VoIP Network Management: A Buyer's Guide, Part 2

A more detailed look at the roles of SNMP-based systems, protocol analyzers, and performance/QoS monitors in keeping VoIP nets healthy.

By Mark A. Miller | Posted Feb 17, 2009
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In the first part of this buyers guide, we briefly reviewed the basic network management principles that can be used to guide the operation of any type of communications network implementation—including converged networks with VoIP. We also noted the six broad categories of tools that we presented to the network management vendors, asking them to indicate which of those categories were supported by their products.

In this and the following parts of the guide, we will drill down deeper, providing some highlights of companies and their solutions that support each of these categories.

One note before we begin: You almost certainly don’t necessarily need one tool from each group to adequately support your VoIP network. Smaller networks typically require fewer and less complex tools (such as a performance monitor), while multi-location enterprises might opt for an SNMP-based network management system, protocol analyzer, and network design software.

Test equipment is often available for loan or rent from a vendor if you need to try it out or use it for a month or so. The only downside to this kind of approach is the learning curve that you may have to traverse, especially under trying circumstances, such as a network outage.

With those caveats in mind, here are some details on the categories and some representative product solutions:

SNMP Enterprise Management Systems: are typically VoIP modules that can be integrated as a part of a larger network management solution based on the Simple Network Management Protocol.

SNMP-based network management systems rose to prominence in the 1990s, with all of the big players—Cabletron Systems (now defunct), HP, IBM, and DEC (now part of HP) all marketing solutions for the larger enterprise.

Within SNMP, there are two key entities: the manager, or console, which is overseeing the network operations, and typically running under UNIX or a similar platform; and the agent, which monitors the local operations, and reports key information back to the manager.

Many of the vendors surveyed in Healthy VoIP Nets reported that their systems included some level of integration with SNMP-based systems. For example –

Fluke Networks’ Visual Performance Manager can integrate information from SNMP-based sources and then display it alongside other performance data for a more thorough analysis of the situation from the console.

NetIQ’s AppManager, ViviNet Diagnostics, and ViviNet Assessor, all support SNMPv1, v2 and v3 and RMON (remote monitoring) interfaces to assess, monitor, and diagnose problems on an enterprise network that includes voice traffic.

Protocol Analyzer: Typically reserved for the networking gearheads, this tool captures all the packets of voice and data information that are coming down the wire, analyzes those packets according to the rules of the protocol in use, and then displays that information in several formats such as binary and hexadecimal. The analyzer also typically offers a brief summary (in English) that provides the network manager with some clues as to what is really going on under the hood.

Protocol analyzers are like a Torx screwdriver (that fit those funny looking star-shaped screw heads)—you may only need it once in a blue moon, but when you need it, there is no substitute.

The analyzer that has become the benchmark over the last 20 years is Netscout Systems, Inc.’s Sniffer Portable analyzer, which can decode hundreds of protocols running on just about any type of LAN, WAN, or wireless networking topology available.

In addition to decoding the protocol interactions, the Sniffer also includes real-time traffic analysis, which provides a traffic map and matrix of network conversations. Moreover, it reports information about the protocols in use, applications running, and transport processes utilized; and delivers global statistics reports such as segment traffic, errors, size distribution, and utilization. About half of the vendors we surveyed had a protocol analyzer of some type in their product portfolio.

Performance/QoS Monitor: Less sophisticated than the protocol analyzer, this tool looks at the results, independent of the underlying protocols in use. It will typically display some high-level information that gives you a quick read on the overall health of the network, such as statistics on Mean Opinion Score, packet delay, jitter, and so on.

This category of product typically has the best user interfaces, as they are designed to give a summary of the network performance with a quick glance. Almost all of the vendors surveyed indicated that their product suite includes some form of such monitoring capabilities.

SolarWind’s Orion VoIP Monitor lets users measure and track performance of voice quality across WANs. It is a module within the company’s larger network management suite, thus giving net managers the option of purchasing only what they need.

The NetQoS Unified Communications Monitor lets net managers report on key metrics, such as jitter, latency, packet loss, and frame loss. It assesses call quality and delivers call setup metrics, such as call setup failures and delay to dial tone. It also plus provides video quality metrics, such as frozen video minutes, frame loss, and latency. A manager can assign performance thresholds to specific pairs of network locations (for example, a pair of gateways) to determine which network paths are candidates for further investigation.

Our next tutorial will look at the remaining three categories of network management tools: agents/probes, traffic simulators, and network optimization software.

Copyright Acknowledgement: © 2009 DigiNet Corporation®, All Rights Reserved


Author's Biography
Mark A. Miller, P.E. is President of DigiNet Corporation®, a Denver-based consulting engineering firm. He is the author of many books on networking technologies, including Voice over IP Technologies, and Internet Technologies Handbook, both published by John Wiley & Sons.

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