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Technical White Paper for Visualized IP Network Operation _ Management

VIEWS: 23 PAGES: 40

  • pg 1
									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
   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


Figures
   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



Tables
   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
    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
    service
    • How 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.




2
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




                                                                               3
       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:



4
• 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.




                                                                          5
    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.

    Services Mgmt.                          N2510-                           U2520-
    (Customer                              Fiber/Copper                     IPTV/VOIP/HIS/VPN
    QoE Assurance)                         Line Assurance                   Services Assurance

                                U2560-                                         U2000-IP/Transport/
    Network Mgmt.              Home Network                                   Microwave/PON/
                               Unified Mgmt.                                  DSLAM unified Mgmt



                                                                                 PE
      MDS 6600-                                                                                       FTP    Youtube

     Network                                                                         Backbone         IPTV
                                                                                                             Web
                                                                                                                    VolP

     Planning and                                        Metro
                                                                                PE
                                                                                                             qame
     Designing

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

                                    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.
6
                                                                                                Visualize



                       Service Standus &                      Inregraclon
                       SL A Roaporting                        OSS Ord Party                       Analyze


                                Center
                                                                             Center
                                                                                                Measure
                 HSI
              VoIP
           IPTV                    Access    Metro Edge                                      Internet
                            GSM/Base Station
                                                                                          Softx
                          BTS         BSC         MGW
                 Access          Backhaul          Backbone                           IPTV

                       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
                                                                                                            7
        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 NEs
    •   Automatically 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
8
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.

                                                                                                                            CCTV1
                                                                                          Service                           CCTV2
                                                                                          element
                                                                                                                            BTV1
     SAP                                                                                  Service                           BTV2
                                                                                          element
                                   Aggregation                            Aggregation                     Defined as:       …
             SAP
                                                         Service                          Service
                   SAP
                   SAP                                                                    element                           www.sina.com
                     SAP
                     SAP                                                                  Service                           www.sohu.com
                                                                                          element
                                                                                                                            www.google.com
                     The SAPs                                                             Service                           …
                                         Aggregation
                     belong to                                                            element
                     different
                     SAP groups.

                           SAP group 1      SAP group 2        SAP group 3      SAP group 4

                              Star          Full- mesh             Star            Star


                                          When SAPs are organized in SAP groups, the required SAP topology can be established
                                          for all SAPs of services according to the topology types of SAP groups.


                                                 Figure 4-1 Service architecture of the U2520

                                                                                                                                             9
     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.




10
  SAP                               Network                           Network
                                                                                                        SAP
                                     edge                              edge

                        Access                                                   Access
                        devices                                                  devices

      DSLAM                                                                                    DSLAM
       Switch                                  Carrier network                                 Switch
      Low -end                             (Multi -service network)                           Low -end
       router                                                                                  router
         …
                                                                                                    …



           Access network or                                                    Access network or
              leased line                                                          leased line

                                         Managed by carriers
                                                    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.




                                                                                                              11
     Service
                  Test Type                             Test Indicator
      Type
                                   BTV [channel switching time/MOS/packet
                                   loss ratio]
                Multicast          Multicast receiving [jitter/DF/MLR]
     BTV        receive test       RTSP [flow control time/connection time/
     service    RTSP test          packet loss ratio/jitter/TCP retransmission]
     VoD
                                   RTSP [DF/MLR/MOS/TCPRT15/TCPRT24/
     service
                                   MLT24/MLT15]

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

                FTP test           FTP [download/upload rate]

                DNS test           DNS [parsing]
     HSI
     service                       HTTP [arrival time of the first packet/page
                HTTP test
                                   download duration]

                PPPoE test         PPPoE

                DHCP test          DHCP [IP address acquisition time]
     VoIP
                VoIP RTP           VoIP RTP [packet loss factor/R value/MOS/
     service
                test               delay/jitter factor/jitter/packet loss ratio]

                UDP jitter
     L3VPN                         L3VPN [UDP jitter/packet loss ratio/delay]
                test
     service
                TCP test           L3VPN [TCP delay]

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




12
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.




          IP trail                                              LSP




         IP
         connection         IP site       MPLS site



               IP network                       MPLS network


                            Figure 5-1 Network architecture supported by the U2520




                                                                                     13
     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.
14
Network
        Test Type                    Test Indicator
Type

                                     UDP jitter and packet loss ratio
               UDP jitter test
                                     UDP delay
L3VPN
               TCP jitter test       TCP delay

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

               LSP jitter test       LSP delay, packet loss ratio, and jitter
MPLS
network        LSP TE jitter         LSP TE delay, packet loss ratio, and
               test                  jitter

               Card statistics       Network [load]
Physical
               Physical port         Interface [packet loss ratio]
network
               statistics            Port [bandwidth usage]

IP
               UDP jitter test       UDP jitter and packet loss ratio
network

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




                                                                                             15
     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.


