VoIP Network Management: A Buyers Guide, Part 1

Tuesday Feb 10th 2009 by Mark A. Miller

To make an intelligent choice of net management tools, you need to grasp the underlying concepts. Let's review them.

Sometimes when you set out on a journey, you know the intended destination, but don’t know exactly how you’ll get there—or if there will be a few extra turns along the way. Such was the case when I embarked on this journey through the world of VoIP network management systems. My preliminary research had identified a couple dozen firms in this marketplace, but I was truly surprised to find over 50 solution providers once all of the vendor responses had been tallied.

But before we start summarizing all of this information, let’s quickly review some of the network management principles that guided us on this journey:

Recall from our first installment that the International Organization for Standardization (ISO) has defined a management framework in their ISO 7498-4 document, published in 1989 (see http://www.iso.org/iso/en/CatalogueDetailPage.CatalogueDetail?CSNUMBER=14258 ), which defines five different aspects, called Specific Management Functional Areas. These areas can be applied to any type of communications network, including some of the classic network management architectures that we considered in Part II:

  • Fault Management: "encompasses fault detection, isolation and correction of abnormal operation of the OSI environment," or How well is this VoIP network operating?
  • Accounting Management: "management enables charges to be established for the use of resources in the OSI environment, and for costs to be identified for the user of those resources," or, Is the VoIP network truly saving us the money that the vendor claimed it would?
  • Configuration Management: "identifies, exercises control over, collects data from and provides data to open systems for the purpose of preparing for, initializing, starting, providing for the continuous operation of, and terminating interconnection services," or How do we keep track of the current network configuration, especially now that everything comes out of one wall jack?
  • Performance Management "enables the behavior of resources in the OSI environment and the effectiveness of communication activities to be evaluated," or Is the voice quality with our VoIP system really as good as that old PBX?
  • Security Management: "supports the application of security policies by means of functions which include the creation, deletion and control of security services and mechanisms; the distribution of security-relevant information; and the reporting of security-relevant events," or Have we adequately secured the converged network against malicious or unauthorized use?

We also considered some of the challenges that come with evaluating real-time communication—such as voice and video—especially given the subjective nature of the humans on either end of the channel (see Parts III, IV, and V). These discussions introduced tests including the Mean Opinion Score (MOS), the E-model, for multi-source transmission impairments, Quality of Service (QoS) and Quality of Experience (QoE) that are key elements of VoIP network evaluation.

Next, we looked at the seven layers of the Open Systems Interconnection (OSI) Model, (see Parts VI and VII) and considered some of the additional complexities that a VoIP system brings, such as the ENUM (Electronic Numbering) database, which translates telephone numbers to and from IP addresses; the call signaling using the H.323 or SIP protocols, which establish and disconnect the call; and the selection of the voice codec that converts the analog voice signal into a stream of ones and zeros.

Finally, we looked at the various tools that were available to shed light on all these performance questions (see Parts VIII and IX).

Depending upon the complexity of the enterprise, the net manager might need anything from cable testers and QoS Monitors to a protocol analyzer or enterprise-wide network management system. Smaller enterprises would likely gravitate to the first part of this list, while the larger, multi-location networks would be more likely to require a full network management system and optimization tools.

In order to gather the product information, we distilled the tools down to six categories, and then asked the vendors to indicate whether or not their products provided support in each of these rather broad areas:

  • SNMP Enterprise Management Systems
  • Protocol Analyzers
  • Performance/QoS Monitors
  • Agents/Probes
  • Traffic Simulation and/or Network Stress Testing
  • Network Design, Optimization or Mapping Tools

We’ll look at a sampling of the responses in our next two tutorials.

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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