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The wireless LAN unquestionably has proven itself for warehouses, airports - any place where the floor covering is cement, tile, vinyl, even dirt. So far WLAN has not been a big go-to technology for carpeted offices. But this is changing as network executives discover the value of WLANs in places such as boardrooms and waiting rooms - areas that play host to visitors and shifting arrays of devices.

This small step onto the carpet has been followed by a leap into marketing-driven fantasy: Most office workers already use laptops and PDAs with embedded WLAN adapters. WLANs are becoming super-speedy. The next logical step is making wireless the only LAN connection inside the office and out. Or, in the words of a Cisco Aironet white paper on total cost of ownership, "It is shortsighted to consider wireless as a small, pilot trial without considering the scalability and the TCO benefits across multiple organisations and buildings."

Certainly, a few corporations have discovered the truth in that. After a fast-food giant held a small WLAN trial about five years ago, it rolled out a production network that became wildly popular. Today wireless is the only connection most employees want to use, noted Gary Tomanich, a senior network analyst for the fast-food chain in a recent Network World article.

A frayed fabric For most enterprises, however, WLAN technology is not hardy enough to rival wired Ethernet. For starters, 802.11 implementations are based on shared Ethernet, which requires carrier-sense multiple access with collision detection - a step back from the collision isolation afforded by the wired world's switched networks, users say. Plus, 802.11b/g "accommodates the client with the weakest signal and throughput connection" by sharing the Ethernet at the slowest rate of connection, says Mike Sinno, director of IT infrastructure at Cooper University Hospital in Mount Laurel, N.J. He oversees an 802.11a WLAN comprising 210 Cisco access points and a traditional Ethernet network with a gigabit backbone. Configuring WLANs to allow only higher-speed connections could reduce the coverage area of a network's access points, which means more of them will be needed.

If employees use the LAN only for light applications, such as e-mail or Web surfing, 802.11b/g - and 802.11a - could be fine. If they use latency-sensitive applications or consume bandwidth like potato chips, network executives are going to want to stick with the wires. Bandwidth-hungry medical digital images are a prime example; they're one reason that Sinno says he isn't yanking out the LAN, even though the hospital uses 802.11a.

Spectrum saturation Even if users go easy on the bandwidth, other technical issues arise as the popularity of wireless grows, says George West, senior analyst at research firm West Technology Research Solutions. He's skeptical that WLANs will become the de facto LAN in the carpeted enterprise, at least over the next few generations of WLAN technology. "What's not really been addressed is the issue of spectrum saturation," he says. If every PC in an enterprise is on a WLAN, as are Wi-Fi phones and other devices, the network will need to support voice and video. This will saturate the WLAN and kill performance, he says.

In this imaginary future, the response would be to bolster the network with compression and other "cooperative, sharing technologies," West says. "If you have to add management services to make it work, that's an inhibitor to the enterprise." It also kills that TCO Cisco wants you to examine.

Still, believers in the carpeted enterprise make convincing counterarguments. Craig Mathias, principal at the Farpoint Group, says those who question shared LAN links should remember that all Ethernet is a shared medium at some point. As for forcing everyone onto the slowest-speed link, he says, "Don't mix 802.11b and g on the same channel. That's just foolish." Plus, he notes, "11a performs well enough for full-fledged enterprise use." He predicts the carpeted enterprise will be the norm within two years. "I've been doing wireless for 15 years and haven't seen any reason why wireless won't become the default LAN for the enterprise," he says.

The right fabric for Vo-Fi I'm not so sure. While some of the fantasy likely will materialise, I can't see most enterprises yanking out functional, high-speed LANs, only to struggle up a steep learning curve for wireless.

By 2010, Wi-Fi-enabled phone shipments will hit 22 million worldwide, compared with an estimated 1.8 million this year, West's research shows. Untethering the office phone makes sense in all kinds of situations. Cooper University Hospital is upgrading its WLAN to enable Vo-Fi for nurses, Sinno says. And, sauntering into fantasyland once more, look at the possibilities with Wi-Fi-equipped cell phones - transferring calls from the public network to the free WLAN when they enter WLAN range. Now that's an application that won't pull the rug out from under you.