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Technical White Paper for Visualized IP Network Operation & Management

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Technical White Paper

for Visualized IP

Network Operation &

Management

Contents

Technical White Paper for Visualized IP Network O&M .............1

1 Overview ..............................................................................2

2 Three Invisible Elements in IP Network O&M .........................3

3 Huawei Visualized IP Network O&M Solution ........................6

4 Service Quality Monitoring ....................................................9

5 Network Quality Monitoring .................................................13

6 Deployment Modes ..............................................................16

6.1 Deployment of Probes on the U2520 and Basic Networking Modes ...........16

6.1.1 Deployment of Probes on the U2520 ......................................................16

6.1.2 Basic Networking Modes of Probes on the U2520 ...................................17

6.1.3 Probe Topology and Distributed and Hierarchical Management on the

U2520 .............................................................................................................19

7 Indicator-based Evaluation System ........................................20

7.1 SLA Evaluation ...........................................................................................20

7.2 Hierarchical Measurement ..........................................................................22

7.2.1 KPI ..........................................................................................................22

7.2.2 KQI .........................................................................................................23

8 Reference Standards .............................................................26

Figures

Tables

8.1 MOS ..........................................................................................................26

8.2 RFC4445-MDI ............................................................................................27

8.3 VMOS ........................................................................................................27

9 Typical Applications ..............................................................29

9.1 Flow-by-flow MDI and VMOS Video Monitoring Scheme ............................29

10 Interworking .......................................................................31

10.1 EANTC Test (Video Monitoring Test) .........................................................31

10.2 Compliant Standards and Protocols ..........................................................32

11 Acronyms and Abbreviations ..............................................35

Figure 3-1 Huawei full-lifecycle IP network O&M solution .................................6

Figure 3-2 Network location of the service quality monitoring solution .............7

Figure 4-1 Service architecture of the U2520 ....................................................9

Figure 4-2 SAP management ............................................................................11

Figure 5-1 Network architecture supported by the U2520 ................................13

Figure 7-1 Key points of SLA evaluation ............................................................20

Figure 7-2 Hierarchical indicator system ............................................................22

Figure 7-3 Three-dimensional KQI aggregation .................................................24

Figure 8-1 User satisfaction corresponding to different MOS scores ..................26

Figure 9-1 Typical application of the flow-by-flow IPTV service monitoring scheme ......29

Figure 9-2 Flow-by-flow MDI and VMOS video monitoring scheme ..................30

Figure 10-1 Physical network topology used in EANTC tests ..............................31

Figure 10-2 Topology view associated with a video monitoring test ..................32

Table 4-1 Service types, test types, and test indicators supported by the U2520

V200R001........................................................................................................12

Table 5-1 Network types, test types, and test indicators supported by the U2520

V200R001........................................................................................................15

Table 10-2 Ethernet service standards and protocols .........................................34

Table 10-1 Network standards and protocols ....................................................34

Technical White Paper for Visualized IP Network O&M

Abstract:All IP is definitely the major technology for future network and service development. In addition, end users are always pursuing for better service experience. Nevertheless, the service quality is invisible to end users on an all-IP network. Carriers will thus have to face two troubles. One is how to shorten the time of configuring services and locating faults on a large-scale IP network to achieve highly efficient operation and maintenance (O&M). The other is how to satisfy users' quality of experience (QoE) requirements by monitoring and managing the network quality. Huawei provides the visualized IP network O&M solution, through which the network O&M department and the service department can obtain the same QoE indicators. This document describes the technologies related to visualized IP network O&M and the typical applications of these technologies in the visualized IP network O&M solution from Huawei.

Keywords:U2520, VoIP, IPTV, HSI, O&M

1

2

1 Overview

At present, voice over IP (VoIP), Internet protocol television (IPTV), high speed Internet (HSI), mobile, and virtual private network (VPN) services, games, and value-added services are running on IP and multi-protocol label switching (MPLS) networks. The following challenges are imposed on carriers:

How to manage QoE indicators of end users• How to monitor the service quality in real time• How to quickly and accurately locate faults• How to perform capability evaluation before deploying a new •

serviceHow to evaluate the comprehensive service quality around the •

clock

Though the integrated network management system (NMS) on an IP/MPLS network where various services are carried is available for service configuration, management, and maintenance, how to determine service quality degradation, how to evaluate the service bearing capability of the network, how to monitor the network status, especially how to quickly and accurately locate faults through tests and how to identify whether a fault is a service platform fault or a network fault, are now the new challenges for IP network O&M.

3

2 Three Invisible Elements in IP Network O&M

Three invisible elements exist in IP network O&M, which reduces the O&M efficiency.

The quality of services carried on IP networks is invisible. • Carriers cannot learn end users' experience on the services. The traditional NMS provides the function of viewing network performance, but the quality of carried services is invisible. Network performance is separated from service quality. The service department and the network department have different understandings on faults because there is no uniform measurement. Therefore, experts of different departments need to work together to locate faults. This poses high requirements for skills but results in low fault location efficiency.

Service trails cannot be viewed because routes are invisible. • Dynamic routes are imported to IP networks, and service trails on Layer 3 networks are invisible. As routes are invisible, faults reported by end users usually disappear when O&M engineers perform fault location, and fault causes cannot be located because the faults cannot be reproduced and no associated historical information is available. All of this results in the difficulty of eliminating the potential troubles, and skilled datacom experts need to participate in fault location. In addition, O&M engineers cannot prevent network-wide faults caused by route flapping. Route flapping has a catastrophic impact on networks, and even causes the networks to break down.

