We've written in the past about the feature in Apple's AirPort Extreme Base Station that allows you to connect several base stations together wirelessly to form a larger network (see "AirPort Extreme: In the Key of G" in TidBITS-663). This cool feature goes by the name Wireless Distribution System (WDS), and it's actually a semi-standard specification also found in devices made by manufacturers other than Apple. But Apple and other companies have told us that they are neither focusing on compatibility nor formally testing equipment from other makers. So we decided to try it ourselves.
Buffalo Technology was kind enough to loan me a few of their WLA-G54 802.11g access points to test their version of WDS for the book Adam and I are working on right now, The Wireless Networking Starter Kit, 2nd Edition. I found that Buffalo's WLA-G54s easily attached themselves as "remote" nodes of an AirPort Extreme Base Station network. I opened the AirPort Admin Utility and connected to the AirPort Extreme Base Station in my office. I clicked Show All Settings, selected the WDS tab, and enabled the AirPort Extreme Base Station as a WDS. I then clicked the plus sign to specify the base stations to use as remotes and relays. Amazingly, the AirPort Admin Utility presented the Buffalo WLA-G54 for me to select as a remote. I hadn't yet configured the Buffalo access point - I had just turned it on. But the AirPort Admin Utility lists all of the access points that the AirPort Extreme Base Station can see. (Had that not happened, I could have manually entered the MAC addresses of the WLA-G54s in AirPort Admin Utility.)
The Buffalo WLA-G54 is a pure wireless access point without any gateway features, like assigning IP addresses via DHCP. That's fine, since I'd have to turn off those features in a distributed network anyway. So what's the utility of the Buffalo WLA-G54 for Mac users? Cost: although AirPort Extreme Base Stations start at a reasonable $200, you can find the WLA-G54 for as low as $100, making it a cheaper way of extending your Wi-Fi network.
Keep in mind that using WDS does impact performance for the entire network, since each remote must receive every packet and retransmit them wirelessly with a single radio. That's probably not a huge problem with the 25 Mbps of real-world throughout that 802.11g is capable of in most situations, but you should be aware of it. If you need the fastest performance, stick with creating a roaming network by connecting multiple access points via 100 Mbps wired Ethernet and setting them to use different channels but the same network name. If you're interested in learning more about the nitty gritty of WDS, I've written a more technical article on the subject that appeared last week on O'Reilly Networks.
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