Wireless Networking | Feature
From Zero to Wireless in 4 Essential Steps
A mobile learning effort requires a speedy and stable wireless network. That means making sure to meet a few imperatives.
- By Dian Schaffhauser
Setting up a wireless network is easy enough. Place a few access points in strategic areas, then watch the network traffic fly! Right?
Matt Federoff, CIO of Vail School District, southeast of Tucson, AZ, has a name for that type of network, and it's not a nice one: Starbucks wireless. "That's what you get when the IT guy goes down to Best Buy and buys a bunch of D-Link stuff and installs it," Federoff says.
That approach may hold up reasonably well for a few dozen users, but there's no way it would support a schoolwide 1-to-1 program. Once students take to it with their wireless devices, "they're going to kill it," says Federoff, who has brought wireless access to three of his district's schools. As a result, network stability takes a hit, teachers stop trusting the network altogether, and out the window goes any hope for a mobile learning initiative.
At Birdville Independent School Districtnear Fort Worth, TX, Jonathan Abrams, the district's network engineer, says a temperamental network "used to keep people up at night, wondering if they were going to have an internet connection when they came in the next day." Sixty percent of help-desk service tickets were network related. Even the wired infrastructure wouldn't support streaming video.
That's all ancient history now, six years later, since the district undertook an upgrade of its network and wireless infrastructure.
As Federoff and Abrams can say with authority, the way to building a wireless network that's reliable, scalable, and secure enough to support a robust mobile-learning initiative demands taking care of four imperative steps.
1) Get Physical
Vail's Federoff says planning for a solid wireless infrastructure begins with the wired network, preferably the cost-effective Ethernet. "There's no substitute for that," he says. That's not as obvious to everyone as it would figure to be: Recently, Federoff says received a visit from an IT director who needed help convincing his administration that the presence of wireless access to the internet doesn't do away with the need for the physical network, too.
All those access points have to get plugged in somewhere, Federoff points out, and that requires a physical infrastructure. The good news is that it's a relative bargain. As an example, a wireless implementation at one of Vail's high schools cost about $100,000; a mere tenth of that went to the wired components. "It's so inexpensive," Federoff says, "but you'll use it again and again, for 10 to 15 years."
2) Separate and Unequal
Vail offers campuswide wireless at a trio of schools. Empire High hands out Linux-based netbooks to its students; Cienega High and the K-12 Vail Academy and High School have mobile carts and support bring-your-own-device programs. In both environments, the key, Federoff insists, is the district's ability to set up separate networks. Behind the scenes, access points capable of broadcasting multiple service set identifiers (SSIDs -- the public names for wireless networks) allow for multiple local area networks (LANs) to coexist, each mapped to a different subnet. This allows the network administrator to segment wireless traffic. Staff and teachers, for example, go to a different range of IP addresses than students, granting them a greater range of web surfing options.
"I am still amazed at how many places I go that have one wireless network -- one SSID -- and all the kids and adults are on that same SSID," Federoff says.
That network granularity works hand in hand with web filtering. At Vail, each wireless network has its own set of filtering rules. "Teachers have more freedom than the kids, and some kids have more freedom than other kids," Federoff says, explaining that students who have abused the network have limitations imposed on them.
Vail Academy and High School has established separate wireless networks for high schoolers at one end of the building using their own computers, and K-8 students at the other end working on devices from mobile carts. "They exist side by side, but they have different filtering rules," Federoff says.
3) Mind Your APs
Access points can be problematic. Put them in the wrong spots or use a lower grade of hardware, and some users will get bounced off or never connect to the internet at all. Put in too many of the wrong kind, and managing them can become a headache. Vail uses equipment from Cisco Systems throughout. Federoff "highly recommends" paying, as he did, to have a site survey done to calculate the optimal locations for your chosen APs.
"A good rule of thumb is one AP per learning area -- anywhere 30 or 40 kids are going to land," he says. If an access point fails, the controller that manages the APs within each school automatically detects that it's dead and shifts the traffic to another one.
Birdville ISD is also a Cisco user. Abrams has migrated the district's AP placement strategy from a coverage model, meant to serve a large geographic area, to a density model, aimed at supporting more users. That required a hardware upgrade to Cisco Aironet 802.11n APs, which Abrams manages through Cisco wireless LAN controllers. The changeover also brought greater AP saturation across campus. The result: coverage in the classroom that could support up to two devices per student.
"A good rule of thumb is one AP per learning area -- anywhere 30 or 40 kids are going to land."
-- Matt Federoff, Vail School District (AZ)
Abrams says he has the system set up so that he gets notified when an access point reaches a certain number of clients. "Right now that threshold is set to 30," he says.
Although Federoff says he'd run 802.11n gear in any new school construction, he doesn't see a need to upgrade to the latest and greatest to run an effective wireless network. In fact, his district has equipment supporting 802.11a, b, and g. "Empire [High] has b/g -- as does Cienega -- and we've had zero problems with wireless bandwidth to the client laptops."
Federoff is sold on Cisco's wireless gear, but for his next installation he may consider hardware from Aerohive Networks. "The weak link is the controller itself, which is very expensive and a single point of failure," Federoff says. "If that dies, we're done."
With the Cisco controllers he bought, the licensing can't be expanded. "You buy the 50-station or 100-station controller and that's what you've got. If you didn't buy big enough, you have to throw that one away and buy another." And the cost of that? "As much as a full-time first-year teacher: $40,000."
Aerohive uses a controller-less model. Instead, the access points communicate with each other in a "hive" structure.
4) Speed It Up
"Get as much as you can get and as much as you can afford," Federoff advises any of his district IT peers who are considering their bandwidth options. "I've never heard someone complain about too much bandwidth."
Vail's 60 Mbps internet speed is delivered by Cox Communications. The district's internal network uses fiber and wireless point-to-point links running 30 to 100 Mbps. Within each site, Cisco network switches run Fast Ethernet and gigabit Ethernet. "We're 'oversubscribed' for our total bandwidth," Federoff says, "but as most of our instructional resources are inside our network, this isn't as much of an issue as it may seem."
Oversubscription is true for Birdville, too. The district has two incoming 100 Mbps internet connections -- one supplied by its education consortium, Education Service Center Region XI, and the other by Cogent Communications. The Cogent internet connection was added for extra bandwidth as well as for redundancy. "It's not that expensive and it's totally worth it," says Julie Wallace, executive director of technology and information management services.
Region XI streams educational content from such resources as Discovery Education, which the Birdville schools can access through the internal wide area network (WAN). "We have a full gigabit connection to Region XI," Abrams says. "We spike up around 650 Mbps, so the fact we're paying for 100 Mbps through [the consortium] and we're able to access more than 700 Mbps almost makes it an in-house resource for us."
Abrams says the district has reached its goal of a gigabit to the desktop; it plans to upgrade to a 20 Gbps WAN. "We plan on rolling out multicast IP video to every desktop in the district within the next six months. We want to accommodate that video and not squeeze our [other] traffic."
Ultimately, Federoff says, a wireless implementation is a back-to-basics effort. "Every IT guy in the country has all the pieces. He just [needs to] put them together in a way that makes his life easier and gets the lift out of his gear."