Even if the management capabilities of WLANs improve, you'll still benefit from specialized tools. Handheld wireless LAN analyzers provide the mobility technicians and engineers need to manage this kind of network environment. Most of these products have been on the market for a year or less, but they put a ton of power into your hands. Sure, you can cobble together some free tools to perform some of the same monitoring and troubleshooting tasks, but you'll save time with a more polished tool. Time is money.
Because it's a relatively new market, comparing these products isn't easy. One product might offer superior physical-layer spectrum analysis while another might have the best expert system, letting people in the field quickly identify problems. Two different tools for two different problems. Don't expect these tools to be a substitute for understanding WLANs. They're just tools. We've evaluated what we consider the primary functions, and weighted those functions to the needs of an enterprise with more than 50 APs (access points) in operation.
We asked four leading vendors of handheld WLAN analyzers for products that run on a PDA platform. All four--AirMagnet, Berkeley Varitronics Systems, Fluke Networks and Network Associates--submitted equipment. Although other sophisticated wireless-analysis tools, often priced at $20,000 or more, are available, most of them are generic radio-analysis tools. We picked tools capable of analyzing 802.11b WLAN traffic (handheld analyzers don't support 802.11a traffic yet). Our sweet spot: a sub-$5,000 device that technicians and WLAN design professionals can carry with them in the field, always ready for use. We tested the devices in several different environments and talked to managers of large WLANs to get a better feel for their needs.
When the microwaves cleared, AirMagnet earned our Editor's Choice award. A rapidly maturing offering, AirMagnet provides the best combination of analysis and diagnostic features. Furthermore, its smartly designed interface effectively exploits the strengths and overcomes some of the inherent weaknesses of the Pocket PC platform (which three of the four products use). If Layer 1 RF (radio frequency) analysis is your primary need, Berkeley Varitronics' Yellowjacket WLAN test receiver is the hands-down winner; it provides calibrated spectrum-analysis capabilities to resolve the toughest WLAN problems. Fluke's WaveRunner is a capable first-release offering and the only product we tested that runs under Linux, an attribute that has its pros and cons. Finally, if your main goal is high-layer protocol analysis in the palm of your hand, nothing beats Network Associates' Sniffer.
What Do You Want To Do Today?
To choose the right handheld WLAN analyzer, you must consider its intended use. Which layers of the network stack do you want to analyze? Who will be doing the analysis? If you aim to equip your Tier 1 field technicians, perhaps the same folks who handle your wiring infrastructure, you should match the device to those workers' knowledge and experience with RF and WLANs. In many cases, this means choosing a tool that captures and analyzes WLAN traffic and provides practical expert analysis in real time. These techs also could benefit from having a tool that helps them perform site surveys, troubleshoot connection and performance problems, and identify and locate rogue devices and network attacks or intrusions. All the products we tested can identify rogue devices, but beyond that base functionality, there are lots of differences.
If your needs are advanced, consider a more specialized tool. As RF-based communications systems grow, both in scope and usage, there is a greater need for precise tools that detect physical-layer abnormalities. Remember, these are unlicensed airwaves, so the sources of interference are many. The tool of choice for serious RF engineers is the spectrum analyzer. Sometimes, that's the only systematic way of identifying the source of WLAN performance problems, including those that may be caused by cordless phones or other unlicensed radio devices. While you can easily spend $20,000 on a capable spectrum analyzer, Berkeley lets you carry it in your hand, at a dramatically lower price. Using a spectrum analyzer requires significant RF training, but for enterprise WLANs that must meet four-nines availability, this is a cost you may need to absorb.
Other problems require in-depth, multilayer packet analysis. Often, the root of the problem rests with a client implementation or an application problem, not with the network. But history has taught us that users always blame the network first, so the burden of troubleshooting these problems often rests with the network staff.
One question you'll surely ask is whether a PDA is the right form factor for advanced troubleshooting. As with many applications, sometimes a PDA can be as much a limitation as a benefit. For example, the larger screen and higher resolution of a laptop computer make high-layer protocol analysis much more convenient. If you have a large LAN, you probably have a laptop-based tool anyway, so use it where you can. Furthermore, during our tests, we experienced occasional system lockups that necessitated a reboot. These products stress the capabilities of the underlying hardware and software platforms on which they operate. The painful truth is that handheld analyzers don't replace other tools; they supplement them.