In searching for alternatives for building-to-building or campus-to-campus connectivity, companies with much smaller IT budgets may wonder whether an 802.11b exterior WLAN is a viable alternative. Why not use £50 Linksys APs from Dabs - or wherever - to link two buildings?

This approach is certainly used in many "quick-'n'-dirty" situations, although a low cost is its only significant selling point, especially when you take the long-term view. Otherwise it has numerous limitations, some of which became readily apparent in our tests on the University of Hawaii campus.

What we tried...
We set up four Linksys WAP11 APs across distances of 50m to 100m. We then ran some temporary streaming video solutions across the connection.

One of the challenges of an exterior WLAN is that 802.11b is based on RF, and RF has problems with obstacles such as trees and buildings. That's what necessitated the number of APs we had to deploy across what amounted to only a 225m link (as the Hawaiian crow flies).

Additionally, we faced competition with all the other 802.11b traffic flitting across the campus. Most IT managers in urban areas will face similar interference. For our longest link in the chain, we had to turn off an antenna on our WAP11 AP, replace it with a third-party Yagi long-gain antenna, and then match that to a duplicate setup across the quad. As an additional measure to avoid interference, we configured the AP so it would link to only a particular MAC (media access control) address.

Problems from interference
From there, our $300 rig ran all right for a few hours, but we soon found that it suffered other problems.

  • For one, when a student decided to use his 2.4GHz cordless dorm room phone, our link dropped like a hot rock. That's the downside of 802.11b: It runs in the same frequency range as a wide variety of household electronics.

  • Additionally, we had to house both APs indoors, as the retailer we bought from didn't carry one designed for outdoor use. (You can find outdoor-oriented APs, but you'll lose that attractively low price.)

  • And finally, the range here was limited only to a few hundred feet. Any more than that and you're setting up a long chain of these things, which is unduly burdensome.

Don't forget the support issue
Range, weather, and environment as described above are the obvious concerns when considering the WLAN route. But there are ancillary issues IT managers must keep in mind.

One of them is support: When the leased line dies, you can blame your provider. But when any wholly owned wireless infrastructure pops a red link light, you need not only a reporting mechanism but also the capacity for a fast response time. This is especially challenging in multi-mile links where distance may be a factor. And that's leaving out other 802.11b trouble spots, such as integration into a WLAN management system and, of course, security. VPN management, anyone?

Additionally, none of the inexpensive AP manufacturers designed their units for this type of use, and that will affect how much assistance you'll get when you call their tech support.

Although you might get a green link light for less than $300 (or £200) in hardware costs, you'll pay the differences between this type of product and the more expensive, dedicated bridging products with a stack of human-hours consumed by deployment, management, testing, security, and long-term maintenance. After all, you get what you pay for.