of Switching off the Equipment

Be fully aware of the results and consequences of switching off the equipment in normal operation.



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Warning:

If the equipment is powered off, then the corresponding NE equipment will quit the operation status, interrupting all the services in the NE.

Press down the "OFF" end of the power switch. Then the equipment is powered off.

It is not allowed to power off the equipment by pulling out the power line or switching off the primary power.

1.2.5 Cutting Off the Alarm Sound

There are two ways available of silencing the OptiX 155/622H alarm sound as follows:

One is to switch the ALMCUT on the front of the OptiX 155/622H to the ON position (alarm cutting out status).

The other is to switch the ALMCUT on the back of the OptiX 155/622H to the position where the ALMCUT is indicated (alarm cutting out status).

Either of the two ways will cut out the alarm sound. Of course you can use the two simultaneously to silence the alarm sound. In case that an alarm has not been removed and you put both the ALMCUT switches to the non-alarm-cut-out positions ("OFF" position and none "ALMCUT"), the alarm sounds will still remain activated.

Note:

If either of the alarm cutting-out switches is put to the alarm cutting-out status, then the sound alarm of the equipment is silenced. As a result, the equipment will never give out any alarm sound even if a critical alarm arises.

In normal operation of the equipment, especially when a critical alarm has been removed, the ALMCUT switch on the front of the equipment should be "OFF", and that on the back of the equipment to a non- "ALMCUT" position.

1.2.6 Resetting the SCB Board

The hardware reset and software reset can be conducted with the SCB board through NM.

There is a RST button on the back of the equipment, which is shown as “2” in Figure 1-4. If you press this button, then the SCB board will be hard-reset through hardware.



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Neither the hardware nor the software reset of SCB board will affect the services. However, when the SCB board is in the reset status, the NM communication will not proceed until the SCB board comes into operation again.

1.2.7 SCB Board DIP Switches

The DIP switches of SCB board are located near the front panel, to be specific, where the “3” is marked as shown in Figure 1-5. It is a long narrowed slot, and Figure 1-6 is its amplification.

There are two types of 43 serial SCB board showed in Figure 1-6.

Figure 1-5 Schematic diagram of equipment interface of the OptiX 155/622H



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The least signifacant bit of dip switch

116

The most significant bit of dip switch

The least signifacant bit of dip switch

116

The most significant bit of dip switch

Figure 1-6 Schematic diagram of the SCB DIP switches

As shown in Figure 1-6, a group of DIP switches is composed of two 8-bit switches. The DIP switches can be operated without needing to be plugged out of the SCB board.

DIP switch levered up means “1”, and it means “0” when it is levered down. The rightmost DIP switch is marked “1”, meaning the lowest location of the DIP switch. The leftmost DIP switch is marked “16”, meaning the highest location of DIP switch.

NE ID can be changed by setting different values to the DIP switch. NE ID takes the low 12 bits of DIP switch, so NE ID is expressed as XXX in hexadecimal numbers (X matches 4 toggles).

You can operate DIP switch when the SCB is running. After the DIP switch setting has changed, press the RST button again and restart the SCB board, the setting will take effect.

The high 4 bits of DIP switch are used for researching and debugging. When the SCB boards are running normally, the high 4 IDs should all be set to “0”. Normally, you should avoid changing the high-4-bit ID.

Remember to apply moderate strength when operating DIP switch, especially when the DIP switch is levered up, since they are small and have tender levers. Otherwise, the DIP switch may become broken, and the board damaged.

1.2.8 Operations of Loopback

1. Loopback Types

(1) Software loopback and hardware loopback



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According to the loopback modes, the loopback falls into two cases, that is software loopback and hardware loopback. The software loopback is set through the NMS, while the hardware loopback refers to the loopback operation conducted manually by using tail fibers to loopback the optical and the electrical interfaces.

(2) Inloop and outloop

According to signal flow directions after the loopback, the loopback is divided into two types, that is inloop and outloop. As to the SDH NE that is looped back, if the signal flow goes into the SDH NE, the corresponding operation is mentioned as the inloop, and if the signal flow goes out of the SDH NE, the corresponding operation is referred to as the outloop.

2. Loopback of the SDH Interface

(1) Hardware loopback

As viewed from the signal flow, the hardware loopback generally means the inloop. We therefore mention it as the hardware loopback.

The hardware loopback of the optical interface means to connect the two ends of the tail fiber respectively to the transmitting and receiving optical interface of the board so as to loopback the signal. The hardware loopback falls into two modes: the self-board loopback and the cross loopback.

Obviously, the self-board loopback means to use an optical fiber jumper to connect the two optical interfaces in the same board.

The cross loopback means to use an optical fiber jumper to connect the output end of the west optical interface with the input end of the east optical interface, or to connect the output end of the east optical interface with the input end of the west optical interface.

Note:

Always apply an attenuator in the case of hardware loopback, so as not to damage the optical modules.

(2) Software loopback

The software loopback of the SDH interface refers to setting of the "VC-4 loopback" or the "optical interface loopback" in the NM. Each of the two falls into the inloop and the outloop. Meanings of the inloop and the outloop are as shown in Figure 1-7.



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SDH NE equipment

Line Line

Tributary Tributary

inloop outloop outloop inloop

Tributary Figure 1-7 Inloop and outloop of SDH interface

After selecting the corresponding LU in the NM, you can configure the VC-4 or the optical loopback. For detailed operation, please refer to the operation manual or online help of OptiX iManageer Network Management System.

Note:

Inloop an optical path may affect ECC communication, consequently stopping you from logging in the NE.

As shown in Figure 1-8, NEs 1-5 form a chain network, where the NM is located in NE 3.

W E W E W E W E W E

NM

NE 1 NE 2 NE 3 NE 4 NE 5 Figure 1-8 Chain network

If you want to execute the loopback operation between NE3 and NE4, you can only do so with the east optical interface. If you do so with the west optical interface, you can not log in NE 4. Thus, if you want to do loopback with a non-NM NE, you can only do so with the optical interface boards receiving from instead of transmitting signals to the NM site.

3. Loopback of the PDH Interface

(1) Hardware loopback

As viewed from the signal flow direction, the hardware loopback generally refers to the inloop. The hardware loopback of the PDH interface of OptiX equipment has two positions: one lies in the equipment's wiring area and the other in the DDF. In case of 2M signal, the hardware loopback in the equipment's wiring area refers to using a cable to connect TX and RX of the same 2M port in the SP1/PD2/SM1. The



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hardware loopback in the DDF refers to using a cable to connect the receiving and transmitting ends of the same 2M port in the DDF.

(2) Software loopback

The software loopback of the PDH interface refers to the outloop or inloop set by the NMS for the PDH interface. See Figure 1-9.

SDH NEequipmentLine Line

Tributary Tributary

No loopback OutloopInloop Figure 1-9 Inloop and outloop of the PDH interface

Outloop test

In case of local loopback test, the service input end signals are directly looped back to the local service output end through the input end of local NE.

Inloop test

After transmitted to the destination NE and dropped to tributary, local service input signals are added to the tributary and transmitted to the service output end of the local NE through loopback.

1.2.9 Testing the Receiving Optical Power and Transmitting Optical Power

1. Testing the Transmitting Optical Power

Connectivity of testing the transmitting optical power is as shown Figure 1-10. The test steps are as follows:

(1) Optical power meter/optical multimeter is set to the desired wavelength range.

(2) Select the tail fiber which is used to connect the OUT interface of this station, which is labeled with .

(3) Connect the other end of the tail optical fiber to the input interface of the optical power meter/optical multimeter, and read the optical power value when the receiving optical power gets a constant value.

Note:

(1) Be sure to keep the optical connector clean and properly connected. Be sure to keep the flange clean and properly connected on the front panels of the optical interface board.

(2) Pretest the attenuation of the tail optical fiber.



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(3) Single-mode and multi-mode module should use different optical fiber jumpers.

Power

Display

Control panel

Optical power meter

Optical interface Figure 1-10 Illustration of transmitting power test

2. Testing the Receiving Optical Power

Steps for testing the receiving optical power:

(1) Set the optical power meter/optical multimeter to the desired wavelength range.

(2) Select the tail optical fiber, which is connected to the output optical interface with the label of in the opposite station.

(3) Connect the tail optical fiber to the input end of optical power meter/optical multimeter, and read the optical power value when receiving optical power gets a constant value.

The precautions are the same as that of Transmitting optical power test.

1.2.10 Testing Bit Errors

The test of bit error performance is based on the long-term stability of operation of the whole transmission network service. The service access points provided for users are the test points, for example, E1/T1 interfaces.

Method for the test is as follows:

Pre-select a service channel (E1/T1), upon which find out the corresponding PDH interfaces of the local and remote stations. Then make an inloop on the opposite station's PDH interface (e.g. hardware loopback at DDF). And connect the meter to the appropriate interfaces in this station to test bit errors. Normally, there should be no bit error in 24 hours.

The connection for bit error test is illustrated in Figure 1-11. One tributary service is configured between two NEs. Here, a 2M BER tester is connected to the tributary of the NE at one end, and an inloop is configured at the tributary of the NE at the other end through the NMS or an equipment loopback is done at the DDF. Set the BER tester and observe occurrence of the bit error on this tributary.



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BER tester

(or SDH analyzer)

Tributary port

NE 网网网网NETributary port

Figure 1-11 Connection for bit error test

Note:

The BER tester shall be grounded properly. It is suggested that other electric appliances not be switched on/off in the test course.

1.2.11 Preparing the Ethernet Cable of NM Computer

To connect NM computer with gateway NE through Ethernet cable, you can use a crossover cable or a straight-through cable. The crossover cable is used for direct connection between the NMS computer and the gateway NE while straight-through cable is used for connection between the NM computer and the gateway NE through a hub. The two differ from each other in the connectivity of the cores of the cable.

Both these network cables use the RJ-45 connector, as shown in Figure 1-12:

Figure 1-12 Ethernet cable and RJ-45 connector

The correspondence between core colors of both ends of the straight-through cable is as follows;

Table 1-1 Connection of the straight-through cable

Connector at the head 8-core, category 5 twisted pair Connector at the end

Pin 1 White (orange) Pin 1

Pin 2 Orange Pin 2

Pin 3 White (green) Pin 3

Pin 4 Blue Pin 4

Pin 5 White (blue) Pin 5



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Pin 6 Green Pin 6

Pin 7 White (brown) Pin 7

Pin 8 Brown Pin 8

The connection of the crossover cable is shown in Table 1-2.

Table 1-2 Connection of the crossover cable


Pin 1 White (orange) Pin 3

Pin 2 Orange Pin 6

Pin 3 White (green) Pin 1

Pin 4 Blue Pin 4

Pin 5 White (blue) Pin 5

Pin 6 Green Pin 2

Pin 7 White (brown) Pin 7

Pin 8 Brown Pin 8

1.2.12 Testing Trunk Cables with a Multimeter

In the course of construction and maintenance, you need to test coaxial trunk cable to check if the cable has faulty soldered joints, unsoldered joints, short circuit and if the trunk cable is properly connected at DDF frame. This is usually mentioned as "wire-matching."

Operations of the wire-matching are as follows:

Short connect one end of the signal core of coaxial cable to the shielded layer (using short wire or tweezers and the like), and test the resistance between the signal core and the shielded layer at the other end of the cable, using a multimeter. The resistance should be 0. Then cancel the short connection between the signal core and shielded layer, and use the multimeter to test the resistance at the other end. The resistance should be infinite. If both the tests have been passed, then the two ends tested belong to the same cable. Otherwise, there must be an open circuit or short circuit in the cable. It is also likely that there exist faulty soldered joints, unsoldered joints or short circuit in the cable connection section. Or the two ends do not belong to the same cable.

As to the HM4 × 6PIN/SF6 × 4 pin plug-in E1 connector, for the correspondence between its pins and the signal line and shielded layer of the connector of the coaxial



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cable at the other end, please refer to the wire and cable installation and distribution section in the installation part.

1.2.13 Definition of East and West

If two optical interfaces form an ADM system, we need to logically define the two as East and West, so as to facilitate the service configuration and other operations. According to the principle of "West on left and east on right", the OptiX 155/622H SDH optical transmission products follow the conventions below:

(1) As to an ADM system composed of two single-optical-interface units, the left unit is named as the "west line" and the right unit the "east line". Refer to Figure 1-13.

West line East lineApply the single- optical -interface board

Optical interface board 1 Optical interface board 2

Figure 1-13 Definition of the west line and the east line of single-optical-interface board

(2) As to a pair of dual optical interfaces forming ADM system, the left dual is optical interface 1, named”west line”; the right dual is optical interface 2, named “east line”. Refer to Figure 1-14.

West line East line

Apply the dual - optical - interface board Figure 1-14 Definition of the west line and the east line of dual- optical- interface board

In OptiX 155/622H NEs, if the single optical interfaces form a TM system, it is usually set as the West.

There exist strict demands for connection of optical fibers of ADM sites in a chain or ring network. Take the ring network as shown in Figure 1-15 as an example. First of all, decide a primary ring direction. The primary ring direction can be defined at will. However, it should not be changed once decided. In the ring network, each NE follows the following optical fiber connection sequence: The west one to the upstream NE, and the east optical interface is connected to the downstream NE. Suppose we define the primary ring direction (in the Figure) as B-A-C and each NE in the figure uses the OI2D boards. Then the connectivity of optical fibers in the station A is as follows: The west optical interface in the OI2D board connects itself to



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the station B in the upstream and the east one to the station C in the downstream.

It is unnecessary to decide a primary ring direction in the chain network. However, a chain direction should be decided. The chain direction can be decided at will, but should not be changed once decided. In the chain network, each ADM site follows the following optical fiber connection sequence: The west optical interface is connected to the upstream NE and the east one to the downstream NE. As shown in Figure 1-16, suppose we define the chain direction as B-A-C and the station A uses OI2D board. Then the connectivity of optical fibers in station A is as follows: The west optical interface in the OI2D board connects itself to the station B in the upstream and the east one to the station C in the downstream.

W

WW

E

EE

Station A

Station B Station C

OUT IN

Figure 1-15 Connection of the optical fibers between stations in the ring network

W E

B A C

Figure 1-16 Connection of the optical fibers between stations in the chain network

OptiX 155/622H(Metro1000) Maintenance Manual 2 Regular Maintenance


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2 Regular Maintenance

2.1 Maintenance Overview

2.1.1 Classification of Maintenance

The maintenance falls into the following categories according the maintenance cycle:

Daily maintenance

Daily maintenance refers to those maintenance items you should perform every day. It helps you keep well informed of the equipment operation conditions, so you can locate and remove problems in time. Make a full record of fault phenomenon in regular maintenance for sake of timely maintenance and removal of latent dangers.

Periodical maintenance

Periodical maintenance refers to those maintenance items you should perform periodically, which help you understand the operation status of the equipment on a long-term basis. It falls into monthly, quarterly and yearly maintenance.

Incidental maintenance

Incidental maintenance refers to those maintenance items which arise from transmission equipment fault, network adjustment, and so on, for example, the maintenance items we should perform when the equipment is damaged or the line is faulty. Additionally, problems found and recorded in daily regular maintenance are also the source of incidental maintenance.

In the light of this statement, maintenance is a broad concept which covers regular maintenance and fault treatment. Fault treatment is also incidental maintenance, that is incidental maintenance. In this chapter we will examine the regular maintenance only.



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2.1.2 Basic Principles of Regular Maintenance

The basic principle of regular maintenance is to locate and remove problems in regular maintenance so that you can eliminate they before troubles trouble you.

To be a top maintenance personnel, you should not only be able to locate and remove the problems when they arise, but also be able to find out and remove the latent dangers in the course of regular maintenance, so as to ensure a long-term and stable equipment operation.

Excellent and effective maintenance of the equipment would reduce the fault rate and increase the service life of equipment.

2.1.3 Maintenance Considerations For the OptiX 155/622H

OptiX 155/622H optical transmission equipment provides a variety of maintenance considerations in the box, board, functional configuration and so on. The maintenance functions include the following:

1. In Daily Maintenance

(1) Provide audiovisual alarms. In case of emergency, prompt the network administrator to adopt effective measures in time.

(2) Indicate system operation status. Help network administrator with timely fault location and removal.

2. In the Troubleshooting

(1) Monitor faults of each station in the network through NM system dynamically.

(2) In case of alarm, both equipment and NM can offer audio alarms.

(3) According to network configuration, monitor network operation and service quality on real time basis. In the event of abnormal service interruption, it automatically provides for the service.

(4) Provide the service with a variety of self-test functions through loopback.

(5) Orderwire telephone function provides a dedicated communication path for management personnel in each station.



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2.2 Regular Maintenance Items

The following maintenance items are intended for the equipment maintenance personnel in each station.

2.2.1 Checking the Audio Alarm of the Equipment

In daily maintenance, audio alarms of the equipment are usually more attracting than other alarms. Thus in daily maintenance you should make sure this alarm channel is smooth.

Regularly check the ALMCUT switch on the box. In normal cases, the switch shall be turned on (Note: the ALMCUT switches on the front side and rear side of the equipment box shall be turned on). It should be checked every day.

2.2.2 Viewing the Indicators

The equipment maintenance personnel get access to the alarm information mainly through the alarm indicators. Therefore, in the daily maintenance, you always pay attention to the alarm indicator status, upon which you may initially decide if the equipment operates properly.

The OptiX 155/622H equipment provides two identical sets of indicators, on the front side and back side each. They have the same functions. Colors and meanings of the indicators are as described in Table 2-1.

Table 2-1 Colors and meanings of the indicators

Indicator position

Color Meaning

ETH Yellow Indicator of Ethernet. Keeps on when the equipment is connected with NM terminal through the network cable. Keeps off if not.

RUN Green Operation indicator. Flashes once every two seconds when the equipment comes into operation. Otherwise, the equipment is abnormal.

RALM Red Indicator of critical alarms. Keeps on when a critical alarm arises.

YALM Yellow Indicator of general alarm. Keeps on when a major or minor alarm arises.

FAN ALM Yellow Indicator of fan alarm. Keeps on when one or more fans do not work.

Among the equipment indicators, the green one is the operation indicator whose flashing mode indicates different information as follows:

If the operation indicator flashes rapidly (flashes 5 times per second), that means the equipment does not come into operation, with the possible causes that the data has



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not been configured when the equipment is powered on.

If the operation indicator is on for one second and off for one second alternately, that means this board is working normally or the board data is properly configured when it is powered on.

Each pair of optical interfaces is equipped with a red indicator beside them. If the red indicator goes on, that means the receiving optical interface has not received an optical signal; if it goes off, that means the receiving optical interface has received the optical signal.

You should view the operation and alarm indicator status daily. If you find the red or yellow indicator goes on, you should timely inform the network management personnel in the central station. If the equipment operates properly, you shall see only the "RUN" indicator keeps on.

2.2.3 Checking Temperature of the Equipment

It is not allowed to place some sundries around the equipment, which may affect the equipment ventilation. The equipment dispersion shall be well guaranteed.

Put your hand at the air-vent beside the box to check the air volume and simultaneously check the equipment temperature. If the temperature is high but the air volume is small, check if there is something affecting the ventilation of the equipment, or if the air filter of the fan has a thick layer of dust. If so, clear the dust, or if the fan itself is faulty and if necessary, replace it.

You can feel the surface of the box with your hand to check the temperature of the box.

The equipment temperature should be checked daily.

Requirements for the operating temperature are as shown in Table 2-2.

Table 2-2 Requirements for the temperature of equipment

Operating conditions Temperature (°C )

Long-term operating condition 0°C–45°C

Short-term operating condition –5°C–50°C

The short-term operating condition refers to the continuous operating period as up to 72 hours and a yearly accumulated operating period as up to 15 days.



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2.2.4 Checking and Regularly Cleaning the Fan

The effective heat dissipation plays an essential role in ensuring the long-term normal operation of the equipment.

In cases where the environment of the equipment room cannot satisfy the requirements for cleanness, the air filter of the fan will be easily blocked, giving rise to bad ventilation or even damage to the equipment. Thus operation and ventilation of the fan should be checked regularly.

(1) Make sure the fan always operates properly -- box fan indicator keeps off.

(2) Clean the air filter at least twice a month.

Tips:

The fan alarm (FAN_FAIL) in NMS means the fan operates improperly.

2.2.5 Checking Orderwire Telephone

The orderwire telephone is of great importance to the system maintenance. Especially in the case of critical fault in the network, orderwire telephone acts as an essential communication tool for the network maintenance personnel to locate and remove the fault. Hence in the daily maintenance, the maintenance personnel should regularly check the orderwire telephone, so as to ensure the orderwire telephone functions properly.

The maintenance personnel should regularly dial an orderwire telephone number from the local station to the central station, to check if the telephone is normal and if the voice quality is good; and then ask the opposite party to dial in this station to have a test otherwise.

If the local station is the central station itself, the maintenance personnel should regularly dial in each slave station, to check the quality of orderwire telephone.

If possible, you may dial a conference telephone number from the central station, to check if conference telephone is normal.

If the telephone is blocked, first check if the called party is under on-hook status. If so, check if the configuration data of the corresponding board has been changed in the central station through the NM. If the configuration is correct, then check other boards' performance and alarm to decide the problem lies in the line or the board.

The orderwire telephone should be checked every other week.



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Note:

Make sure the ringing switch of the orderwire telephone is put to the ON position, lest the orderwire telephone should not ring when an incoming orderwire telephone call arises.

After completing a telephone call, press the "TALK" key again to make sure you close the telephone set, lest the orderwire telephone be left in the off-hook status and the following incoming orderwire telephone calls from other station can not dial in. When you close the telephone set, the red indicator on the panel will go off.

2.2.6 Checking Performance of ATM Layer

Protocol structure of ATM test

ATM protocol structure includes physical layer, ATM layer, service layer and ATM signaling, etc. In ATM test, all the above layers are tested from bottom to top. Since mainly physical layer and ATM layer are involved in hardware test of hybrid equipment, this lecture mainly covers the test items of ATM physical layer and ATM layer.

ATM test objects

According to ATM test objects, ATM test is divided into two major aspects: test on ATM equipment (hybrid equipment OptiX 155/622H) itself and test on ATM network.

Test of equipment mainly refers to test of respective technical indexes and functions of the hybrid equipment, and it should be made one by one from bottom to top (that is, from physical layer to high-level protocol) according to the hierarchy of ATM, so as to verify whether the function realization of each layer conforms to the standards.

You need to test not only individual functions, but also integrated product performances, such as multi-port test, congestion control capability test under full load, the performance test after multiple devices are connected. Besides, to ensure compatibility and inter-operability of the hybrid transmission equipment with other products in Company and equipment of other manufacturers, the overall consistency test is also necessary. With system functions and indexes guaranteed, environment trial (high/low temperature, hot/humid) and EMC test should also be conducted on the equipment.

Network test usually refers to test on the general performances of the hybrid equipment network, mainly the test on the performance indexes between trans-network end-to-point nodes (such as cell error code, cell delay, cell jitter, cell loss ratio and cell error ratio between two remote nodes).



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2.2.7 Checking Service --Bit Error Test

Error characteristic test is a test on the performance of long-term stable running of services in the entire transmission network. In routine maintenance, service paths should be sampled and tested periodically while not affecting current running services, to judge whether performances of all service paths are normal.

Method 1

If there are unused service paths configured between two stations, the service path quality between two stations can be inspected by testing the unused service paths.

Method 2

If there are no unused configured service paths between two stations, when there is small service volume, service paths used for protection can be temporarily disconnected to have error code test performed, thus to estimate service path quality between two stations.

Method 3

If both of the above conditions are missing between two stations, service path quality can be supervised using performances and alarms reported by NM.

For service paths specified for error code test, usually error codes are tested by configuring internal loopback in the tributary board in remote station and connecting a meter. The test time is 24 hours, and there should be zero error code as the test result.

It should be noted that the meters should be well grounded in test, and it is recommended not to turn on/off other electrical appliances in test to avoid interference.

Bit error code test in routine maintenance should be performed once a month. When the test is completed, the internal loopback setting in the tributary board must be cancelled.



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2.3 Regular Maintenance Items of NMS

The OptiX iManager T2000 NM is an important tool for the regular maintenance. To ensure safe and reliable operation of the equipment, the maintenance personnel in the NM station should check the equipment through NM daily.

T2000 routine maintenance items include:

Starting and shutting down OptiX iManager T2000

Modifying T2000 user login password periodically

Logging in T2000 as a lower-level user

Checking NE and board statuses

Checking alarms

Monitoring performance

Checking protection switching

Querying operation log

Checking ECC route

Checking NE time

Checking board configuration information

Backing up NE database

Maintaining T2000 database

Maintaining T2000 computer hardware and software platform

Testing remote maintenance function

OptiX 155/622H(Metro1000) Maintenance Manual 3 Basic Thoughts and Methods


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3 Basic Thoughts and Methods

This chapter introduces basic troubleshooting methods of some common faults.

3.1 Requirements for Maintenance Staff

In telecommunication the service interruption means revenue loss. This put much pressure on maintenance staff to locate faults quickly and clear them as soon as possible. The following are some important tips for maintenance personnel.

3.1.1 Professional Skills

1. Be Familiar with SDH Fundamentals

2. Be Familiar with Alarm Generation Mechanism and Signal Flow in Transmission System

For details, refer to chapter 5 of this manual.

3. Be Familiar with Common Alarms

(1) SDH line alarms

R_LOS

R_LOF

R_OOF

AU_AIS

AU_LOP

MS_AIS

MS_RDI



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B1_EXC

B2_EXC

(2) PDH tributary alarms

HP_LOM

HP_SLM

HP_TIM

HP_UNEQ

TU_AIS

TU_LOP

T_ALOS

T_DLOS

P_LOS

EXT_LOS

UP_E1_AIS

LP_RDI

LP_SLM

LP_TIM

LP_UNEQ

B3_EXC

(3) Protection switching alarms

PS

(4) Clock alarms

LTI

SYNC_C_LOS

SYN_BAD

(5) Equipment alarms

POWER_FAIL

FAN_FAIL

BD_STATUS



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4. Be Expert in Transmission Equipment Handling

5. Be Familiar with the Basic Maintenance Instruments and Tools

Maintenance personnel should know how to operate various maintenance instruments, including 2M BER tester, optical power meter, SDH analyzer, oscilloscope, multimeter, etc. For the usage, see their respective user manuals.

3.1.2 Aware of Network Layout

Maintenance personnel should have the complete knowledge of his office network, power supply, power cable layouts, ODF cabling, DDF cabling, boards type & version and the equipment location in the equipment room. He should keep the inventory list and make sure that important components always have spares.

3.1.3 Collecting and Storing On-site Data

Before fault handling, maintenance personnel should first collect and store the on-site data. The detailed on-site data is very useful in finding the cause of a fault. The main data to be collected and stored includes the system alarm & performance data, the configuration & running states of each NE and board, operation log of the NMS. In addition, maintenance personnel should make operation log and record manually, respective operation procedures during troubleshooting. These log reports with complete fault analysis can be used as a reference for future problems.



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3.2 Basic Principles of Fault Locating

During fault locating of transmission equipment, locate the fault in a single station precisely.

The general principles of troubleshooting can be summarized as: "external first, then transmission; network first, then NE; high-speed section first, then low-speed section; and higher order first, then lower order".

External First, then Transmission Equipment

During fault localization, first confirm that external conditions are normal, for example, line optical fiber is correct or there should be no power failure or switching equipment fault.

Network First, then NE

First, analyze the fault in the protocol of the network, and then precisely locate the fault to an NE.

High-speed Section First, then Low-speed Section

From the alarm signal flow, we can see that the alarms of the high-speed signals usually trigger the alarms of the low-speed signals. Therefore, when locating faults, first clear the faults of the high-speed section.

Higher Order Alarms First, then Lower Order Alarms

Always handle critical alarms first, so that the service can be maintained. Then go for major and minor alarm removal, respectively.

3.3 Common Methods of Fault Locating

The common methods and general procedures of fault locating of the OptiX 155/622H can be summarized as “first analysis, then loopback and finally board replacement”.