End-to-end (E2E) channels are invisible. • The process of creating E2E channels is complex and the status of the channels is invisible. Cross-domain deployment is required for the creation of E2E channels and the configurations are rather complex. Nevertheless, traditional single-domain NMSs cannot achieve visualized and efficient service deployment and the status of IP channels is invisible after service deployment. O&M engineers

4

need to consider the relationships between service deployment parameters on every node because incorrect parameter settings are hard to discover and rectify. Therefore, high skills of O&M engineers are required.

The preceding troubles really afflict O&M departments of carriers. Is the reliability of IP networks really low?

Seeking a Solution is fairly urgent.

Actually, the reliability of IP networks can be guaranteed. Reactive IP network O&M must be changed to proactive IP network O&M.

In reactive O&M, O&M engineers locate and rectify faults only after receiving complaints from end users. This cannot satisfy IP network O&M requirements. Carriers need to forecast weak parts of networks according to daily network running information and take proper measures. Therefore, the change of the O&M mode is much important for the evolution towards all IP. Then, what proactive O&M is suitable for IP networks?

Proactive O&M requires the monitoring on service experience of end users. Therefore, O&M personnel need to periodically collect network performance and service quality data, analyze the data, extract the trend information, and pre-locate possible fault points and weak parts. In this manner, carriers can learn the service experience of end users, check whether the service quality will be degraded, and solve problems caused by the degradation in advance. In this manner, complaints from end users will be reduced, customer loyalty will be improved, and O&M costs will be decreased.

The distribution of carriers' investment drive on the O&M system proves the necessity of proactive O&M. The result of a survey conducted by Gartner shows that the first O&M investment drive of carriers is proactive preventing network performance faults. This drive accounts for 27% of the total. The second and third are quickly troubleshooting network fault s and meeting application performance service level agreement (SLA), which account for 15% and 12% respectively.

IP network O&M imposes the following requirements:

5

Quick troubleshooting• Network and service faults should be rectified quickly to implement fast fault identification and location.

Proactive fault prevention• Service quality and network performance should be monitored in real time so that faults can be discovered in time; faults of the IP bearer network should be associated with affected services, and alarms should be generated based on trend analysis.

Routine network management• The network quality monitoring and health evaluation system should be established. The KQI/KPI indicator system reflects and manages user experience, and helps to learn the actual network running status, thereby continuously improving end users' loyalty.

Measurability is the basis of manageability, and manageability is the basis of improvability. After all IP is implemented, measurability must be ensured first, that is, IP network O&M must be visible.

6

3 Huawei Visualized IP Network O&M Solution

Figure 3-1 shows Huawei full-lifecycle IP network O&M solution. The U2520 is responsible for visualized O&M of IP networks and carried services.

Figure 3-1 Huawei full-lifecycle IP network O&M solution

Though IP networks can be managed in many ways, network reliability can be guaranteed and services can be better carried only if network management is fully associated with services, QoE indicators are concerned, and visualized IP network O&M is implemented. Huawei sets an unprecedented example of visualized IP network O&M in the industry by implementing the visualization of IP service quality, trail, and deployment and completely solving the "black box" problem of IP network O&M.

The U2520 is the IP network evaluation system launched by Huawei. As a key device for visualized IP network O&M, it consists of the service monitoring system and the network evaluation unit, and supports the operation of full broadband services.

The network monitoring system provides the functions of network quality monitoring, service quality monitoring, on-demand test, threshold crossed alert (TCA) management, probe management, system management, and report management.

The network evaluation unit is a case-shaped external probe that can be deployed at the network access layer and convergence layer to collect network and service performance data and report it to the monitoring system.

Services Mgmt.(CustomerQoE Assurance)

●N2510-Fiber/CopperLine Assurance

●U2520-IPTV/VOIP/HIS/VPNServices Assurance

Network Mgmt.●U2560-Home NetworkUnified Mgmt.

●U2000-IP/Transport/Microwave/PON/DSLAM unified Mgmt

●MDS 6600-NetworkPlanning andDesigning

MetroBackbone

Home Access line Network (access/metro/backbone) Service Centers

FTP

Web qame

VolPIPTV

YoutubePE

PE

7

Figure 3-2 Network location of the service quality monitoring solution

The U2520 service quality monitoring solution is based on the distributed hierarchical architecture that consists of the probe measurement layer, server data analysis and collection layer, and user Webpage display layer. As shown in Figure 3-2, with the probe measurement layer, the service quality monitoring solution can fully function in the VoIP, HSI, IPTV, and Multi-Play scenarios. The server data analysis and collection layer of the U2520 center is used to manage the NEU100 probe network and collect the KPIs gathered by probes. At the access layer, the U2520 works with the N2510 to achieve E2E service quality monitoring. At the user Webpage display layer, the U2520 implements deep KPI data analysis and provides the customized report system.

The U2520 is acclaimed as the dashboard of an IP network. It has the following technical advantages:

Visualized IP forwarding plane• The U2520 detects the quality of IPTV, VoIP, HSI, an VPN services on IP networks and reflects end users' service experience. By comparing the quality of services segment by segment, the U2520 implements service-based fault identification and responsibility clarification, which helps O&M personnel to quickly rectify faults on the IP forwarding plane. The IP network O&M department and the service operation department have the same QoE indicators and thus fault identification is easy to achieve.

