cdot introduction

8/10/2019 CDOT Introduction

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10/20/2014 110/20/2014 1

WELCOME

TO

C-DOT MBM

110/20/2014
http://a/Presentations/INTRO1.exe


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GENERAL

C-DOT DSS MAX is a universal digital switch

which can be configured for different

applications as local, transit, or integrated localand transit switch.

High traffic/load handling capacity upto8,00,000 BHCA with termination capacity of

40,000 Lines as Local Exchange or 15,000 trunks

as Trunk Automatic Exchange. 2


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BASIC BUILDING MODULES

Base Module Central Module

Administrative Module

Input Output Module

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The Base Module (BM)

The basic growth unit of the system.

It interfaces the external world to the switch.

The interfaces may be subscriber lines,analogue and digital trunks.

Each Base Module can interface upto 2024

terminations. It carries out majority of call processing

functions

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The Single Base Module (SBM) In Single Base Module (SBM) exchange

configuration, the Base Module acts as anindependent switching system and providesconnections to 1500 lines and 128 trunks.

In such a configuration, the Base Module directly

interfaces with the Input Output Module . It is a very useful application for small urban and

rural environments.

With minimum modifications in hardware a BaseModule(BM) can be remotely located as aRemote Switch Unit (RSU), parented to the mainexchange using PCM links.

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Central Module (CM)

It consists of a message switch and a spaceswitch to provide inter-modulecommunication

It perform voice and data switching betweenBase Modules.

It communicates with Administrative Module

for operation and maintenance functions. It also provides clock and synchronisation on a

centralised basis.

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Administrative Module

It support administration and maintenancefunctions

It communicates with the Base Module via the

Central Module. It supports the Input Output Module for

providing man- machine interface.

It also supports the Alarm Display Panel forthe audio-visual indication of faults in thesystem.

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Input Output Module (IOM)

It is a powerful duplex computer system

It interfaces various secondary storage devices

like disk drives, cartridge tape drive and floppy

drive.

It supports printers and ports for video

display units which are used for man- machine

communication interface.

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REMOTE SWITCH UNIT

The normal BM can be modified for remoting

with the host exchange via 2 Mbps digital links. The number of 2 Mbps links between the Main

Exchange and RSU is primarily determined by the

traffic. Operation and maintenance functions are

handled by the host exchange.

A maximum 16 RSUs are possible in C-DOT DSSMAX-XL and 8 RSUs in MAX-L.

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HARDWARE

ARCHITECTURE

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BASE MODULE (BM)

The subscribers may be individual or grouped

PBX lines, analog or digital lines.

The trunks may be :-

1 Two Wire Physical

2 E&M Four Wire

3 E&M Two Wire 4 Digital CAS or CCS.

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BASE MODULE (BM)

The basic functions of a Base Module are

Analog to digital conversion of all signals onanalog lines and trunks

Interface to digital trunks

Switching the calls between terminals connectedto the same Base Module

Communication with the Administrative Modulevia the Central Module for administrative and

maintenance functions

Provision of special circuits for call processingsupport e.g. tones, announcements, MF/DTMF

senders/receivers 13


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BASE MODULE (BM) (Contd)

Analog Terminal Unit - to interface analog lines/trunks, and

providing special circuits as conference, announcements and

terminal tester.

Digital Terminal Unit - for interfacing digital trunks i.e. 2Mbps E-

1/PCM links

Signalling Unit Module - to support SS7 protocol handlers and

call processing functions for CCS7 calls.

ISDN Terminal Unit - to support termination of BRI/PRI

interfaces

Time Switch Unit - for voice and message switching and

provision of service circuits.

Base Processor Unit - for control message communication and call

processing functions.

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Analog Terminal Unit (ATU)

The Analog Terminal Unit (ATU) is used for interfacing 128analog terminations which may be lines or trunks.

It consists of terminal cards which may be a combination ofLine Circuit Cards (LCC), CCB with Metering (CCM) cards,Two Wire Trunk (TWT) cards, E&M Two wire (EMT) Trunkcards and E&M Four wire (EMF) trunk cards

provision to equip Conference (CNF) card

Announcement (ANN) to support 15 user friendlyannouncement messages

Terminal Test Controller (TTC) for testing of analogterminations.

Power Supply Unit (PSU-I) is used.

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Analog Subscriber Line Cards

Subscriber line cards as LCC or CCM withinterfaces upto 8 subscribers, provide basicBORSCHT functions for each line.

Each CCM card has the provision of batteryreversal for all the 8 lines with the last two lineshaving provision to generate 16 KHz meteringpulses to be sent to subscriber's meteringequipment.

output of four LCCs is multiplexed to form a 32-channel, 2 Mbps PCM link - also called a terminalgroup (TG).