That is, when the fault occurs, first determine the possible faulty points by analyzing the alarm events, performance data and signal flow. Then locate the fault on the particular NE by looping back station by station. Finally, clear the fault by replacing faulty board.

The following are some methods to locate a fault in an optical transmission network.



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Table 3-1 Common faults handling

Methods Application Features

Alarm and performance analysis

Universal 1. Evaluate the whole network situation.

2. Can locate the faulty point preliminarily based on the collected data.

3. Cause no negative effect on normal services.

4. Depend on the NMS.

Loopback Locate the fault to a single station or board

1. Independent of alarm and performance event analysis.

2. Rapid and effective.

3. May affect the ECC and normal services.

Replacement Locate the fault to a board or isolate external faults

1. Convenient

2. Require spare parts/equipment.

3. Applied with other methods.

Configuration data analysis

Locate the fault to a single station or board

1. Can find the fault cause.

2. Fault locating time is longer.


Configuration modification

Locate the fault to a board 1. Have a high risk.


Meter test Isolate external faults and resolve interconnectivity problem

1. A general method, with high accuracy.

2. Have certain requirements for the meters.

3. Applied with other methods.

Experience Special cases 1. Fast fault handling.

2. High probability of mistake.

3. Need experience accumulation.

3.3.1 Alarm and Performance Analysis

In SDH frame, there are abundant overhead bytes, which carry system alarms and performance information. Therefore, a number of alarm and performance events will be generated when the SDH system fails.

Alarm and performance data analysis is used to get accurate and timely overall fault



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information. The fault information either can be obtained by data queries from the NMS or from the board & cabinet indicators flashing. Both methods have advantages and disadvantages, which are discussed in the following section.

1. Querying Alarm and Performance through NMS

The NMS monitors and manages the running states of the transmission equipment. The fault information acquired through the NMS is comprehensive. The fault information is also accurate. Through the obtained information, one can know the alarm category and alarm history.

Aided with graphic display, maintenance personnel can quickly locate the fault on its occurrence. However, this method fully depends on the normal operations of computer, software and communication. Once any one is faulty, the capability of obtaining fault information in this way will be greatly decreased, and even lost completely.

For further understanding, consider a chain network, as illustrated in Figure 3-1. The NMS computer is attached with NE 1.

w ww we eNE1 NE2 NE3 NE4

NMS Figure 3-1 The chain network

Suppose E1 service between NE 1 and NE 4 is interrupted. NE 4 cannot be accessed from NE 1. Meanwhile, there are MS_RDI and HP_RDI alarms at eastbound optical board of NE 3. Also, LP_RDI alarm is displayed corresponding to the service between NE 1 and NE 4.

After analyzing the alarms, it is observed that the signals from NE 3 have not been correctly received at NE 4, while NE 3 can correctly receive the signals from NE 4. The potential problems may be:

Disturbance in NE3 signal transmission.

Broken optical fiber or connectors.

Disturbance in NE 4 signal receiver.

Note:

When obtaining the alarm or performance information via the NMS, ensure that all NEs are set correctly. Otherwise, the alarm and performance information may be incorrect or some time even nothing is received.

During the maintenance, special attention should be paid to setting the NE time at current time. Otherwise, the NE will work at the default time, which is not the current time.



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2. Obtaining the Alarm Information through the Equipment Indicators

There are various running and alarm indicators with different colors and flashing times, in the OptiX 155/622H. On/Off and flashing states of these indicators, indicate the status or possible alarms in particular equipment.

Table 3-2 Description of cabinet indicators

Indicator name Status Description

Off Ethernet cable not connected

On Ethernet cable connected, no data transmitted

ETN (yellow)

Ethernet indicator

Flashing Ethernet cable connected, data being transmitted

Flashing once every two seconds

Normal working

Flashing once every four seconds

Database protection mode; communication between board and mailbox of SCC unit interrupted (such as SCB board is out, board not in position or mailbox error.)

Flashing five times every second

Program started/loaded; board not working

Flashing twice every second

Erasing host software

RUN (green)

Running indicator

Flashing once every second

Host software not loaded

On Critical alarm RALM (red)

Critical alarm indicator Off No critical alarm

On Major alarm and minor alarm YALM (yellow)

Major alarm indicator Off No major alarm nor minor alarm

On At least one fan not working normally

FANALM (yellow)

Fan alarm indicator

Off Fan working normally

Through the flashing states of these indicators, one can roughly determine the category and position of the fault.

For example, when a fault occurs, the green running indicator flashes quickly. This state indicates there may be configuration problem. In this case, the fault can be cleared by downloading configuration data again. If the green indicator is flashing



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slowly, we can guess that the fault might be in mailbox communication unit.

Another example: As shown in Figure 3-1, if only the red indicator of the optical interface board at station 4 is on, it indicates the optical interface board of station 4 receives no optical signal, while the optical signals received by station 3 from station 4 is normal. It is consistent with the fault judged by NM. Then, use one tail fiber to self loop the optical interface board at station 4, to further analyzing the fault cause.

Fault locating through the equipment and the board indicators has the following features:

On site maintenance personnel can locate the faulty board and determine the alarm level, without any special instrument or tool.

By observing the indicators using the related instruments, maintenance personnel can analyze, locate and handle the basic faults of equipment. This method assists the on-site maintenance staff, especially when the transmission between NMS and equipment is interrupted

Because there are too many fault types to accurately analyze and locate the fault just by observing On/Off and flashing states of the indicators.

For details about the indicators of respective boards, refer to OptiX 155/622H(metro1000) STM-1/STM-4 MSTP Optical Transmission System Hardware Description Manual

Note:

1. The equipment indicators only indicate the current operation of the equipment. The fault, which occurred but now ended in the equipment, can not be observed through indicators.

2. The flashing cycles of the indicators corresponding to respective alarm category can be redefined through the NMS. Even a certain kind of alarms can be screened.

3. The alarm level reported in the flashing mode of the alarm indicators on the board should be consistent with the highest level alarm detected by the board.

3. Comparison between Above Two Methods

From the above descriptions, it is obvious that either method has its advantages and disadvantages. Through the NMS, one can know the overall running status of the equipment. He can also conveniently locate the fault of specific equipment.

Through indicators, one can have direct access to the equipment. It is helpful in on-site maintenance.

In practice, both methods are supporting each other and used during fault locating. In case of serious faults, NMS and on-site maintenance staff cooperate and work jointly to resume the system in minimum outage time.



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The comparison between these two methods is shown in Table 3-3.

Table 3-3 A comparison between maintenance through the NMS and through board indicators

Item Network management system

Indicator

Main user NMS maintenance personnel

Equipment maintenance personnel

Function Central source Assist NMS staff

Alarm information Entire network alarms and performance

Only local NE alarms and status

Alarm history Available Unavailable

Alarm Time Determined Can not be known

Performance event Determined Can not be known

Computer, software, and communication

Fully dependent Independent

4. Limitation of Alarm and Performance Analysis

If the service and the fault information are complicated, a number of alarms and performance events will be generated when a fault occurs. This may cause difficulty for maintenance personnel to perform analysis.

3.3.2 Loopback

Loopback is the most popular and effective method to locate faults in an SDH transmission network. The most significant feature of this method is there is no need of thorough data and performance analysis. This saves time in testing faults and reduces the outage time.

Warning:

Loopback affects the normal traffic. It is recommended only when there is complete failure of services or during off-peak hours.

A user can loopback the system either by software or through hardware.

Compared with software loopback, hardware loopback is more reliable. However, hardware loopback always needs on-site physical presence. In addition, the overload of the receiving optical power should be considered during the operation.



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Software loopback is easier but less reliable than hardware loopback. For example, during station testing, an optical board’s normal running cannot be determined through software loopback (inloop on the optical port). The optical board is tested by hardware loopback (optical fiber jumper is connected with transmitter and receiver of the optical board).

1. Provisions of Software Loopback in the OptiX 155/622H

Provisions of software loopback at different levels, with respect to boards are listed in Table 3-4. Note that all kind of software loopback is given by the NMS.

Table 3-4 Software loopback offered by the OptiX 155/622H

Board involved Loopback options Loopback level Application

Tributary board Inloop/ outloop Loopback at path level

Separates switching faults from transmission faults. Roughly determines the tributary board failure. Not necessary to modify service configuration.

Line board Inloop/ outloop Loopback at VC-4 level or whole STM-N level

Locates single station faults. Roughly determines the line board failure. No need to modify service configuration.

Cross-connect board

Line loopback, tributary loop-back

Loopback at service path level

Determines whether line or tributary side is faulty in a specific faulty station.

Requires much professional knowledge, and service configuration needs to be modified.

The line and tributary board loopback is widely used because they can locate a fault to a station and can roughly determine if a line or tributary board is faulty. So the maintenance personnel are required to be skilled in it.



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Warning:

Some line boards in the OptiX transmission system support the VC-4-level software loopback, and some support the software loopback only at STM-N level.

During loopback of the whole STM-N in a remote station, the ECC communication may be interrupted. Also, it may be interrupted if looping back the first VC-4. So, be cautious during this operation.

Remember ECC is responsible for the communication between NMS and NE. Once it is interrupted, the loopback only can be cleared only from the remote station to recover the ECC communication. This delays the troubleshooting and prolongs the outage time.

In a chain network, the NMS has only a single path to access an NE. However, in a ring network, NMS can access an NE from two paths. If one ECC fails, NMS can access the NE from other ECC. Therefore, be careful during software loopback of the line board in a chain network. In a ring network there is no problem in performing software loopback for the line board. Note that a ring network is considered a chain network if an optical fiber is broken between any two NEs.

Note:

Figure 3-2 shows how the software loop-back affects the ECC communication. In this figure, NE 2 and NE 3 are the remote stations for the NMS. If westbound (W) board of NE2 is looped-back, the ECC between NE 2 and NE 1 will be interrupted, and the NMS will lose the control on NE 2, i.e. the remaining network is also out of access. If eastbound (E) board of NE2 is looped-back, the ECC will not be interrupted and NE2 will be still accessible.

W E W EW

NE1 X XNE2 NE3

NMS

Figure 3-2 Effect on the ECC communication caused by the software loopback

The cross-connect board loopback can be used to determine whether the fault of the station occurs at the line side, or the tributary side, or the cross-connect side. The failure side of line board can be also determined by this loopback. However, the cross-connect board loopback is seldom used due to its complications.



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Tips:

The simplest way to perform cross-connect board loopback is to configure a loopback for a line or tributary board via the NMS. For service recovery, first make service backup prior to performing loopback.

2. Procedures

Before loopback, one should determine the path and timeslot to be looped-back. Also make sure, which kind of loopback will be used, inloop or outloop.

Following steps are recommended during software loopback:

Step 1 Select service path for loopback.

From collected alarm and performance data, select faulty service path as an object.

Tips:

Usually, services failed simultaneously are related to each other. Once one of them is recovered, others are also recovered subsequently. In addition, the principle of simplified sampling makes the fault analysis and handling easy. Especially, it is more effective in case that the faulty service is very complicated.

The process of simplifying the sampling of service path for loopback is:

(1) Select one of the faulty stations.

(2) Select one of the faulty service paths of the selected station. Since self-loop of the first VC-4 affects the ECC, do not select the first VC-4 for loopback.

(3) First, analyze the service in one direction of the selected service path.

Step 2 Draw the complete loopback path

Draw the complete loopback path, in which all the NEs in between are clearly showed. Mark the source and sink of this service, VC-4 number and timeslots it occupied.

Step 3 Now loopback each section, step-by-step until faulty NE is located.

Step 4 Locate the faulty board.

After locating the faulty NE, further locate the possible faulty boards by looping-back the line, tributary or cross-connect boards. Confirm the faulty board by applying other test methods. Finally, replace the faulty board.



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3. Example

Let us use Figure 3-1 again. Figure 3-1 shows a chain network with four NEs. Figure 3-3 is the timeslot allocation of these NEs.

NE1

＃1VC-4

ENETime

slot W

NE2

t1:1-161-16

t2:1-16

EW

17-32

EW

t1:1-16

33-48

EW

t1:1-16

t1:1-16t3:1-16

NE3 NE4

＃2VC-4

＃3VC-4

＃4VC-4

Figure 3-3 Timeslot allocation diagram

In the figure above, there are four VC-4s available. The network uses the service of two VC-4s. t1, t2, and t3 represent the 2M tributary board in slots 1, 2, and 3 in NE 1. The number 1-16 along with tributary board number (for example, t1) represents the 2M number. The numbers above the transverse lines indicate the timeslot number of the VC-4 occupied. For example, consider NE 1 and third transverse line, t3: 1–16 shows 2M paths 1-16 of the tributary board in slot 3 of NE 1. The 33–48 indicates, the timeslots occupied by the second VC-4. The service distribution from this diagram is:

(1) The 2M paths 1–16 of the tributary board in slot 1 of NE 1 are connected with 2M paths 1–16 of the tributary board in slot 1 of NE 2. The timeslots 1–16 of the first VC-4 carry the service between them.

(2) The 2M paths 1–16 of the tributary board in slot 2 of NE 1 are connected with 2M paths 1–16 of the tributary board in slot 1 of NE3. The timeslots 17–32 of the second VC-4 carry the service between them.

(3) The 2M paths 1–16 of the tributary board in slot 3 of NE 1 are connected with 2M paths 1–16 of the tributary board in slot 1 of NE4. The timeslots 33–48 of the second VC-4 carry the service between them.

Suppose NE 1 could not communicate with any other NE. Let us apply our recently discussed loopback to handle this fault:

Step 1 Select the interrupted service for analysis

(1) Services between NE 1 and NEs 2, 3, and 4 are interrupted. Select the service of NE 3 for analysis.



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(2) There are 16 interrupted services in NE 3. Select the first 2M service of the t1 tributary board for analysis.

(3) Analyze the service from NE 1 to NE 3.

Step 2 Draw a complete path from NE 1 to NE 3 including intermediate stations.

From the timeslot allocation diagram, we can see that the source of the selected interrupted service is t2:1 of NE 1, i.e. the first 2M path of the second tributary board. It occupies the 17th 2M timeslot of the second VC-4, and takes NE 2 as the intermediate station. The sink of the service is t1: 1 of NE 3. Thus, the service path diagram will be as shown in Figure 3-4.

NMS

NE1w2:17 w2:17 w2:17e2:17

t2:1 t1:1

NE2 NE3

Figure 3-4 Loopback path from NE 1 to NE 3

Step 3 Perform loopback section by section to locate the faulty NE.

According to Figure 3-4, connect a 2M BER tester to the first 2M path of the second tributary board of NE 1.

Tips:

If you are familiar with the alarm signal flow, you can also determine the service from alarm status. Usually, when the service is recovered, many alarms will vanish; when service interruption happens, many alarms will occur.

Perform the following operations in turn (note that you must cancel previous loopback before starting the next):

Inloop the second VC-4 of the westbound optical board of NE 1. Observe the 2 M BER tester reading. If the reading is normal, then the fault is not in NE 1 and move to the next step. Otherwise, the fault is in NE 1.

Remove the inloop, and make outloop for the second VC-4 of the westbound optical board in NE 2. Observe the 2M BER tester reading. If the reading is normal, then the fault is not in fibers between NE 1 and NE 2 and move to the next step. Otherwise, the fault is in this section.

Remove the outloop and make inloop from the second VC-4 of the eastbound optical board of NE 2. Observe the 2M BER tester reading. If the reading is normal then the fault is not in NE 2 and move to the next step. Otherwise, the fault is in NE 2.



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Remove the inloop from NE 2 and make outloop from the second VC-4 of the westbound optical board of NE 3. Observe the 2M BER tester reading. If the reading is normal, then fibers between NE 2 and NE 3 are normal and the fault must be in NE 3. Otherwise, the fault is in this section.

Tips:

When there are many NEs in a chain network, the dichotomy can be adopted for loopback, so as to locate the fault quickly. That is, perform the loopback on one NE located in the middle of the network first, thus locating the faulty point to the first half or the second half of the network.

4. Summary

From above discussion we realize that, loopback does not require much time in alarm and performance analysis, and through it one can locate the faulty NE or board quickly. However, path loopback temporarily interrupts the normal service, which is not affordable in a live network. Therefore, as a general rule, loopback is used only when service is interrupted or major faults occur. Remember again, when the first VC-4 path of the line is looped back, the ECC communication among NEs may be affected.

3.3.3 Replacement

1. Overview

In this method, an abnormal article is replaced with normal article. If the problem persists, then it means that particular article is not faulty and there may be some other problems. Here, the article might be a section of fiber, a board, a flange or an attenuator.

2. Application

Replacement method is applicable in handling the problems of external equipment, such as optical fiber, flange, accessed SDH equipment, and power supply equipment, etc. It is also used to remove the problem in the board or module in the single station.

3. Example

Refer to Figure 3-1 again. This time, consider the service between NE 3 and NE 4 is interrupted completely. The doubt is, optical fibers between the transmit end of NE 3 and the receive end of NE 4 are abnormal. Interchange the receiving and transmitting fibers between them. After the interchange, if the R_LOS alarm is generated at the receive end of the eastbound optical board of NE 3, it means optical fibers are faulty. However, if the fault still persists, then the optical board is faulty.



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To confirm the faulty board, apply this method again and replace the eastbound board of NE 3 with the new one.

If the alarm still persists, then replace the westbound board of NE 4 with a new one. This time the alarm should be removed.

Similarly, if there is T_ALOS alarm on 2M path of the tributary board. The possibilities are that the external switch or trunk cable is faulty. Interchange this path with a normal one. After the interchange, if the T_ALOS alarm has been shifted, it indicates the external trunk cable or the external switch is faulty and the transmission equipment is normal. If the T_ALOS alarm persists, then there should be fault in transmission network, either in the board or in the connector, etc.

By applying this method, we can also solve other problems such as power supply and grounding.

4. Summary

This method requires the least skill. It is easy for the maintenance personnel to grasp, and thus it is very practical. However, this method requires spare parts and extra care during its application. For example, wrong handling of the board or component during replacement may cause damages or lead to another fault.

3.3.4 Configuration Data Analysis

1. Overview

Sometimes sudden change in ambient conditions or improper operations may change or damage the configuration data (for example, NE and board data) of the equipment. This may affect services. In this case, after locating the fault to a single station, we can further locate the fault by analyzing the configuration data

2. Application

Locate the fault by querying and analyzing the current configuration data of the equipment. The configuration data include logical system and its attributes, node parameters of the multiplex section, path loopback setting of the line and tributary boards, protection attributes of the tributary path and path trace byte.

If the path protection of a tributary board does not work, we should check if the protection at the tributary level is enabled.

Any improper operation from the NMS can be verified from the operation log.

3. Summary

This method is applicable to the further analysis of a faulty station. It can help in finding the original causes of a fault. However, this is a time-consuming method. This method requires much expertise and knowledge in the field of optical transmission, as well as the product knowledge.



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3.3.5 Configuration Modification

1. Overview

In this method, we modify the timeslot configuration, slot configuration and board parameter configuration. It is applied to remove problems that are caused by configuration errors in a faulty station. In addition, the typical application of this method is to eliminate the problem of pointer justification.

2. Application

If some paths of a certain tributary board may be faulty, or a certain tributary board may be wrong, we can clear this doubt by modifying timeslot configuration. In this case, we can shift this payload to other tributary board or paths. Similarly, we can shift the traffic over one VC-4 to another. If a certain slot becomes faulty, we can change the slot configuration. Moreover, loopback of the cross-connect board is also considered one of the applications of this method.

During the upgrade or expansion, if you doubt the new configuration is not correct, you can re-load the original configuration.

However, modifying the timeslot configuration is not helpful in locating the faulty point or board, for example, a line board, cross-connect board or backplane. In this case, apply the replacement method to further locate the fault. Therefore, this method is applicable to the preliminary fault locating when there is no spare board available. Also, other service paths or slots shall be used to resume the service temporarily.

To solve the pointer justification problem by modifying configuration, modify the tracing direction and reference source of the clock.

3. Summary

This method is not convenient and efficient for the maintenance personnel. It is usually used to resume the service temporarily when there is no spare board available for replacement, or used to handle the pointer justification problem. Before applying this method, save the original configuration. Meanwhile, record carefully the steps executed to facilitate the fault locating.

Note:

For the multiplex section protection ring, modifying the service configuration in switching may interrupt the multiplex section protocol, which will interrupt the services.



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3.3.6 Meter Test

1. Overview

This method is usually applied to clear the external problems or to locate the interconnection problems.

2. Application

If the power supply tends to be abnormal, use a multimeter to measure the input voltage. If you suspect that the poor interconnection between the transmission equipment and other equipment is due to the grounding, use a multimeter to measure the voltage between the shielding layer of coaxial ports of the transmitter and receiver of the interconnection path. If the voltage value exceeds 0.5 V, then there is some problem with grounding. If you doubt that the poor interconnection is due to the incorrect signal, you can use appropriate analyzers to observe whether the frame signals are normal, whether the overhead bytes are normal, and whether there is any alarm.

3. Summary

This method provides highly accurate results. However, this method rather depends on meters and professional knowledge.

3.3.7 Experience of Maintenance

1. Overview

Sometimes a running board enters in abnormal state because of transient power supply behavior, low voltage or strong external electromagnetic interference. Service interruption and ECC communication interruption might be or might not be accompanied with corresponding alarms. The configuration data might also be correct. In this case, the fault can be cleared and the service can be resumed in time by board reset or board swapping. Sometimes give power reset to the subrack or re-send the system configurations.

2. Summary

The main disadvantage of this method is uncertainty, because the problem is not fully known and there is probability that the alarm persists after board or even power reset. This method is not recommended.

3.3.8 Comparison of Fault Locating Methods

Table 3-5 shows the comparison between these methods. In practice, the maintenance personnel usually need to apply more than one method to locate and clear the faults.



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Table 3-5 Comparison between various fault locating methods

Methods Application Features Skills requirement

Configuration data analysis

Locate the fault to a board Can find out the causes of fault. Need more time for fault locating.

Highest


Universal Evaluate the situation as a whole. Can foresee latent dangers of equipment. Do not affect services

High


Locate the faulty point to the board. Can solve the pointer justification problem.

The operation is complicated and may affect services.

Higher

Meter test Isolate external faults. Solve the problem of poor interconnection.

Accurate. Require meters. Higher

Loopback Locate the fault to a single station or isolate external faults

Independent of analysis of alarms and performance events but may affect ECC and normal service.

Lower

Replacement Locate the fault to a single station or isolate external faults

Simple, but need spares. Low

Experience Special cases Simple Lowest



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3.4 Classified Fauts & Troubleshooting

The troubleshooting procedures of transmission equipment are basically the same. It does not matter which type of the fault it is. That is, start from the external equipment, and then locate the faulty station. After that, locate the fault to the board or component for the final solution.

3.4.1 External Faults Handling

Before locating faults of the transmission equipment, first eliminate the external faults like, grounding, optical fibers, trunk cables, external switch or power failure.

1. Troubleshooting External Switch Fault

Method 1: Self-loop the switch trunk interface. If the switch trunk board is abnormal after self-looping the trunk interface, it can be determined that the switch fails. Otherwise, something is wrong with the transmission equipment.

Method 2: Loopback the accessed 2 Mbit/s or 34 Mbit/s service path of transmission equipment as shown in Figure 3-5. If alarm indications disappear from the tributary unit, it means that the transmission equipment is normal. That is, the external switch is abnormal. Ask the concerned switch staff to assist you in the fault removal.

SDH NE

Switch Meter

Line

Tributary

AB

Tributary

SDH NE

Figure 3-5 Looping back the PDH interface

Select a faulty service path in station A and attach a BER tester to it. Loopback the corresponding path of the tributary board of NE B. This loopback will isolate the external switch. Check the BER tester reading, if the reading is normal, it means the service is normal and the transmission equipment is ok. If the BER tester shows some errors, it means the fault is in the transmission equipment. Check carefully the tributary and line boards according to the above-described methods.

2. Troubleshooting Optical Fiber Fault

When an R_LOS alarm is displayed in the NMS and the red indicator of the line board is on, it means communication path is interrupted and something wrong with either board or optical fiber. To further determine whether the problem lies in the board or in the optical fiber, the following methods are used.

Method 1: Use the OTDR to check the optical fiber continuity. By analyzing the line attenuation curve displayed on the analyzer, we may determine whether there



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is a breaking point on the optical fiber.

Method 2: Measure the transmitting and receiving optical power of the optical board at the both ends of the optical fiber. Compare these values; if the transmitting optical power of opposite end optical board is normal while the receiving optical power of this end is abnormal, then the optical fiber is faulty. If the transmitting optical power of the optical board is very low, then the optical board is faulty.

Method 3: Check the transmitting optical power. If it is normal, it means the fault is after this point. Now hardware loopback the board, by connecting the transmit port and the receive port of the board with a fiber jumper. Make sure that an attenuator is attached, to avoid any optical power overload. If the alarm indicator of the board is still on, the board is faulty. Otherwise, similarly check the corresponding opposite board. If both boards are ok, there must be problem in optical fiber.

Method 4: Use the replacement method. Use a piece of fine fiber to replace that suspected to be faulty.

As to ADM stations in a ring network, the eastbound optical board of this station shall be connected to the westbound optical board of the next station, and so are other connections of the rest stations. For ADM stations in a chain network, the connection of the optical fibers should be made according to a specified direction. The eastbound optical board of this station should be connected to the westbound optical board of the next station. When the optical fibers are connected improperly, a great amount of pointer justification events will be generated. For further localization, the following methods can be adopted.

Method 1: Judge the fiber connection by drawing out fibers or shutting down the laser. Note that this method will affect the service.

Method 2: Fulfill the judgment by inserting the MS_RDI alarm via the NMS. This method will not affect the service, and is recommended.

Method 3: Modify the trace byte J1 of the higher order path via the NMS. Modifying the trace byte may affect the service.

These three methods fulfill the analysis by observing whether the corresponding optical board of the adjacent station reports the alarms. For method 1, the R_LOS alarm shall be reported when the corresponding optical board of the adjacent station cannot receive optical signals. For method 2, the corresponding optical board of the adjacent station shall report the MS_RDI alarm. For method 3, the HP_TIM alarm shall be reported by the corresponding optical board of the adjacent station. If you cannot find the appropriate alarms reported from the corresponding optical board of the adjacent station, but another optical board in the adjacent station reports the alarm, it usually means the fiber is misconnected.

3. Troubleshooting Trunk Cable Fault

After making sure the transmission equipment and the switching equipment is normal, the problem probably lies in the media between them, that is, trunk cable or DDF connections. In case of cable blocking or poor-connection, an alarm can be observed on the corresponding path of the tributary board. In this case, you can use



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wire-matching method (refer to Chapter 1 of this manual) to determine whether the cable is connected properly. Also, to confirm the fault, replace the trunk cables and observe the behavior. If the alarm is shifted along the trunk cable, it indicates that the fault is in trunk cable.

4. Troubleshooting Power Supply Fault

If an NE is not accessible and the R_LOS alarm is reported from the related optical board, then the power supply of this station may fail. If this station turns to be abnormal suddenly, such as failure of path switching or multiplex section switching, abnormality of some boards, service interruption or abnormal login, the problem may come from its power supply system. Check if the power supply voltage of the transmission equipment is too low, or if there is instantaneous voltage fluctuation.

5. Troubleshooting Grounding Fault

If the equipment is struck by lightning or can not be interconnected you need to check whether the grounding is correct. First check if the grounding is in line with the standards, if any equipment is not grounded together, and if the grounding of equipment in the same room is consistent. Then use meters to measure grounding resistance and voltage difference between working ground and protection ground, and check if they are within the range allowed.

3.4.2 Localizing Fault to a Single Station

In fault handling, the most important step is localizing the fault to a single station. The popular method is loopback. That is, perform either inloop or outloop to check the faulty NE, station by station. The other efficient method is alarm and performance analysis. Generally, with the combination of these two methods, you can easily localize a fault to a single station.



