Test Drive: Wireless LAN Handheld Analyzer

By Jim Geier

AirMagnet’s Wireless LAN Handheld Analyzer provides WLAN administration, installation surveying, security assessment, connection troubleshooting and performance management functions. The standard product currently includes software (Version 1.20) supporting Pocket PC 2002, one AirMagnet 802.11b PC Card, and three months of toll free telephone technical support. The standard pricing of $2,495 does not include the actual Pocket PC hardware, however.

The screens on AirMagnet’s analyzer are an effective user interface, offering very good navigation throughout the functions. AirMagnet does a great job of implementing “drill down” menus to avoid unnecessary scrolling through a small screen to find data. For example, you begin by viewing a packet by only seeing the top level information, then you can click on specific elements, such as 802.11 header, to examine details of fields and bits.

At $2,500, the AirMagnet product has a lower price than other 802.11 protocol analyzers. The price for the software and special radio NIC, combined with the cost of a relatively inexpensive Pocket PC device, makes the overall cost of AirMagnet’s analysis solution very affordable.

An issue with AirMagnet’s software is that it lacks effective RF spectrum analysis. One of the functions does indicate signal power within each 802.11 RF channel (which is better than nothing), but the tool could use a more advanced spectrum analysis function that clearly identifies sources of non-802.11 interference. The product tends to focus most of its functions on 802.11 protocol analysis.

Developers of protocol analyzers have difficulties making their products operate with a wide range of radio NICs. It’s not practical for the vendors to keep up with all radio NIC hardware and firmware versions in order to interface with each card. In fact, AirMagnet only supports their private labeled radio NIC. AirMagnet claims, however, that they’ll be supporting other brands, such as Cisco, Symbol and Agere within the next year.

Pre-installation Survey Tools
When performing an RF site survey, AirMagnet’s device has the right features. An auto discovery function collects information, such as SSID and signal strengths, from authorized and unauthorized access points. A bar graph indicates the signal strengths that the tool detects on each of the 802.11 RF channels. As a result, the AirMagnet device identifies potential co-channel interference from unknown access points. This is especially useful when installing a wireless LAN in office buildings, apartment complexes and housing areas that may be within close proximity to other potentially interfering wireless LANs.

After installing one or more access points, you can use AirMagnet’s site survey tools to collect applicable RF signals and performance data to make decisions on the optimum placement of access points. The lightweight nature of the device certainly eases the burden of lugging equipment around as you test each potential access point location. After collecting the site survey information, you can export the data to a laptop or PC for archiving or printing functions.

Operational Support Tools
Security assessment features of the AirMagnet product help you detect if anything appears out of place on the network. For example, a failure analysis tool isolates the source of transmission, authentication, and reassociation problems, indicating a possible unauthorized user. This would alert network support staff and possibly security officials to find the culprit and take appropriate action.

AirMagnet allows the capturing and decoding of 802.11 frames and other protocol packets in real time. The unit records this data for later viewing and analysis. You can play back the packets in time sequence as they occurred to help detect network problems.

Built-in troubleshooting tools help resolve connectivity problems with specific access points. Performance tools also help discover problems and provide the basis for making decisions on how to improve performance. For example, the product monitors channel throughput and provides alerts when access points or users overload the channel.

You can program a series of alarms in the product to indicate a specific situation. As examples, items that trigger alarms could include the presence of rogue access points and clients, a denial of service, users not using WEP, excessive CRC errors, or too many access points on a particular channel. The use of alarms dramatically increases your ability to spot issues before they become big problems.

The AirMagnet product includes an intelligent connection diagnostics utility. For example, the utility identifies a mismatch dealing with SSIDs, WEP keys, transmission rates, or RF channels. This quickly identifies what to fix in order to establish connectivity for specific users.

Installation and Setup
I found the installation and setup of AirMagnet very straightforward. In addition to the software, you need a Pocket PC that meets the following requirements: 64MB of Memory, Microsoft Pocket PC Operating System, and Open Slot for Type 2 CF Card or PCMCIA Card. AirMagnet has certified their software on the Compaq iPAQ, Casio Cassiopeia, and HP Jornada.

I highly recommend AirMagnet’s Wireless LAN Handheld Analyzer as a tool for performing RF site surveys and supporting an 802.11 network. The extremely effective protocol analysis capability, small size, and low cost make this unit practical for just about anyone, even smaller companies having tighter budgets.

Jim Geier provides independent consulting services to companies developing and deploying wireless network solutions. He is the author of the book, Wireless LANs (SAMs, 2001), and regularly instructs workshops on wireless LANs.

Model Number: AM-1001-11b ($2,495 MSRP)

Pros: Excellent usability despite the relatively small display; comprehensive protocol capturing and analysis functions; low price in comparison to similar devices.

Cons: Limited RF spectrum analysis; only supports the Airmagnet radio NIC

Reprinted from 80211-planet.

Small Business Computing Staff
Small Business Computing Staff
Small Business Computing addresses the technology needs of small businesses, which are defined as businesses with fewer than 500 employees and/or less than $7 million in annual sales.

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