Options for Wi-Fi benchmarking ahead of 802.11.2

There are several factors fueling the need for consistent Wi-Fi performance benchmark testing, a goal of 802.11 Task Group T in its design of an 802.11.2 recommended best practices standard.

Final 802.11.2 recommendations are expected, at the earliest, in January 2008.

Among the drivers:

* Wireless LANs are maturing and finding new applications. As a result, they are likely to grow, which means you need to know how well they will perform on a large scale under various RF conditions.

* The ever-imminent arrival of real-time voice and other multimedia traffic on WLANs means you have to control performance metrics more tightly than when good old forgiving data is the only traffic riding the WLAN. How do you know how to make performance “better” if you can’t benchmark it in the first place?

The wired LAN world has standards in the form of IETF Request For Comments (RFC) for how Internet routers (RFC 2544) and Ethernet switches (RFC 2889) should be benchmark-tested. This allows apples-to-apples performance testing across different vendors’ equipment, and 802.11.2 aims for a counterpart in the wireless environment. Today, Wi-Fi performance testing is conducted inconsistently under any number of conditions, making comparative performance rankings impossible.

Wi-Fi Alliance certification testing – though an important yardstick of industry interoperability – tests only whether a given piece of gear will peacefully cohabitate with a limited number of other vendors’ certified gear.

If you don’t want to wait for 2008 and 802.11.2, VeriWave is releasing “pre-802.11.2” performance testing analyzers and applications like crazy. Last week, it announced an 802.11 benchmark application for its WaveTest 90 traffic generator/analyzer, which emulates thousands of WLAN clients under several sets of conditions. At the Interop conference in Las Vegas this week, VeriWave is demonstrating its application by emulating 45,000 clients accessing Foundry Networks WLAN switches with real traffic.

Next week, the company intends to launch an application that tests WLAN performance as clients roam between access points. Roaming metrics that can be established include roaming delay, call quality during roaming, power save, and some voice mean opinion score (MOS) components, according to Veriwave CTO Tom Alexander.

Alexander, coincidentally, is the technical editor of the emerging 802.11.2 standard for 802.11 performance benchmarks.

The VeriWave system, he said, emulates 500 clients on each one of its traffic generator cards within a single WaveTest 90 system, and nine cards can fit into a chassis for emulating up to 4500 wireless clients. Multiple chassis can be daisy-chained to emulate thousands more. Testers can emulate a mix of “golden clients” (those behaving exactly as expected in ideal conditions) with aggressive clients that grab large amounts of bandwidth, those putting out higher power levels, and under conditions where packets are withheld to determine performance impact, says Alexander.

Finally, a request: If you can find a few minutes to take the Webtorials WLAN State-of-the-Market survey, I’d really appreciate it. For the third consecutive year, I’m collecting information from those deploying or considering deploying WLANs to track usage trends. The results will be compiled into a findings report, offered free of charge, in June. You can access last year’s report (abstract without registration). Thanks in advance.