Optical/IP Networks

SpectraLink Seeks New Standard

Wireless LAN VOIP leader SpectraLink Corp. will call for the Institute of Electrical and Electronics Engineers Inc. (IEEE) to create a new 802.11 task group to develop a standard for fast, secure roaming between access points, at a meeting of the venerable industry body this Tuesday.

SpectraLink claims that yet another 802.11 variant is necessary because current mandated security standards degrade the performance of "enterprise-class VOIP" when users roam among access points. The firm wants to make the existing fast, secure roaming study group into an official 802.11 Task Group and have it hammer out a better standard for corporate applications.

This standard -- if it comes ever comes to pass -- will be different from the upcoming VOIP-related 802.11e standard, which is concerned with implementing quality-of-service (QOS) mechanisms on 802.11 networks, so that voice or multimedia traffic can be prioritized above plain ol' data packets (see Is 802.11 Ready for VOIP?). The new roaming standard, on the other hand, would be aimed at minimizing call dropping and network jitter when users move between so-called secure access points while making calls on mobile WLAN handsets.

Ben Guderian, director of marketing at SpectraLink, says that the company has been testing roaming with its mobile handsets between wireless LAN access points using the wireless protected access (WPA) specification with Pre Shared Key (PSK) authentication (see 802.11 Security Issues Sorted?). SpectraLink claims that the delays and dropouts on phone calls caused by waiting for handoffs when users move between access points are "unacceptable" for corporate applications.

Guderian says that handoff times of 70 milliseconds or more were common when using WPA and PSK. He says that handoff times of 50 milliseconds or less (i.e., better than cellular) are what SpectraLink is looking for in an enterprise VOIP system.

"What we say is good voice quality may seem excessive to some," Guderian admits. However, he adds, SpectraLink is basing its judgments on implementing wireless LAN VOIP systems for hospitals and the like. "They [Doctors] don't want dropouts walking down the corridor," says Guderian [ed. note: and he wasn't even trying to be funny!].

Meta Group Inc. analyst Chris Kozup agrees that WPA handoff times "totally break" voice-over-WLAN applications and wonders why it took SpectraLink -- arguably one of the major players in 802.11 VOIP systems -- so long to recognize the problems with the security standard.

"It's about time," huffs Kozup.

Guderian says that SpectraLink has talked to other firms about formalizing a new task group but won't name names yet. "[They are] companies that have identified voice [over WLAN] as important to their business."

It's worth noting that SpectraLink is currently working with firms such as Airespace Inc., Cisco Systems Inc. (Nasdaq: CSCO), and Trapeze Networks Inc. (see Airespace Talks Up VOIP and Trapeze Makes Connection).

Some of these companies already have -- or are working on --proprietary methods, as opposed to a standard, for circumventing the problems with WPA when trying to enable voice roaming. Cisco is planning fast, secure roaming protocol as part of its "Cisco Compatible Extensions" (CCX) version 2 release (see Cisco Bolsters Its WLAN Hand).

Many switch vendors use techniques to try and anticipate and hide these handoff delays, such as forwarding user data to the access points in the vicinity -- so that the boxes have the information before the user arrives on that part of the network -- or by holding user information at the switch.

— Dan Jones, Site Editor, Unstrung

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