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3.4.3 Localizing Fault to the Board

Once faulty NE is recognized, use the replacement method to localize the fault to the board or unit. In addition, the configuration modification, configuration data analysis, and experience methods also are commonly used during commissioning. Further fault locating will be introduced in the next chapter, which deals with the troubleshooting of various common faults. Table 3-6 shows procedures and common methods of troubleshooting.

Table 3-6 Troubleshooting procedures and methods

Procedure Method Additional measures

Removing external faults

Replacement, meter test, and loopback


Localizing fault to a single station

Loopback Alarm and performance analysis

Localizing fault to the boards

Replacement Alarm and performance analysis, configuration modification, checking configuration data, and experience



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3.5 Contact Huawei for Assistance

During routine maintenance or fault handling, if you encounter problems that are hard to handle, contact the Huawei Technologies Co., Ltd. Meanwhile, make the trouble report for Huawei engineer, with the following information:

Detailed name of the faulty spot

Name and phone number of the contact person

Name and phone number of the contact person on site

Exact time when faults happen

Equipment type and network type

Fault level and expected settlement time

Measures taken and results

3.6 Obtaining the Latest Technical Documentation

You can get the latest technical documentation from the technical support web site http://tech-support.huawei.com, where you can get online information and assistance.

OptiX 155/622H(Metro1000) Maintenance Manual 4 Common Faults Treatment


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4 Common Faults Treatment

Common faults in the course of OptiX transmission equipment maintenance are classified as follows:

Payload Interruption

Bit Errors

Pointer Justification

ECC Fault

Orderwire Fault

Equipment Interconnection Fault

Ethernet Interconnection Fault



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4.1 Payload Interruption

In this section, we will discuss how to settle problems under long-term payload interruption. As to instantaneous payload interruption problems, please turn to the technical support department of local agency of Huawei Technologies Co., Ltd.

4.1.1 Common Cause Analysis

1. External Causes

Power supply faults, for example, equipment power failure, over-low voltage of power supply.

Switching system problems.

Optical fiber and cable problems, such as deteriorated optical performance, high loss and broken fibers, or loose, broken and poorly connected cables.

2. Personal Factors

The loopback of an optical or tributary path is set by improper operation.

Change or delete the configuration data by improper operation.

3. Equipment Faults

Ineffective or deteriorated boards.

4.1.2 Common Treatment Methods

Alarm and performance analysis.

Loopback section by section.

Replacement.

4.1.3 Fault Treatment Procedures

When you cannot locate the faulty points in a short time by viewing NM alarm data or equipment alarm indicators, you can directly try the method of self-loop.

1. Equipment Maintenance Personnel

Step 1 Check indicator status

If the green operation indicator flashes quickly, inform the NM maintenance personnel to re-download the configuration data.

Step 2 View the red alarm indicator status on LU

If the red indicator of the LU of a station remains on, it means the board has received no optical signal.



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Note:

Some operations in the course of equipment maintenance may interrupt the payload, or even result in a network-wide payload interruption. We therefore strongly suggest that the maintenance personnel communicate with the NM maintenance personnel of the center station for a solution, lest maintenance of a single station should affect the payload of the whole network.

2. NMS Maintenance Personnel

Step 1 Check whether each station can be properly logged in to and if optical paths of the station have critical alarms.

In case that a station cannot be logged in to, the neighboring stations get such critical alarms as R_LOS and the like on their optical paths, the station may have been under power failure or the optical fibers or LUs connected to this station may have gone wrong.

If there is no alarm on the optical path but you still cannot log in to a station, the ECC path may be blocked by too heavy information reported. In this case, you can reset the SCC unit of a neighboring station. If this does not work, inform the equipment maintenance personnel to replace the SCB board and LU of this station and the neighboring station, to locate and remove the fault.

Note that in a multiplex section protection ring, replacing an SCB board or LU will bring a stop to the multiplex section protocol of the NE where the board lies. Therefore, when replacing a board, make sure the normality of the whole network, and you need to re-download NE configuration data after replacing the SCB board.

Either replacing an LU or re-downloading the configuration data will result in instantaneous payload interruption. Thus, you should perform these operations at a moment with light traffic volume.

Step 2 Check if the path in the TU of the station with interrupted payload gets the T_ALOS alarm.

If so, you should first check to see if something is wrong with some items outside the transmission equipment, such as the switching system or the trunk cables. Inform the equipment maintenance personnel at the station to make an inloop of the electrical interface on the DDF side or on the equipment board side. Then check via NM if the alarm has disappeared, so as to decide whether the fault lies in the transmission equipment or outside it. If the fault lies outside the equipment, it shall disappear after the loopback. Otherwise, it will not.

If you can locate the fault with the above method, then the TU board may have gone wrong. Replace the TU board to see if the TU board is faulty, so as further to remove the fault.

Step 3 Make loopback section by section

Connect the meter to the NE on one end of the path with interrupted payloads in



4-4

order to monitor the payload conditions. Along the payload direction, make loopback of the LU of each station section by section, viewing the payload conditions shown in the meter. If the meter displays the payload as normal after the loopback, this line is ok; if the meter shows it interrupted, then the line section is faulty.

Tips:

If a number of alarms arise with the payload interrupted, you do not necessarily use a meter when making the loopback. Rather, you can determine if the payload is normal by viewing the alarm conditions. As a rule, the alarms accompanied with the payload interruption will disappear after the payload recovers.

With the fault points narrowed down to either of the stations or the line between two stations, you can further the fault location and removal by means of board replacement.

Be fully aware that if you make the line loopback, that may affect the ECC path and interrupt the ECC communication; if so, you will have to undo the loopback through local log-on, thus considerably delaying the troubleshooting.

4.1.4 How to Remove Some Payload-Interruption Faults in Typical Network

In the event you fail to locate a fault by viewing the alarm events, you can try the method of loopback. Here, we will exemplify the methods of handling payload faults in the chain network and unidirectional path protection ring.

1. Non-protected Chain Network

(1) Networking configuration

Figure 4-1 Unprotected chain network

As shown in Figure 4-1, the networking system is an unprotected chain containing four stations. NM center station, NE1 is connected to the NM terminal. The payload is the concentrated payload type. Each station gets 2M payload with NE1, the payload occupying No.1 VC-4.

(2) Fault phenomenon

The 2M payload between NE1 and NE4 is interrupted, other payloads normal. All stations are reachable, LU getting no alarm.

(3) Treatment steps



4-5

Step 1 View via NM the monitored alarm performance information, making an analysis to locate the fault. If you have difficulty in locating the faulty station by viewing the alarm data or the equipment alarm indicators, go on with step 2, using the method of loopback.

Step 2 In NE1, use a 2M bit error meter to monitor the 2M with interrupted payload between NE1 and NE4, when the bit error meter displays the payload as interrupted. Make via NM a software inloop of the TU in NE4. If the meter displays the payload as normal, that means a problem of NE4; go on with Step 3. If the meter displays the payload as interrupted, that means a problem of transmission equipment; go on with Step 4.

Step 3 At the TU interface or DDF distribution frame in NE4, make, for the corresponding path, a hardware inloop of the transmission equipment. In the event that the meter still displays the payload as normal, that means the transmission equipment is sound. You need to troubleshoot the switching system or trunk cable. If the meter takes the payload as abnormal, that may mean a problem of the TU, and then you can further the fault location by means of board replacement.

Step 4 Perform in turn software inloop of the west LU in NE1, east LU in NE2 and east LU in NE3. If you get blocked loopback payload in a station, that is a problem of this station or the LU in the preceding station. To be more specific, if you get blocked loopback payload in NE1, that is a problem of NE1; if you get normal loopback payload in NE3, it may be a problem of NE4 or the east LU in NE3.

Taking blocked loopback payload in NE3 as an example, here we will discuss how to further the fault location.

First be aware that if you get normal payload when making a software loopback of the east LU in NE2, and if you get blocked payload when making a loopback of the east LU in NE3, that may be a problem of NE3, the east LU in NE2 or the optical path (inc. optical cables and the optical connectors) between two stations.

If you have in NE2 some maintenance personnel to cooperate with, you can get made in this station a hardware inloop of the east LU to check if the payload is normal. If it is abnormal, that is a problem of the east LU in NE2; if normal, NE2 is sound. Now, you can use the method of optical fiber replacement to troubleshoot the optical path between NE2 and NE3.



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Tips:

As to the inloop of the east optical interface in NE2, if the interrupted payload does not belong to No.1 VC-4 path, you can via NM make a software outloop of the west LU in NE3; or, if NE2 is not farther separated from NE3, where the optical power of optical signals is, when the signal has made a round trip, still greater than the receiving sensitivity of the east optical interface board in NE2, then you can even make, at the ODF of NE3, a hardware inloop of the east optical interface board in NE2.

In either of the above loopback methods, you may have measured the optical path between the two stations and the east optical interface board in NE2.

If the payload is tested as normal when making the above loopback, then NE3 has gone wrong.

Note that when you make a loopback of the optical interface board hardware, the receiving optical power should neither be lower than the receiving sensitivity nor be so high as to result in overload.

After going through the above checks, we will have narrowed down the fault points to a station. In case of faulty optical path, just ask the maintenance personnel in the station to replace an optical fiber or optical cable. In case of faulty NE2 or NE3, the equipment maintenance personnel in the center station will have to go, carrying standby boards with them, to NE2 or NE3, so as to further the troubleshooting on site.

The standby boards carried should include the LU and SCB board.

Step 5 If the fault results from the east optical interface board in NE2, then replace the board to remove the fault.

If the fault results from NE3, then replace in turn the east, west LU and SCB board in NE3, till the fault is removed.

Step 6 If you can not remove the fault after going through the above steps, then that is a complicated problem. Please turn to the technical support department of local agency of Huawei Technologies Co., Ltd.

2. Path Ring

(1) Networking Configuration



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Figure 4-2 Path protection ring

As shown in Figure 4-2, the networking system is a path protection ring composed of 4 stations. NE1 is the NM center station. The payload is the concentrated type, i.e. each station has the 2M payload with NE1.

(2) Fault Phenomenon

The payload between NE1 and NE4 are interrupted, other payloads being normal. Four stations are reachable, line getting no alarm.

(3) Treatment Steps

Step 1 Get via NM the alarm and performance information, making an analysis to locate the fault. If you have difficulty in locating the faulty station by viewing the alarm data or the equipment alarm indicators, go on with step 2, using the method of loopback.

Step 2 Unplug the west optical fiber in NE1, and then the path ring as shown in Figure 4-2 will grow into a chain network which is the same as the one shown in Figure 4-1. After the transformation, you can do the troubleshooting work as with the chain network.

Tips:

With the payload interrupted, the path ring will grow into a broken ring. Hence, you can take it as the chain network for treatment.

Step 3 Re-plug the west optical fiber in NE1, and then unplug the east optical fiber in NE1. Then go on with the troubleshooting as with step 2.

The troubleshooting process is the same as that in the former example of chain network. Remember, however, to recovery the ring network after troubleshooting.



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4.2 Bit Errors


1. External causes

Deteriorated optical fiber performance and high loss.

Impurity of optical fiber plugs or incorrect connectors.

Improperly grounded equipment.

Strong disturbance source near the equipment.

Bad dissipation and too high operating temperature of the equipment.

2. Equipment specific causes

LU gets too high signal attenuation on the receiving side; the opposite transmitting circuit is faulty; local receiving circuit is faulty.

Bad clock synchronization performance.

The cross-connect unit does not match the LU and TU properly.

Faulty TU.

Faulty fan.

Ineffective or deteriorated board.



Usually, the payloads have not been interrupted when the bit errors occur. Since the method of loopback may affect normal payloads, you should make a careful analysis of the bit error performance events so as to locate the fault points, before you begin to deal with the problem. Table 4-1 lists the performance and alarm events which are of vital importance in analyzing bit error specific problems.



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Table 4-1 Monitor positions and functions of alarm and performance events for bit error threshold crossing

Performance events Alarm events Description Bit errors monitored in local station

Bit errors monitored in opposite station

Bit errors monitored in local station

Bit errors monitored in opposite station

Regenerator section

RSBBE - B1_EXC -

Multiplex section MSBBE MSFEBBE B2_EXC MS_REI

Higher order path HPBBE HPFEBBE HPCROSSTR HP_REI

Lower order path LPBBE LPFEBBE LPCROSSTR LP_REI

Replacement

In case of bad or deteriorated performance of parts and components of the equipment, you can use the method of replacement, i.e. replacing the optical fiber, parts and components, boards, etc., so as to help locate the fault or to check the correctness of the fault location.

Loopback section by section

Of course you can use, if possible, the method of loopback to locate the faulty station rapidly. Steps for using the method of loopback to handle bit error specific problems are the same as those with the payload interruption problem. Please refer to the relative sections in this manual.

4.2.3 Fault Treatment procedures

Step 1 Analyze the LU bit error performance events to locate and remove the LU bit errors.

First locate and remove external faulty factors, such as bad grounding, too high operating temperature, too low or too high receiving power of the LU and so on; then view LU bit error conditions. If every LU in a station gets bit error, that may be a problem of the synchronous timing unit in this station. So replace the SCB board. If only one LU reports bit errors, that may be a problem of the LU in this station, or of the opposite station or the optical fiber. With the faulty board located, you can remove the fault by means of board replacement.

If possible, you can use the method of loopback to locate the fault.

Step 2 Analyze the tributary bit error performance events to locate and remove the tributary bit errors.

If only the tributary gets bit errors, that may result from mismatched cross-connect unit and TU in this station. So replace the TU and SCB board to locate and remove the fault.



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4.2.4 Cases of Typical Faults

1. Bit Errors Resulting from Line Faults


Figure 4-3 Chain network

As shown in Figure 4-3, the networking system is an unprotected chain composed of four stations. NE1 is the NM center station. The payload is the concentrated type, i.e. all other stations have the 2M payload with NE1.


The 2M TU in NE1 gets the LPBBE bit error; the east optical interface board in NE3 gets RSBBE, MSBBE, and HPBBE bit errors; the west optical interface board in NE4 gets MSFEBBE and HPFEBBE bit errors and the 2M TU in NE4 gets LPFEBBE bit errors.

(3) Treatment steps

Step 1 By analyzing the reported performance events, we can conclude that the problems may result from the receiving end of east optical interface board in NE3, optical path (inc. optical fiber and the optical connectors), transmitting end of west optical interface board in NE4.

By and large, the principle of analysis is as follows: NE3 receives the signal transmitted by NE4; then when it finds bit errors in the signal by means of computation, it reports such values worked out as RSBBE, MSBBE and HPBBE to this station's SCC unit and through this unit to NM; meanwhile NE3 transmits back the detected bit error information to NE4; NE4, with the bit error information detected, reports the corresponding performance values MSFEBBE and HPFEBBE to NM through its SCC unit.

Step 2 Go to NE3. Use the tail optical fiber to make a loopback of the east optical interface board in NE3. Bit errors in the east optical interface board of NE3 and those in the 2M TU of NE1 disappear. This means the problem arises from the west optical interface board in NE4 or from the optical path.

Step 3 Use the method of replacement. Interchange the two optical fibers between NE3 and NE4 to view the bit errors. If the bit errors have changed-- the data reported from NE3 and NE4 has changed into the opposite of the data before the interchange, which is an optical fiber problem. So check the optical path. If the bit errors disappear after the interchange, the problem may result from bad contact in the optical fiber. In general, the optical path specific problems can be settled by replacing a new optical fiber.

Step 4 If the optical path is normal when tested, then the problem may arise from NE4.



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So replace the west optical interface board in NE4 to settle the bit error problem.

2. Bit Errors Resulting from Faulty Synchronous Timing Unit


Figure 4-4 Unidirectional path protection ring

As shown in Figure 4-4, the networking system is a unidirectional path ring composed of four OptiX 155/622H stations. NE1 is the NM center station. The payload is the concentrated type, i.e. all other stations have 2M payload with NE1. The global clock trace direction is 4→3→2→1, where the sign "→" means "to trace."


In NE1, NE3 and NE4, the corresponding 2 M payload paths report the LPBBE and LPFEBBE bit errors. The east and west optical interface boards in NE3 and the west optical interface board in NE4 report a number of RSBBE, MSBBE, HPBBE, MSFEBBE and HPFEBBE bit errors. In the meantime, NE1, NE3, NE4 get a large number of the TU pointer justifications; the west optical interface board in NE1 and NE4 get a number of AU pointer justifications, too.

(3) Treatment Steps

Step 1 As judged by the bit error performance events, the fault may result from faulty east optical interface board in NE2, faulty synchronous timing unit in NE3 or faulty cross-connect unit.

The principle of analysis is as follows: generally, bit errors do not give birth to the pointer justification while a number of pointer justifications give rise to bit errors. Thus, if the fault gets both bit errors and pointer justifications, we should start with analyzing the pointer justifications. In this fault phenomenon, the tributary pointer justifications come from and after NE3, this is a problem of timing source lock in NE3. Since the extracted timing source is the line timing source, the problem may arise from the fact that the LU in the upstream station or this station gets a problem with the provision of timing source reference, or that the synchronous timing unit in this station has a problem with the lock of timing source reference. If payloads of this station will not be dropped to the tributaries, then the pointer justifications in the line can be detected only in the downstream stations. After analyzing, we form the above judgment.

Step 2 Replace the east optical interface board in NE2. Then LPFEBBE bit errors in the TU of the NE2 disappears; bit errors in NE3 and NE4 persist. Thus, NE3 is faulty.



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Step 3 Replace the SCB board in NE3 and the bit errors disappear, the fault removed.

4.3 Pointer Justification


1. External Causes

The optical fibers are misconnected. So there are two NEs tracing each other.

If an NE traces the external clock, check the external clock quality.

2. Personal Factors

The timing source is improperly configured. So two timing sources appear in the same network.

Tracing level of the timing source is improperly configured. So there are two NEs tracing each other.

3. Equipment Problems

The LU is faulty, providing bad clock.

The synchronous timing unit is faulty, proving bad timing source or being unable to lock the traced timing source.



Configuration Modification

Replacement


Step 1 Locate and remove the problem of optical fiber misconnection. Only in the event of path protection ring, may it be possible that misconnected optical fibers lead to normal payload. In other networking system, misconnected optical fibers will result in interrupted payloads.

Step 2 If the NE traces the external clock, you should check the quality of external clock.

Step 3 Locate and remove possible configuration based problems.

Step 4 Analyze the pointer justification performance events. Change the position of the timing source, the clock tracing direction and so on to locate the fault.

4.3.4 Treatment of Pointer Justification Problems in Two Typical Cases

In the following two typical cases of networking system, if the pointer justification appears, you can directly locate the faulty station.



4-13

1. All Stations have 2 M Payload Add/Drop or Through-Connection


The network system is as shown in Figure 4-5. NE1 is the payload center station. It has the 2M payload with all other stations. All intermediate stations are through connected at VC-12 level. NE1 clock is the internal clock, other stations tracing the NE1 clock westwards.

Figure 4-5 Ideal networking system (1)


NEs 1, 3, 4, 5 and 6 report the TU pointer justification events.

(3) Treatment steps

Step 1 By analyzing the performance events, we can decide that NE3 clock is out of synchronization. This problem may arise from the clock which is badly extracted by the west optical interface board in NE3, faulty unit or faulty east optical interface board in NE2.

Step 2 Replace the SCB board in NE3. The pointer justifications disappear. This means that the pointer justifications result from faulty synchronous timing unit.

Tips:

In case of concentrated 2 Mbit/s payload, payload center station is where the global timing source reference (free-run or tracing the external clock) lies. Along the clock tracing direction, the first station (exc. the payload center station) whose TU gets the pointer justification is the station with out-of-sync clock. The problem may result from the fact that the synchronous timing unit or LU that extracts the clock is faulty, or that the upstream LU which transmits the signal is faulty. This conclusion applies to any networking system, chain network or ring network.

2. The Payload is Through Connected at VC-4 Level


The networking system is as shown in Figure 4-6. NE1 and NE6 have their 2M payload through connected at NEs 2, 3, 4 and 5 at the VC-4 level. The NE1 clock is set as the internal clock. Other stations trace the NE1 clock.



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1 2 3 5 64

2M payload

VC4through connect

2M payload

Internal clock West tracing West tracing West tracing West tracing West tracingW W W W WWe e e e

LU LU LU LU LUVC4 VC4 VC4

through connect through connect through connect

Figure 4-6 Ideal networking system (2)


The TU in NE1 and NE6 report the TU pointer justification performance events; the west optical interface boards of NEs 1, 4, 5 and 6 report the AU pointer justification performance events.

(3) Treatment steps

Step 1 By analyzing the performance events, we can decide that NE3 clock is out of sync with NE2 clock and that it may arise from faulty synchronous timing unit or faulty west optical interface board in NE3, or from faulty east optical interface board in NE2.

Step 2 Replace the west optical interface board in NE3, the pointer justification performance events disappear. That means the pointer justifications result from faulty west optical interface board in NE3.

Tips:

In case a payload has itself, along the clock tracing direction, is through connected more than one intermediate NE in a row at the VC-4 level, then, along the clock tracing direction, the station which is followed by the first station which reports the AU pointer justifications is the station with an out-of-sync clock. This conclusion applies to any networking system, chain network or ring network.



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4.3.5 Examples of Typical Faults

1. Pointer Justification Resulting from Incorrect Configuration


Figure 4-7 Path protection ring

As shown in Figure 4-7, the networking system is a path protection ring composed of four OptiX 155/622H equipment items. NE1 is the NM center station. The clock is configured as the internal clock. Payload is the concentrated 2M payload type. The timing source tracking direction of the NEs is 4→3→2→1. The payload time slot assignment is as shown in Table 4-2.

Table 4-2 2M time slot assignment table

VC-4 W 1 2 3 4 E

1

-->

-->

-->

t4: 1–16

t4: 17–32

t4: 33–48

1–16

-------

-------

-------

------>

17–32

-------

-------

t4:1–16

--------

33–48

--------

-----

---->

-----

--------

t4:1–16

--------

-----

-----

--->

--------

--------

t4:1–16

->

->

->

The payloads as shown in Table 4-2 can be described as follows: The 1–16 2 M paths in the t4 TU of NE1 interchange payloads with 1–16 2 M paths in the t4 TU of NE2 via 1–16 timeslots of the first VC-4. The 17–32 2 M paths in the t4 TU of NE1, interchange payloads with 1–16 2 M paths in the t4 TU of NE3 via 17–32 timeslots of the first VC-4. The 33–48 2 M paths in the t4 TU of NE1 interchange payloads with 1–16 2 M paths in the t4 TU of NE4 via 33–48 timeslots of the first VC-4. The payload is the unidirectional. Each payload travels all over the ring.


All 2 M TUs in NE1, NE3 and NE4 report a number of pointer justifications.

(3) Treatment steps



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Step 3 This is similar to typical case 1. The fault points can be narrowed down to the clock in NE3.

Step 4 When checked, the clock configuration in NE3 is free-run.

Step 5 Change the clock configuration to trace the west optical interface board clock. The pointer justifications disappear, indicating the fault has been removed.

2. Pointer Justification Resulting from Faulty LU


The networking configuration is the same as the above. NE1 clock is the internal clock. Other NEs trace the NE1 clock westwards.


All 2 M TUs in NE1, NE3 and NE4 report a number of pointer justifications.

(3) Treatment steps

Step 1 This is similar to typical case 1. The fault points can be narrowed down to the clock in NE3.

Step 2 Change the tracing direction of NE3 and NE4 as shown in Figure 4-8. More specifically, change NE3 and NE4 into tracing NE1 clock eastwards. Pointer justification performance events disappear. This means the west optical interface in the OI2D board of NE3 has problem with the clock extraction.

Figure 4-8 Clock tracing direction after changed

Step 3 Replace the optical interface board in NE3 to remove the fault.



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4.4 ECC Fault

4.4.1 Introduction to ECC

SDH NEs communicate with one another via the ECC communication, physical layer of which is the DCC path, that is, the D1–D12 bytes in the section overhead (SOH) at 768 kbit/s and used for OAM information exchange among NEs. The SCB board provides several SCC serial ports for DCC bytes.

The NM communicates with non-GNEs as follows: First, The NM and the GNE communicate with each other via the TCP/IP; then the GNE and non-GNEs communicated with each other via the ECC. Thus, the communication between the NM and non-GNEs is affected.

In a ring network, when the NM logs on other NE via the GNE, it takes the same path to and fro.

(1) If the route is sound, it takes the short path.

(2) If the short path is abnormal, it takes the long path.

(3) If both long and short paths are abnormal, it can not log in NEs.

(4) The assignment of ECC route is independent of the payload configuration, but dependent on the optical interface board loopback.

4.4.2 Common Causes of ECC Faults

1. External causes

Faulty power supply, such as the equipment off-power, too low power supply voltage and so on.

Faulty optical fibers, such as deteriorated optical fiber performance, high loss, or broken fibers and so on.

2. Personal factors

Make by mistake a loopback of the LU optical interface on the ECC receiving side in an undesired station (in chain network).

Forget to reset toggle switch when replacing the SCB board, thus resulting in a duplicate of an NE ID in the network.

Forget to add NEs into the system management domain.

3. The equipment specific faults

Faulty SCC unit

Faulty optical interface board

Faulty synchronous timing unit



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NEs report so much performance data to the NM that the ECC path is blocked.



Replacement

Experience


Step 1 Locate and remove external factors, such as off-power, broken fibers, deteriorated optical fiber performance and so on.

Step 2 Locate and remove personal factors. Avoid making by mistake a loopback of the LU optical interface on the ECC receiving side in an undesired station (in chain network). Avoid making a duplicate of any NE ID in the network. Add NEs into the system management domain, etc.

Step 3 Narrow down the fault points to a station or between two NEs. Note: as to ECC problem, making loopback section by section will not work to locate a fault. The fault location is usually decided on the first unreachable station.

Step 4 Check the SCB board.

Step 5 Check the optical interface board.

4.4.5 Removal of Typical ECC Faults

Here, we will exemplify the methods and steps of removing ECC faults.


The networking system is as shown in Figure 4-9. NE1 is the GNE, connected to the NM. The connectivity of optical fiber between NEs is as shown in the figure, where "w" stands for the west optical interface in the optical board and "e", the east optical interface.

Figure 4-9 ECC problem in the chain network


You cannot log in to NE3 and NE4 via NMS.

(3) Treatment steps

Step 1 First locate and remove external faults.



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If off-line or low voltage arises from NE3, you cannot log in the station via NM, to say nothing of NE4, because NE3 cannot forward the ECC data. Likewise, if the two optical fibers between NE2 and NE3 are broken, the NM cannot log in to NE3 and NE4. You can locate external fault by using the method of alarm analysis.

Additionally, such factors as deteriorated optical fiber transmission performance, loose optical fiber connector, impurity in optical fiber plug and so on will give birth to a large number of bit errors in the optical path, consequently resulting in intermittently or completely disconnected ECC communication. Under the circumstances, you can use the method of performance data analysis to view the performance.

With these obvious external faults located and removed, you can take the location of ECC problems one step further.

Step 2 Check the setting of system management domain. Make sure you have added the NEs into the system management domain.

Step 3 Narrow down the fault points to a station or between two NEs.

Note that you cannot locate an ECC problem by making loopback section by section. As a rule, the fault location is based on the first station that you cannot log in to. As shown in Figure 4-9, if you can log in to neither NE3 nor NE4, the fault can be located in NE2 and NE3. In case of ECC problem, you should analyze not only the station that you cannot log in, but also its upstream NEs. For example, if the NM cannot log in to NE3, you should analyze both NE2 and NE3.

Step 4 Check SCB board.

First check if the SCB boards in the relative NEs get hardware faults or if they keep on resetting. In the example above, to conduct this check, you need help from the maintenance personnel in the equipment rooms of NE2 and NE3, mainly to check if the red and green indicators on the SCB board display normally. If the green indicator keeps on, that means the SCB board gets a hardware fault. In the event, you can reset the SCB board or unplug and plug the SCB board according to requirements for this operation. If the fault persists when viewed, you will have to replace the SCB board.

Note:

1. If the payload is normal, do not unplug/plug the SCB board at will, or the payload will be interrupted. However, a reset of the SCB will not affect the payloads.

