How we tested VoIP analysis tools

The test bed was configured with two subnets simulating a headquarters and a branch location. The network infrastructure at both sites consisted of Extreme Networks Summit 48 L2/L3 switch/routers. The two sites, labeled A and B, powered by Zultys MX250 IP PBX systems, were connected by a T-1 IP WAN link.

Each VoIP analysis tool tested was configured and inserted, one at a time, into the test bed. The WAN connection was simulated using a Hurricane IP Network Emulator from PacketStorm Communications. The PacketStorm Emulator let us vary our network environment, simulating various impairments that included numerous latency, jitter and packet loss scenarios. A mirrored port was configured on the headquarter subnet for the vendors to insert their respective analysis tool.

An average of 5,000 channels of simulated SIP traffic was generated and delivered from the site A by Touchstone Industries WinSIP (2.4.0) Generator. An average of 128 channels of simulated SIP traffic was also generated from a Spirent Abacus 5000 (v3.2) SIP traffic generator from site A. These site A calls were terminated at respective matching endpoints across the WAN link, at the B site.

Each of the products was evaluated on its ability to capture, monitor and analyze these calls. All of the participating products varied slightly in the overall results on MOS, latency, jitter and packet loss, but all reported accurately on the effects of the network and the VoIP calls in progress.

Thanks

Miercom and Network World thank these vendors of test equipment and analysis software for the use of their products in this testing: Zultys, Touchstone, Spirent, PacketStorm and Extreme.

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