                 DSLAM                   Fiber FE/GE
                                                         To Metro Ethernet


         Copper Line
                           Copper Line


                                                           FE
                                              Modem

        IPTV
                              PC


     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
16
FE interfaces are required. When the service quality is monitored in
reactive mode, a mirrored port needs to be configured.

 Fiber FE/GE                      Fiber FE/GE



                                       Fiber/LAN FE/GE
         Switch


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.




 Fiber FE/GE                         Fiber FE/GE



                                  Fiber/LAN FE/GE
          Router
                                  Mirror Port/Common port




                                                                         17
     6.1.2 Basic Networking Modes of Probes on the U2520

     Loopback Through the Cooperation of Two Probes



                             GRS

                              CDMA
          Source                          NTP      Destination




     HSI Service Monitoring in C/S Mode
                                                         Server



         Client




     Monitoring of Audio and Video Flows in Reactive Mode


          Receiver
                                                 Media




     Quality Monitoring in Trace Mode

       Source




18
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.




                                                                     IP Network




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.




                                                        Responder
        Controller
                                      IP Network
                                                        Responder



                                                        Responder


Here, a hierarchical U2520 management system is formed.
                                                                                  19
     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.

                        To define overall standards for evaluating networks and services


      To abstract networks and services
      that are to be evaluated                                             To establish an indicator system
                                                      SLA


                           Inventory                                       Metric


                                              Measurement
                                              Measurement


                  To obtain data through tests


                                                                  Figure 7-1 Key points of SLA evaluation




20
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.




                                                                           21
     7.2 Hierarchical Measurement
                                                                                                 Service KQIs and
         SLA KQI
                                                                                                 network KQIs
                                                                                                 KQIs
     Intermediate                                                                                associat ed
             KQI                                                                                 with the SAP, LSP,
                                                                                                 connection, path,
              KPI                                                                                board, and int erface

         Original
            data
                          Service test    Service              Network              Network
                          result          statistics           test result          statistics
                                                  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:


22
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




                                                                          23
     are aggregated by interface KPIs and interface KQIs. During the
     aggregation from lower-level KQIs to upper-level KQIs, all the lower-          Time                                   pe
                                                                                                                         Ty
                                                                                                                    ic
                                                                                                                etr
     level KQIs should be averaged, and the number of KPIs used for lower-                                  M
     level KQI calculation should be taken as a weight during averaging.

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

     Certain KQIs, such as the SAP KQI and channel KQI, are used only in         Figure 7-3 Three-dimensional KQI aggregation

     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.

     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.



24
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 inventories
     Examples: protocol interface traffic, protocol site traffic, and
     network traffic

     − I calculation 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.




                                                                         25
     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.

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

                       90                          4.34                Very satisfied
                       80                          4.03                satisfied
                       70                          3.60                Some users dissatisfied
                       60                          3.10                Many users dissatisfied
                       50                          2.58                nearly all users dissatisfied

                               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.




26
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;

                                                                             27
     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.
28
9 Typical Applications

      Access                                  Metro                                     Core                         Application




               DSLAM
                                                                                                                      Internet




                                                                                                                         BTV
                                                                                                                       Headend


               DSLAM


  MonitorB Verifier E               Verifier D            VerifierC                        Verifier B   Verifier A    Monitor A
  VMoS=3.2 VMoS=3.2                 VMoS=3.2              VMoS=3.2                         VMoS=4.8     VMoS=4.8


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



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.




                                                                                                                                   29
                  MQMC


               Encoder
               Central node      Regional node       Edge node



               HMS              HMS                  HMS


            Backbone                       MAN
             network
                   Router        Router            Router          BAS       LS W     DS LAM      STB


                                                                                                Detection
                        U2520: deployment of network nodes and fast location of faulty points   point

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

     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)