Visualized IP control plane•

Center

Inregraclon OSS Ord Party

Service Standus & SL A Roaporting

Access Metro Edge

BTS BSC MGW

Access Backhaul Backbone

GSM/Base Station

Center

Internet

IPTV

Softx

Visualize

Analyze

Measure HSI VoIPIPTV

8

Trails are available for IP services and the U2520 automatically calculates and displays service trails and dynamically monitors and analyzes route changes to prevent network-wide faults caused by route flapping, which helps O&M personnel to quickly analyze, forecast, and locate faults on the IP control plane.

Visualized IP forwarding plane and visualized IP control plane can be combined. The forwarding plane proactively simulates the service packet test by using service trails. If Layer 3 service trails change, the test simulated by the forwarding plane adjusts dynamically to implement automatic monitoring management on service bearing. If the service bearing quality is degraded, the intelligent diagnosis assistant is automatically started to locate the degradation cause in a while and provide troubleshooting suggestions, which greatly improves IP network O&M efficiency and end users' satisfaction.

In addition to completely monitoring the IP forwarding plane and IP control plane, the U2520 provides a powerful indicator system, a network health evaluation system, and O&M evaluation rules to improve the IP network O&M capability. According to the analysis statistics of the indicator system, O&M personnel not only can rectify faults, but also can know fault causes and improve accordingly to prevent certain faults that result from human factors, thus improving the IP network O&M efficiency.

The U2520 can also implement network-wide service monitoring and provide the service quality monitoring solution for the networking scenario where multi-vendor devices are used.

The U2520 works with Huawei U2000 that provides the following functions:

Managing the resource pool for E2E service parameters• Automatically creating E2E services after users click source and sink nodes• Dynamically allocating service parameters• Automatically managing logical relationships between E2E service • parameters on NEsAutomatically checking configurations• Automatically checking connectivity• Deploying services at a time• Supporting one-stop batch NE configuration• Deploying VPN data for E2E services• Supporting visualized E2E operations• Supporting visualized display of channel quality•

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4 Service Quality Monitoring

IP services have the characteristics of wide coverage, complicated service features, and large service traffic. This causes the difficulty in monitoring the quality of IP services. In addition, carriers face challenges regarding the following problems:

Evaluating services before service deployment• Collecting data to generate alarms when the service quality degrades• Identifying whether a service fault is caused by service problems or• network problems, and locating the faulty point of the service

IP services that can be monitored by the U2520 are classified into HSI, IPTV, VoIP, and L3VPN services. The services can be monitored in proactive and reactive modes. In proactive mode, user behaviors are simulated through probes to evaluate the service quality and monitor services in real time. In reactive mode, service flows on the current network are received, and the quality of each service flow and session is evaluated and monitored. In the former mode, users can flexibly deploy services and easily locate faults. In the latter mode, all service flows and sessions are monitored and the monitoring result is accurate; however, this mode requires traffic mirroring and high probe costs and causes the difficulty in deployment.

Figure 4-1 Service architecture of the U2520

SAP

SAP

Service

SAP group 1

SAP

SAP

SAP

SAP

Service element

Service element

Service element

Service element

Service element

CCTV1

CCTV2

BTV1

BTV2

www.sina.com

www.sohu.com

www.google.com

Defined as:

SAP group 2 SAP group 3 SAP group 4

When SAPs are organized in SAP groups, the required SAP topology can

for all SAPs of services according to the topolog

be established

y types of SAP groups.

Star Full-mesh Star Star

Aggregation

Aggregation

Aggregation

The SAPs belong to different SAP groups.

10

A service on the U2520 consists of three parts: service element, service access point (SAP), and SAP group.

Service element: As a sub-service or a part of a service, a service • element is used to evaluate the service quality. For example, from a user's point of view, community antenna television (CATV) providers and network providers are service providers (SPs), and specific services provided by channels such as http://www.sina.com and http://www.sohu.com are service elements. Service elements work on the networks provided by SPs, and the service quality can be evaluated.

SAP: A SAP is a conceptual point where a service is delivered to • users. SAPs are used to differentiate between users and SPs. SPs push SLA-compliant services to all the SAPs. Therefore, each service has at least one SAP, each SAP can belong to only one service, and each user has to access a service through SAP(s).

SAP group: SAPs can be organized into different SAP groups • that use a star or full-mesh topology. In this manner, any type of topology can be created for the SAPs that support various service topology tests.

Managing a service is managing the SAPs of the service. SAPs must be attached to physical networks. In service monitoring of the U2520, all test instances are generated based on SAPs. A SAP needs to be associated with an interface on an NE to indicate the location of the SAP and with an interface on a probe to indicate the device that initiates tests.

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Figure 4-2 SAP management

An IP service can have a single SAP or multiple SAPs.

Only one SAP is required to access a single-SAP service, such as a • broadband TV (BTV) service, a video on demand (VoD) service, or an HSI service. These services that are provided by network servers are accessed through only a single SAP.

Two or more SAPs are required to access a multi-SAP service, such • as a VoIP service or a point to point (P2P) service. These services are accessed based on the interaction of SAPs.

The U2520 supports the ability to test various key indicators of end users' services, such as the IPTV, VoIP, and HSI services. This facilitates the quality evaluation of end users' services. Table 4-1 lists the service types, test types, and test indicators supported by the U2520 V200R001.

