AirMagnet WiFi Analyzer PRO 9 Troubleshoots WiFi Roaming

 
 
By Andrew Garcia  |  Posted 2010-11-16
 
 
 

With its new support for multiple analysis sensors, AirMagnet WiFi Analyzer Pro 9.0 delivers the much-needed ability to analyze WiFi client roaming behavior, albeit with some annoying but not critical limitations.

AirMagnet (a Fluke Networks company) started shipping Analyzer PRO 9.0 this month, finally delivering multiadapter support to a laptop-based WiFi analysis solution and making it possible to simultaneously troubleshoot and analyze activity occurring on multiple channels, including roaming events. The new version also delivers a more action-oriented interface and troubleshooting tools with better connections.

Analyzer PRO 9.0 costs $3,995, but is available as a free upgrade to current customers with up-to-date support contracts.

Version 9.0 is the first version of Analyzer PRO fully supported on 64-bit Windows operating systems (although the application itself is still 32-bit), and I successfully installed and tested the product on a Dell Inspiron XPS 1330 running 64-bit Windows 7 Ultimate.

Unlike previous versions of Analyzer PRO, which used only a single WiFi adapter to detect wireless traffic, commonly scanning across the entire spectrum, Analyzer PRO 9.0 can utilize up to three WiFi adapters to listen into traffic on three channels at the same time without missing a frame on any channel, thanks to time-sliced scanning behavior. This capability is particularly helpful because it finally allows administrators to see both sides of a client's roaming actions from a single analysis station.

Customers can use any combination of a handful of AirMagnet-supported adapters for multichannel detection, but AirMagnet recommends using its new multiadapter kit to ensure that each adapter gets equivalent antenna placement. The kit for Analyzer PRO ($495) consists of a 5-port USB hub that gets double-taped to the top of the back of a laptop screen and three USB Proxim model 8494-US 802.11a/b/g/n adapters to plug into the hub, which stick straight up from the top of the laptop.

Customers can use the multiple adapters in conjunction with the new roaming analysis tool to examine connection details before and after roaming. For instance, I started a Netflix streaming video on an iPhone 3GS, then walked around the office, triggering roaming between the different access points on my test network. The roaming analysis tool automatically detected my roaming client, subsequently reporting metrics such as client signal strength, AP and channel-both before and after roaming-with time stamps to indicate when the roaming occurred.

For voice over WiFi traffic, Analyzer PRO also generates bidirectional MOS (Mean Opinion Scores) values before and after roaming, allowing an administrator to see the effects the roaming behavior has had on voice quality. To aid in generating that score, the roaming analysis tool enumerates detected delays, breaking that value down further to identify delays caused by AP selection, 802.11 association, authentication and key exchange.

Analyzer PRO's AirWise technology also attempts to identify the conditions that potentially caused the roaming to occur.

I was disappointed to find, however, that Analyzer PRO currently does not allow customers to affix detections to specific channels with a subset of the adapters while scanning across channels with those remaining. When starting Analyzer PRO, I found I needed to select which adapters I would use for the detection session. If I selected multiple adapters, I needed to set each adapter to a one specific channel, but if I selected only a single adapter, I could specify a single channel or I could conduct a sweep across all supported spectra.

To switch between modes, I needed to close and restart Analyzer PRO. This means that if I wanted to sweep the local environment to find the channels on which the local access points are transmitting and then conduct a targeted analysis of certain channels, I needed to restart the application between these actions. Nor could I listen in on a roam using two sensors while sweeping with the third.

I'd also avoid connecting or disconnecting adapters from the PC while Analyzer PRO is running, since I experienced a sudden-onset Blue Screen of Death when I tried that.

"When we first developed the multiadapter feature, it was primarily to target two primary feedback scenarios: WLAN client roaming analysis and the ability to focus on three channels without losing frames," said Dilip Advani, AirMagnet's director of product management. "For both of these requirements, we needed to be fixed on the channels, and hence the implementation."

Advani continued, "Technically we are not limited to allowing two (adapters) fixed on a channel, while one is scanning, and [we] will revisit that in the future."

Analyzer PRO 9.0 comes with a new dashboard to highlight network conditions in need of immediate attention, delivering second-by-second updates showing top networks by usage, top talkers, channel utilization and a global count of WiFi security types in use. Users can customize the dashboard with additional charts highlighting the access points experiencing the most security or performance, as well as a few other charts. However, the dashboard contains a maximum of six charts at one time.

Previous versions of Analyzer PRO would instead dump the user into view of all devices detected-a view that can now be found on the new Devices tab. Version 9.0 also makes it more straightforward to filter detected devices as access points, stations or ad hoc connections.

At this time, Analyzer Pro 9 does nothing special to highlight devices connected via WiFi Direct, although AirMagnet officials say they are looking at the new specification in their labs.

Version 9 also improved the connection tests available to wireless administrators, adding new FTP or HTTP performance tests plus the Ping and Trace tools previously available. Version 9 allowed me to create profiles for each of the connections tests-now dubbed One Touch Connection tests-making it easier to spotcheck performance against certain online services without having to recreate the test each time.

Rocket Fuel