Bill Gates decided in 1999 that it was time for Microsoft to get serious about wireless LANs . At a public CEO summit, he announced that the software maker would have a wireless network blanketing its Redmond, Wash., campus within 12 months.

That announcement sent the company's Operations and Technology Group scrambling.

Today, there are about 2,500 Cisco Aironet access points  at headquarters and another 1,200 worldwide, making Microsoft's WLAN rollout one of the largest.

But networks of this size are still uncommon, and for good reason: They're a lot of work.

That's the verdict from network professionals who've built them. If you're thinking about rolling out a big WLAN, they say, be prepared for a project that will rival, if not surpass, in complexity and detail any LAN you've built.

Cut corners and you'll end up with a WLAN that could have spotty throughput, gaping security holes and a cumbersome end-user experience. It also could be a nightmare to manage.

Planning is key

If not carefully planned, WLANs become disproportionately more complicated when deployed as an enterprise network compared with a department network. 

Procedures and practices that work fine for 10 access points fall apart when the project is 10 times larger. "That just doesn't scale" is a constant refrain from the network builders interviewed for this story.

Microsoft began to get a grip on scale with its pilot WLAN. During the four-month project that included 600 users in two six-story buildings, the company uncovered several problems, from end-user fears of radio-wave irradiation to potentially huge delays and cost caused by having to run power cables to each access point.

Another problem was network operations and maintenance.

"We found that about [every] 40 access points generated about one service call per day," says Don Berry, senior network engineer of the Operations and Technology Group at Microsoft. "This was not scalable to what we envisioned."

"Working out an end-to-end support model before you begin is very important," he says. That means asking, and answering, questions such as: How will we service the unit, and who will replace it?

Thinking big led the Microsoft engineers to come up with innovative solutions. One was creating, in effect, its own power-over-Ethernet technology, before any commercial implementations were available. That saved $600,000 and shortened the install cycle by eight weeks, Berry says.

But more importantly, it lets network managers switch power on and off remotely, causing a reboot or reset of the access point without having to send a technician to the device.

At the same time, Microsoft linked each access point console port to a terminal server in a cable room. "We now have remote access to all console ports," Berry says. That means that a local building facilities technician, instead of a network administrator from the data center, can install or replace an access point. "Then, the standard access-point configuration is brought up remotely from our operations center," he says.