(Multi -

Managed by carriers

Carrier network

service network)

Network edge

Network edge

Access

devicesAccess

devices

DSLAM

Switch

Low -end router

DSLAM

Switch

Low -end router

Access network or leased line

Access network or leased line

SAPSAP

12

Table 4-1 Service types, test types, and test indicators supported by the U2520 V200R001

Service Type

Test Type Test Indicator

BTV serviceVoD service

Multicast receive testRTSP test

BTV [channel switching time/MOS/packet loss ratio]Multicast receiving [jitter/DF/MLR]

RTSP [flow control time/connection time/packet loss ratio/jitter/TCP retransmission]RTSP [DF/MLR/MOS/TCPRT15/TCPRT24/MLT24/MLT15]

Video RTP Test

Video RTP [MLR/packet loss ratio/MOS/jitter/DF]

HSI service

FTP test FTP [download/upload rate]

DNS test DNS [parsing]

HTTP testHTTP [arrival time of the first packet/page download duration]

PPPoE test PPPoE

VoIP service

DHCP testVoIP RTP test

DHCP [IP address acquisition time]

VoIP RTP [packet loss factor/R value/MOS/delay/jitter factor/jitter/packet loss ratio]

L3VPN service

UDP jitter test

L3VPN [UDP jitter/packet loss ratio/delay]

TCP test L3VPN [TCP delay]

13

5 Network Quality Monitoring

The U2520 can be used to comprehensively monitor the quality of IP/MPLS networks in real time. Network quality analyse (NQA) is a key to network monitoring. The NQA-enabled internal probe from Huawei helps to detect and diagnose the network quality in real time, and measure network performance through performance indicators such as jitter, delay, and packet loss ratio. Users can use the NQA-enabled internal probe to perform tests based on test instances. Internal probes can be flexibly configured. For example, users can configure internal probes through command lines, or remotely configure internal probes and collect data by using the U2520. Each test instance provides a series of test policy options through which users can set parameters such as the length of sent packets, interval for sending packets, and protocol type. Based on settings of the parameters, the NQA-enabled internal probe can flexibly perform tests according to the current network situation.

Figure 5-1 Network architecture supported by the U2520

IP site MPLS site

MPLS networkIP network

IP trail

IP connection

LSP

14

Networks that can be monitored by the U2520 are classified into physical networks and logical networks. A physical network consists of NEs and physical links between NEs. It manages elements associated with physical NEs, such as interfaces, boards, and frames. The U2520 evaluates the quality of a physical network according to indicators such as the CPU usage, memory usage, interface packet loss ratio, and interface bandwidth usage of physical NEs.

A logical network consists of network sites and logical connections. A physical network can be abstracted as many different network sites. As shown in Figure 5-1, the route connecting the IP network and the MPLS network is abstracted as two logical sites: an IP site and an MPLS site. The two sites belong to the IP network and the MPLS network respectively. Different network sites have different network interfaces. For example, the MPLS site has only MPLS interfaces. The U2520 evaluates the quality of a logical network according to indicators, such as delay, jitter, packet loss ratio, connectivity, and trace, associated with logical links and logical trails. In addition, the U2520 supports the abilities to locate and identify faults on logical networks.

The features of network monitoring through the U2520 are as follows:

The bearer network provides service-sensitive functions of • diagnosing network faults and monitoring the network quality, which ensures that the bearer network can meet users' SLA requirements.

The U2520 provides abundant fault diagnosis tools. With these • tools, users can quickly locate faults according to the relation between networks and service layers, thus greatly shortening the fault location time.

The data of typical services on the bearer network can be simulated • according to traffic characteristics. In this manner, users can obtain information about the bearing of simulated services, thus accurately understanding the bearing capability of the bearer network. This helps to dynamically adjust policies according to the current situation to continuously improve network status.

The U2520 can be used to test various key indicators on IP, MPLS, and physical networks, which helps to accurately evaluate the network quality. Table 5-1 lists the network types, test types, and test indicators supported by the U2520 V200R001.

15

Table 5-1 Network types, test types, and test indicators supported by the U2520 V200R001

Network Type

Test Type Test Indicator

L3VPN

UDP jitter testUDP jitter and packet loss ratio

UDP delay

TCP jitter test TCP delay

ICMP jitter test ICMP delay, packet loss ratio, and jitter

MPLS network

LSP jitter test LSP delay, packet loss ratio, and jitter

LSP TE jitter test

LSP TE delay, packet loss ratio, and jitter

Physical network

Card statistics Network [load]

Physical port statistics

Interface [packet loss ratio]

Port [bandwidth usage]

IP network

UDP jitter test UDP jitter and packet loss ratio

16

6 Deployment Modes

6.1 Deployment of Probes on the U2520 and Basic Networking Modes

6.1.1 Deployment of Probes on the U2520

Probes on the U2520 can be deployed at the access layer of end users, the convergence layer, and the core layer.

Deploying Probes at the Access Layer of End Users

Active probes on the U2520 are equipped with FE interfaces. Probes deployed through FE interfaces are nearest to end users, thus ensuring the most accurate service monitoring results. The scale of probes deployed on the user side is usually large. Therefore, in the case where a lot of probes are deployed and a lot of services need to be monitored, the U2520 occupies many bandwidth resources, which affects actual services. If probes need to be deployed at the access layer of end users, it is recommended that representative locations (for example, locations of key customers) be selected to deploy probes, or an active probe be mounted to a downstream modem of a DSLAM.

Deploying Probes at the Convergence Layer of a Network

Probes deployed on nodes at the convergence layer of a network can be equipped with FE and GE interfaces. When services are simulated in active mode to monitor the service quality, only common GE or

Modem

To Metro EthernetFiber FE/GE

FE

PC

IPTV

Copper Line

Copper Line

DSLAM

17

Deploying Probes on Core or Edge Routers at the IP Bearer Layer

Deploying probes on core or edge routers at the IP bearer layer is similar to deploying probes on nodes at the convergence layer. Users can connect an active probe to such a router directly through a fiber, a LAN, an FE interface, or a GE interface. To deploy a passive probe to monitor the audio and video signals on the network in real time, users can connect the probe to the router through a mirrored port, without considering whether the load on the router is increased.

