Carrier WiFi

AirFlow's Second Coming

Wireless LAN switchmaker AirFlow Networks has today made available a system that it claims will remove the need for any kind of site survey because its switch and access points buck all the interference problems normally associated with 802.11 technology.

Eagle-eyed regular readers will remember that AirFlow originally unveiled its wireless LAN switch strategy back in January (see AirFlow's WLAN Switch Packs a Big MAC). Nine months later and the company's new CEO, Bob Machlin, says that the firm is finally ready to start shipping the AirFlow switch and tiny little access points [ed. note: aw, how cute!].

On the face of it, the AirFlow offering looks similar to those of Airespace Inc., Aruba Wireless Networks , Trapeze Networks Inc., and others.

AirFlow is offering the AirSwitch 1200, a wireless LAN switch that sits in the wiring closet and can also handle wired switching functions; and the AirServer 500, a WLAN appliance that offers the same functionality as the AirSwitch but works with a customer's existing switch infrastructure. These boxes can get hooked up to the firm's handheld-computer-sized 802.11b (11-Mbit/s over 2.4GHz) access point (AirHub) via Ethernet cable and enable network administrators to handle the usual gamut of management and security tasks.

Where AirFlow's technology differs from its rivals' is in the way the company has completely stripped away the media access control (MAC) layer from AirHub access points and centralized it in the management box. The MAC address of an access point is its network ID tag, so even the new breed of "skinny" access points maintain some thin layer of MAC functionality.

However, as far as the AirFlow system is concerned, a distributed network of APs actually looks like one big access point. This, says Machlin, is why the AirFlow access points can be placed very close together without causing radio channel interference -- as far as the system is concerned, they are all part of the same three-channel 802.11b system.

Removing the MAC address has required AirFlow to come up with a new way to shuttle data to users using the right access point. Once the AirFlow system has associated (made an initial connection) with a user, the system takes a reading of the radio signal strength emanating from the wireless LAN client and uses that measurement to decide which access point is closest to the user.

Machlin says there are two major benefits to the AirFlow system. The first being that new access points can be plugged in and up and running in five seconds.

"All you need is your receptionist to plug it in," he says.

The system will also enable users to dedicate different channels to different types of traffic, according to Machlin. For instance, an administrator can set up a system so that only voice-over-WLAN traffic is run on one channel, video on another, and data on a third.

Meta Group Inc. analyst Chris Kozup says that he finds the AirFlow technology "very interesting" but thinks that there are still some unanswered questions about the company's methodology. If a company has set up a segregated voice/video/data-channel approach, Kozup wonders what happens if a data-oriented device tries to associate with the wrong channel.

"It does seem to defy some of the ingrained laws of cross-channel interference," he says, "but without testing the system, it's hard for me to really say for sure." We'll keep you posted with more on this as we talk to actual real-life customers.

— Dan Jones, Senior Editor, Unstrung

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