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VoIP Performance Management and Optimization (Networking Technology: IP Communications)

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If you know anything about the Internet Protocol, then meeting VoIP for the first time can be a surprise. While laypersons might complain about low VoIP sound quality, the very fact that you can often still carry on a conversation in real time using it is quite impressive, given the unreliable underlying IP.

But as VoIP has become popular, expectations have rise and thus the need for comprehensive metrics of performance. Leading to KPI, which the book explains in detail. It is a set of metrics for which software exists that measure it in real time (or as close to it as possible) and then to display results in some visually clear manner for the sysop. The visuals let the sysop's wetware (ie. brain) see if outages exist, or if some quality metric is decreasing. To some extent these can be subjective performance issues if there is no outright network failure.

A key idea is for proactive monitoring, where the sysop in a Network Operations Centre can use a fault management system for diagnosis. The text discusses how to do fault isolation, especially in the common case where your network has several switches, gateways and subnets. For a sysop, the examples in chapters 7 and 8 may be the most valuable portions of the text, as they deal with those sometime difficult scenarios. You can use the examples to guide how you might reduce down your network problems to a given piece of equipment or subnet.

In some respects, the diagnosis for VoIP problems is harder than for generic IP traffic, or indeed for streaming video. Bottleneck problems in the latter are less jarring than having a VoIP conversation repeatedly "time out" and the different KPI metrics explore various dimensions of possible problems.

You can also see that Cisco offers a sophisticated VoIP dashboard and associated debugging facilities, as evidenced by Appendices C and D.