2. After replacing SCB board, you should re-download NE configuration data, for the NE configuration data is kept in the SCB board.

If the indicators on the SCB board display normally, try to reset the SCB boards. In the example above, you may first reset the SCB board in NE2. If this does not work, try to reset the SCB board in NE3. If the fault persists, then unplug and plug the SCB boards in NE2 and NE3 respectively. In this case, you need help from the



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maintenance personnel in the equipment rooms of NE2 and NE3.

Step 5 Check optical interface board.

If the optical interface board gets any alarm, begin with finding out the causes. If not, replace the optical interface board or unplug and plug the optical interface board. In some cases, blocked ECC may stem from the fact that the optical interface board is not put in position, and it may resume to normal with the board unplugged and plugged again. In the example above, if you cannot log in NE3, you can firstly reset the west (W) optical interface board in NE2, and then the east (E) optical interface board in NE3. If these do not work, try to use another optical interface board of the same type.

Warning:

1. If you unplug/plug or reset an optical interface board, that will interrupt the relative payloads! It is suggested that you do so at night when the traffic is not heavy. Never do so at will!

2. Bit errors in line or system operating environment (for example, temperature conditions) may result in disordered time sequence in DCC coordination between the optical interface board and the SCC unit or result in the deadlock of the software and hardware. Thus a unidirectional ECC arises in the system or the NE gets completely disconnected ECC. In conclusion, you can reset the SCB board or LU to recover a blocked ECC in most cases.

Step 6 Check the synchronous timing unit.

4.4.6 Tips for ECC Fault Location

1. View Routes via NMS

In the OptiX iManager T2000 NMS, you can query each NE's current ECC route. In the column "Destination NE", all NEs except the selected should be displayed and columns "Transferring NE" and "Distance" should be normal.

2. Unreachable GNE

If you cannot log in to the GNE, it means the problem lies in between the NM computer and the GNE rather than ECC communication between NEs. Usually, you may check network cable, computer and GNE IP address, or reset computer, or PING local computer and GNE IP address to settle this problem. For operation details, see the related sections in Operation Manual for OptiX iManager NMS.

3. Change NE's Network Parameters via the ECC Path

In case that you change network parameters such as GNE IP address on NM. It is



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likely that you perform improperly and this results in connection failure between NM and GNE. In this case, you may connect other NEs in the same network to the system, and then log in to the faulty station via ECC path to correct the network parameters.

4. ECC Problems in the Ring Network

1

2

3

4STM-NMain ringdirection

Figure 4-10 ECC problem in the ring network

As shown in Figure 4-10, suppose NE1 is GNE and connected to NM. If you want to log in to NE4, you may take the short path 1⇒ 4 or the long path 1⇒2⇒3⇒4. In a ring network, even if the short path 1⇒4 fails, you may take the long path to log in to NE4. Hence, you cannot decide if the ECC is normal according to if you can log in to the NEs. Rather, you should frequently view the ECC route via NMS and if you find that the ECC route takes the long path, you should locate and remove faults accordingly.

You can check NEs' alarm and performance on the short path to locate the fault. If you cannot form a judgment, you can close the SCC serial port of 1⇒2, and force the ECC to take the short path for further check, or you may disconnect the optical fiber of the long path at night for further check.

As to the uniform of the ECC, it refers that ECC path between NE1 and NE4 takes the direction of 1⇒ 4 or 1⇐ 4, that is, to transmit in the same optical fiber pair.



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4.5 Orderwire Fault

4.5.1 Introduction to Overhead Processing Unit

The orderwire telephone set of the OptiX 155/622H equipment is controlled by the overhead processing unit. In NMS, you can see the OHP2 board it employs.


Telephone is improperly set.

The data of overhead processing unit is incorrectly configured.

Faulty board -- optical interface boards, SCB board.

External factors -- power-off, broken fibers, and so on.


Replacement.

Alarm and performance analysis.

Configuration data analysis.

Experience.


To check the orderwire specific problem, follow the steps below:

Step 1 Check the optical path.

With blocked optical path, the orderwire telephone is blocked consequently. In the ring network, if only the optical path is connected in one office orientation (i.e. receiving and transmitting directions) between two stations, the orderwire telephone is connected.

Step 2 Check settings of the telephone sets at both parties.

In most cases, the orderwire problems result from improperly telephone set.

The ringing current switch "RING" on the telephone shall be put to "ON", thus the telephone rings when there is an incoming call.

The dialing mode switch should be put to "T", namely DTMF.

If there is no conversation, the telephone shall be in on-hook status, and the red indicator shall keep off at the upper right corner on the front side of the orderwire telephone. If the indicator is on, it means the telephone is not in on-hook status, and you should press the "TALK" button on the telephone. It is very common that the maintenance personnel press the "TALK" button accidentally and leave the telephone in off-hook status, thus stopping any incoming call.

The orderwire telephone set line is usually connected to the "PHONE" interface in



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the SCB board.

Step 3 Check the SCB board. If you always get the dialing tone when dialing, the SCB board may be faulty.

Step 4 Check the configuration of overhead processing unit. To perform this step, the maintenance personnel should be very familiar with the configuration of OptiX equipment.

Step 5 If you go through with the above steps but the problem yet persists, try to replace the SCB board.

Warning:

If you unplug a SCB board, that will interrupt the relative payloads! It is suggested that you do so at night when the traffic is not heavy. Never do so at will!

4.5.5 Common Orderwire Problems

(1) In case of normal line, if you cannot make a successful orderwire call even if you have tried many times, there may be a variety of reasons. If you get the busy tone immediately after you dial a number, the number may belong to this station. If you get the busy tone in 2–3 seconds, then the station you are dialing in may be in off-hook status. If you get the busy tone in a long time (exceeds the limit of the orderwire telephone response time, which is usually set to 5 seconds) after you dial a number, it usually means you are dialing a vacant number or dialing a faulty station. After you dial the conference number, if the station does not give conference tone, it means the conference number may be changed.

(2) If you get the dialing tone after dialing a number, first check to see if dialing mode switch on the telephone set is put to "T", which is a normal setting and means DTMF. If the orderwire telephone keeps giving the dialing tone when you dial a number, it means the overhead processing unit may be faulty.

(3) A blocked orderwire telephone may also arise from improperly configured logic subsystem of the equipment. Specifically, the option of enabling or disabling talk of the logic subsystem is incorrectly configured. If you get no tone, any whistle or other abnormal tone, you should check the equipment logic subsystem configuration of the orderwire telephone set.

(4) The orderwire telephone call is transmitted by overhead bytes E1 and E2. If station A can dial a conference number to station B, while addressing call is unsuccessful, it means the called party's overhead processing unit is faulty, for the conference telephone is based on the unidirectional signaling, while the addressing call on the two-way signaling.

(5) If the local telephone does not ring, but you can talk with the calling party when the set is off-hook, it means the orderwire phone does not ring when there is an



4-24

incoming call. Check if the ringing current switch "RING" is set to "ON."

(6) If the orderwire telephone gets the "No Tone" status, it may be a problem of either the overhead processing unit or the synchronous timing unit. In this case, you have to replace the SCB board.

The so called "No Tone" status refers that the telephone gives no ringing tone, no dialing tone or no ringback tone, but the outgoing call is normal and the called line can ring and hear voice; in the talk, the called party can hear the calling party', but the calling party cannot hear the called party.

(7) The line does not support two stations which have the same orderwire telephone number, or the orderwire telephone is blocked. All stations share one and same conference telephone number.

(8) In a conference call, many people talk at the same time, so the tone quality of the conference telephone is not as good as that of general addressing call.

4.5.6 Removal of Typical Orderwire Faults

(1) Telephone is improperly set

The network architecture is as shown in Figure 4-11. It is a 622 Mbit/s two-fiber unidirectional path protection ring with a 155 Mbit/s chain, composed of six 155/622H NEs.

1

23

45

6STM-4 STM-1

Figure 4-11 Networking system of typical case of orderwire problem

Number of the orderwire telephone in each station is as follows: NE1–101, NE2–102, NE3–103, NE4–104, NE5–105, NE6–201. The conference call number is 999.


When dialing an orderwire telephone number, equipment room personnel in NE6 always gets dialing tone but fails to make an outgoing call.

(3) Treatment steps

As viewed from the fault phenomenon, NE6 may suffer from the following: improperly configured overhead processing unit, faulty overhead processing unit, or faulty orderwire telephone set. Firstly check the configuration data of orderwire telephone set to find that the signaling selection switch (P/T) is put to "P", i.e. the pulse mode. However, in the configuration of overhead processing unit, the signaling mode is set as DTMF, thus the overhead processing unit does not acknowledge the pulse dialing signal. Consequently, the dial tone is always given when you dial a



4-25

number. Put the P/T switch to "T" and the fault is removed.

4.6 Equipment Interconnection Fault

OptiX series equipment boasts super performance and normalized interface. Its technical specifications are in conformity with the standards. Thus it has been widely used on the network. In fact, it has been proved that the OptiX transmission equipment can successfully interconnect itself to the SPC switching system, PDH, SDH, ATM switch, GSM, power monitor and so on of different manufacturers.

Due to diversified transmission services, the transmission equipment is confronted with various equipments with miscellaneous service requirements for the performance of the transmission path. Thus unsuccessful interconnection results from time to time in practice. Under the circumstances, you can check the corresponding check points mentioned in this section and use some experience accumulated in the daily work. In most cases, you will not take difficulty in handling the problems.


Wires and cables are improperly connected. For example, the optical fiber or cable is connected to an incorrect position.

Equipment grounding problem. It may be that one equipment has not been properly grounded, or that the two equipments are jointly grounded.

Clocks are out of sync. For example, clocks within the transmission or switching are in synchronization respectively, but clocks between the two networks are out of sync.

Definitions of overhead bytes in the SDH frame architecture are different.

Signals are transferred for too many times.



Meter test


Experience

Loopback

4.6.3 Fault Treatment Steps

1. Check for Correctness of Physical Connection of Equipment

Check to see if cables and optical fibers are properly connected between equipment and if there are faulty soldered joints, unsoldered joints, bad contact or especially misconnected cables. Misconnected cables will lead to much complicated situations on the switching equipment side and the transmission equipment side. In the first



4-26

place, ensure the correctness of physical connection.

Note:

The misconnected cables refer to a situation as follows: In the event that the 2 M trunk system of the switching network is connected with the OptiX transmission equipment. The transmit end of system A connects to a position where that of system B should connect, while the transmit end of system B is connected to the position where that of system A should connect. Under the circumstances, no T_ALOS alarm will be reported to the NM for the alarm only detects whether there is any signal, not whether the signal is correct.

In the course of engineering installation, all the cables should be carefully tested to make sure that they are correctly distributed and the cable connectors are of good quality. Software loopback should not be made of paths which have got payloads, and existing loopback should be undone, thus avoiding the improperly made loopback and consequently equipment interconnection failure.

If payloads of a switching system are to be cut over to the OptiX transmission equipment of Huawei from that of other manufacturers, attach tags properly to each trunk cable prior to the cut over to avoid cable misconnections.

Common methods: Experience and loopback.

2. Check Alarm and Performance Data

Checking the alarm and performance data on both interconnected equipment items will help locate a fault. For example, if the 2 M port of OptiX transmission equipment gets T_ALOS alarm, you can check if the cable is disconnected or if the receiving and transmitting cables of the same 2 M trunk are misconnected, to locate and remove the fault accordingly. In some cases, the 2 M interface of the OptiX transmission equipment keeps on generating and terminating the T_ALOS alarm, which means the 2 M trunk board of interconnected equipment keep being reset, as a result of improperly debugged interconnected equipment, bad quality of 2 M path provided by the OptiX transmission equipment, or misconnected cables.

In the event the transmission equipment provides a path of bad quality, bit errors may result. Some bit errors may be so slight as to result in noise in a talk, while others may be so serious as to result in bit slip or payload interruption. In maintenance, you can view the performance events of each board (path) via the OptiX transmission equipment NM, so as to decide the performance of the transmission path. In general, bit errors (LPBBE) monitored by the NM result from the transmission equipment itself, while those arising from the interconnected equipment or tested by the meter may be dependent not only on the bit error (LPBBE) in the transmission equipment, but also on faulty cables or faulty TU.

The path bit errors may be tested by meter off line or on line. The problem of bit errors tested in off-line mode is easy to handle, so we will not discuss it here. In the



4-27

event bit errors can be tested by meter on line but not off line, begin with checking if the path is properly connected to the DDF (for example, if there are any faulty soldered joints or unsoldered joints) and if the path reports the FIFO alarm and so on.

Generally, external signal input based reasons will not give rise to bit errors or alarms at LP or TU level in the OptiX transmission equipment.

3. Check the Grounding

The PGND hereafter refers to the protection ground and the BGND, power ground usually known as the work ground.

(1) Check the grounding and joint ground of both equipment items:

If the equipment is in bad grounding, that will directly affect not only the long-term stability of the operation of the OptiX transmission equipment, but also the interconnection between itself and other equipment. Common grounding problems include that the two interconnected equipment items are not actually in joint ground, that the BGND and PGND are misconnected, that resistance of BGND and PGND can not satisfy the requirements and that the DDF distribution frame is not grounded in conformity with the requirements.

Generally, the equipment room employs the joint ground. As to the stations which do not employ the joint ground, you should make careful test when installing the hardware. Before the OptiX transmission equipment is powered on, you can analyze by testing the resistance (with the OptiX equipment disconnected) between BGND and PGND copper connectors in the equipment room. After the equipment is powered on, you can make analysis only by testing the voltage. To check the joint ground of two interconnected equipment items, you can measure the resistance between grounding points of the two equipment items, or test if there is a potential difference between the two grounding points.

For those stations which suffer from frequently damaged equipment resulting from bad grounding, you should use an earth-resistance meter to measure if the ground resistance is in line with the values given in the specification. Please refer to the specifications for grounding of the transmission equipment in the equipment installation section.

In case of interconnection failure, mainly check if the equipment items are actually in joint ground. In many cases, unsuccessful interconnection arises from the fact that the two equipment items are not jointly grounded in fact.

(2) Check the grounding of the shielding layer of coaxial port.

For the external conductor (shielding layer) of 75 Ω non-balanced coaxial port, the common grounding method is that the transmitting end is connected to PGND and the receiving end is suspended (or connected to PGND). At present, the 2M port of the equipment (inc. OptiX transmission equipment from Huawei) from most manufacturers employs this method. However, as to the 2 M port of the equipment from some other manufacturers, the shielding layers of their receiving and transmitting ends are connected to BGND. If you use a multimeter to test the voltage between the shielding layer of the coaxial port and the equipment PGND, you may



4-28

decide in the main the method of grounding of the shielding layer of the coaxial port.

If the shielding layer is in bad grounding, potential difference and alternative interference may result from between BGND and PGND, thus affecting the waveform of the signal in equipment interconnection and accordingly leading to an unsuccessful interconnection.

Additionally, in case of unsuccessful interconnection, you should check if the shielding layers of coaxial port of two equipment items are consistent in grounding method. If not, you will have changed the grounding method of one equipment item, so that the two share the same grounding method. As a general rule, the change should be made to the equipment whose coaxial port uses the unconventional grounding method, where the shielding layer is connected to PGND.

You can also disconnect all signal lines between the interconnected equipment, and use a multimeter to measure the levels between the shielding layers of the coaxial ports of the receiving and transmitting ends of the OptiX transmission equipment on the one hand, and their counterparts in the other equipment on the other hand. If you get a great potential difference (0.5 V or above) between the two points, you should take it seriously and further decide if it results in the failure of the payload interconnection.

The 2M payload of 120 Ω balanced port is transmitted in the form of difference. In general, grounding specific problems will not affect the interconnection of this payload type.

Even if the equipment room employs the joint grounding, there may also be problems with grounding the shielding layer of coaxial ports. In some cases, the equipment room employs the joint ground method, but the shielding layers are grounded in different manners. This may result in interconnection problems.

Common solution: Meter test.

4. Check Network-wide Clock Synchronization

The switching equipment and GSM equipment from some manufacturers set strict requirements for the network-wide clock synchronization. After passing through the SDH transmission network, if the clocks of modular exchange and host exchange under the switching system are out of synchronization, this will give rise to the trunk bit slip, interruption of network-inward-dialing users, or even frequent interruption in talk. Be aware that, by the network-wide clock synchronization, we mean not only the clock synchronization within the SDH transmission network, but also a global clock synchronization of the switching network plus transmission network or the mobile network plus transmission network.

A network-wide clock out-of-synchronization does not necessarily mean a problem of the transmission equipment itself. Rather, it may be a problem of an unreasonably planned clock synchronization. For example, the switching equipment traces a timing source reference while the transmission equipment traces another, thus resulting in a certain deviation between the two network clocks. Under the circumstances, most switching and mobile equipment may operate properly, provided that the deviation between their synchronous clocks and those of the transmission network do not go beyond the tolerance for the equipment interface. On the other hand, some



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equipment has set strict requirements, where you should first make sure the clock synchronization of the transmission network composed of the OptiX equipment. If the problem persists, you may adjust the global clock synchronization mode of the local network, so as come to a network-wide clock synchronization. For example, you can make both the switching equipment and the OptiX transmission equipment of the host exchange trace the high-precision BITS clock signal, aim at improving the transmission performance of the system. Or, you can make the OptiX transmission equipment of the host exchange extract the clock from its TU's 2M input signal (2M signal from the switching system at the host exchange); other OptiX transmission equipment keeps in synchronism with the timing source reference; modular exchange of the switching system extracts the clock from 2M signal from the output of the OptiX transmission equipment. As a result, a network-wide clock synchronization comes true. Generally, in OptiX transmission network, NEs in the central station employs the internal timing source and other NEs trace this source reference. Thus it can satisfy the transmission requirements and after interconnected to most switching and transmission equipment, the OptiX transmission equipment can operate properly.

A variety of network applications have proved that, normally, the OptiX transmission equipment can successfully connect to various switching, GSM, access network equipment which currently operate in the network.

To see if the clocks in OptiX transmission network are in synchronization, you can view pointer justification performance events via NM. If there are a number of pointer justification events, it is likely that the OptiX transmission equipment itself has gone wrong. Therefore, you should troubleshoot the OptiX transmission equipment and then settle the problem otherwise.

If the transmission equipment operates properly and the interface waveform is normal when tested, you should check to see if the equipment connected to the OptiX transmission equipment has a problem with clock processing performance, which leads to the failure of the interconnection.

Moreover, you should be aware of the difference between timing signal transmission of PDH equipment and SDH equipment. The multiplex architecture of the PDH equipment employs the bit interleaved mode, which does nearly no damage to the transmitted timing signal. SDH equipment employs the pointer justification technology, unavoidably introducing jitter and wander into the transmitted timing signal and thus resulting in phase difference. As a result, the timing signal transmitted by the 2M path of the SDH equipment is theoretically inferior to that of PDH. Since the OptiX transmission equipment is the SDH optical synchronous transmission equipment, it is suggested that you do not transmit the 2 Mbit/s timing signal from tributary interface of OptiX. You can transmit the timing signal via the clock input/output port of the OptiX transmission equipment.

Common solution: Configuration modification.

5. Check the Waveform

The signal waveform may be deformed and distorted. A severely deteriorated waveform may provide incorrect information, and thus the receiving equipment at both ends will form incorrect judgments. This is one of the major reasons for



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unsuccessful interconnection.

Usually, the waveform distortion stems from the fact that the interface resistance is a mismatched one, that the signal grounding is not in line with the requirements, that the signal is greatly interfered in transmission, or that trunk cable is too long.

To test the waveform, you can use the off-line (payload will be interrupted) or on-line method. In case of off-line test, first loopback in the distribution frame the signal (e.g. 2 Mbit/s signal) of the OptiX transmission equipment, and then use an oscilloscope to test the waveform via the test hole in the distribution frame. If the waveform is normal, which means the input and output signals of the OptiX transmission equipment are normal. If they are abnormal, replace the relative board. And then use the same method to test the waveform of the opposite equipment.

If the waveform is normal when tested after the loopback of both equipment items, interconnect the two equipment items. And then test the after interconnection waveform on line in the distribution frame to see if the after interconnection waveform outputs are normal at both parties. If the waveform is abnormal, go on with investigation and analysis of abnormality.

Due to the grounding method (suspended or PGND) of the shielding layers of coaxial electrical interface of receiving ends of the interconnected equipment, the signal waveform monitored in interconnection may vary. In general, this will not affect the interconnection.

Common solution: Meter test.

6. Check the Cable Distance

As a rule, the 75 Ω 2 Mbit/s trunk cable can transfer for more than 200 meters. However, if the trunk cable distance is too long, it will result in an unsuccessful payload interconnection, which takes the form of blocked payload or payload with frequent interruption. The reason is that in some cases, if the trunk distance is too long, it will suffer from mismatched resistance, interference, reliability of the opposite equipment and so on, thus giving rise to waveform distortion of the 2M interface and payload interruption when the interference is great. Moreover, if a cable is too long, it may travel a complicated route, catching external interference (e.g. alternative current interference) and thus distorting the waveform.

To offset these influences, you can add a resistance in the opposite input interface to match the network. As a result, it is likely that the waveform and payload are recovered. Taking for example, you can add a resistance of 25 Ω or so to the cable core of the opposite equipment, or you may additionally add a capacitance of dozens of PF in parallel with the resistance.

Note: In case of interconnection made with some GSM base station or PDH equipment, if you use a very long cable (for example, longer than 50 m), you should check to see if the interconnection deterioration results from the distance.

Common solution: Experience.

7. Check if the Signal Is Transferred Too Many Times

The transmission network has been developing by leaps and bounds. Manufacturers



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are providing diverse transmission equipment, and users are using them miscellaneously. Thus it is unavoidable that a certain payload will be transmitted by equipment of different types or different manufacturers.

It is no wonder that unsuccessful interconnection arises from too may transfers from time to time, for many reasons such as out-of-synchronization between clocks of the transmission equipment of different manufacturers, distortion of signal after too many transfers and so on. In general, this situation is very different to deal with. You can check the waveform to locate and remove the problem section by section.

8. Check the Opposite Equipment

In some cases, an unsuccessful interconnection may result from the fact that opposite equipment has not passed the proper debugging test, or that the equipment has a certain problem. However, you are not as familiar with the equipment as to locate such faults. Under the circumstances, you can, if possible, connect the suspected faulty 2 M path of the opposite equipment to an originally good 2 M path of the OptiX transmission equipment, to decide the faulty equipment.

4.6.4 About STM-N Optical (Electrical) Interface Interconnection

Note that the interconnection between the OptiX transmission equipment and ATM switch cannot be made via the 622 Mbit/s optical interface, for the 622M architecture of ATM is VC-4-C (cascade architecture) instead of multiplex structure of SDH. On the other hand, successful interconnection can be made with the 155 Mbit/s payload. In the event of interconnection, J1 and C2 bytes can use the default values, when the HP_TIM (higher order path tracing identifier mismatch) or HP_SLM (higher order path signal label mismatch) alarm may result. However, this alarm will not affect the payload. To remove this alarm, you will have to unify the configuration of J1 and C2 bytes of the two equipment items.

Generally, the OptiX transmission equipment can be successfully interconnected with other SDH equipment via the STM-N optical (electrical) interface. If any problem results, you can connect a 2M bit error meter to the 2M interface of the opposite SDH transmission equipment, interchanging the line signals. First set the LU of the OptiX transmission equipment to regenerator section outloop. If the meter displays normally, then select the multiplex section outloop to see if the meter displays properly. If the payload is abnormal, that may arise from the fact that the opposite equipment may have set some overhead bytes of the multiplex section and thus that when receiving STM-N signal from the equipment of other manufacturers, the multiplex section inserts AIS in the downstream circuit. In this case, you can mask this setting to interchange the payload. This calls for cooperation from the opposite company.

Some of the steps above may be very complicated, and they usually need to be performed under help and guidance of technical support personnel from Huawei.

Note additionally that modes of effecting the multiplex section protection of the transmission equipment from different manufacturers are incompatible. Consequently, interconnection of the multiplex section protection of the equipment of different manufacturers can not be made in general.

Independent of protection protocols, unidirectional path protection and subnetwork



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connection protection of the equipment from different manufacturers are usually compatible.

4.6.5 Typical Case of Equipment Interconnection

1. System Overview

The transmission network in ABC area employs the OptiX 155/622H. The network is an unprotected chain contains seven OptiX 155/622H stations, as shown in Figure 4-12. The local exchange 1 is the GNE, connected to NM terminal. Other stations have payloads only with the local exchange. The synchronous source of NE1 is the internal timing source. Other stations trace the timing source reference.

The OptiX transmission equipment of NE1 is connected to the access network host exchange from Q company. The OptiX transmission equipments of other stations are connected to the access network's remote access module from Q company.

1567 2 3 4

Local exchange Figure 4-12 Networking system

2. Fault Phenomenon

When the trunk circuit of the remote module of the access network of Number 3 branch exchange is switched over from the original PDH equipment of Q company to the OptiX transmission equipment of Huawei, network-inward-dialing users in Number 3 branch exchange are found to be abnormal, with too low connection rate and frequent off-line.

3. Fault Analysis and Location

(1) Check the OptiX transmission equipment, which operates properly with each index meeting with the requirement.

(2) Check the grounding of the OptiX transmission equipment and access network equipment. Everything is normal and nothing is found to be relative to the off-line problem of data users.

(3) We suspect that the fault may result from the clock coordination of the OptiX transmission equipment and the access network equipment.

4. Fault Removal Steps

(1) Change the clock tracing source of the OptiX transmission equipment for the tributary timing source. Specifically, the OptiX transmission equipment extracts the timing signal from the 2 M trunk of the access network equipment of the local exchange and takes the signal as the timing source reference of the OptiX transmission network; the remote module of the access network extracts the timing signal from the 2 M output signal of the OptiX transmission equipment. As a result, the network-wide clock synchronization of the switching network and transmission



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network is effected. However, the data users still cannot log in the network.

(2) Connect the OptiX transmission equipment in the local exchange to the BITS equipment, so that the OptiX transmission network traces the external timing source, thus improving the clock performance of the whole transmission network. However, the fault persists.

(3) View the payload cut-over in retrospect, the access network engineers deleted in software the trunk data that correlated the host exchange to Number 3 branch exchange. At the same time, disconnect the local exchange the trunk cable and the physical connection of the PDH equipment from the access network equipment of the local exchange to Number 3 branch exchange. However, the physical connection of the trunk cable between the remote module of Number 3 branch exchange and the PDH equipment is not disconnected. As a result, PDH's AIS all "1" code is transferred to the remote module, and the Number 3 branch exchange extracts the clock (the clock tracing line of the remote module was plugged in the DT trunk board which had physical connection with the PDH) from the AIS code, resulting in out-of-synchronization between clocks of remote module of Number 3 branch and the OptiX transmission equipment and consequently the above problems.

(4) In No.3 branch exchange, completely disconnect the trunk cable between the PDH equipment and the remote module of access network of Q company, and simultaneously connect the clock tracing line to no DT trunk board. Then make log-on test and find everything is normal and the fault removed.

5. Summary and Suggestions

As a result of the off-line problem of the network- inward -dialing user, we come to three conclusions as the following:

(1) The above problems are independent of the quality of the equipment in interconnection.

(2) The above problems are independent of the introduction of BITS clock signal.

(3) The fault arises from the fact that the clock tracing error in branch exchange 3 results in out-of-synchronization between the branch exchange equipment and host exchange.

From the above case, we can sum up the experience of equipment grounding as follows:

(1) Ensuring the synchronization of switching network and that of SDH transmission network is a prerequisite for normal equipment interconnection.

(2) The network-wide (inc. switching network and transmission network) clock synchronization is one of the effective methods of solving the interconnection based problems.

(3) The introduction of BITS clock into the transmission network has improved the performance of the transmission network clock. It is also an effective measure in dealing with the interconnection problem of the equipment.



