Healthy VoIP Nets�Part XXII�Network Management Architectures: Nortel Networks

Nortel Networks Corporation, headquartered in Toronto, Ontario, has a history in telephony that dates back to 1882, when the Bell Telephone Company of Canada established a separate department to begin manufacturing telephone sets. That effort grew to become Northern Electric, which designed the switching systems of the Trans-Canada telephone toll system in the 1930s, and later became a separate subsidiary, Northern Telecom, which was established in 1971 to manufacture and sell equipment in the United States.

In 1995, the Nortelbrand name was established, which was formally changed to Nortel Networks in 1999. Today, the company does business in over 150 countries around the globe, claims the top 25 service providers as its customers, and serves over 100 million enterprise users worldwide.

The company is active in a number of communication areas, including digital, optical, wireless, IP, VoIP, broadband, multimedia, and Ethernet technologies. One of the largest equipment providers in the industry, the company employs over 33,000, with around a third of these individuals devoted to R&D activities, and posted US$11.4 Billion in revenues during 2006.

Nortel VoIP switching systems serve both enterprise and carrier class customers, with the Communication Server family of softswitches capable of handling over 100,000 IP phones. With systems that large, a solid network management scheme is essential—which is what Nortel has named its Proactive Voice Quality Management,or PVQM.

Vivinet Assessor interface
Figure 1—NetIQs Vivinet Assessor readout
Click to see full-size image

The PVQM solution was co-developed by Nortel and NetIQ, and is specifically designed to ensure that the system’s voice quality is effectively monitored and managed. PVQM is based upon a life-cycle model of IP telephony implementation, which defines four key phases of that process: assessment, pre-deployment, ongoing monitoring, and reporting and planning.

The network assessment phase addresses the question: “is this network ready for VoIP?” to determine if the current data network is capable of handling the increased traffic loads that the voice and/or video system will bring. NetIQ’s Vivinet Assessor is used for this phase, and evaluates and reports on the network’s ability to support VoIP requirements, collects network metrics to predict the overall expected call quality, and provides an inventory of key networking devices, including switches and routers (see Figure 1).

In the pre-deployment phase, Nortel’s Enterprise Policy Managerprovides centralized management of the network quality, making for a more consistent QoS across the entire enterprise.

Once the network has been deployed, ongoing monitoring of end-user voice quality and of the overall health of the network is required, which maximizes the uptime, reliability, and quality of the connections. This phase utilizes the NetIQ AppManager, and also the Vivinet Diagnosticsthat combine the platform, system, and call quality metrics for the Nortel Call Servers with information regarding the availability and status of other network devices (see Figure 2). The Vivinet Diagnostics is an automated troubleshooting tool that can quickly pinpoint call problems, and assist in determining why call quality has suffered.

Vivinet Diagnostics interface
Figure 2 – The Vivinet Diagnostics interface
Click to see full-size image

The final phase, reporting and planning, provides voice and network quality reporting for service level agreement (SLA) management and planning purposes, and also utilizes the capabilities of the NetIQ AppManager. This element of the solution allows for a number of applications, such as IP phones, voicemail, call servers, contact centers, and so on, to be supported from a single management console.

In addition to the NetIQ products, Nortel has embedded Telchemy’s Vqmon agents (see in Nortel IP phones, which allow the phone to monitor its own call quality in real time and immediately send on RTCP XR messages for troubleshooting analysis when predefined QoE thresholds are exceeded. (The RTP Control Protocol Extended Reports (RTCP XR) are diagnostic packets defined in RFC 3611 ( that can be used for network management purposes.)

If a threshold is exceeded, a notification is sent on to NetIQ AppManager and Vivinet Diagnostics, which automatically performs a trace-route and root cause analysis while the call is in progress. Nortel’s Enterprise Network Management System (ENMS) can then provide a network view of the alarm and diagnostics to further isolate the problem. In addition, Nortel’s Enterprise Policy Manager(EPM) can be used to apply a policy to correct the cause of the network degradation impacting voice quality.

Further details on the Nortel Networks architecture and products can be found at Our next tutorial will continue our examination of vendors’ network management architectures.

Copyright Acknowledgement: © 2008 DigiNet Corporation ®, All Rights Reserved

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