Everything You Need To Know About Wireless LAN

Set up properly, wireless networks based on the IEEE 802.11b standard, also known as Wi-Fi, created by the Institute of Electrical and Electronics Engineers, offer enough fast, reliable and secure connectivity to bring the Internet unimposingly and cheaply into any classroom. As such, wireless LANs get raves from coast to coast.

“It was a great move when we moved to a wireless world,” says Chuck Phillips, interim administrator for technology at the Clovis Unified School District in California. The district saved hundreds of thousands of dollars and improved instruction with wireless LANs in its eight secondary schools. Meanwhile, in Virginia’s Henrico County Public Schools, educators beam about flexibility of the Wi-Fi LANs.

“It really is amazing going to a classroom and seeing how it can be reconfigured on an hourly basis because it is wireless. Straight rows one time, then students in groups of three or four,” says Mike Smith, director of technology and information services at Henrico.

The combination of cost savings from not having to install cables and improved instruction drove one of the biggest K-12 rollouts of wireless LANs in the country. New York City’s Department of Education began rolling out wireless networks last year. By the beginning of the 2003-2004 school year, 550 schools will have networks based on Cisco wireless LAN hardware. Given further funding, the Education Department wants to implement the technology in 1,291 of its schools, says network architect Tony Biongiorno.

“When people see it, everybody wants it,” Biongiorno says. “The feedback we have gotten from the teachers is that it is phenomenal.”

While some districts have taken to wireless, others are still evaluating the technology. Take the fast-growing, 7,500-student Olentangy Local School District, for example. Located near Columbus, Ohio, Olentangy hopes to give teachers mobility if the district installs a wireless LAN.

“It allows you to integrate technology into the instruction in a way that is appropriate, rather than as an add-on,” says Keith Pomeroy, instructional technology supervisor for Olentangy. As a teacher in the nearby Hilliard City School district, Pomeroy rewired his classroom’s network several years ago, so that his fourth-graders could comfortably work in groups. The room’s four PCs were initially installed in a cramped corner. With a wireless LAN, they could easily have been moved anywhere in the room.

How To Do It Right

If Olentangy indeed goes the wireless route, it will find a lot of great advice out there from school IT staff who exploited the power of wireless LANs by shrewdly overcoming their liabilities. They made them reliable by maximizing coverage while minimizing interference. They made them fast enough by accounting for user load and made them secure by keeping them separate from networks with sensitive data.

When Smith and his staff in Henrico installed their wireless networks last year for more than 25,000 users, they started with a solid plan. Smith mounts each access point—the main transmitter—near the ceiling so it can cover the whole classroom with minimal power. In many rooms, Henrico uses Cisco access points with variable power settings, which give them adjustable range. Keeping the power low prevents the access points from interfering with each other.

Smith’s team further managed interference by pulling out a blueprint of each school and mapping out which of the available channels each access point would use. Although access points using 802.11b technology—the most popular standard—operate with 11 channels, consecutive channels often interfere. Smith’s team came up with channel arrangements of 1, 4, 7 and 11 to minimize overlap.

New York battled interference by doing detailed surveys that looked not only at power settings and access point placement, but also optimal antenna types. The city’s Cisco 350 routers accept a variety of antennas. After a pilot test in December 2001 at a Queens junior-high school, the city learned which antennas best cover a classroom without bleeding over into neighboring rooms.

With 5 to 6Mbps of throughput, the access points support more than 30 users each, Smith says, but the fewer that use an access point the better. Like Henrico, New York City designs its LANs so about 25 to 30 students can use each access point. Both districts put one access point in each classroom.

Covering the classroom is only half the battle in managing user loads, however. Because campuswide wireless networks bring the Internet to classrooms (and even cafeterias) that never had access before, they can inspire a surge in usage. Districts should prepare to meet the resulting growth in bandwidth needs. During some weeks of the rollout, 1,000 new users came online in New York City, and the city is now upgrading high schools from T1 lines to much faster lines. Henrico County also upgraded its lines to accommodate the surge in usage.

If Not Secure, Then Separate

IT directors universally acknowledge that wireless networks are inherently less secure than wired ones. It is just too easy to invade their coverage area. As Phillips notes, “We have sensitive equipment behind a firewall, but that doesn’t block traffic from the inside. With a wireless world, you open yourself up to the inside being everywhere.” Clovis is rolling out security software, called Cisco LEAP (Light Extensible Authentication Protocol). LEAP discerns teachers from students, blocking the kids from sensitive administrative networks. It essentially acts like a hall monitor, allowing only those with privileges to pass between two wireless networks.

Other schools simply keep their administrative networks out of the wireless world entirely. Rather than hoping to secure their wireless networks, even with passwords and encryption, they confine their use to classroom contexts where data security is relatively unimportant. In Henrico, Smith says, “Teachers cannot even do their grades wirelessly. They must plug in to take attendance.” All of New York City’s administrative servers are similarly on a separate wired network.

In security, speed and reliability, wireless networks have their limits, but that is not what IT directors who have implemented them tend to talk about. They seemingly can’t help but talk about the effect wireless has in the classroom, and that is something worth considering. “I wish we had this when I was teaching,” says Olentangy’s Pomeroy. .