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4.7 Ethernet Interconnection Fault

Ethernet interconnection refers to the interconnection between the Ethernet interface board of the OptiX 155/622H equipment and other equipments, including OptiX Metro series equipments and Ethernet switch. The rate of the Ethernet signals in the interconnection can be 10Mbit/s and 100 Mbit/s.

The Ethernet interface boards of the OptiX 155/622H include ET1, ET1D, EF1 and EFS. The troubleshooting while ET1 boards are interconnected is introduced here.

4.7.1 Ethernet Interface Board and Configuration

1. Working Mode of Ethernet

(1) Processing of the Ethernet service signal on the OptiX 155/622H

Processing of the Ethernet service signal differs on different Ethernet interface boards. The ET1 board of the OptiX 155/622H is taken as an example in the following description.

After the Ethernet service signals access the ET1 board, they are encapsulated into each VC-12 as packet after segmentation and reassembling of the Ethernet frames. Then, they are sent to the cross-connect unit after being multiplexed and mapped into VC-4 for service timeslot allocation. Finally, the signals are sent to the line board.

(2) Fixed mode and auto-negotiation mode

Ethernet at different rates can not be interconnected. It is necessary to set the same Ethernet rate of the interconnected equipments before interconnection.

The Ethernet auto-negotiation mechanism is generated for automatic interconnection of the Ethernet equipments. It allows the equipments at both ends of the physical link to exchange information and then select a best operation mode supported by both parties. Contents to be selected in this mechanism include duplex mode, running rate and flow control. Once the negotiation is accepted, equipments at both ends of the link will be locked to such an operating mode.

When auto-negotiation mode is adopted, the interconnected equipments are required to use the same mode at the same time.

(3) VLAN mode and Tag

VLAN, Virtual Local Area Network.

Compared with Ethernet frame, the 802.1q VLAN frame is added with a 4-byte 802.1q frame header in the source address of the frame header. The 4-byte 802.1q tag header contains a 2-byte Tag Protocol Identifier (TPID) and a 2-byte Tag Control Information (TCI).

Port whose attribute is Tag can identify packets containing Tag labels, in which twelve bits are used for identifying the VLAN ID.



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2. Parameter Setting

(1) Flow Control

When the flow from the interconnected equipment exceeds the bandwidth capacity of the OptiX 155/622H, the OptiX 155/622H will send flow control packet to the interconnected equipment. The flow of the interconnected equipment is controlled, and the normal operation of the equipment is ensured and loss of packets is avoided.

(2) Binding and bound path

Binding means that designating a binding number to identify the VC-4s for the same virtual concatenated service when virtual concatenated services are configured. Once one of the bound VC-4s has a fault, all the VC-4s bound will be switched as a whole.

Bound path refers to the 2M paths bound together for transmitting Ethernet data. It is an entity between the Ethernet port and 2M path for future routing and convergence.

There are eight Ethernet ports on the ET1 board, and the number of bound paths configured for each ET1 board can be up to 16. Number of the VC-12s for each bound path can be configured. Since the maximum number of VC-12s provided by an ET1 board is 48 in networking application, a bound path can be configured with 48 VC-12s at most.

NM system entry: (Main View/Configuration/Ethernet Configuration/Ethernet Interface Management/Bound Path)

Note:

Number of E1s contained in the bound path at both the interconnected ends must be the same. Otherwise, it will cause loss of Ethernet data.

(3) Port enable

It sets the port to work or not. Port enable means the port can receive/transmit packets, while port disable means the opposite.

NM system entry: (Main View/Configuration/Ethernet Configuration/Ethernet Interface Management/Port Enable)

(4) Tag port

If an Ethernet port can identify and transmit packets with 802.1q tag headers, it is regarded as Tag port. Otherwise, it is considered as UnTag port.

Port set as Tag can identify packets with 802.1q tag headers only, and those packets with no such headers will be discarded.



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Port set as UnTag takes all the packets as ordinary ones that can pass itself no matter they carry 802.1q tag header or not. Also, the UnTag port will detach the 802.1q tag header from the packets and transform them into ordinary ones when it sends out packets with such tag headers.

NM system entry: (Main View/Configuration/Ethernet Configuration/Ethernet Interface Management/Tag Identifier)

Note:

If the interconnected equipments do not support the 802.1q tag header, such as computers we use at present, attributes of their Ethernet ports must be set to UnTag.

In convergence networking mode, Tag attribute of the convergence port must be set to Tag.

(5) Transmission rate

According to IEEE standard, transmission rate of the Ethernet port falls into 10Mbit/s, 100Mbit/s and 1000Mbit/s.Ports with different transmission rates have different clock rates and encoding modes, which determines that ports with different rates can not be interconnected.

(6) Half-duplex and full-duplex

Port in half-duplex mode can not receive and transmit packets at the same time, whereas port in full-duplex mode can.

NM system entry: (Main View/Configuration/Ethernet Configuration/Ethernet Interface Management/Working Mode)

Note:

The interconnected equipments must be set with the same working mode. Otherwise, when one Ethernet equipment in half-duplex mode interconnects another in full-duplex mode, loss of packets will occur since the Ethernet port in full-duplex mode does not detect the collision or re-send the data. The heavier the traffic, the more packets will be lost, even resulting in network breakdown consequently.

(7) Auto-negotiation mode

It is used to set working mode for the Ethernet port (e.g., 10Mbit/s half-duplex, 10 Mbit/s full-duplex, 100 Mbit/s half-duplex and 100 Mbit/s full-duplex). When the ports



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are set to auto-negotiation mode, through the negotiation information sent between the two interconnected ports, the highest working mode (e.g., 10 Mbit/s full-duplex) is negotiated to be supported by both ports at the same time.

NM system entry: (Main View/Configuration/Ethernet Configuration/Ethernet Interface Management/Working Mode).

Note:

Once ports of the interconnected equipments are set to auto-negotiation mode, ET1 board of the OptiX 155/622H should also be set to the same mode. Generally, ports at both ends are required to be set with fixed mode, i.e., with the same rate and in duplex mode. Auto-negotiation mode is not recommended.

(8) Default VLAN of port

Board can add port default VLAN for the packets entering the port. The default VLAN of port is closely related to Tag attribute. When attribute of the port is set to Tag, this parameter is meaningless. However, when the port is set to UnTag, the board can add port default VLAN for the packets entering the port.

NM system entry: (Main View/Configuration/Ethernet Configuration/Ethernet Interface Management/VLAN ID)

Note:

In convergence networking mode, VLAN ID is required to be set when attribute of the non-convergence port is set to UnTag. Meanwhile, the default VLAN set at each port should be different.

(9) Static routing

It refers to the mapping relationship between the Ethernet port and bound path. Type of the static routing includes port route and VLAN route.

Port route is the one configured between the Ethernet port and bound path port, usually applied in point-to-point networking communication.

VLAN route is the one configured between the Ethernet port and bound path port based on VLAN service. This kind of routing can be flexibly applied in point-to-point, point-to-multipoint and multipoints networking communications. VLAN route can be fulfilled through branching and convergence of data flows according to VLAN label of the packet.



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NM system entry: (Main View/Configuration/Ethernet Configuration/Static Routing Management)

Note:

Index number of static routing can not be identical.

When configured as VLAN route, the VLAN configured is required to be the same as the port default VLAN, or as the VLAN of packet entering the port (when content of that packet is pre-known).

4.7.2 Common Faults and Causes

The following are faults frequently occurring to Ethernet interconnection:

The interconnected service is blocked;

The activated service is abnormal, for example, the network access speed is low, the equipment delay is great or loss of packet and data error in received/transmitted packet.

Common causes for such interconnection faults are shown in Table 4-3.

Table 4-3 Common cause for equipment interconnection fault

Fault type Cause

Cable or fiber is in poor contact.

Cable or fiber connection error.

Ethernet cable is in use.

Attenuation of the interconnected signal is too much or does not meet the specifications.

Service configuration of the interconnected equipment error.

Interconnected equipment fault.

Transmission length of the network cable or optical fiber exceeds that stipulated in specifications.

Transmission of the network cable is affected by serious ambient electromagnetic interference.

Negotiation between equipments at the two ends failed. Broadcast storm.

External causes

Optical interface selection for the interconnected equipments wrong (single-mode or multi-mode).



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Fault type Cause

Attribute of the port is set incorrectly (Tag attribute and default VLAN).

Route configuration error.

2M numbers bound by the bound paths at the two ends are not consistent.

Rates of the interconnected signals are different.

Working modes of the interconnected signals are different (full-duplex or half-duplex).

Ambient temperature or subrack temperature is too high.

Ethernet board fault.

Physical features of the optical interface are abnormal (transmitting optical power is too low or jitter is too much).

Service configuration at SDH part error.

Equipment causes

SDH fault (line board or cross-connect board fault, switching failed, bit error in line, etc.).

4.7.3 Common Methods for Fault Localizatio

1. Testing Instrument

The ping command is frequently used for testing the Ethernet service.

Procedure: Configure a connection with the Tag attribute of ports at both ends set to UnTag. Connect a PC to the user access port of each end and set the two PCs in the same network segment. Then use the ping command to ping IP addresses of the other PCs.

Length of the ping packet is required to be within 64 ~ 10000 bytes. If the ping test is successful, the equipments are proved normal.

If there is only one PC, use the following method:

Connect the PC to one of the ports of the Ethernet board at this station.

Connect one port of the Ethernet board at opposite station to the Ethernet interface of the SCC board at the same station.

At this station, use ping packets with different length to ping IP address of the opposite station.

Note that the Ethernet board should be set to 10Mbit/s half-duplex or auto-negotiation mode at this moment.



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2. Loopback

When method of loopback is adopted for locating Ethernet interconnection fault, MAC layer loopback, E1 tributary loopback, VC-4 external loopback and optical interface loopback is performed in turn generally.

Usually, this method is used together with ping command. That is, first set loopback for the port as required, then ping any of the IP addresses. View the packet increase through performance events counted at the port. If the received and transmitted data of one packet do not synchronously increase, it indicates something is wrong with where loopback is performed.

3. Comparison

Perform the same operation at the same time and in the same place with the same configuration to determine whether the transmission equipment or Ethernet interconnected equipment is faulty.

Procedure:

(1) Connect two local PCs through the crossover cable and perform the ping test. Keep record of the result.

(2) Configure two Ethernet routes on the transmission equipment. Then cascade them at the remote station of the equipment. (i.e., configure a route from VC-Trunk to VC-Trunk or perform hardware loopback at the Ethernet port)

(3) Connect the two PCs in step (1) to the two Ethernet ports configured in step (2) respectively and perform the same ping test as that in step (1).

OptiX 155/622H OptiX 155/622HPC 1

PC 2

Figure 4-13 Connection method for ping test

(4) Compare the ping test results in steps (1) and (3). If there is difference in order of magnitude, it means the problem is with the transmission equipment.

4.7.4 Procedures

Troubleshooting flowchart for Ethernet service unavailability is shown in Figure 4-14.

Troubleshooting flowchart for Ethernet service abnormity is shown in Figure 4-15.



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结束

Remove SDHproblem

Y

N

N

Contact TechnicalSupport, Huawei End

Transmission networkmanagement system

SDH service abnormal?

Any ETH_LOS alarms?

Ethernet serviceconfiguration error?

Port attributeconfiguration error?

Fiber/Cable connectionabnormal?

Use loopback to determinewhether the equipment at this

end is faulty

Interconnectedequipment failed?

Continue local stationfault location orreplace board

Configuration error of Ethernet-related SDH parameters and

SDH services?

Virtual path and static routingconfiguration error?

Troubleshooting Ethernetservice blocked

Any SDH alarms on NE?

Interconnection faultremoved?

1

2

3

5

4

6 Handleinterconnected

equipment

Type of fiber/cablemismatch?

Optical power abnormal?

Any such alarms oninterconnected equipment?

Remove SDHservice fault

Connect the fiber/cable again

Replace with correctfiber/cable

Clean opticalconnector and check

fiber jumper

Handleinterconnected

equipment

Re-configure portattribute

Re-configure virtualpath and static

routing

Re-configure theSDH configurationrelated to Ethernet

N

N

N

N

N

N

N

N

N

Y Y

Y

Y

Y

Y

Y

Y

Y

Y

N

N

Y

Y

Y

N

N

N

Continue nextcondition

Figure 4-14 Troubleshooting for Ethernet service unavailability



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11

2

N

结束

23

14

Y

N

11

Interconnectionfault removed?N

End

14

Transmission networkmanagement system

TroubleshootingEthernet service abnormity

Any SDH abnormalalarms on NE?

Test whether the SDHservice is abnormal

Any abnormalperformance events?

Port setting andvirtual path error?

Ethernet cableis faulty?

Length of network cablebeyond specifications?

Extra high attenuation ofinterconnected signal or

specifications non-compliance?

Ambient electromagneticinterference serious?

Physical features of opticalinterface abnormal?

Remove problem ofSDH equipment

Remove SDHproblem

Remove SDHproblem

Make Ethernet cableaccording tospecification

Add relays

Check input signal ofinterconnected

equipment

Replace withshielded cable

Replace the board

Perform loopback testto confirm if localequipment is faulty

Remove problem ofinterconnected equipment

Remove the problembased on the localizationor replace the board

Continue nextcondition

Contact TechnicalSupport, Huawei

N

N N

N

1515

N

N

N

Y

Y

Y

Y

Y

Y

YY

Y

Y

N

Figure 4-15 Troubleshooting for Ethernet service abnormity

1. Check SDH Alarms and Services

When fault occurs to Ethernet services, check whether the SDH service is normal and whether there are SDH alarms through the NM system first.



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2. Check and Analyze Performance Event

Generally, the OptiX 155/622H will report performance event when the Ethernet service is abnormal. Table 4-4 lists the relation between the performance events and fault causes.

Table 4-4 Performance events and causes

Performance event Cause

RXCRC (packet containing CRC error received),

RXBBAD (incorrect packet received),

RXSCRC (wrong short packet received)

RXLCRC (ultra-long packet containing CRC error)

Working modes of the ports mismatch, board fault

Txcol (collision number during transmission)

Txxcol (number of datagrams exceeding 16)

Working modes of the ports at both ends are inconsistent.

Txscok (packet transmitted correctly after one collision),

Txmcok (packet transmitted correctly after multiple collisions)

Txlc (number of packets stopped due to late collision)

Working modes of the ports at both ends are inconsistent.

Rxpause (flow control packet correctly received) Flow sent to the interconnected equipment is too big.

Txpause (flow control packet correctly transmitted) Flow transmitted by the interconnected equipment is beyond the equipment bandwidth.

Txerr (number of packets transmitted due to underflow error) and TXBBAD (report of byte number transmitted incorrectly)

Board fault

4.7.5 Classified Fault Localization and Handling

1. Board service configuration

Check the configuration and perform the configuration according to data setting specification. Table 4-5 lists the setting requirements for Ethernet configuration items in different networking mode.



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Table 4-5 Configuration items and requirements

Configuration requirement Configuration item Transparent transmission

networking Convergence networking

Port enabling

External ports at both ends need to be enabled.

External ports at both ends need to be enabled.

Port working mode

Consistent with that of the interconnected equipment.

Consistent with that of the interconnected equipment.

Bound path Keep the number of virtual paths bound at both ends the same, and keep the E1 resources in the virtual paths the same.

Number of virtual paths bound at both ends should be the same, so should the E1 resources in the virtual paths. (The number of convergence points shall be the same as that of virtual paths created.)

Port Tag attribute

Tag attributes of the interconnected virtual paths should be set the same. External ports at both ends should be set according to attribute of the interconnected equipment.

Tag attribute of the interconnected virtual path should be set to Tag, so should the port at the convergence side. Port at the non-convergence side should be set according requirement of the interconnected equipment.

Port VLAN ID

It is related to port Tag attribute described above. If Tag attribute of the port is set to Tag, the VLAN ID is invalid. If that of the port is set to UnTag, the VLAN ID can be chosen freely.

It is related to port Tag attribute described above. If Tag attribute of the port is set to Tag, the VLAN ID is invalid. If that of the port (generally the non-convergence point) is set to UnTag, it is necessary to distinguish the VLAN of each port from each other.

Static routing

It can be configured as port route or VLAN route.

When configured as port route, no requirement is for it.

If configured as VLAN route, it is related to the VLAN ID described above. The VLAN in the route is required to be consistent with the port VLAN ID described above or with the VLAN ID in the accessed packet.

The non-convergence point can be configured as either port route or VLAN route. But the convergence point can only be configured as VLAN route. Also, the VLAN in the route should be kept consistent with the default VLAN ID of the port at non-convergence point.

Flow control setting

Set it according to the requirement for the interconnected equipment.

Set it according to the requirement for the interconnected equipment.



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2. Signal Rate and Duplex Mode

The service is blocked if rates of the interconnected signals are different (10Mbit/s at one end and 100Mbit/s at the other end, for example).Adjust the signal rates of both ends to the same level and the duplex modes at the two ends the same, too.

3. Connection of Fibers and Cables

Check whether connection of the fibers and cables is correct and reliable, whether the fibers are over-bent or tightly bound.

4. Optical Power

Measure the received and transmitted optical power of the Ethernet optical interface. If they are out of the standard range, check the fiber attenuation or clean the optical interface with fiber paper.

5. Fiber Mode and Cable Type

Check whether the single-mode fiber and multi-mode fiber are mixed in use. Fiber of the same mode should be used for the optical interfaces and connection of the interconnected equipments.

6. Network cable

Check whether application of the crossover cable and straight-through cable is correct. Use crossover cable when the Ethernet board interconnects the PC, while use straight-through cable when the Ethernet board interconnects the HUB.

The pinouts of the above kinds of cables should be correct. Note that connectors 1 and 2 use one twisted-pair, and connectors 3 and 4 use the same twisted pair.

The network cable falls into shielded cable and unshielded cable. The shielded cable features strong resistance against the electromagnetic interference. It is recommended when there is too much ambient electromagnetic interference for the equipment.

Check whether length of the network cable exceeds its maximal transmission distance. Generally, the network cable made by regular manufacturers can transmit Ethernet signals with no attenuation within 100m. If longer transmission distance is required, relays are needed.

7. Ambient Temperature

Check whether air conditioner of the equipment room and the subrack fans work normally, and whether the board temperature is too high.

8. Board

If specifications of the board are tested to be not standard, replace the board.

Method of loopback level by level can also be used to localize the fault. For example, if the 2M loopback is normal while the VC-4 loopback is not, it can be determined that the line board is faulty.



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4.7.6 Common Troubleshooting Cases

1. Service Unavailability Caused by Port Settings Mismatch

(1) System overview

Two OptiX 155/622H NEs form a two-fiber bidirectional unprotected chain in a certain networking application, as shown in 错误！未找到引用源。.Users access the network through the ET1 board.

NE1 NE2OptiX 155/622HPC PCOptiX 155/622H

Figure 4-16 Networking diagram

(2) Fault

Users report network access problems. Query the NM system, but there is no alarm information. Connect two PCs to the two ends and perform ping test, but failed.

(3) Troubleshooting

Check the hardware such as connection network cable, PC and fiber jumper first, but no problem is found.

Check the configurations such as virtual path setting, route setting and working mode of the port. It is found that working mode setting of the Ethernet interface is incorrect. The PC supports data at rate of 10 Mbit/s only, but the working mode of port on the ET1 board is set to 100 Mbit/s and full-duplex. After modifying the working mode of the port, the ping command shows that they are connected. And the service is restored to normal.

(4) Conclusion and suggestion

When interconnecting equipments, port working modes of the equipments at the two ends should be set the same. For example, if the opposite end is set to fixed working mode (100 Mbit/s and full-duplex, for instance), this end should be set the same; If the opposite end is set to auto-negotiation, set the same for this end.

2. Service Unavailability Caused by Bound Virtual Paths Mismatch

(1) System overview

A transmission network is composed of the OptiX 2500+ and the OptiX155/622H. 10 × 2 Mbit/s Ethernet services are bound for the central station, OptiX 2500+ and another station on the ring, OptiX155/622H.

(2) Fault

Users report that they can not access the network. Perform ping test to the two PCs and find that they are unreachable to each other.



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(3) Troubleshooting

Step 1 Query alarms in the whole network, but no abnormal ones are found. It means the 2 Mbit/s service is normal.

Step 2 Check settings of working mode and attribute of the interconnected transmission equipments with problem of service unavailability and those of the Ethernet port at the switch side, no problem is found.

Step 3 Connect the OptiX 2500+ at central station to the switch side. Then, connect a portable PC to the OptiX 155/622H at this station and ping IP address of the opposite switch, succeeded. Besides, there is no problem with the ping test to the domain name server (DNS).

From the above we can learn the network is normal. The possible reason for user service unavailability is that transmission rate of the Ethernet service is too low.

Now, if the Ethernet cables at both ends are confirmed to be normal, we can focus on the service configuration. Through checking, it is found there are 11 × 2 Mbit/s paths bound at the central station OptiX 2500+, while only 10 × 2 Mbit/s paths at this station OptiX 155/622H. Set the bound paths at both ends to 10 × 2 Mbit/s, then the fault is removed.


Generally, the Ethernet service unavailability is caused by the following reasons:

Working modes mismatch of the Ethernet port and the router or switch side.

Incorrect Tag attributes setting of the Ethernet port or bound path port of the ET1 board.

Incorrect Tag attributes setting at the switch side.

Ethernet cable is faulty.

Inconsistent configuration of the virtual paths bound at both ends.

3. Loss of Packets Caused by Network Cable Mismatch

(1) System overview

A telecom office uses ET1 board of the OptiX 155/622H to interconnect the Ethernet switch of company C.

(2) Fault

During interconnection, the Ethernet indicator of the Ethernet board in the OptiX 155/622H, there is no alarm. The Ethernet indicator on the switch of company C is on and off in turn. Many packets are lost in ping

(3) Troubleshooting

Step 1 The problem should be with the level detection since the Ethernet indicator of the interconnected equipment keeps on and off continuously. It has nothing to do with the service configuration. otherwise, the Ethernet indicator will not be ON.



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Step 2 Check pinouts of the network cables and find they are not the standard ones.

Step 3 After replacing the cables with ones with standard pinouts, the fault phenomena disappear and no packet is lost in the ping operation. The delay is 3–4 ms.


The making of the network cable must meet the related specifications.

4. Service Unavailability Caused by Fault of Interconnected Equipment

(1) System overview

Two OptiX 155/622Hs are adopted in a transmission network to form a chain. One ET1 board is configured to each NE respectively, through which, NE1 interconnects the ATM switch of Company B, and NE2 interconnects the 8-port layer 2 switch of Company A, as shown in Figure 4-17.

NE1 NE2

OptiX 155/622HATM switch Layer 2 switchOptiX 155/622H Figure 4-17 Networking topology

(2) Fault

The signals of the interconnected equipment can not access the network after passing through the OptiX 155/622H, and the service is blocked. No alarm occurs.

Connect the third port of the layer 2 switch to the first port of ET1 board of the OptiX155/622H through straight through cable, and connect a portable PC to the fifth port of the same switch to perform the ping command test, failed.

(3) Troubleshooting

Step 1 Check the network cable and no problem is found.

Step 2 Connect the switch of Company A to that of Company B directly through the UPLINK port with straight through cable. Then, connect the former with portable PC. Network access is normal.

Step 3 Connect the switch of Company A to the first port of ET1 board of the OptiX 155/622H at NE2, and connect the switch of Company B to that at NE1. Then, connect portable PCs to both ends of the switches. The ping command test is successful.

Step 4 Connect NE1 with switch of Company B and NE2 with portable PC. The ping command test is successful. With correct IP address set, the network can be accessed normally.

Step 5 Used the ping command to find the switch address of Company B section by section and find there is no problem with the network cable of each section. Then, the setting of switch of Company A is suspected to be incorrect.



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Step 6 Check service configuration and port attribute of the OptiX equipment, no problem is found.

Step 7 Consult the technician of Company A and learn a VLAN is set separately for each of the eight ports of the switch before delivery. As the ports are isolated, communication among them can only be fulfilled through the UPLINK port.

Step 8 Replace the cable connecting the OptiX equipment and switch of Company A with crossover cable. The connection is established through the UPLINK port. Connect portable PC to any of the switch ports second through eighth. The network can be accessed normally.


Connect portable PC to the first port of ET1 board of the OptiX equipment, the portable PC can be connected to the switch of Company B at NE1 normally through the OptiX equipment, and the network can be accessed normally. Therefore, there must be no fault with the OptiX equipment, but with switch of Company A.

5. Service Blocked Due to INCORRECT ET1 Board Setting

(1) System overview

A metropolitan area network (MAN) adopts eight OptiX 155/622Hs to form a bidirectional MSR. ET1 board is used to add/drop Ethernet services, and its interconnected equipment is router.

(2) Fault

The Ethernet service is blocked, and the board has no alarm.

(3) Troubleshooting

Step 1 Check the network connection, no problem is found.

Step 2 Check type and pinouts of the network cable to be correct.

Step 3 The interconnected equipment is also all right.

Step 4 Then, check port attributes of the OptiX equipment and the interconnected equipment. It is found that their Tag attributes are not the same. After modifying Tag attribute of the OptiX equipment to UnTag, the fault is cleared.


As the interconnected router does not support 802.1q protocol, port of the OptiX equipment must be set to UnTag to normally transmit/receive packets when interconnected with the router.

It is important that port attribute of the equipments should be kept consistent in the interconnection.

6. Slow Network Access Speed Caused by ET1 Board Fault

(1) System overview

The OptiX 155/622H is adopted by a transmission network to form a two-fiber



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bidirectional unprotected chain. ET1 board is used to interconnect Ethernet switch for Ethernet services transmission.

(2) Fault

User reports that the network access speed is quite slow, but no alarm information is there.

(3) Troubleshooting

Step 1 Connect the Ethernet switch to equipment of other manufacturer for test. It is found that the network access speed increases obviously. Then, it can be confirmed that the Ethernet switch is normal.

Step 2 Check the network cable and Ethernet port settings of the Ethernet switch and OptiX equipment, no problem is found.

Step 3 Perform inloop at the MAC layer of NE2, and modify service of NE1 to be IP1->MP1 and MP1->IP2 unidirectionally. Then, send signals from IP1 to the opposite end IP2, and test the returned data with SMARTBITS 600. In the test for stability, number of packets transmitted is the same as that received and no packet is lost (with the flow control enabled). In the test for throughput, it is found that the throughput is 60% when the frame size is 64 bytes, whereas the normal value is 100%; and the throughput is 48% when the frame size is 1518 bytes, whereas the normal value should be above 90%.

Step 4 Set inloop at the line port of NE1 for port test, and find the throughput is normal and there is no alarm on the line. So, the ET1 board at NE2 is suspected to be faulty.

Step 5 Continue the loopback test to locate the fault. Divide the 48 2M paths on the ET1 board at NE2 into two parts and perform loopback test to narrow down the fault location. When the paths 33–48 are included, the throughput is 0. At this point it can be preliminarily determined the ET1 board of NE2 is faulty.

Step 6 Replace the ET1 board of NE2 and perform relevant tests again. Everything is all right this time.


The method of loopback can be used to locate the fault when there is no alarm or performance event. It can be applied specially to cases such as board failure or some paths of the board failure.

When performing loopback, dichotomy can be used to facilitate the localization by separating the test area. Some unused paths can also be used to test the original service. Usually, we can replace the virtual path or E1 resource of the virtual path, or replace the external port to locate the fault.

OptiX 155/622H(Metro1000) Maintenance Manual 5 Alarm Generation Principles of OptiX Equipment


5-1

5 Alarm Generation Principles of OptiX Equipment

The SDH frame architecture contains a variety of overhead bytes, including regenerator section overhead, multiplex section overhead and path overhead bytes. By virtue of the alarm and performance information transmitted by these overhead bytes, the SDH transmission system supports strong on-line alarm and bit error monitor function. A good understanding of generation and detection modes of alarm information will greatly facilitate the fault location.



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5.1 Alarm Generation Principles of the System

5.1.1 System Signal Flow

Signal flow of the OptiX 155/622H system is as shown in Figure 5-1.