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Ana og Su scr er L ne Car s

(Contd..)

Since a Terminal Unit has a maximum of 16

terminal cards, there are four such terminal

groups.

The signalling information is separated by a

scan/drive logic circuit and is sent to the

signalling processor

The LCC/CCM also provides test access relay

to isolate the exchange side and line side to

test it separately by using the Terminal Test

Controller (TTC). 18


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Analog Trunk Cards

Analog trunk cards interface analog inter-

exchange trunks which may be of three types

as TWT, EMT and EMF.

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Signalling Processor (SP) Card

Signalling Processor (SP) processes the signallinginformation received from the terminal cards.

This signalling information consists of scan/drivefunctions like origination detection, answerdetection, digit reception, reversal detection, etc.

The validated events are reported to TerminalInterface card.

Based on the information received from theTerminal Interface Controller, it also drives theevent on the selected terminal throughscan/drive signals.

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T i l I t f C t ll


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Terminal Interface Controller

(TIC) Card

Terminal Interface Controller (TIC) controls thefour terminal groups (TG) of 32 channels,

Multiplex them to form a duplicated 128-channel,8 Mbps link towards the Time Switch (TS).

For signalling information of 128- channels, itcommunicates with Signalling Processor (SP) toreceive/send the signalling event on analogterminations.

Terminal Interface Controller is built around 8-bitmicroprocessor with associated memory andinterface and it is duplicated for redundancy.

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Special Service Cards

A Terminal Unit has some special service cards such asConference (CNF) Card.

Terminal Test Controller (TTC) Card is used to test

analog terminal interfaces via the test access relays onthe terminal cards.

Announcement Controller (ANN) Card provides 15announcements on broadcast basis.

Only one service card of each type is equipped in aBase Module with provision of fixed slot for TTC andvariable slots for CNF/ANNC.

Two slots are occupied by each card i.e. 16 channels foreach card are used out of 128 channels available on a

Bus between a TU & TS. 22


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Digital Terminal Unit

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SS7 Signalling Unit Module (SUM)

Any one of the ATU or DTU in a BM can be

replaced by SUM frame to support CCS7

signalling.

Only one such unit is equipped in the

exchange irrespective of its configuration or

capacity.

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#7 Signalling Unit Module

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ISDN Terminal Unit

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Time Switch Unit (TSU)

Time Switch Unit (TSU) implements three basicfunctions

As time switching within the Base Module,

routing of control-messages within the BaseModule and across Base Modules and supportservices like MF/DTMF circuits, answeringcircuits, tones, etc.

These functions are performed by three differentfunctional units, integrated as time switch unit ina single frame .

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Time Switch Unit

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(1) Service Unit (SU)

Service Unit is integrated around three

different cards as Tone Generator with

Answering Circuit (TGA), Service Circuit

Interface Controller (SCIC). and MF/DTMFController (MFC) Card.

Two MFC cards are grouped to form a terminal

group.

Upto four MFC Cards can be equipped

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(2) Base Message Switch (BMS)

Base Message Switch (BMS) routes the control

messages within the Base Module, across different

Base Modules, and also Administrative Module via

the Central Module.

It is implemented around two different cards asMessage Switch Controller (MSC) with six direct

HDLC-links and the Message Switch Device (MSD)

Card implementing 16 switched HDLC links.

As a unit, total 22 HDLC channels are implemented

for communication with the Base Processor

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(2) Base Message Switch (BMS)

To support 8,00,000 BHCA, MSC and MSD

cards are replaced by a High performance

Message Switch (HMS) with high speed, 32 bit

microprocessor (MC 68040).

It implements 38HDLC links

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(3) Time Switch (TS) The Time Switch complex is implemented using three

different functional cards as multiplexer/demultiplexer(TSM), time switch (TSS) and time switch controller (TSC).

The Time Switch complex receives the following PCM linksand performs time- switching on them for switching withinthe Base Module :

(1) Four 128-channel multiplexed links from four differentTerminal Units which may be any combination of ATU, DTU,#7SU and ISTU.

(2) One 128-channel multiplexed BUS from theService Circuits Interface Controller (SCIC) in the Time

Switch Unit. (3) Three 128-channel links to support onboard

three party conference circuits (3 x 128).

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Base Processor Unit (BPU)

Base Processor Unit (BPU) is the master

controller in the Base Module.

It is implemented as a duplicated controller

with memory units.