FE interfaces are required. When the service quality is monitored in reactive mode, a mirrored port needs to be configured.

SwitchFiber/LAN FE/GE

Fiber FE/GE Fiber FE/GE

RouterFiber/LAN FE/GE

Mirror Port/Common port

Fiber FE/GE Fiber FE/GE

18

HSI Service Monitoring in C/S Mode

Monitoring of Audio and Video Flows in Reactive Mode

Quality Monitoring in Trace Mode

Source Destination

GRS

CDMA

NTP

Client

Server

Source

6.1.2 Basic Networking Modes of Probes on the U2520

Loopback Through the Cooperation of Two Probes

MediaReceiver

19

6.1.3 Probe Topology and Distributed and Hierarchical

Management on the U2520

Probes among different administrative regions or among different districts in a city are connected in full-mesh mode. That is, a full-mesh topology is established among all the nodes deployed with probes, as shown in the following figures.

The probes from administrative regions to the egress of the provincial backbone network or from districts in a city to the egress of the city network are connected in Hub&Spoken mode. That is, the probe on the central node is connected to the probe on each edge node, as shown in the following figures.

Here, a hierarchical U2520 management system is formed.

IP Network

IP Network

ControllerResponder

Responder

Responder

20

7 Indicator-based Evaluation System

7.1 SLA Evaluation

As a formal agreement that is reached through the communication and negotiation between two parties, the SLA is widely applied to various fields. In the telecom industry, a group may sign SLAs with its branch companies, a carrier may sign SLAs with SPs, and a carrier may frequently sign SLAs with end users. An SLA can cover various contents, such as service performance, problem rectification time, and fault time.

With the rapid development of telecom services, the market value chain becomes increasingly complicated, and more and more SPs provide telecom services for end users. In that situation, the quality of services provided to end users can be guaranteed only when SLA-based monitoring is performed throughout the value chain. Any misunderstanding of SLAs may affect the quality of E2E services. Figure 7-1 shows the key points of SLA evaluation.

Figure 7-1 Key points of SLA evaluation

Measurement

SLA

Inventory Metric

Measurement

To abstract networks and services that are to be evaluated

To define overall standards for evaluating networks and services

To establish an indicator system

To obtain data through tests

21

The U2520 is mainly used to perform SLA evaluation of IP services and networks. For the U2520, a system of most concerned indicators involved in the IP service development and IP network operation of carriers is established, thus forming a series of SLA clauses. Users can add required indicators to the SLA according to different situations. The indicators fall into the following types:

HSI service indicators: for example, PPPoE dial-up duration, DNS • parsing time, and HTTP download time

VoIP service indicators: for example, mean opinion score (MOS), • delay, jitter, and packet loss ratio

IPTV service indicators: for example, v-MOS, MDI (DF, MLR, MR, • and MLT) delay, jitter, and packet loss ratio

Network indicators: for example, delay, jitter, packet loss ratio, • bandwidth usage, LSP delay, LSP jitter, LSP packet loss ratio, LSP TE delay, LSP TE jitter, and LSP TE packet loss ratio

The U2520 adopts the SLA to evaluate services and networks. In terms of service evaluation, the SLA can be used to evaluate a service, a SAP, or a SAP group. When the SLA is used to evaluate a service, all the SAPs of the service are evaluated, and the quality of each SAP is assigned a weight that affects the service quality. In terms of network evaluation, all the inventories, such as LSPs, connections, trails, and interfaces, associated with the network are evaluated. According to quality indicators that are added to the SLA by users and inventories associated with the network or a certain service, the U2520 automatically generates test instances in batches and modifies test instances when inventories change, thus reducing the workload of manual configuration.

22

7.2 Hierarchical Measurement

Figure 7-2 Hierarchical indicator system

7.2.1 KPI

In general, carriers periodically report key performance indicators (KPIs) of networks or services. As the most concerned data, KPIs actually reflect the performance of a network or a service at a certain time point. The KPIs, however, cannot provide information about the E2E performance, the service quality or network quality in a certain period, or the overall service status. Despite the preceding disadvantages, KPIs still play an important role in the evaluation system because of its data aboriginality and wide application.

KPI calculation method:

The KPI indicates the performance value of an object at a certain time point. A KPI may be obtained by the aggregation of multiple levels of KPIs. The KQI indicates the threshold-crossing rate of multiple KPIs of an object in a certain period. A KQI is calculated based on the lower-level KQIs or KPIs.

Unlike most KPIs that directly come from original test results, certain KPIs are calculated based on multiple test results.

Example:Assume that a VideoRTP test needs to be carried out, and VideoUpJitterKPI needs to be collected.

The KPI calculation formula is as follows:

Service test result

Network statistics

Network test result

Service statistics

KPI

Originaldata

IntermediateKQI

SLA KQIService KQIs and network KQIs

KQIs associated with the SAP, LSP, connection, path, board, and interface

23

KPI = [AboveThPkts/(AboveThPkts + BelowPkts + BetweeenThPkts)] x 100%The indicators to be collected are as follows:

AboveThPkts, BelowThPkts, BetweenThPkts, MaxJitter, and MinJitter

7.2.2 KQI

In consideration of KPIs' disadvantages, KQIs are developed to comprehensively, accurately, and continuously evaluate network status. KQIs are used to evaluate the quality of an object, such as a product, product component, service, service element, or network, thus reflecting the object's health. A KQI is aggregated by KPIs or original data. During the aggregation, users can set the weights of original indicators according to the importance of the indicators, thus forming a hierarchical KQI system.