IU1

IU4

IU2

IU3

IU1

IU4

IU2

IU3

OptiX iManager Auxiliary data interface

order wire

16 x 16space divisioncross-connectmatrix

STM-4/STM-1

STM-4/STM-1

STM-4/STM-1

Ethernet,G.SHDSL

E1/T1ATM/Ethernet service

Interfaceunit

Interfaceunit

overheadprocessing

system control& communation

synchronoustiming

E1/T1, E3/T3,N x 64K

E1/T1, E3/T3,N x 64K

Ethernet,G.SHDSLE1/T1, E3/T3,N x 64K

Ethernet,G.SHDSLSTM-4/STM-1

STM-4/STM-1

STM-4/STM-1

Ethernet,G.SHDSL

E1/T1ATM/Ethernet service

E1/T1, E3/T3,N x 64K

E1/T1, E3/T3,N x 64K

Ethernet,G.SHDSLE1/T1, E3/T3,N x 64K

Ethernet,G.SHDSL

Figure 5-1 Signal flow of OptiX 155/622H system

1. Control Bus

The system control bus is the communication path between the SCC unit and the cross-connect unit, SDH units and PDH units. Different units can communicate with one another through the control bus. For example, the SCC unit can send configuration parameters to SDH and PDH interface units, and send configuration data to the cross-connect unit. In return, SDH and PDH interface units can report their performance or alarm results to the SCC unit through the same channel.

During equipment operation, check regularly whether the communication between respective units and the SCC unit is normal.

2. Timing Bus

The system timing bus is the path through which the synchronous timing unit issues the synchronous clock to each unit, which will take the clock from the timing unit as the reference to start its work. Thus each unit can be ensured to operate properly.

In addition, SDH units and PDH units can extract the clock which is input in the service flow, and send it to the timing unit through the timing bus. Then the timing unit will select the clock source for trace.



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3. Service Bus

Various service signals, such as E1, T1, E3, T3 input in the PDH interface unit and ATM/IP interface unit are mapped into VC-4 and then sent to the cross-connect unit for assignment and dispatch, so as to effect the cross-connect at the lower order VC12 level. Then they are sent to the SDH interface unit in VC4. The SDH unit will multiplex these VC4 signals into STM-1 signals to be sent to the optical cables, thus inserting the PDH or ATM/IP service in the SDH signals. On the other hand, the SDH signals from the optical cable line are also multiplexed into VC-4 signals by the SDH line interface unit. Then they go through the cross-connect unit to complete the service assignment and flow into the SDH interface unit to complete the cross-connect of the optical path service, or flow into the PDH unit and ATM/IP unit. Then go through the signal process and interface adaptation to grow into the signal output of different tributaries.

4. Overhead Path

Each SDH interface unit extracts overhead bytes from the STM-1 signal, and sends the order wire information together with the maintenance information to the SCC unit for further processing, so as to affect the interconnectivity between different NEs' orderwire and DCC information. By virtue of the DCC, the NM gets control over the whole network's NEs via the GNE.

5.1.2 System Alarm Flow

1. System Alarm Signal Flow

In the OptiX 155/622H, the alarms generated by the SDH unit, PDH unit and the cross-connect timing unit are reported to the SCC unit. Then the SCC unit sends the alarms to the equipment for display and sends them to NM via the maintenance interface. The NM will display the equipment alarm status, simultaneously indicating the causes of alarms.

Neighboring NEs' alarms will be sent to the SCC unit through the DCC channel, and then reported to the NM. Thus the NM can monitor the alarm status of NEs the network wide.

The alarm signal flow of OptiX 155/622H system is as shown in Figure 5-2.



5-4

SDH unit alarmDCC

PDH unit alarm

NM maintenance

Power Fan Alarm

Neighboring NE alarm

Synchronous timing unit

Alarm indicator Indicator display

Cross-connect

SCC unit

display

unit

Figure 5-2 The alarm signal flow of OptiX 155/622H system

2. System Service Alarm Signal Flow

The SDH frame architecture contains a variety of overhead bytes, which enables it to support powerful on-line alarm and bit error monitor function, so as to facilitate fault location. The service alarm signal flow of OptiX 155/622H is as shown in Figure 5-3.

PDHinput

TU levelpayload

alarm analysis

Payload

cross-

matrix

SDH

alarm

SDHalarm insertion

SCC unit

Mapping Demapping

Payload signal

overheadSTM-1

E1/T1

STM-1

E1/T1PDH

output

Payload signal

extraction

SDH

PDH

input

SDH

signal

synthesis

analysis

overhead

alarm analysis

connect

Figure 5-3 Service alarm signal flow of OptiX 155/622H system

Each SDH interface unit extracts the overhead information from the received SDH signals for analysis and then reports the results to the SCC unit, directly generating some output alarm information in the meantime. These directly generated alarms and the alarm information from the SCC unit are sent to the overhead bytes of the SDH output signals.

The PDH interface unit will analyze the received PDH signal's alarm information and report the analysis results to the SCC unit and, additionally, it will check to see if the TU level services sent by the cross-connect unit have any alarm and then report the results to the SCC unit.



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5.1.3 Analysis and Explanation of Alarm Principles

1. Terminology

To facilitate the explanation of positions and modes of generation of major alarms and performance, we might as well explain them one by one along the signal flow.

According to the processing modes of overhead bytes in the signal flow, the signal flow is divided into two parts, the higher order part and lower order part.

Higher order part: the signal flow between the SDH interface unit and the cross-connect unit, with the cross-connect unit being the limitation.

Lower order part: signal flow between the cross-connect unit and the PDH interface unit, with the cross-connect unit being the limitation.

Note:

In the service alarm signal flow, the cross-connect unit processes no overhead byte. For the sake of clear presentation, we take it as the limitation to split the signal flow into the higher order part (SDH interface ←→ the cross-connect unit) and lower order part (the cross-connect unit ←→PDH interface) so as to offer the explanations.

According to the flow direction, the service signal flow falls into downstream signal flow and up signal flow.

Downstream signal flow: SDH interface → cross-connect unit →PDH interface.

Up signal flow: PDH interface→ cross-connect unit →SDH interface.

2. Two Common Alarms

AIS alarm (all "1"s alarm): Inserts the all "1"s signal in the lower circuits, indicating the signal is unavailable. Common AIS alarms include MS_AIS, AU_AIS, TU_AIS, and E1_AIS.

RDI alarm (Remote defects indication) refers to such alarms as LOS (loss of signal), AIS and TIM (trace identifier mismatch), which are detected and sent back to this station by the opposite station. Common alarms include MS_RDI, HP_RDI and LP_RDI.



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Note:

A station with any alarm occurrence does not necessarily mean it has gone wrong. Rather, the station has detected the alarm, which may result from the opposite station or other causes. For example, the R_LOS that actually stems from broken fibers, the HP_LOM alarm that is caused by the opposite station cross-connect unit but reported by the local station.



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5.2 Generation and Detection of Alarm and Performance Signals in the Higher Order Signal Flow

According to the principle of "From line to tributary and from upper to lower" in fault location, the alarm and performance signals arising from between the SDH interface unit and the cross-connect unit are the considerations we should focus on in the first place, because it is the alarm and performance data generated from this higher order part that gives rise to the report of the alarm and performance data in the lower order part. The alarm signal flow in this route section is as shown in Figure 5-4.

LOSSTM-N

B1BI Err.

K2

AIS

MS-AIS

k2MS-RDI

B2

M1

Frame synchronizer

overhead processor overhead process

C2

AU-AISAU-LOP

J1HP-UNEQ

HP-TIM

B3B3 Err.

G1G1

HP-REI

HP-RDI

MS-REI

H4C2

HP-LOM

HP-SLM

B2-Err.

Downstream signal flow path

AIS

A1, A2LOF

Signal transmission point Alarm termination point(report to the main control unit)(insert all- "1" signal)

Pointer processor and higher order

H1,H2H1,H2

“1”

Report alarm or report alarm back

(RST) (MST) (MSA, HPT)

Multiplex section

Optical

interface

and regernation sectionpath overhead processor

“1” “1”

CrossBoard

Figure 5-4 Flow chart of alarm signal generation between SDH interface and the cross-connect unit

Note:

According to their positions in the STM-1 frame architecture, the overhead bytes fall into three types: regenerator section overhead bytes, multiplex section overhead bytes, and higher order path pointer and overhead bytes. If the overhead bytes in the former two modules have gone wrong, then that will affect all the higher order paths; if the overhead bytes in latter one have gone wrong, that will affect only a single higher order path. Upon this, we usually can judge the problem coverage and select a path to perform tests.



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5.2.1 Down Signal Flow

1. Frame Synchronizer and Regenerator Section Overhead Processor

This section deals with the alarm and performance specific regenerator section overhead: frame alignment byte (A1 and A2), regenerator section trace identifier (J0), and bit error parity byte (B1).

The signal alarm is described as follows:

(1) After the STM-N optical signals from optical paths come into the optical receiving module of LU, they are firstly resumed, via the O/E conversion, to electrical signals and then sent to the frame synchronizer and scrambler for further processing. In this course, the O/E module will check the signals. In case it finds out there is no optical signal, the optical power is too low or too high, or that the input signal code pattern is a mismatched one, it will report the R_LOS alarm.

Hint:

Generally, no optical signal is input may result from broken fibers, faulty transmitting optical module in the opposite station or faulty receiving optical module in local station.

As a rule, a too low optical power stems from too high optical fiber attenuation, bad contact or impurity in optical connectors, while a too high optical power refers to the overload of the receiving optical power, where you should check to see if the optical attenuator is faulty or transmitting distance of the optical interface board is appropriate. Mismatched code patterns often result from the inconsistency between signal rates of the upstream and downstream stations or from disordered transmitting data arising from the STG unit of the upstream station, where you should check if the optical interface boards of the upstream and downstream match each other or if the STG unit and the cross-connect unit operate properly.

The R_LOS alarms are independent of the overhead bytes, and relative to only the quality of the input signals. In the case of the R_LOS alarm, the system will insert the all- "1" signal to the lower circuits.

In case of R_LOS alarm, the SDH equipment will not recover from the R_LOS status, until the receiving optical module in the local station has detected the correct code pattern for two times in a row and in the meantime, no new R_LOS alarm has been found.

(2) After the frame synchronizer receives the STM-N signal from the O/E conversion module, it will, according to A1 and A2 bytes in this signal, trap the frame alignment signal and meanwhile, extracts the line reference synchronization timing source to send it to the STG unit for the clock lock.

Normally, the A1 value is always F6, and A2 value 28. However, if the frame



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synchronizer detects that A1 ≠ F6 or A2 ≠ 28, then it will report the R_OOF alarm (out - of- frame alarm). In case the R_OOF alarm persists for more than 3 ms, it will report the R_LOF alarm (loss -of -frame alarm) and inserts the all "1" signal in the lower circuits. In case of R_LOF, if the frame alignment status persists for more than 1 ms, that means the equipment has resumed to normal.

The J0 byte is used to check if both ends of the regenerator sections are in the continuous status. The J0 bytes at both ends should match each other. Otherwise, the J0 trace identifier mismatch alarm will be reported.

Scrambler is mainly engaged in unscrambling the bytes in the STM-N signals except for the A1, A2 and J0 bytes.

(3) The regenerator section overhead processor extracts and processes other regenerator section overhead bytes in the STM-N signal. Of the bytes, B1 byte is the most important one.

If the B1 byte recovered from the STM-N signal does not consist with computation result of BIP-8 in the last received STM-N frame, then there reports the B1 bit error alarm. If the B1 bit error exceeds the threshold 10-3, there reports the B1-OVER alarm.

In case there come 10 regenerator section SESs in a row (In one second, the errored blocks account for 30% of the total), then there comes the RSUATEVENT (regenerator section unavailable time event).

Meanwhile, in this section the F1, D1-D3 and E1 bytes which are independent of the alarm and performance will be sent to the SCC unit and the overhead unit.

2. Multiplex Section Overhead Processor

In this section, the regenerator section overhead to be processed relating to the alarm and performance includes: automatic protection switching path byte (K1, K2) and multiplex section bit error monitor byte (B2). The signal flow path is as follows:

(1) The multiplex section overhead processor extracts and processes the multiplex section overhead byte in the STM-N signal, executing the SF (signal failure) and SD (signal deterioration) detection and sending D4-D12, S1 and E2 bytes and the like, which are independent of the performance and alarm, to the SCC unit and the overhead unit and simultaneously effecting the function of sharing multiplex section protection (MSP), by virtues of the K1 and K2 bytes, the SCC unit and the cross-connect unit.

If the processor has detected that K2 (bits 6, 7 and 8) is 111, then it reports the MS_AIS alarm and inserts the all- "1" signal in the lower circuit. If it has detected that K2 (bits 6, 7 and 8) is 110, then it reports the MS_RDI alarm.

(2) If the B2 byte recovered from the STM-N signal does not consist with the computation result of BIP-24 in the lastly received STM-N frame (All bits expect for the regenerator section overhead), then the processor reports the B2 bit error.

Meanwhile, it will decide whether to report MS_REI alarm according to the M1 byte (multiplex section remote faulty module indication). The information the MS_REI transmits is about the number of improperly interleaved bit blocks detected by the B2



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byte.

If the B2 bit error exceeds the threshold 10-6, there reports the B2_SD alarm. If the B2 bit error exceeds the threshold 10-3, there reports the B2_OVER alarm. In case of multiplex section protection, the B2_SD and B2_OVER alarm will give rise to the multiplex section protection switching.

In case there come 10 multiplex section SESs in a row (In one second, the bit_ errored blocks account for 30% of the total), then there comes the MSUATEVENT (multiplex section unavailable time event).

3. Pointer Processor and Higher Order Path Overhead Processor

This section deals mainly with the higher order pointer justification and higher order path overhead bytes. The pointer justification specific bytes include H1, H2 and H3, whereas the alarm and bit error specific bytes include the higher order path trace byte (J1), signal label byte (C2), higher order path bit error monitor byte (B3), path status byte (G1), and multiframe position indication byte (H4). The signal flow path is described as follows:

(1) The pointer processor, according to the H1 and H2 bytes of each AU_4, conducts the pointer translation and pointer justification, completing the functions of aligning the frequency and phase, absorbing the phase jitter and wander in the network, and simultaneously locating each VC-4 and sending it to the corresponding higher order path overhead processor. If it has detected that the AU pointer H1 and H2 bytes are all- "1" signal, it reports the AU_AIS alarm and inserts an all- "1" signal in the lower circuit. If the H1 and H2 bytes stand for invalid pointer value (beyond the normal range 0–782) and if 8 consecutive frames have received the invalid pointer values, then it reports the AU_LOP alarm and inserts the all- "1" signal in the lower circuit. In case of AU pointer positive justification, the number of the PJCHIGH of the MSA increases by 1. In case of AU pointer negative justification, the number of the PJCLOW of MSA increases by 1.

(2) The higher order path overhead processor processes the HPOH (higher order path overhead) bytes of the N VC-4s received as follows:

If it has detected that the J1 byte differs from the preset value, then it reports the HP_TIM alarm and inserts the all- "1" signal in the lower circuit.

If it has detected that byte C2 is 00, then it reports the HP_UNEQ alarm and inserts the all- "1" signal in the lower circuit. If it has detected that C2 byte differs from the preset value, then it reports the HP_SLM alarm and inserts the all- "1" signal in the lower circuits. The preset value of C2 corresponding to the TUG architecture is 02.

If the computation result of B3 byte recovered from the HPOH is inconsistent with that of BIP-8 in the last frame's VC-4 signal, then the processor will report the B3 bit error.

To extract the TU_12 signal from the VC-4 in the OptiX STM-N (N<=4) SDH interface board, The H4 byte should indicate to what frame of the current multiframe the current TU_12 belongs. If the processor has detected that the H4 byte is invalid, then it will report the HP_LOM alarm, and inserts the all- "1" signal and the valid H4 byte in the lower circuit. If it has detected G1 (bit 5) is 1, then it reports the HP_RDI alarm. According to the value of the G1 (bit 1-bit 4), it forms a judgment on whether to report



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the HP_REI alarm. If the value ranges 1-8, it will report.

In case there comes 10 B3 SESs in a row (In one second, the errored blocks account for 30% of the total), then it will report the HVCUATEVENT (higher order path unavailable time event).

Other overhead bytes, such as F3, K3 and N1, are reserved.

(3) After going through the above processes, the N # STM-1 service are finally sent to the cross-connect unit for the cross-connect of the higher order path and lower order path.

5.2.2 Up Signal Flow

If we can say that the higher order part down signal flow deals mainly with extraction and termination of the overhead byte, then the up signal flow of this part deals mainly with the generation of the initial value of the overhead byte and with the transmission of the alarm feedback to the opposite station.

1. Pointer Processor and Higher Order Path Overhead Processor

(1) The N # STM-1 service signals from the cross-connect unit are first sent to the higher order path overhead processor.

(2) The higher order path overhead processor generates N higher order path overhead bytes, which are sent, together with the N services, to the pointer processor, so as to complete the function of setting the higher order path overhead bytes, including J1, C2, B3, G1, F2, F3 and N1, along the up signal flow path.

If the processor has detected there are AU_AIS, AU_LOP, HP_UNEQ or HP_LOM (HP_TIM and HP_SLM are optional) alarms in the down signal flow, then it sets the G1 (bit 5) to 1, and sends the HP_RDI alarm back to the remote station. If it has detected the B3 bit error in the down signal flow, it will, according to the detected bit error value, set the G1 (bit 1–bit 4) to the corresponding value (1–8), and sends the HP_REI alarm back to the remote station.

The H4 byte will not be processed in the up signal flow path.

(3) The pointer processor generates N # AU_4 pointers, and adapts the VC-4 into the AU_4. The AU_4 pointer is expressed in the H1 and H2 bytes. The multiplex section processor multiplexes the N AU_4s into the STM-N signal and sends the signal to the multiplex section overhead processor.

2. Multiplex Section Overhead Processor

The multiplex section overhead processor sets the MSOH bytes (inc. K1, K2, D4–D12, S1, M1, E2 and B2) to the received STM-N signal.

If the processor has detected R_LOS, R_LOF or MS_AIS alarms in the down signal flow, then it sets K2 (bit 6–bit 8) to 110, and sends the MS_RDI alarm back to the remote station.

If it has detected the B2 bit error in the down signal flow, then it sends the MS_REI alarm to the remote station by virtue of the M1 byte.



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3. Frame Synchronizer and Regenerator Section Overhead Processor

(1) The regenerator section overhead processor is responsible for setting regenerator section overhead bytes (including A1, A2, J0, E1, F1, D1-D3 and B1), and sending the complete STM-N electrical signals to the frame synchronizer and scrambler.

(2) The frame synchronizer and scrambler will scramble all bytes (excluding the first line bytes in the frame architecture) of the STM-N electrical signals. And then the E/O module converts the STM-N electrical signals into the STM-N optical signals and sends them out via the optical interface.



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5.3 Generation of Alarm and Performance Signals in the Lower Order Service Signal Flow

The PDH service mainly includes services at 1.5 Mbit/s and 2 Mbit/s. PDH services at different rates use different path overhead bytes. Thus the alarm signal generation modes differ slightly. Next, we will take the 2 Mbit/s service as an example, describing the signal flow processing methods and the alarm generation mechanism between the PDH interface and the cross-connect unit. The signal flow diagram is as shown in Figure 5-5.

HPA , LPT

Signal flow pathSignal transmission point Alarm termination point

(Report SCC unit)(insert the all-"1" signal down)

V5V5 LP-UNEQ

J2

V1. V2

V1. V2

H4

LP-TIM

TU-LOP

TU-AIS

HP-LOM

LP-RDIV5

BIP-2

LP-REI

T-ALOS

All "1"

LPA PPI

V5

V5

LP-TFIFO

LP-RFIFO

All "1"

Report alarm or report alarm back

E1-AIS

E1-AIS

E1interface

LP-SLM

Crossboard

Figure 5-5 Flow chart of alarm signal generation between 2M PDH interface and the cross-connect unit

As shown in the above figure, due to each part processes the overhead bytes in different way, we divide them into different function blocks in turn as follows: higher order path adaptation (HPA), lower order path terminal (LPT), lower order path adaptation (LPA) and asynchronous physical interface (PPI). Here, we will take the function block classification as an index to introduce the signal flow.

5.3.1 Down Signal Flow

1. Higher Order Path Adaptation Functional Block (HPA) and Lower Order Path Termination Functional Block (LPT)

This section is the core of the lower order part, for a majority of lower order overhead bytes, including lower order path pointer indication bytes (V1, V2 and V3), V5 byte



5-14

and lower order path identifier (J2), are processed in this section.

(1) Sends the VC-4 signal received from the cross-connect unit to HPA.

(2) The HPA demaps the VC-4 into VC-12. Pointers of all VC-12s are decoded, so as to provide the frame misalignment information in byte between the VC-4 and the VC-12.

In case that the node clock of the position where the TU_12 lies is not in synchronism with the local clock reference, this process will need continuous pointer justification. The TU pointer positive justification (LPPPJE) and the TU pointer negative justification (LPNPJE) will be detected in the down signal flow. The TU pointer justification counter threshold crossing (The threshold is adjustable) is expressed in a group of alarms HPADCROSSTR. HPADCROSSTR includes HPADPJCHIGHCX15 (TU pointer positive justification crosses the threshold after the timer times for 15 minutes), HPADPJCHIGHCX24 (TU pointer positive justification crosses the threshold after the timer times for 24 hours), HPADPJCLOWCX15 (TU pointer negative justification crosses the threshold after the timer times for 15 minutes) and HPADPJCLOWCX24 (TU pointer negative justification crosses the threshold after the timer times for 24 hours).

If incorrect H4 multiframe byte sequence is detected in the down signal flow, then the HP_LOM alarm is reported.

If the lower order pointer bytes V1 and V2 are detected to be all- "1" signal, then the TU_AIS alarm is reported. If the V1 and V2 value are detected as invalid, then TU_LOP alarm is reported. In the event of the two alarms, the block will insert the all- "1" signal in the lower circuits.

In addition, if the block has received the TU_AIS alarm, it will not only insert the AIS signal in the down data, but also send back the LP_RDI, that is, to set the bit 8 of the V5 byte as "1".

(3) The VC-12 signal flow is sent to the LPT unit for the V5 byte processing.

Time slot architecture of the V5 byte is as shown in Figure 5-6.

b1 b2 b3 b4 b5 b6 b7 b8

BIP-2 bit error parity

V5 byte

Inconsistent: LPBBE 1:LP-REI Idle

Signal label

000:LP-UNEQ 1:LP-RDI Figure 5-6 Structure of V5 byte

In the event bits 5, 6, and 7 of the V5 are detected in the down signal flow to be reported as the signal label, if the value of bits 5, 6 and 7 is 000, that means the lower order path has not been loaded, the LP_UNEQ alarm reported and the lower circuit inserted with all- "1" signal. In case of the signal label mismatch, the LP_SLM alarm is reported, the lower circuit inserted with the all- "1" signal.

The path RDI information of bit 8 of V5 byte will be terminated, and the LP_RDI is reported.



5-15

Check and recover V5 byte's BER monitor bits: bit 1 and bit 2, and computes BIP-2 for the VC-12. Compare the BIP-2 value computed in this frame with the values of bits 1 and 2 of V5 byte recovered from the next frame. If the two are inconsistent with each other, then the LPBBE (lower order part background block error) alarm is reported. In the meantime, bit 3 of V5 byte is recovered. If it is "1", then the LPFEBBE (lower order part far end background block error) is reported, indicating that the remote station has detected the BIP-2 error. Bit 4 of the V5 byte is idle.

In case there comes 10 SESs in a row (In one second, the errored blocks account for 30% of the total) in the BIP-2 detection, then the LVCUATEVENT (lower order unavailable time event) is thought to be having generated.

(4) In the meantime, the lower order path identifier, the J2 byte, is also recovered, and the received J2 byte is detected. If the actually received value is inconsistent with the preset value, the lower order path trace identifier mismatch alarm (LP_TIM) is reported.

2. Lower Order Path Adaptation Functional Block (LPA) and Asynchronous Physical Interface Module (PPI)

(1) After going through the above process, the C-12 data is sent to LPA, where the data signal flow and the relative clock reference signal are recovered together from the container and sent to PPI as the data and timing reference.

(2) After going through the LPA process, the data and clock are sent to PPI to constitute the 2048 kbit/s service signal.



5-16

5.3.2 Up Signal Flow Path

1. Lower Order Path Adaptation Functional Block (LPA) and Asynchronous Physical Interface Module (PPI)

(1) After entering the PPI, the E1 electrical signal is extracted and regenerated to be sent to the mapping and demapping processors, where it receives the jitter suppression.

The PDH interface checks and terminates the T_ALOS alarm. When it has detected the T_ALOS alarm, it inserts the all- "1" signal in the upper circuits.

(2) The LPA conducts the data adaptation function.

If the received E1 signal is AIS, then E1_AIS alarm is reported. The T_ALOS will give rise to the E1_AIS alarm, but it can also suppress the E1_AIS. That is to say, when querying the alarm, you get only the T_ALOS alarm.

If the up data rate is too big, then it will make the lower order path sending side FIFO overflow, thus the LP_TFIFO reported.

2. Higher Order Path Adaptation Functional Block (HPA) and Lower Order Path Termination Functional Block (LPT)

(1) LPT allows insertion of the POH in the C-12 to make up the VC-12.

The LPT inserts the "signal label" in bits 5, 6 and 7 of the V5 byte, computes the BIP-2 for the last multiframe data and sends the result to bits 1 and 2 of the V5 byte of this frame. If the " Path terminal bit error" is detected in the down signal process, then bit 3 of the V5 byte will be set to "1" in the next frame, the LP_REI alarm sent back.

(2) The HPA adapts the VC-12 into TU_12 and then maps it to the higher order VC-4, so as to be sent to the cross-connect unit. The frame misalignment in byte between the VC-12 and VC-4 is expressed in a TU_12 pointer. Each frame decides a V (one of the V1, V2, V3 and V4) byte, and every four frames constitute a multiframe. The H4 byte which is used to decide the V byte is so generated, too.



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5.4 Suppression Relations between Alarm Signals

By virtue of the above analysis of the major alarms in the signal flow, we can find that most of them are relative to one another. Some alarms will usually give birth to other alarms. Especially the occurrence of the higher order alarms usually leads to that of the lower order alarms.

For example, in the event the R_LOS alarm arises from the optical interface board for reasons of the optical path, the alarm will insert AIS in the lower circuit. Thus, all the overhead bytes become all- "1", which will further give rise to an alarm family: R_LOF, R_OOF, and MS_AIS. Of course, these alarms should come out, but they are of no use for the maintenance personnel. Obviously, with a cutoff upstream, it is pointless to pay attention to the downstream.

Additionally, if these alarms are reported simultaneously, that, on the one hand, will result in too heavy data volume and increase the load of the NM and SCC unit (Just think what if dozens of NEs in a great network simultaneously report all the alarms), and on the other hand will make the operator feel at loss to deal with so much information.

To prevent this situation from happening, we use the alarm suppression to mask those alarms which do not need to be reported.

Suppression relations between some major alarms are as shown in Figure 5-7.

R-LOS R-LOF

B2-EXC MS-AIS

AU-LOP AU-AIS HP-UNEQ HP-TIM HP-SLM

TUAIS

Figure 5-7 Suppression tree of some major alarms

The higher alarms at the arrowhead will mask the lower alarms at the arrow end. Now, we can concentrate on the higher alarms.



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Hint:

There is one thing we should make clear here. Although the masking relations exist between alarms at different levels, it is not the case with the performance data, for the data at different levels lacks cause-and-effect relation. For example, in case of B1 bit error, the system will not act this way or that to give birth to the B2 bit error. Data of the B2 bit error is computed according to the items in its coverage.



5-19

5.5 Examples of Locating a Fault According to the Signal Flow

Through the above study, we have laid a theoretical foundation for the fault location. It is our ultimate goal to combine theory with practice and promptly locate and remove the faults according to the signal flow principles. Next, we will introduce two typical cases to help you in constructing some initial principles of troubleshooting.