These duplicated sub-units are realised in the

form of the following cards :

Base Processor Controller (BPC) Card

Base Memory Extender (BME) Card

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Base Processor Unit

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CENTRAL MODULE (CM)

Central Module (CM) is responsible for space switching ofinter-Base Module calls, communication between Base

Modules and the Administrative Module, clock distribution

and network synchronisation.

For these functions, Central Module has a Space Switch,

Space Switch Controller and a Central Message Switch.

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CENTRAL MODULE (CM)

(Contd) CM provides connectivity to 16 BMs if it is CM-L and

32 BMs if it is CM-XL. Each BM interfaces with CM via

two 512-channel parallel buses as BUS-0 and BUS-1,

each operating at 4 Mbps.

In a 32 Base Module configuration, there are 64

parallel buses carrying the voice information from

Base Modules to the Central Module, and also the

switched information in the reverse direction.

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Space Switch (SS) and Space Switch

Controller (SSC)

In order to take care of the large number of

interface signals, the switch portion of CM is

divided into three stages viz. MUX stage,

Switch stage and DEMUX stage.

The MUX and DEMUX stages are

implemented on single card to provide the

Base Module to Central Module interface ineach direction.

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SS and SSC (contd..)

Interfacing and switching are controlled by

SSC which provides control signals for the

MUX/DEMUX cards and the Space Switch

Switch cards.

These time-slots carry control message from

each Base Module and these messages are

sent to the Central Message Switch (CMS).

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Clock Distribution


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Clock Distribution

CM provides the central clock for distribution tothe Base Modules.

The 8MHz clock may be locally generated at theCentral Clock (CCK) card in case of CM-XL and of

Space Switch Clock (SCK) card in case of CM-L byusing high stability VCXO crystal

or may be derived from an external referenceclock using the Network Synchronisation

Controller (NSC) card in case of CM-XL andNetwork Synchronisation Equipment (NSE) incase CM-L under the control of SSC.

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NETWORK SYNCHRONIZATION

IN C-DOT DSS

Locked Mode Holdover Mode

Free Run Mode

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Central Message Switch (CMS)

. It is implemented as four different message

switches, working in load-sharing mode.

Each message switch is a high performance

message routing block, implemented by using

high speed 32 bit microprocessor MC 68040 in

case of CM-XL and 16 bit microprocessor MC

68000 in case of CM L.

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ADMINISTRATIVE MODULE (AM)

Administrative Module (AM) consists of a duplicated16/32-bit controller called the Administrative Processor(APC).

It communicates with Base Processors via the Central

Message Switch for control messages and with theduplicated Input Output Processors in the Input OutputModule for interfacing peripheral devices

Administrative processor is responsible for global

routing, translation, resource allocation and all otherfunctions that are provided centrally in C-DOT DSS MAX

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INPUT OUTPUT MODULE (IOM)

Input Output Module (IOM) consists ofduplicated Input Output Processor (IOP).

The Input Output Processor (IOP) is a general

purpose computer with UNIX Operating System. It is used as the front end processor in C-DOT

DSS.

It handles all the input and output functions in C-

DOT DSS.

The IOP is connected to AP/BP via HDLC links

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d hi


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IOP-VH Hardware Architecture

The IOP-VH is value engineered high performance IOP,designed using a single card.

The IOP CPU uses MC 68040 (25 MHz) processor on theVHC card.

All active IOP processes reside in the dynamic RAM. Also the data being transferred through HDLC links,

secondary storage devices and terminals, use the dynamicRAM.

The IOP as a module is duplicated to provide redundancy

for cartridge and disk drives as well as serialcommunication terminals and printers..

Presently the two ports, namely X.25 and ETHERNET arenot supported in current UNIX release.

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IOP VH P i h l


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IOP-VH Peripherals

Input Output Processor (IOP-VH) supports

three standard SCSI-2 interfaces, on VHC card,

one each for Winchester Drive, Cartridge Tape

Drive and one as spare.

Here, it may be noted that only the

peripherals with SCSI-2 interface can be used

in IOP-VH.

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F P l Di l


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Front Panel Display

The CPU Reset and Abort switches are

provided along with lock and key.

Run and Halt LEDs for the CPU status

indication is also extended on the front panel. A Reset LED is provided along with RESET

switch and glows when the CPU is reset bypressing RESET switch on the front panel.

Power I/P LED is provided to indicate thepresence of I/P power on the front panel.

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ALARM DISPLAY PANEL


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ALARM DISPLAY PANEL

It is a three card implementation. A matrix ofLEDs is provided to indicate the maintenancestatus of the switch units and their level of

initialisation. A seven-segment display shows the count of

lines and trunks currently faulty.

Keys are provided for manualacknowledgment, initiating self test andselective audio disable.

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