KQI calculation method:

For a service, a SAP KQI is obtained by calculating the threshold-crossing percentages of all KPIs of a SAP; an SLA KQI (service KQI) is obtained by averaging the KQIs of all SAPs. During averaging, the number of KPIs used for SAP KQI calculation is taken as a weight.

For a network, a network KQI is obtained by aggregating the KPIs and KQIs of connections and trails. A network KQI can also be obtained by aggregating board KQIs and device KQIs, both of which

24

are aggregated by interface KPIs and interface KQIs. During the aggregation from lower-level KQIs to upper-level KQIs, all the lower-level KQIs should be averaged, and the number of KPIs used for lower-level KQI calculation should be taken as a weight during averaging.

Note: In fact, an upper-level KQI can be obtained through KPI calculation. The KQI value is the same as that obtained by aggregating lower-level KQIs based on weights.

Certain KQIs, such as the SAP KQI and channel KQI, are used only in reports or for trend viewing.

Example:

Assume that a VideoRtpUpJitterKQI test needs to be carried out, and the video RTP [abnormal jitter packet rate] KQI needs to be collected.The KQI calculation formula is as follows:

KQI = [∑(A(KPI))]/n

Required KPI: VideoUpJitterKPI

The U2520 adopts three-dimensional KQI aggregation. That is, KQIs are aggregated by dimensions of time, metric, and inventory. On the U2520, one indicator can be aggregated into a KQI by time, which is a common aggregation mode. In addition, different indicators or indicators of different inventories can be aggregated into a KQI by weight, and indicators based on different dimensions can be calculated at the same time.

Figure 7-3 Three-dimensional KQI aggregation

As a basic part of an SLA, KQIs are basically used to calculate SLA compliance. In general, one SLA contains multiple KQIs. The SLAs applicable to the U2520 are classified into customer SLAs (also referred to as service SLAs) and internal SLAs (also referred to as network SLAs). Customer SLAs contain only service-related KQIs that indicate the quality of services provided by SPs to customers; internal SLAs are used by carriers to evaluate the quality of internal networks.

The U2520 helps to form a hierarchical network structure through an inventory model and metric instances developed according to the SLA definition.

Time

Metric Type

Inventory Instance

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In the hierarchical network structure, metric instances are associated with each other, indicating the rules for indicator calculation. These rules are called indicator aggregation calculation rules. The U2520 supports the following types of indicator aggregation calculation:

Indicator aggregation calculation by inventory (hereinafter referred • to as I calculation)

This type of calculation aggregates the indicators of lower-level inventories into indicators of upper-level inventories according to the aggregation relation or including relation between inventories. According to whether the weights of inventories are considered in calculation, I calculation is subclassified as follows:

− I calculation without considering the weights of inventoriesExamples: protocol interface traffic, protocol site traffic, and network traffic

− I calculat ion taking the weights of inventories into consideration

Example: SAP KQIs are aggregated into a service KQI on the condition that SAP weights are considered.

Indicator aggregation calculation by metric (hereinafter referred to • as M calculation)

Indicator aggregation calculation by time (hereinafter referred to • as T calculation)

Test results displayed on the U2520 are original data. After important original data is calculated, a KPI that reflects the performance of an object at a certain time point can be obtained. A KQI is aggregated by one or more KPIs, and KQIs can be aggregated into an upper-level KQI. Only the upper-most KQI is displayed in SLA clauses and takes part in SLA compliance calculation.

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8 Reference Standards

8.1 MOS

The MOS indicator defined by ITU-T is used to evaluate the service quality through scores from 1 to 5. It is the most popular quality indicator that is used to show user satisfaction. In addition, it is a main indicator that is used to monitor VoIP signaling.

Figure 8-1 User satisfaction corresponding to different MOS scores

Based on ITU-T G.107E-Model, the MOS indicator on the U2520 is developed in compliance with the ETSI 101329-5 standard recognized by European Telecommunications Standards Institute (ETSI).

Jitter buffer is another important indicator that affects user satisfaction. During the processes of generating, sending, receiving, and processing voice packets, problems such as delay, jitter, and packet out-of-order may occur. To reduce the impact of these problems on packets, the decoder temporarily stores packets in a jitter buffer so that the packets can be played at an even rate. The jitter buffer size of a user's decoder directly affects user satisfaction in voice quality. The U2520 can simulate the jitter buffer size of the user's decoder, which helps the measured voice quality be consistent with the experience of end users.

R-value ( lower limit ) MOSCQE ( lower limit ) User satisfaction

90

80

70

60

50

4.34

4.03

3.60

3.10

2.58

Very satisfied

satisfied

Some users dissatisfied

Many users dissatisfied

nearly all users dissatisfied

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8.2 RFC4445-MDI

The MDI indicator defined in the RFC4445 standard is used to evaluate the quality of transmitting IPTV video flows on an IP network. This indicator involves the delay factor (DF) and media loss rate (MLR) parameters.

As a very important evaluation indicator for the VoIP network, MDI can be used to precisely measure and monitor network jitters and delays that affect the video transmission quality. In addition, it can accurately reflect the quality of a lot of concurrent media flows, and provide measurement results that are more accurate than the results of subjective observation. Network evaluation helps to determine how many IPTV users are supported by a network so as to provide a basis for network design and device deployment. It can also help to analyze potential problems on a network so that users can take correct protection measures before faults occur on the network.