5.5.1 Bit Error Problems

The networking diagram in A, B and C is as shown in Figure 5-8.

A B C

W EW W

Figure 5-8 Networking diagram

This is a chain network composed of three OptiX 155/622H equipments, with the transmission rate of 155 Mbit/s, station A being the gateway station to be connected to NM terminal equipment. Each station is equipped with the 2 Mbit/s service, with the service being the distributed type.

Fault phenomenon:

When queried via the NM, the performance data monitored is as follows: station A finds that the service between itself and the station B and C get a large number of lower order bit error LPBBE and that the west line gets a number of HPBBE and MSBBE bit errors; station B finds that its west line gets a large number of HPFEBBE and MSFEBBE, and that in the tributary the services between itself and station A gets a number of LPFEBBE while the services between itself and station C are normal; station C finds that only the services in the tributary between itself and station A gets a large number of LPFEBBE.

Fault Analysis:

(1) According to the principle of "From station to board", we first troubleshoot NEs.

From the fact that the payloads between station A and station B, and those between station A and station C get bit errors, while those between station B and station C get no bit error, we can conclude that the fault rises from between station A and station B. Now, we can analyze the performance data to find out the cause and location of the fault.

(2) According to the principle of "From upper to lower and from line to tributary", we analyze the performance data in the line first.

As we have learned of the signal flow, there are 3 bit error monitor overhead bytes, B1, B2, and B3, in the line. Each of them is responsible for monitoring the quality of the route between its generation point and termination point. B1 byte monitors the route between regenerator sections of two stations; B2 byte monitors the route between the multiplex sections of the two stations; B3 monitors only the route between higher order paths of the two stations. Obviously, the route monitored by B3



5-20

covers that monitored by B2 and B1, and the route monitored by B2 covers that monitored by B1.

As seen from the on-site data, there is only B2 and B3 bit error data. This means that the route between the regenerator sections of the two stations is sound, thus indicating the optical path is good. The B2 bit errors mean that the route between multiplex sections of the two stations is faulty. As seen from the bit error data, station A gets background block bit error BBE while station B gets the far end background block bit error FEBBE. This means that the bit errors in the signal are monitored in station A. Nevertheless, this does not necessarily mean that station A has gone wrong. As you know, all bit errors are monitored in the down signal flow. Therefore, the bit errors monitored by station A may result from the receiving end of station A, or from transmitting end of far end station B.

(3) Now, we can troubleshoot the stations one by one. First make a loopback of the west optical path of station A, and find that the bit errors in station A have disappeared. This means station A is sound. So replace the OI2D board from station B to find that the network-wide bit errors have disappeared and the problem removed.

Tips:

According to the inclusion relation of the routes respectively monitored by B1, B2 and B3 bit error, we use a hypothesis in the above analysis that B1 bit errors will give birth to B2 and B3 bit errors while B2 bit errors to B3 bit errors.

In fact, the hypothesis is not absolutely true, for the routes the three monitor have the inclusion relation, but the content the three monitor do not. B1 monitors all the bytes of the STM-N frame; B2 monitors only the bytes except the regenerator section overhead byte; B3 monitors only all bytes of VC-3 and VC-4 of each path. Hence, if the overhead bytes get bit errors, the inclusion relation among the three will be broken off. For example, B1 can monitor bit errors in the regenerator section overhead bytes, but B2 and B3 can not.

However, we find in practice that it is unusual that only the overhead byte gets bit errors. Thus, locating a fault by using the inclusion relation among the routes monitored by B1, B2, and B3 can be usually taken as an empirical method.

5.5.2 Alarm Specific Problems

The alarm based troubleshooting principles are similar to the aforementioned performance parameters based troubleshooting principles, except that bit error problems are usually simple while the alarm problems are interleaved with one another and it is difficult to form a judgment. However, if we take each alarm into consideration in a comprehensive manner according to its generation mechanism in the signal flow, we will resolve general problems in most cases.



5-21

A

B

CE

F

D

W E

W

E

E

W

WE Figure 5-9 Networking Diagram

The network in ABC area is as shown in Figure 5-9, where the six stations A, B, C, D, E and F constitute a multiplex section ring composed of OptiX 155/622H NEs, the service mode being the intensive type, each station having service with station A.

Fault phenomenon:

After the equipment operates for some time, it can be seen that the abnormal switching of the whole network has given rise to totally blocked services as follows:

(1) Stations F and B are switched over to the east and west respectively; stations C, D, and E are under through connection status; station A always under idle status.

(2) In the switching, instantaneous T_LOS alarm occurs in east and west optical interface board of station A; HP_LOM alarm in east of station F and west of station B. Seen from NM, all stations except station A have protection switching indications; service in each station has TU_AIS alarm.

Fault analysis:

(1) According to the principle of " From station to board", first narrow down the problem area to a single station: loss of alarm T_LOS in sending signals usually means that the cross-connect unit has not sent any signal to the LU or the sent signals do not have a frame, and thus the alarm has been detected in the up signal flow. HP_LOM is the alarm which is found out in the down signal flow, which indicates that the H4 byte has gone wrong somewhere from the generation point in the opposite station to the termination point in this station. And thus it has become invalid. Since both alarms are relative to station A, we will locate the problem at station A at first.

(2) Through analyzing the two alarms, we see that an invalid H4 usually arises from the fact that the cross-connect unit is poorly fitted in with the LU or that the LU or cross-connect unit has gone wrong. On the other hand, the T_LOS is usually relative to the signals which the cross-connect unit sends to the LU. Additionally, since east and west optical interface boards of station A report the T_LOS alarm simultaneously, it is thus clear that the possibility of a faulty cross-connect unit is greater than a faulty LU. So we decide to replace the SCB board.

(3) After replacing the SCB board, view the equipment operation conditions for some time. If the fault phenomenon does not occur again, it shows that the problem has been successful resolved.



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5.5.3 Summary

Under the help of each alarm's position in the alarm signal flow, you can narrow down the problem area gradually, with an aim of rapid fault location. Therefore, it is necessary for the professional maintenance personnel to grasp the corresponding principles of the alarm and performance signal flow.

For alarm and performance list of OptiX 155/622H SDH optical transmission system, refer to the appendices.



5-23

5.6 Generation and Detection of ATM Service Alarms

It is known that in OptiX equipment, ATM service is processed by AIU first, and then mapped into STM-N frames for transmission. So inspection for ATM signals is mainly performed in AIU.

5.6.1 Logic Diagram of Board

AIU consists of four parts: ATM layer processing module, SDH layer processing module, Control module and Physical layer interface module. AIU logic diagram is shown in Figure 5-10.

Physicallayerinterfacemodule

ATM layerprocessingmodule

Cross-connect unit

BackplaneFront panel

SDH layerprocessing module

SCC unit4 X STM-1opticalsignal

Controlmodule

Figure 5-10 Logic diagram of AIU

ATM service data flow with SDH frame structure is input via optical interface board. After being processed by physical layer processing chip, the data flow is sent via interface to be processed by ATM layer processing chip, then sent to SDH layer processing module for physical layer processing, overhead processing, and TELECOM bus adaptation. Next it is sent to XC board to be crossed to other optical interfaces, before transmission on optical fiber. This board does not provide optical interfaces directly, but has 2 × or 4 × 155 Mbit/s PECL difference lines connected with the optical interface board, and it can access 2 × or 4 × 155 Mbit/s optical signals at most.



5-24

5.6.2 ATM Signal Flow

AMulti-service transmission MAN

B

C

D

rSDHlayer

SDH

layer

ATMlayer

ATM layer

AMulti-service transmission MAN

B

C

D

rSDHlayer

SDH

layer

ATMlayer

ATM layer

155M

155M155M

155M

ATM layer

SDHlayer

SDHlayer

ATM layer

155M

155M155M

155M

ATM layer

SDHlayer

SDHlayer

ATM layer

Figure 5-11 Equipment networking diagram

ATM signal flow is as follows.

1. Accessing Signals from AIU Optical Interface to SDH

Signals entering AIU optical interface are the frames bearing ATM cell of STM-1. The signals enter the physical layer processing module, where inspection of SDH alarm and performance is completed, and contents in the frame structure are extracted, i.e. ATM cells are extracted according to the cell delimitation rules of ATM physical layer. Alarms such as LCD, OCD and HCS can be generated according to the signal quality when cells are extracted. Meanwhile, statistics can be made for cells received; idle cells extracted are discarded, while effective cells are transmitted to ATM layer processing module via UTOPIA interface to be processed.

ATM layer processing module mainly conducts ATM layer processing, substitutes cell header, controls flow, and processes XC of VP/VC, processed cells are transmitted to SDH layer processing module via UTOPIA interface.

SDH layer processing module receives cells from UTOPIA interface, transforms them into SDH frame structure, converts UTOPIA interface into TELCOM bus, adds signals onto SDH optical board via SCB board, and sends the signals out.

2. Transmission from SDH Optical Interface to AIU Optical Interface

Optical signals accessed by SDH optical board dispatch service through SCB to SDH layer processing module. SDH layer processing module delimits and extracts the cell, and generates such alarms as LCD, OCD and HCS based on the signal quality. Meanwhile, it counts the received cells, discards the idle ones and transfers the valid ones to ATM layer processing module. ATM layer processing module substitutes the cell header, controls the flow, processes switching of VP/VC and transfers the processed cells to the physical layer processing module via UTOPIA



5-25

bus. The physical layer processing module assembles the cells in SDH frames and sends them out via optical interface.

5.6.3 Detection of ATM Alarms and Performances

SECTIONLOS/LOF

PAIS

LOP

"1"

"1"

AIS

LINE

PMD

"1"

PATH

LAIS

"1"

LRDI

PRDI

LCD

VC

AIS

AIS

PHY ATM

VPTC

VPRDI

VPAIS

VCAIS

AIS

AIS

AIS

F1 F2 F3 F4 F5

Figure 5-12 OptiX 155/622H alarm check flow chart

Functions realized by respective modules in equipment are as follows.

1. Layer Processing Module

ATM optical receiving/transmitting module provides overhead processing, SDH alarm processing and performance statistics.

In f1–f3 sections (f1–f3 respectively corresponds to RST, MST and HP of SDH), it checks alarms such as B2_OVER, B2_SD, LOS, LOF, MS_AIS, MS_RDI, AU_LOP, AU_AIS and HP_RDI.

In f1–f3 sections, it processes such performances as B1, B2, B3, LFEBE and PFEBE.

It provides K1K2 byte processing of APS protection. It provides S1 byte processing of synchronous clock.

In f4–f5 sections, it checks the frame header of ATM cell, counts the total of received cells, idle cells, error cells and lost cells, and counts the total cells and



5-26

idle cells that are sent.

In f4–f5 sections, it monitors OCD, LCD and HCS alarms of ATM cell.

In f4–f5 sections, it provides ATM cell insertion, cell service scramble, HCS calculation and insertion.

2. ATM Layer Processing Module

Flow monitoring of double leaky buckets is provided for each VC connection.

It supports five service types and provides powerful traffic dispatching algorithm.

It can support OAM powerfully, as well as loop-back, continuity check and error check in FM function.

3. SDH Layer Processing Module

Check frame header of ATM cell, count the received cells, idle cells, error cells and lost cells, and count the total cells and idle cells which are sent.

Monitor OCD, LCD and HCS alarms of ATM cell.

Insert ATM cells, scramble cell service, count and insert HCS.

Conduct conversion from UTOPIA bus to TELECOM bus.



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5.7 Alarms and Signal Flows of Ethernet Service

5.7.1 Logic Diagram of ET1O Board

The principle diagram of ET1O is shown in Figure 5-13, covering PHY layer, MAC layer, control unit, interface conversion unit and mapping/demapping unit.

PHY

MAC

Ethernet interface module

Encapsulation unit

Mapping/demappingunit

Cross-connect unit

Control unit SCC unit

Front panel Backplane

ALM(R)

RUN(Y)

Power3.3V

8×10

M/1

00M

Eth

erne

t ser

vice

Store-forwardunit

5V

2V1.8V

Mailbox

Driv

er c

hip

Figure 5-13 Logic diagram of ET1O board

IP signals are processed in ET1O/EF1/ET1D board as follows.

1. PHY Layer

PHY layer mainly performs encoding/decoding, serial/parallel converting, clock extracting, scrambling/de-scrambling, baseline wander correcting, carrier sense and collision output for data.

2. MAC Layer

MAC layer belongs to the second layer, namely the data link layer, in OSI network model. Major functions of MAC layer are:

Framing

Addressing

Control and maintenance for various MAC protocols

Error detection and correction, aiming at error free communication

Defining access rules of various media



5-28

3. Conversion

Convert MAC frame into 2 Mbit/s signals. Many functions such as VLAN processing can be added.

4. Mapping

Map 2M to VC-12 then transmit it to SCB board.

5.7.2 Generation and Detection of Alarms

According to IP OVER SDH standard issued by ITU-T, Ethernet services are transmitted by mapping 10 M/100 M Ethernet interface into 1 or multiple 2 Mbit/s. Thus, the problem of interface is solved, and this method is also used by ET1O/EF1/ET1D board. This board provides multiple 10 M/100 M compatible Ethernet electrical/optical interfaces, and then converges the services and maps them into multiple E1s for transmission.

Ethernet services are transmitted after being mapped into multiple E1s, and as E1s, they are also in point -to-point mode (non-sharing). Therefore, in SDH, various protection schemes for E1 services apply to Ethernet services, and E1 alarms and detection principles also apply to ET1O/EF1/ET1D boards.

OptiX 155/622H(Metro1000) Maintenance Manual 6 Flow of Serious Fault Handling


6-1

6 Flow of Serious Fault Handling

6.1 Flowchart of Handling Serious Fault

Serious fault is defined as service interruption for the customers. A timely and effective handling is necessary to this type of fault, following the flowchart shown in Figure 6-1. This flowchart also serves as a guide for the maintenance personnel during the equipment maintenance.



6-2

Start

Record fault phenomena

External causes

Other handling process

Work out solutions togehter

Service recovery?

Running and observing

Summary and filing

Fault removed?

End

Analyze andlocate fault

No

Yes

Feed back to Huawei Co.

Fault removed？

Try to solve

No

Yes

No

Yes

No

Yes

Figure 6-1 Flowchart of serious fault handling



6-3

6.2 Flowchart Description

When recording the fault phenomena, make sure that record is true and detailed, including occurrence time and operations performed before and after the fault occurrence. Meanwhile, important data such as alarm information and performance event should also be well saved and observed via the NMS.

If the fault is caused by obvious external reasons in optical cable or terminal equipment, such as switch, turn to other handling process in due time.

Follow the principle of recovering the service as early as possible when handling such faults.

Follow the operation specifications strictly when performing operations on the equipment, for example, wear an ESD protection wrist strip.

Try to eliminate the fault by fault analysis. Such operations as power-off, swapping board, and replacing board, should not be done at random. In this way, new problems can be avoided and the fault range will not be enlarged.

If you fail to solve the problem yourself, please contact the local office of Huawei for technical supports. The maintenance engineer of Huawei will work together with you within the shortest time to locate the fault and to work out a solution.

After service recovery, the running status of the equipment and network must be traced and observed to make sure the fault has been eliminated.

After handling the fault, fill up corresponding reports and forms, such as SDH Outburst Problem Handling Record, to complete a closed loop of the fault handling flow.



6-4

6.3 Recommendations

It is recommended to adopt the system of special-person maintenance on the NMS and equipment, to implement hierarchical management on software and hardware and increase the personnel training.

After the fault is removed, arrange the writing of a case to provide experiences for maintenance later.

Read relevant manuals delivered along with the equipment to get more theory knowledge.

Visit the Huawei’s websites as below at your convenience.

http://www.huawei.com

http://tech-support.huawei.com

OptiX 155/622H(Metro1000) Maintenance Manual A Alarm Signal Flow


A-1

A Alarm Signal Flow

(C2)

LOS/LOFRS-TIMBIP Err.

MS-AISMS-BIP Err.

MS-REIMS-RDI

AU-AISAU-LOP

HP-UNEQHP-TIMHP-BIP Errr.HP-REI

HP-RDITU-AISTU-LOPLOMHP-SLM

LP-UNEQLP-TIMLP-BIP Err.LP-REI

LP-RDI

LP-SLM

"1"

AIS

"1"AIS

"1"

"1"

AIS

"1"

"1"

AIS

"1"AIS

(J0)

(B1)

(K2)

(B2)(M1)(K2)

(J1)

(B3)(G1)(G1)

(H4)

(C2)

(V5)(J2)

(V5)

(V5)(V5)

(V5)

RST HPA LPT

Generation of related alarm or signalDetection of related alarms

HPT MSA MST

Figure A-1 SDH alarm signal flow

OptiX 155/622H(Metro1000) Maintenance Manual A Alarm Signal Flow


A-2

SECTIONLOS/LOF

PAIS

LOP

"1"

AIS

"1"AIS

LINE

PMD

"1"

PATH

LAIS

"1"

LRDI

PRDI

LCD

VC

AIS

AIS

PHY ATM

VPTC

VPRDI

VPAIS

VCAIS

AIS

AIS

AIS

F1 F2 F3 F4 F5

Figure A-2 ATM alarm signal flow

OptiX 155/622H(Metro1000) Maintenance Manual B List of Alarms and Performance


B-1

B List of Alarms and Performance

B.1 Common Alarms

AU_AIS

Item Description

Alarm name AU_AIS

Full name AU alarm indication

Alarm level Major

Alarm type Communication alarm

Alarm cause (1) AU_AIS alarm in VC4 channel caused by MS_AIS, R_LOS and R_LOF.

(2) Service configuration error.

(3) The opposite end sends the AU_AIS.

(4) Fault lies with the transmitting part of the opposite station.

(5) Fault lies with the receiving part of the local station.



B-2

Item Description

Solutions (1) For the AU_AIS alarm in VC4 channel caused by MS_AIS, R_LOS and R_LOF of the local station, analyze the MS_AIS, R_LOS and R_LOF to locate the fault.

(2) Another possible reason is that the receive and transmit services may be staggered in the corresponding VC4 channel, resulting in the AU_AIS alarm to the receiving end in the channel concerned. In this situation, the TU_AIS will occur to the corresponding TU in the AU_4. At this time, please check the station where the AU_AIS happens and its interactive stations, and check if the service pass-through stations in-between have wrong configuration of service time slots.

(3) Replace the SCB board and line board corresponding to the opposite station.

(4) Replace the line board and SCB board of the local station.

Remarks



B-3

AU_LOP

Item Description

Alarm name AU_LOP

Full name AU Loss of Pointer

Alarm level Major


Alarm cause (1) Fault lies with the transmitting part of the opposite station.

(2) Service configuration error in the opposite station.

(3) Too many receiving error codes in the local station.

Solutions (1) Check the service configuration of the opposite and local stations. If it is not right, reconfigure the services.

(2) Generally, this fault does not happen to the 155 Mbit/s optical interface board. If it does occur, it may be due to the wrong configuration of the board. When the 622M optical interface board receives the AU_LOP alarm, please check if the remote clock board works normally and if the cross-connect unit detected the clock.

(3) Replace the SCB and line boards corresponding to the remote station one by one to locate the fault.

(4) Replace the line board and the SCB board of the local station.

Remarks



B-4

B1_EXC

Item Description

Alarm name B1_EXC

Full name Regenerator section (B1) excessive errors

Alarm level Minor

Alarm type QoS (quality of service) alarm

Alarm cause (1) The attenuation of the receiving signal is on the large side.

(2) Fault lies with the transmitting part of the remote station.

(3) The optical fiber head is not clean or the connector is not correct.


Solutions (1) Check the receiving optical power. If it is too low, check if the optical fiber cable is intact and if its connector is clean, then check if the transmitting optical power of the remote optical board is normal.

(2) Loopback at the local station. If the error codes disappear, then the remote optical board failed; if the error codes increase, the local optical board failed, just replace it.

(3) Check the working temperature and fan failure.

(4) Replace the faulty boards.

Remarks The service will be affected when the optical boards are being looped back.



B-5

B2_EXC

Item Description

Alarm name B2_EXC

Full name Multiplex section (B2) excessive errors

Alarm level Emergency

Alarm type QoS alarm


(2) The optical fiber is not clean or the optical fiber connector is not correct.



(5) Caused by B1 bit error.

Solutions (1) If B1 bit error also appears, clear it first.

(2) If there are only B2 bit error, the fault is usually with the optical interface board, please replace it.

(3) Check if the working temperature of the equipment is over high.

(4) Replace the faulty boards in other cases.

Remarks



B-6

B3_EXC

Item Description

Alarm name B3_EXC

Full name High order path (B3) excessive errors

Alarm level Major



(2) The optical fiber head is not clean or the optical fiber connector is not correct.



(5) Caused by B1 and B2 bit errors.

Solutions (1) If B1 and B2 bit errors also happen, solve them first.

(2) If there are only B3 bit error, the fault is usually with the optical interface board, please replace it.

(3) Check if the working temperature of the equipment is over high.

(4) Replace the faulty boards.

Remarks

DOWN_E1_AIS

Item Description

Alarm name DOWN_E1_AIS

Full name 2M down signal alarm indication

Alarm level Minor


Alarm cause (1) All "1" indication for the 2 M down signal.

Solutions (1) It may be due to the high order alarm, just eliminate the alarm.

(2) Replace the tributary board. If this does not work, replace the SCB board.

Remarks



B-7

ETH_LOS

Item Description

Alarm name ETH_LOS

Full name Ethernet receive loss of input signal


Alarm cause (1) The attenuation of the received signal is too large, which is caused by electrical cable break or excessive cable attenuation.

(2) The working mode of the port is set incorrectly.

(3) The TAG attribute of the port is set incorrectly.

(4) The EMS3/EFT board at the upstream station or this station fails.

Solutions (1) Observe the green indicator to the right of the Ethernet port of the EFT board.

(2) Check the working mode configuration of the board and that of the interconnected equipment for consistency.

(3) Check the configuration of the board TAG attribute and that of the interconnected equipment for consistency.

(4) Replace the EFT board of the upstream station and this station in turn.

FAN_FAIL

Item Description

Alarm name FAN_FAIL

Full name Fan failed

Alarm level Major

Alarm type Equipment alarm

Alarm cause (1) Fan not powered on.

(2) Fan failed.

Solutions (1) Check if the fan works normally.

(2) Check the fuse on the fan board. If it melts down, replace it with a new one.

Remarks



B-8

HP_LOM

Item Description

Alarm name HP_LOM

Full name High order path loss of multiframe

Alarm level Major


Alarm cause (1) Service configuration error.

(2) H4 bytes are lost or not correctly configured.

Solutions (1) This is mainly caused by the remote station problems, such as cross-connect unit fails, or the C2 byte receive/transmit mismatch.

(2) Check the service configuration of the remote and local station. If the configuration is wrong, change it and reconfigure the services.

(3) Check if the bus selection of the remote board is correct; if it has the T_LOS alarm; if the cross-connect unit and the line board are faulty. Loopback the optical path to check the hardware of the remote station. If it is the fault of the remote station, replace the cross-connect unit and line board in sequence, then check its subrack.

(4) Loopback the optical path to check the local station. If it is faulty, replace the faulty board.

Remarks



B-9

HP_RDI

Item Description

Alarm name HP_RDI

Full name High order path remote defect indication

Alarm level Minor


Alarm cause (1) The remote station receives the AU_AIS/AU_LOP alarm signals.

(2) Fault lies with the receiving part of the remote station.

(3) Fault lies with the transmitting part of the local station.

Solutions (1) If this alarm happens, check if the high order alarm happened to the equipment. If yes, analyze its causes and solve them.

(2) Check if the AU_AIS and AU_LOP alarms happened to the line boards of the remote station. If yes, solve them. After that, the HP_RDI alarm will be over.

(3) If the alarm does not occur to the remote station or the HP_RDI lingers when the corresponding alarm is over, then the fault is with the board, replace it.

Remarks



B-10

HP_REI

Item Description

Alarm name HP_REI

Full name High order path remote error indication

Alarm level Prompt


Alarm cause (1) The remote station receives the B3 bit error.

Solutions (1) Check if the B3 bit error happens to the remote station. If the remote station has B3 bit error and B1 and B2 alarms, the fault is always caused by over attenuation of the line or the failed optical interface board. The fault is located in the same way as that of locating the R_LOS fault.

(2) If only small number of B3 bit error happens to the remote station, it is usually the fault of the equipment. In this case, check if the cross-connect board and the tributary board of the remote station are normal.

(3) Check if the cross-connect board and the tributary board of the local station are normal.

(4) Check the equipment grounding to see if there is any big interference source nearby.

Remarks



B-11

HP_SLM

Item Description

Alarm name HP_SLM

Full name High order path signal label mismatch

Alarm level Minor


Alarm cause (1) The signal label to be received by the local station mismatches that transmitted by the remote station.


Solutions (1) Check if the signal label of the corresponding high order path on the line board of the remote station matches the signal label of the local station. If not, change their setting and drop them again. If they are the same, then the board is faulty, you can replace the faulty board.

(2) Check the service configuration of the remote station and the local station. If the configuration is wrong, change it and drop it again.

Remarks



B-12

HP_TIM

Item Description

Alarm name HP_TIM

Full name High order path trace identifier mismatch

Alarm level Minor


Alarm cause (1) The path trace identifier to be received by the local station mismatches that to be transmitted by the remote station.


Solutions (1) Check if the high order path trace identifier of the corresponding high order path on the line board of the remote station matches the path trace identifier of the local station. If they are not the same, change their setting and drop them again; if they are the same, then the board is faulty, you can replace the faulty board.

(2) Check the service configuration of the remote station and the local station. If the configuration is wrong, change it and drop it again.

Remarks

HP_UNEQ

Item Description

Alarm name HP_UNEQ

Full name High order path unequipped

Alarm level Minor


Alarm cause C2 byte is 0.

Solutions Check the configuration to determine if the C2 byte is wrongly configured. If it is wrong, change the configuration and download it again; if it is correct, then the board is faulty, just replace the board.

Remarks



B-13

ILL_SQ_VC12

Item Description

Alarm name ILL_SQ_VC12

Full name Sequence Indication is illegal in VC12

Alarm level Major

Alarm cause (1) The virtual concatenation delay is too long.

(2) Link error

Solutions (1) Check whether there are line alarms on the equipment, such as R_LOS and R_LOF. If there are, handle them accordingly.

(2) Check the service configuration in the local station and the opposite station. For example, check the consistency of the binding timeslot and SDH timeslot configuration. If they are not consistent, you need to modify the configuration.

Remarks

ILL_SQ_VC3

Item Description

Alarm name ILL_SQ_VC3

Full name Sequence Indication is illegal in VC3

Alarm level Major


(2) Link error



Remarks



B-14

ILL_ MFI _VC12

Item Description

Alarm name ILL_ MFI _VC12

Full name Multiframe indication is illegal in VC12

Alarm level Major


(2) Link error



Remarks

ILL_ MFI _VC3

Item Description

Alarm name ILL_ MFI _VC3

Full name Multiframe indication is illegal in VC3

Alarm level Major


(2) Link error



Remarks



B-15

LCAS_BAND_DECREASED

Item Description

Alarm name LCAS_BAND_DECREASED

Full name LCAS bandwidth protecting alarm

Alarm level Minor

Alarm cause LCAS bandwidth protection function is enabled and VC-Trunk service bandwidth is reduced.

Solutions Check whether the related SDH channels of VC-Trunk fail and whether the related SDH link is normal.

LP_RDI

Item Description

Alarm name LP_RDI

Full name Low order path remote defect indication

Alarm level Minor


Alarm cause (1) The remote station receives the TU_AIS/TU_LOP alarm signals.



Solutions (1) Check if the TU_AIS and TU_LOP alarms happened to the path corresponding to the tributary board of the remote station. If they did happen, solve them, the LP_RDI alarm will clear.

(2) If the remote station does not have alarms or the LP_RDI lingers when the alarm concerned is over, the fault may lie with the board, just replace it with a new one.

