Test kit makes voice appear visible

If you’re not hearing voices, there’s probably nothing wrong with you. More likely it’s your network configuration that’s ailing your aural satisfaction.

Voice can be high maintenance for an Internet Protocol network, with all its sensitive issues around packet loss, delay, latency and jitter. Missteps in the server, router or switch ports can scatter the smoothest voice into fragmented packets of nonsense.

With the right tools, a systems administrator or network architect can take the guesswork out of managing voice over IP. Fluke Networks Inc. has made enhancements to its Visual UpTime Select monitoring and testing software that renders voice quality as graphical measurements based on mean opinion scores (MOS).

Fluke Networks inherited the VoIP testing tool with its acquisition in January of Rockville, Md.-based Visual Networks Inc. Fluke describes MOS as a metric that reflects end-user quality of experience and says Visual UpTime Select can trace those scores at every site throughout the network for every call.

One of its more valuable strengths is the tool’s systemic view of the entire network infrastructure, according to analyst Dennis Drogseth. “It’s able to look at QoS (quality of service) across different application types, such as Microsoft Exchange, SAP, CRM traffic, Web-based apps, and understand how one might be impacting the other,” says Drogseth, a vice-president at Enterprise Management Associates Inc. in Boulder, Col.

Rich new capabilities make the tool a complete product, he says. Synthetic testing can support predeployment as well as deployment of VoIP, and the tool provides blanket monitoring of MOS.

David Cuddy, a telecom veteran of more than 20 years, helped set up and manage a voice- and signal-processing test lab for one of the larger telcos through the eighties and nineties. Nowadays he’s in charge of developing IP telephony products and then running the software in a simulated test environment.

In the old days MOS was exactly what it stood for: an average of ratings based on human opinion. Over the past five years as VoIP became mainstream, says Cuddy, the scoring system has become more scientific and analytical.

“Labs have been doing MOS measurements where they vary the amount of jitter from five milliseconds to 10ms, and then 20ms to 30ms. A certain amount of jitter, or noise or delay, will lead to a particular level of impairment of subjective quality,” says Cuddy.

Scientific models have been created that attempt to match objectively measured impairment, like lost packets and reduced bit rate, to the original opinion-based MOS methods.

Cuddy says Fluke’s new Visual UpTime Select has made these scores easy to understand and strong reporting features can help network managers pinpoint problems in connectivity.

“It’s a self-evident tool that’s aimed at an unsophisticated market. We like the simplicity that the visual aspect brings,” says Cuddy, chief technology officer for Ottawa-based Natural Convergence Inc.

Fluke has added more granular reporting for detailed per-call investigation of the network’s performance, which can be historically stored for back-in-time troubleshooting. “This takes VoIP management beyond assessing and monitoring the network to much higher levels of managing and optimizing voice traffic on the network,” says Naresh Kannan, director of product management for Fluke’s Visual Networks division.

QuickLink: 065357

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