The DF value, expressed in milliseconds, indicates the delay and jitter of tested video flows. With the DF, jitter changes of video flows are converted into requirements for video transmission and decoder buffering. A higher jitter level of tested video flows indicates a greater DF value. If the time of video contents stored in the network device or the decoder's buffer is no less than the DF value of tested video flows, the playing quality of the video contents does not degrade.

The MLR, expressed by the number of media packets lost per second, indicates the rate of media packet loss during the transmission of tested media flows. The loss of encapsulated video packets directly affects the playing quality of video contents. Therefore, during the transmission of IP video flows, the desired MLR value should be zero.

8.3 VMOS

The VMOS model developed by Huawei is used to monitor the video quality. Focusing on users' QoE, this model can be used to estimate and quantify users' experience of video quality degradation according to network factors of packet loss and jitter.

If the video playing quality is degraded but the video flows are properly sent by the head end, packet loss or jitter during transmission is the major cause. Packet loss leads to shrink of media information;

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jitter causes playing discontinuity. As a result, the playing quality becomes poorer when more packets are lost or the jitter becomes higher. Packet loss or jitter, however, does not directly affect users' experience because users' experience is also affected by the video type, basic compression damage, and forms of packet loss and jitter.Compared with the MDI algorithm, the VMOS model adopts five MOS values to represent different video quality experience of users. The MOS values are 5 (very good), 4 (good), 3 (average), 2 (poor), and 1 (very poor). Users can determine whether the video quality is good according to specific MOS values.

The MOS calculation formula is as follows:

MOS = V0 + V1 x Original experience value x Network damage factor x Application damage factor x Terminal repairing factor

V0 and V1 are constants. Their values are from 1 to 4.•

The MOS algorithm adopts ACR MOS values as references. ACR • MOS values are 1, 2, 3, 4, and 5, among which 1 indicates the poorest quality and 5 indicates the best quality.

The original experience value indicates the video quality experience • in the case where video files are directly played without being transmitted on the network. This value is affected by factors such as the coding type (for example, MPEG2 or H264), coding bit rate, and frame rate.

The network damage factor indicates the experience degradation • caused by network factors such as packet loss, jitter, packet out-of-order, and delay.

The application damage factor indicates the experience degradation • caused by errors of application-layer parameters, such as the error of TS parameters.

The terminal repairing factor is the value that is calculated • according to network factors such as the terminal decoder type, retransmission of lost packets, and AL-FEC.

The network damage factor, represented by P-net, is calculated • according to network factors such as packet loss, packet out-of-order, delay, and burst.

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9.1 Flow-by-flow MDI and VMOS Video Monitoring Scheme

In principle, the flow-by-flow MDI and VMOS video monitoring scheme is used to view the quality of service flow bearing on each node. In compliance with the RFC4445 standard, the U2520 provides measurement indicators (MDI and VMOS) that are the same as those used by service departments to evaluate the quality of a service system. The U2520 also provides information about the bearing quality comparison of all nodes on the bearer network, which helps to locate the links whose quality degrades and to identify the root cause of degradation. In addition, the U2520 supports the networking of devices from different vendors.

9 Typical Applications

Figure 9-1 Typical application of the flow-by-flow IPTV service monitoring scheme

ApplicationAccess Core Metro

Verifier EVMoS=3.2

Verifier DVMoS=3.2

VerifierCVMoS=3.2

Verifier BVMoS=4.8

Verifier AVMoS=4.8

Monitor AMonitorB

InternetDSLAM

DSLAM

VMoS=3.2

BTVHeadend

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The U2520 detects the entire path of video flows on a flow-by-flow basis to identify faulty points.

In cooperation with the MQMC (IPTV service platform monitoring system), the U2520 helps service maintenance engineers to monitor the video quality in E2E mode.

The main test indicators on the U2520 are as follows:

IP transport indicators• − Packet loss− Jitter− Discarded packet− Packet out-of-order− MDI: Loss rate and DF

Media flow transmission indicators• − PAT/PMT/NIT/CAT frequency and error− Sync error− PID missing error− TS error− PCR error− PRS error− CRC error

Video contents-related indicators• − Frame rate− Frame loss− ETSI TR 101-290 parameter− PCR jitter− Media quality index (MQI)− Noticeble loss (IEFT RFC 3357)

Figure 9-2 Flow-by-flow MDI and VMOS video monitoring scheme

Regional node Edge node

DetectionpointU2520: deployment of network nodes and fast location of faulty points

DSLAM

Central node

STBBAS

Backbone network

Router

Encoder

LSW

MAN

Router

MQMC

HMS HMS HMS

Router

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10 Interworking

10.1 EANTC Test (Video Monitoring Test)

In January 2010, the European Advanced Networking Test Center (EANTC) carried out a series of multi-vendor MPLS interworking tests. Over 10 equipment vendors and testing instrument vendors, such as Huawei, Cisco, Alcatel-Lucent, Juniper, and ZTE, took part in the tests. Figure 10-1 shows the physical network topology used in the tests.

Figure 10-1 Physical network topology used in EANTC tests

Huawei, Cisco, and Spirent took part in the video monitoring test. To carry out the test, Spirent provided the service head end system and the hardware damage environment; Huawei provided the NE40E and the U2520 to interwork with Cisco ASR900. Then, according to the RFC4445 standard, the EANTC tested the video monitoring capabilities of products from these vendors.