30
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


                                                                                       31
     system, the U2520 supports the E2E information display in GUIs
     and helps to perform SLA monitoring of services. When the damage
                                                                                                               Spirent
     environment was started by the disturber from Spirent, the external                                       TcstCenter

     probe on the U2520 and Cisco ASR9000 immediately showed that the                                  Huawei
                                                                                                       NE40E-X8
     bearing quality of the node from Cisco had degraded. Through the
     NEU100, the U2520 succeeded in displaying indicator values that are the
                                                                                            Spirent
     same as those provided by Cisco. In addition, the U2520 supports the                   xGEM                     Huawei
                                                                                                                     U2520
     abilities to display the status of each node and to compare the indicator
                                                                                    Cisco
                                                                                    ASR 9000
     data of all nodes so that users can quickly identify and locate faults.
                                                                                                      Huawei
     The EANTC carries out continuous tests in compliance with the RFC4445                            NEU100
     standard. The test results show that Huawei U2520 supports the E2E                      MPEG Transport Stream
                                                                                             SNMP
     video monitoring solution and provides the function of detecting the
     quality of a third-party device. In addition, indicators can be aggregated
                                                                                  Figure 10-2 Topology view associated with a
     and associated with SLAs. The U2520 supports data display through            video monitoring test
     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.


       Standard/Protocol
                                        Standard/Protocol Title
           Number
                             Triple-play Services Quality of Experience (QoE)
      DSL Forum TR-126
                             Requirements
                             Digital Video Broadcasting (DVB)
      ETSI TR 101 290
                             Measurement guidelines for DVB systems
                             Information technology — Generic coding
      ISO/IEC 13818-1        of moving pictures and associated audio
                             information: Systems
                             The E-model, a computational model for use
      ITU-T G.107
                             in transmission planning
                             Pulse code modulation (PCM) of voice
      ITU-T G.711
                             frequencies
                             Dual rate speech coder for multimedia
      ITU-T G.723            communications transmitting at 5.3 & 6.3
                             kbit/s


32
 Standard/Protocol
                                 Standard/Protocol Title
     Number
                     40, 32, 24, 16 kbit/s Adaptive Differential
ITU-T G.726
                     Pulse Code Modulation (ADPCM)
                     Coding of speech at 8 kbit/s using conjugate-
ITU-T G.729          structure algebraic-code-excited linear-
                     prediction (CS-ACELP)
                     Quality of experience requirements for IPTV
ITU-T G.1080
                     services
ITU-T G.1081         Performance monitoring points for IPTV
ITU-T H.248          Gateway control protocol
                     Packet-based multimedia communications
ITU-T H.323
                     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
                     Domain names - implementation and
RFC 1035
                     specification
RFC 1305             Network Time Protocol (Version 3)
RFC 1350             The TFTP Protocol (Revision 2)
RFC 2131             Dynamic Host Configuration Protocol
                     Internet Group Management Protocol,
RFC 2236
                     Version 2
RFC 2326             Real Time Streaming Protocol (RTSP)
RFC 2327             SDP: Session Description Protocol
RFC 2330             Framework for IP Performance Metrics
                     A Method for Transmitting PPP Over Ethernet
RFC 2516
                     (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
                     IP Packet Delay Variation Metric for IP
RFC 3393
                     Performance Metrics (IPPM)



                                                                     33
     Standard/Protocol
                                     Standard/Protocol Title
         Number
                         Management Information Base (MIB) for
     RFC 3418            the Simple Network Management Protocol
                         (SNMP)
     RFC 3433            Entity Sensor Management Information Base
                         Media Gateway Control Protocol (MGCP)
     RFC 3435
                         Version 1.0
                         RTP: A Transport Protocol for Real-Time
     RFC 3550
                         Applications
                         Dynamic Authorization Extensions to Remote
     RFC 3576
                         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
                                    Standard/Protocol Title
         Number
     IEEE802.1ad         Provider bridges
     IEEE802.1ag         Connectivity fault management
     IEEE802.1D          Media access control (MAC) bridges
     IEEE802.1Q          Virtual bridged local area networks
                         OAM functions and mechanisms for Ethernet
     ITU-T G.1731
                         based networks
     ITU-T G.8010        Architecture of Ethernet layer networks
                         Ethernet over Transport - Ethernet services
     ITU-T G.8011
                         framework
     ITU-T G.8012        Ethernet UNI and Ethernet NNI
                         Characteristics of Ethernet transport network
     ITU-T G.8021
                         equipment functional blocks
     ITU-T G.8031        Ethernet protection switching
                         Requirements and framework for Ethernet
     MEF MEF2
                         service protection in metro Ethernet networks
                         Metro Ethernet network architecture
     MEF MEF4
                         framework - Part 1: generic framework
                                 Table 10-2 Ethernet service standards and protocols




34
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




                                                        35
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