Remarks



B-16

LP_SLM

Item Description

Alarm name LP_SLM

Full name Low order path signal label mismatch

Alarm level Minor


Alarm cause (1) The low order path signal label of the local station does not match that of the remote station.


Solutions (1) Check if the signal label byte configuration of the corresponding low path on the tributary board of the remote station is the same as that of the local station. If their configurations are not the same, change them and drop them again; if they are the same, the fault may lie with the board, just replace it with a new one.

(2) Check the service configuration of the remote station and the local station. If they are wrongly configured, change them and drop them again.

Remarks



B-17

LP_TIM

Item Description

Alarm name LP_TIM

Full name Low order path trace identifier mismatch

Alarm level Minor


Alarm cause (1) The low order path trace identifier of the local station does not match that of the remote station.


Solutions (1) Check if the trace identifier configuration of the corresponding low path on the tributary board of the remote station is the same as that of the local station. If their configurations are not the same, modify them and then download them again; if they are the same, the fault may lie with the board, just replace it with a new one.

(2) Check the service configuration of the remote station and the local station. If they are wrongly configured, change them and drop them again.

Remarks



B-18

LP_UNEQ

Item Description

Alarm name LP_UNEQ

Full name Low order path unequipped

Alarm level Minor


Alarm cause No 2 M service access.

Solutions (1) Check the service configuration of the remote station and the local station. If they are wrongly configured, change them and download the new configuration.

(2) Check if the attributes of the tributary boards in the two stations are correct.

Remarks



B-19

LTI

Item Description

Alarm name LTI

Full name Loss of timing input

Alarm level Major


Alarm cause In the non-S1 byte mode:

(1) The optical fiber is broken (if the line clock source is traced).

(2) The external source clock stops input (if the external clock source is traced).

In the S1 byte mode:

(1) The optical fiber is broken.

(2) Enter the free running mode.

(3) Wrong setting of the synchronous source.

Solutions (1) Check the clock synchronous configuration to see if the synchronous clock source traces the clock source not existed. If the configuration is wrong, change it and drop it again.

(2) If the configuration is correct, then check if the traced synchronous source is normal. If it is not normal, please solve the fault to make it normal (if the line clock is traced and there is the signal loss alarm on the line, please first of all handle the signal loss alarm; if the external clock is traced, check if the external clock is normal and if the external clock line is well connected).

(3) If the traced synchronous source is normal, the fault may lie with the board, just replace it.

Remarks



B-20

MS_AIS

Item Description

Alarm name MS_AIS

Full name Multiplex section alarm indication

Alarm level Major


Alarm cause (1) The remote station transmits the MS_AIS.

(2) The clock board of the remote station is faulty.

(3) The receiving part of the local board is faulty.

Solutions (1) Check if the line board of the remote station is faulty. Reset or replace the board to see if the alarm disappears.

(2) Check the line board of the local station. You can also reset or replace the board to see if the alarm disappears.

Remarks



B-21

MS_RDI

Item Description

Alarm name MS_RDI

Full name Multiplex section remote defect indication

Alarm level Minor


Alarm cause (1) The remote station receives the R_LOS/R_LOF/MS_AIS.



Solutions (1) Check if R_LOS, R_LOF and MS_AIS happened to the line boards of the remote station. If they did happen, remove them, and the MS_RDI alarm will clear.

(2) If there is no alarm in the remote station or the MS_RDI is still there when the corresponding alarm is over, please replace the alarm board.

(3) It is rare to encounter the broken optical fibers because the alarm will occur to the local station only when the local transmitting optical fiber is broken and the receiving optical fiber is in good condition. If the receiving/transmitting optical fibers are all broken, the MS_RDI will not be sent back to the local station. Please check mainly the optical fiber connection (ODF side, and the optical interface board side) between the local station and the remote station.

Remarks



B-22

MS_REI

Item Description

Alarm name MS_REI

Full name Multiplex section remote error indication

Alarm level Prompt


Alarm cause (1) The remote station receives the B2 bit error.



Solutions (1) Loopback the optical interface board concerned in the local station to see if the bit error increases in the local MS_REI performance events in order to judge if the problem lies with the local or the remote station.

(2) If the bit error stops increasing, then the receiving terminal on the remote board is faulty, replace the board.

(3) If the bit error keeps increasing, the transmitting terminal on the local board is faulty, replace the board.

Remarks The loopback of optical fibers is forbidden when running services.

POWER_FAIL

Item Description

Alarm name POWER_FAIL

Full name Power failure

Alarm level Major


Alarm cause Secondary power supply module failed.

Solutions Check if the secondary power supply output is normal. If not, replace the faulty board.

Remarks



B-23

PS

Item Description

Alarm name PS

Full name Protection switching indication

Alarm level Major


Alarm cause (1) Protection switching occurred.

(2) Wrong setting of board parameters.

Solutions PS alarm on the tributary board

(1) In the path protection ring, if there is PS alarm on the tributary board, check if there is R_LOS, R_LOF and excessive error codes leading to the protection switching. If there are such alarms, please remove them first.

(2) In the chain network or the multiplex protection ring, if the PS alarm happens to the tributary board, check if the parameter setting on the tributary board is correct, that is if it is set as unprotected.

Remarks



B-24

R_LOF

Item Description

Alarm name R_LOF

Full name loss of frame



Alarm cause (1) The attenuation of the receiving signals is on the large side.

(2) There is no frame structure for the remote transmitting signals.

(3) The local receiving direction is faulty.

Solutions (1) If the R_LOF happens, usually it indicates that the optical fiber is broken, the optical fiber attenuation is too large or the board is faulty.

(2) Check if the optical fiber is intact.

(3) Check if the optical fiber connector is in good contact state. Clean it if it is dirty.

(4) In case of the faulty board, replace it.

Remarks



B-25

R_LOS

Item Description

Alarm name R_LOS

Full name Loss of signal



Alarm cause (1) Broken fiber.

(2) The line attenuation is too large or the optical power is overloaded.

(3) Fault lies with the transmitting part of the remote station, or the line transmission failed.

(4) The remote cross-connect unit is faulty.

(5) The remote clock unit is faulty.

Solutions (1) If the R_LOS happens, it indicates that the optical fiber is broken, the optical fiber attenuation is too large, the receiving optical power is overloaded or the board is faulty.

(2) Check if the optical fiber cable is intact, if the optical connector is in good contact situation, and if the optical cable connector is cleaned.

(3) Add the attenuator if the receiving optical power is overloaded.

(4) If the board is faulty, replace it.

Remarks



B-26

R_OOF

Item Description

Alarm name R_OOF

Full name Out of frame



Alarm cause (1) The attenuation of the receiving signals is too large.

(2) Excessive error codes during the transmission process.


(4) The local receiving direction is faulty.

Solutions (1) Usually, the reasons are the optical fiber is broken, the optical fiber attenuation is too large, the receiving optical power is overloaded or the board is faulty.

(2) Check if the optical fiber cable is intact, if the optical connector is in good contact state, and if the optical cable connector is cleaned.

(3) Add the attenuator if the receiving optical power is overloaded.

(4) If the board is faulty, replace the board.

Remarks



B-27

SYNC_C_LOS

Item Description

Alarm name SYNC_C_LOS

Full name Synchronous source level loss

Alarm level Prompt


Alarm cause The high level clock source is unavailable:

(1) The optical fiber is broken (Trace the line clock source).

(2) The external clock source stops input (Trace the external clock source).

Solutions (1) If the priority level of the clock source is lost, please reset it.

(2) If the line clock source is traced, please check if the R_LOS alarm happens. If it did happen, please remove it in a proper method.

(3) If the tributary clock source is traced, remove the T_ALOS alarm if it is detected.

(4) If the external clock source is traced, check if the external clock source works normally.

Remarks

SYN_BAD

Item Description

Alarm name SYN_BAD

Full name Synchronous source degraded

Alarm level Minor


Alarm cause The quality of the traced synchronous source indexes is degraded.

Solutions (1) Check and remove the bit errors and pointer justification performance events occurred in the traced clock source direction.

(2) The setting of clock trace will not cause clock trace loop.

Remarks



B-28

TU_AIS

Item Description

Alarm name TU_AIS

Full name TU alarm indication

Alarm level Major


Alarm cause (1) Service configuration error.

(2) The corresponding remote path failed.

(3) Caused by a higher order alarm, such as R_LOS.

(4) Cross-connect unit fault.

Solutions (1) Check if there is high order alarm, such as R_LOS. If there is one, please remove it first.

(2) Check the service configuration. If it is wrong, change it and download it again.

(3) Check if the alarm is caused by the faulty cross-connect unit or the tributary board. If so, replace the faulty board.

Remarks



B-29

TU_LOP

Item Description

Alarm name TU_LOP

Full name TU loss of pointer

Alarm level Major


Alarm cause (1) The fault is with the interface between the tributary board and the cross-connect unit.


Solutions (1) Check the configuration of the cross-connect unit or the tributary board. If it is wrong, correct it and download it again.

(2) Loopback to check if there are inverted pointers on the backplanes in both local and remote stations, and change the positions of the corresponding tributary board and cross-connect unit.

Remarks



B-30

T_ALOS

Item Description

Alarm name T_ALOS

Full name 2M interface loss of analog signal

Alarm level Major


Alarm cause (1) 2 Mbit/s service not accessed.

(2) The output port of the 2M interface at the DDF side falls off or gets loose.

(3) The output port of the 2M interface of the local station falls off or gets loose.

(4) Board fault.

(5) Cable fault.

(6) Switch reset.

Solutions Divide the alarm sections through the multi-level loopback and locate the alarm point.

(1) Determine the board position and channel number of the alarm at the NMS.

(2) Loopback the channel at the 2 Mbit/s tributary board interface. If the alarm is not over after the loopback, replace the 2M tributary board.

(3) If the alarm disappears after the loopback, then you can determine that the fault is not with the transmission equipment. Loopback the DDF in the direction of the transmission equipment to see if the cable between the DDF and the transmission equipment is faulty. If the alarm still exits after loopback, then the problem surely lies with the DDF connector or the cable between the DDF and the tributary board.

(4) If the alarm is over after the loopback on the DDF, then loopback the transmission equipment on the DDF to see if the problem is with the cable from the DDF to the switch or with the switch itself.

Remarks



B-31

T_DLOS

Item Description

Alarm name T_DLOS

Full name 2M interface loss of digital signal

Alarm level Minor


Alarm cause (1) 2 Mbit/s services not accessed.

(2) The output port of the 2M interface on the DDF falls off or gets loose.

(3) The output port of the 2M interface of the local station falls off or gets loose.

(4) Board fault.

(5) Cable fault.

Solutions Divide the alarm sections through the multi-level loopback to locate the alarm point.

(1) Decide the board position and channel number of the alarm at the NMS.

(2) Loopback the channel generating the alarm at the 2M tributary board interface to locate the fault.

(3) Replace the faulty board and the 2M cable.

(4) Replace the faulty board and 2M cable.

(5) If the switch is faulty, ask the maintenance engineer to solve it.

Remarks



B-32

UP_E1_AIS

Item Description

Alarm name UP_E1_AIS

Full name 2M up signal alarm indication

Alarm level Minor


Alarm cause All "1" indication of the 2 M up signal.

Solutions (1) This may be caused by the high order alarm, remove it.

(2) If the tributary board is faulty, replace it.

Remarks

VC_DELAY_TL

Item Description

Alarm name VC_DELAY_TL

Full name VC delay too long


Alarm cause The actual delay in the SDH network crosses the compensation threshold of the concatenation delay.

Solutions Modify the configured trail.



B-33

B.2 Category of System Performance

RS (Regenerator Section) Performance Events

Abbreviation Full name

BBE Background Block Error

ES Error Second

SES Severely Error Second

OFC Out of Frame Counts

OFS Out of Frame Second

CSES Consecutive SES Counts

UAS Unavailable Second

MS (Multiplex Section) Performance Events



ES Error Second


REI Remote Error Indication

FEES Far End Error Second

FECSES Far End Consecutive Severely Error Second




B-34

MSA (Multiplex Section Adaptation) Performance Events


PJCHIGH AU Pointer High Justification Counts

PJCLOW AU Pointer Low Justification Counts

NDF AU New Data Flag

HP (Higher Order Path) Performance Events



ES Error Second




FECES Far End Consecutive Error Second

CSES Consecutive Severely Error Second



HPA (Higher Order Path Adaptation) Performance Events


PJCHIGH TU Pointer High Justification Counts

PJCLOW TU Pointer Low Justification Counts



B-35

LP (Lower Order Path) Performance Events



ES Error Second




FECES Far End Consecutive Error Second

CSES Consecutive Severely Error Second



PS (Protection Switching) Performance Events


PSC Protection Switching Count

PSD Protection Switching Duration

Framing Performance Events


TFECNT Transmission Framing Error Count

RFECNT Receiving Framing Error Count

OptiX 155/622H(Metro1000) Maintenance Manual C Guidance for OptiX Routine Maintenance and Record


C-1

C Guidance for OptiX Routine Maintenance and Record

C.1 Daily Maintenance Recommendations

Respected users:

Thanks for choosing Huawei SDH transmission equipment. In order to maintain the normal and stable running of the equipment, please follow the proposals below and the daily maintenance manual.

1. The transmission equipment should be maintained by specially trained technicians due to its great significance.

2. The transmission equipment room should be kept clean, dustproof, moisture-proof and rodent-proof.

3. Check and test the SDH equipment every day according to the Guidance for SDH Daily Maintenance and record the results.

4. Clean the fan air filter once every two weeks. If the equipment surface temperature is too high, check if the fan air filter is blocked. The fan must be turned on.

5. The transmission NMS password should be strictly managed and periodically changed, which is open only to the person in charge of maintenance. The password at the system level should be controlled by maintenance director only.

6. It is strictly prohibited to load other software to the transmission NMS computer and use the transmission NM computer to play games. Please kill virus periodically for the NM computer.

7. If there are serious alarms occur due to unknown causes, please handle them according to the “Flow of Serious Fault Handling” stated in this Manual, if the problem is with the equipment itself, please contact Huawei.



C-2

8. Please perform maintenance according to the relevant specifications provided by Huawei so as to avoid accidents caused by human factors.

9. Be cautious to adjust the optical fibers and cables. Mark them before adjustment to avoid cable mixture when restoring them.

10. Please wear an ESD wrist strap when performing operations on the equipment hardware.

11. Do not reset the equipment or change the service data at random.



C-3

C.2 Explanation of SDH Daily Maintenance Record and Guidance for SDH Daily Maintenance

(1) The SDH Daily Maintenance Duty Log shall be filled by the transmission equipment maintenance personnel every day. This log should record contain the information about the equipment room environment and the equipment running conditions during their duty. The user may change the contents of the SDH Daily Maintenance Duty Log according to their local office situation, or transform the table into a duty log manual with the Guidance for SDH Daily Maintenance attached at the back.

(2) The SDH Monthly (Quarterly) Maintenance Record records the items of monthly (quarterly) maintenance of SDH transmission equipment. For the monthly maintenance methods, refer to Guidance for SDH Monthly Maintenance and Guidance for SDH Quarterly Maintenance.

(3) The SDH Outburst Problems and Solutions Record records the outburst problems and the solutions as the basis for future maintenance or check. The user can modify the contents of SDH Outburst Problems and Solutions Record.

(4) The Board Replacement Record records the replacement of boards.

(5) The Data Modification Record records the data change modification made to the SDH equipment.



C-4

C.3 Guidance for SDH Daily Maintenance

Maintenance type Maintenance item Guidance Reference standard

Equipment room power supply (AC/DC)

Check the power supply monitoring system or test the output voltage of power supply.

Output voltage normal, no alarm in the power supply.

Equipment room cleanliness

Refer to the attached Table.

Refer to the attached Table.

Equipment room temperature

Test temperature. Temperature range: 0°C–45°C; recommended 15°C–30°C.

Outside Ambient environment check

Equipment room humidity

Test the relative humidity.

Relative humidity: 10%–90%; recommended 40%–65%.

Status of the indicator on the chassis

Observe the indicator on the chassis.

Normally green indicator is on for 1 second and off for 1 second

Board indicator status Observe each board indicator.

SCB board indicator: normally only green indicator is on for 1 second and off for 1 second. Ethernet indicator (ETN) of gateway station is on.

For the indicators on other boards, please refer to Hardware Description Manual.

Equipment surface temperature

Test the equipment surface temperature.

The maximum equipment temperature queried through NMS should not exceed 40°C.

Equipment fans status

(check on about the 1st and 15th of each month.)

Observe the fan running status.

Only the green fan indicator on, then its ventilation is normal.

Equipment running status check.

Orderwire telephone status.

(Checked on about the 1st and 15th of each month.)

Test the communication status.

Addressing call and conference call are all normal.



C-5

Maintenance type Maintenance item Guidance Reference standard

NMS login Log into NMS as a user with low priority, and recommend one account number for one maintenance person.

Able to log into NMS.

NE status check. Log into NE through NMS, and check the status.

All NEs can be logged in; NEs are in operation.

Board status check Observe the in-position and in-service status of board through board position diagram in the NMS.

Board on the board position diagram should be in position, and in service.

NMS maintenance item.

Alarm check View the current and history alarm through NMS alarm query and browse function.

No abnormal alarm in the system.


Performance events monitoring

Query the current and history performance data through NMS performance data query function.

Performance report normal. Bit error, pointer justification performance data conforms to the ITU-T Recommendation. No performance data threshold-crossing.

Protection switching check

Check switching status and switching alarm.

For path protection, there should be no PS alarm in all the tributary board channels when no protection switching occurs.

For multiplex section protection, status of all the protocol controllers on the ring should be “normal”, and meanwhile, there is no PS alarm in the cross-connect unit and line board, no APS-INDI alarm in the SCB board.

Query to the log record

Apply querying function of NMS operation log.

No attempt to log in to NMS;

No abnormal data modification operation.


Equipment environmental variables check

No temperature and voltage alarms;

Temperature performance data normal.



C-6

Annex: Requirement for the equipment room cleanliness: Maximum diameter (µm) 0.05 1 3 5 Maximum density (particles/m3)

1.4 x 106 7 x 105 2.4 x 105 1.3 x 105



C-7

C.4 Guidance for SDH Monthly Maintenance

Maintenance type

Maintenance item Guidance Reference standard

Service check Sample test of 24-hour bit error on the unused service channel.

Test one unused channel with a bit error meter for 24 hours.

The 24-hour bit errors should meets relevant standard (for a 2 M-channel, the 24-hour bit error should be 0).

Check the NMS start and shutdown.

Start and shut down the NMS software and computer.

Both the start and shutdown should be normal.

ECC route check. [NE communication management/NE ECC route management].

The route is smooth and the traffic takes the shortest path.

NE time query. [Basic configuration/Synchronize NE time].

NE time is consistent with the current actual time, and the time of all NEs is consistent.

Querying board configuration information.

Check the relevant configuration information of timing unit, overhead processing unit, tributary board and line board.

Configuration data are consistent with the practical demands, and comply with the latest modification records.

Periodical modification of the login password of NMS user.

Modify the password of NMS user each month.

Modify the password each month.

NMS maintenance item

Dump and arrangement of NES NMS database.

Dump the NMS database file, and compress and recover the database each month.

Do so periodically, and NMS runs normally.

NMS database backup.

Backup NMS database each month.

Backup each month, and NMS and database run normally.

NMS computer maintenance.

PC: check directory; check the hard disk space and kill virus.

Workstation: check directory and database operation status; backup configuration file of users.

PC: the directory is normal; the file is normal without any illegal file such as game; the hard disk has sufficient space.

Workstation: no illegal file is stored, and the database runs normally.


Interface status of each hardware.

Check the working status of the mouse, keyboard, display and printer.

They can be used normally.



C-8

C.5 Guidance for SDH Quarterly Maintenance

Maintenance type

Maintenance item

Guidance Reference standard

Remote maintenance test

Remote maintenance test

Log into NE from the remote end.

NE login is normal, and the remote maintenance can be done normally.

Cabinet cleanliness check

Cabinet cleanliness check

Observe interior and exterior of the cabinet.

The cabinet surface is clean, and its interior should not be dusty, either. Otherwise, clean it.

C.6 Guidance for SDH Yearly Maintenance

Maintenance type

Maintenance item Guidance Reference standard

Grounding resistance check

Use a grounding resistance meter to test the ground resistance.

Joint grounding resistance is less than 1 ohm.

Grounding cable connection check

Check whether the connection of the grounding cable to the grounding bar of the buyer is safe and reliable.

(1) Each connection point is safe and reliable, and free from corrosion. (2) The grounding cable is free from aging. (3) The grounding bar is free from corrosion, and the corrosion-proof processing is appropriate.

Check of grounding, grounding cable connection and power cable connection

Power cable connection check

Check whether connection of the power cable to the power supply of the buyer is safe and reliable

(1) Each connection point is safe and reliable, and free from corrosion. (2) The power cable is free from aging.



C-9

C.7 SDH Daily Maintenance Duty Log

Date: On-duty time: To: Handed over by: Handed over to: Maintenance type

Maintenance item Maintenance status Remarks Maintained by:

Exterior status (power supply system, fire alarm, dust, and lightning strike)

Normal Abnormal

Temperature (normally 15–30°C) Normal Abnormal

Humidity(normally 40%–65%) Normal Abnormal

Equipment operating environment

Equipment room cleanliness (good, bad)

Good Bad

Status of the indicator on the chassis

Normal Abnormal

Board indicator status Normal Abnormal

Equipment surface temperature Normal Abnormal

Equipment fan status (check it on about the 1st and 15th of each month)

Normal Abnormal

Check of the equipment operation status

Orderwire phone status (check it on about the 1st and 15th of each month)

Normal Abnormal

NMS login Normal Abnormal

NE status check Norma l Abnormal

Board status check Normal Abnormal

Alarm check Normal Abnormal

Performance events monitoring Normal Abnormal

Protection switching check Normal Abnormal

Log record query Normal Abnormal


Equipment environmental variables check

Normal Abnormal



C-10

On-duty time: To: Handed over by: Handed over to: Maintenance type


Fault description and its solution

Suspended problem

Check by chief operator



C-11

C.8 SDH Monthly (Quarterly) Maintenance Record

Maintenance Cycle: Date: to Date: Maintenance type


Service check Sample test of the 24-hour bit error on the unused channel

Normal Abnormal

Check of NMS start and shutdown

Normal Abnormal

ECC route check Normal Abnormal

NE time query Normal Abnormal

Board configuration query Normal Abnormal

Modifying login password of NMS user periodically

Finished Not finished

Dump of NMS database Finished Not finished

NMS database backup Finished Not finished

NMS computer maintenance Finished Not finished


Interface status of each hardware

Normal Abnormal

Remote maintenance test Normal Abnormal Quarterly maintenance

Cabinet cleanliness check Normal Abnormal

Fault description and its solution

Suspended problem




C-12

C.9 SDH Yearly Maintenance Record

Maintenance Cycle: Date: to Date: Maintenance type

Maintenance item Maintenance status Remarks Maintained by

Grounding resistance check

Normal Abnormal

Grounding cable connection check

Normal Abnormal

Check of grounding, ground cable connection and power cable connection

Power cable connection check

Normal Abnormal

Problem description and its solution

Suspended problem




C-13

C.10 SDH Outburst Problems and Solutions Record

Occurrence time: Solution time: On-duty person: Handled by:

Problem type:

Power supply problem

Trunk cable problem or distribution frame problem

NMS computer problem

Equipment board problem

Equipment software problem

NMS software problem

Grounding or power supply connection problem

Data setting problem

Operation problem

Others (temperature, humidity, rodent damage, electromagnetic interference, etc.)

Fault description:



C-14

C.11 Board Replacement Record

Reason for replacement

Name and model of the replaced board

Name and model of the current board

Number of replaced boards

Replacement date

Replaced by



C-15

C.12 Data Modification Record

Modified by Modification time Reasons for modification

Modification Content

OptiX 155/622H(Metro1000) Maintenance Manual D Abbreviations and Acronyms


D-1

D Abbreviations and Acronyms

Abbreviations Full name

ADM Add/Drop Multiplexer

AIS Alarm Indication Signal

APS Automatic Protection Switching

ATM Asynchronous Transfer Mode


BITS Building Integrated Timing Supply

DC Direct Current

DCC Data Communication Channel

DTMF Dual Tone Multi Frequency

ECC Embedded Control Channel

EMC Electro Magnetic Compatibility

ES Errored second

FIFO First In First Out

GSM Global System for Mobile Communications

HCS Higher Order Connection Supervision

IC Integrated Circuit

IP Internet Protocol

ITU-T International Telecommunication Union-Telecommunication Sector



D-2


LCD Loss of Cell Delimitation

LOF Loss of Frame

LOM Loss Of Multiframe

LOP Loss of Pointer

LOS Loss of Signal

LP Lower Order Path

LPA Lower Order Path Adaptation

LP-REI Lower-order Path Error Indicator

MAC Media Access Control

MS Multiplex Section

MSA Multiplex Section Adaptation

MSOH Multiplex Section Overhead

MSP Multiplex Section Protection

MST Multiplex Section Termination

OAM Operations, Administration and Maintenance

OCD Out-of-Cell Delineation

ODF Optical Distribution Frame

OFS Out-of-frame Second

OHP Overhead Processor

OSI Open System Interconnection

OTDR Optical Time-Domain Reflectometer

PCM Pulse Code Modulation

PDH Plesiochronous Digital Hierarchy

PGND Protection Ground

PHY Physical Layer

POH Path Overhead

PPI PDH Physical Interface

RDI Remote Defect Indication




D-3


RS Regenerator Section

RST Regenerator Section Termination

SCC System Control & Communication Unit

SDH Synchronous Digital Hierarchy

SES severely errored second

SOH Section Overhead

STM Synchronous Transport Module

TCP Transport Control Protocol

TM Termination Multiplexer

TU Tributary Unit

TUG Tributary Unit Group

TU_LOP TU Loss of Pointer


UTOPIA Universal Test & Operations PHY Interface for ATM

VC Virtual Channel

VLAN Virtual Local Area Networks

VP Virtual Path

OptiX 155/622H(Metro1000) Maintenance Manual Index


i-1

Index

A alarm principle, 5-2

B bit error, 4-8

cause analysis, 4-8 common treatment methods, 4-8 fault treatment procedure, 4-9

board replacement, 3-15

C classification of maintenance, 2-1 cleaning the fan, 1-5 comparison of fault locating methods, 3-18 configuration modification, 3-17 control bus, 5-2 cutting off the alarm sound, 1-10

E ECC fault, 4-17

cause analysis, 4-17 fault treatment procedures, 4-18 introduction, 4-17

electrical safety, 1-2 ESD precautions, 1-2 Ethernet cable, 1-17 experience, 3-18 external fault handling, 3-20

I inserting a board, 1-6

L laser safety, 1-1 localizing fault to a single, 3-22 localizing fault to the board, 3-23

loopback, 1-12, 3-9

M maintenance operations, 1-5 mechanical safety, 1-4 meter test, 3-18

O orderwire fault, 4-22

cause analysis, 4-22 common treatment methods, 4-22

overhead path, 5-3

P payload interruption, 4-2

cause analysis, 4-2 common treatment methods, 4-2 fault treatment procedure, 4-2

pointer justification, 4-12 cause analysis, 4-12 common treatment method, 4-12 fault treatment procedures, 4-12

precaution, 1-1 pulling out a board, 1-8

R regular maintenance, 2-3

checking temperature, 2-4 checking the audio alarm, 2-3 cleaing the fan, 2-5 viewing the indicators, 2-3

replacement, 3-15 replacing a board, 1-8 resetting the SCB board, 1-10

S safety, 1-1

eclectrical safety, 1-2

OptiX 155/622H(Metro1000) Maintenance Manual Index


i-2

laser safety, 1-1 mechanical safety, 1-4

service bus, 5-3 shutting off the alarm sound. see also cutting off the alarm

sound swapping the board, 1-6 system signal flow, 5-2

T testing bit errors, 1-16 timing bus, 5-2 troubleshooting, 3-20

U using the orderwire telephone, 1-5

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