During testing, Huawei adopted the U2520 that was deployed with the internal and external probes, becoming the sole vendor that could provide the E2E flow-by-flow MDI value. As an upper-layer monitoring

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SpirentTcstCenter

HuaweiNE40E-X8

SpirentxGEM

CiscoASR 9000

Huawei NEU100

HuaweiU2520

MPEG Transport StreamSNMP

Figure 10-2 Topology view associated with a video monitoring test

Standard/Protocol Number

Standard/Protocol Title

DSL Forum TR-126Triple-play Services Quality of Experience (QoE) Requirements

ETSI TR 101 290Digital Video Broadcasting (DVB)Measurement guidelines for DVB systems

ISO/IEC 13818-1Information technology — Generic coding of moving pictures and associated audio information: Systems

ITU-T G.107The E-model, a computational model for use in transmission planning

ITU-T G.711Pulse code modulation (PCM) of voice frequencies

ITU-T G.723Dual rate speech coder for multimedia communications transmitting at 5.3 & 6.3 kbit/s

system, the U2520 supports the E2E information display in GUIs and helps to perform SLA monitoring of services. When the damage environment was started by the disturber from Spirent, the external probe on the U2520 and Cisco ASR9000 immediately showed that the bearing quality of the node from Cisco had degraded. Through the NEU100, the U2520 succeeded in displaying indicator values that are the same as those provided by Cisco. In addition, the U2520 supports the abilities to display the status of each node and to compare the indicator data of all nodes so that users can quickly identify and locate faults.The EANTC carries out continuous tests in compliance with the RFC4445 standard. The test results show that Huawei U2520 supports the E2E video monitoring solution and provides the function of detecting the quality of a third-party device. In addition, indicators can be aggregated and associated with SLAs. The U2520 supports data display through GUIs, which helps to precisely reflect network devices' capabilities of bearing video services.

For descriptions of EANTC test instances, see the EANTC-MPLSEWC2010-WhitePaper.

10.2 Compliant Standards and Protocols

Table 10-1 and Table 10-2 list the standards and protocols that the U2520 complies with.

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Standard/Protocol Number

Standard/Protocol Title

ITU-T G.72640, 32, 24, 16 kbit/s Adaptive Differential Pulse Code Modulation (ADPCM)

ITU-T G.729Coding of speech at 8 kbit/s using conjugate-structure algebraic-code-excited linear-prediction (CS-ACELP)

ITU-T G.1080Quality of experience requirements for IPTV services

ITU-T G.1081 Performance monitoring points for IPTV

ITU-T H.248 Gateway control protocol

ITU-T H.323Packet-based multimedia communications systems

RFC 0768 User Datagram Protocol

RFC 0791 Internet Protocol

RFC 0792 Internet Control Message Protocol

RFC 0793 Transmission Control Protocol

RFC 0854 Telnet Protocol Specification

RFC 0959 File Transfer Protocol

RFC 1034 Domain names - concepts and facilities

RFC 1035Domain names - implementation and specification

RFC 1305 Network Time Protocol (Version 3)

RFC 1350 The TFTP Protocol (Revision 2)

RFC 2131 Dynamic Host Configuration Protocol

RFC 2236Internet Group Management Protocol, Version 2

RFC 2326 Real Time Streaming Protocol (RTSP)

RFC 2327 SDP: Session Description Protocol

RFC 2330 Framework for IP Performance Metrics

RFC 2516A Method for Transmitting PPP Over Ethernet (PPPoE)

RFC 2543 SIP: Session Initiation Protocol

RFC 2616 Hypertext Transfer Protocol -- HTTP/1.1

RFC 2679 A One-way Delay Metric for IPPM

RFC 2680 A One-way Packet Loss Metric for IPPM

RFC 3393IP Packet Delay Variation Metric for IP Performance Metrics (IPPM)

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Standard/Protocol Number

Standard/Protocol Title

RFC 3418Management Information Base (MIB) for the Simple Network Management Protocol (SNMP)

RFC 3433 Entity Sensor Management Information Base

RFC 3435Media Gateway Control Protocol (MGCP) Version 1.0

RFC 3550RTP: A Transport Protocol for Real-Time Applications

RFC 3576Dynamic Authorization Extensions to Remote Authentication Dial In User Service (RADIUS)

RFC 3611 RTP Control Protocol Extended Reports (RTCP XR)

RFC 4445 A Proposed Media Delivery Index (MDI)

Table 10-1 Network standards and protocols

Standard/Protocol Number

Standard/Protocol Title

IEEE802.1ad Provider bridges

IEEE802.1ag Connectivity fault management

IEEE802.1D Media access control (MAC) bridges

IEEE802.1Q Virtual bridged local area networks

ITU-T G.1731OAM functions and mechanisms for Ethernet based networks

ITU-T G.8010 Architecture of Ethernet layer networks

ITU-T G.8011Ethernet over Transport - Ethernet services framework

ITU-T G.8012 Ethernet UNI and Ethernet NNI

ITU-T G.8021Characteristics of Ethernet transport network equipment functional blocks

ITU-T G.8031 Ethernet protection switching

MEF MEF2Requirements and framework for Ethernet service protection in metro Ethernet networks

MEF MEF4Metro Ethernet network architecture framework - Part 1: generic framework

Table 10-2 Ethernet service standards and protocols

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11 Acronyms and Abbreviations

Acronym/Abbreviation Full Spelling

VoIP Voice over IP

SAP Service Access Point

SE Service Element

NQA Network Quality Analyse

SLA Service Level Agreement

KPI Key Performance Indicator

KQI Key Quality Indicator

DSQ Degraded Service Quality Event

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