Users Fill Up the Pipe

Dartmouth College's network -- and its users -- are very similar to the network and users of most ISPs, except that the college users take advantage of all the bandwidth. What's being deployed at Dartmouth know gives us a glimpse of what may be deployed elsewhere in the future.
Posted September 23, 2004

Alex Goldman

Hanover, N.H.-based Dartmouth College is well-known in wireless circles for being one of the first colleges to embrace Wi-Fi technology. Recently, the college went through a network upgrade.

The original network, says Brad Noblet, Dartmouth director of technical services, cost $1.2 million. That covered 200 access points (APs) and the wiring they required. ''Now we want to go to 1,500 APs.''

But that's not all. The original Cisco APs were 802.11b only, and now the college wants to serve 802.11a, b, and g, using Aruba 52 APs.

Of course, the college doesn't sell wireless, so that's not the problem. ''People on the campus love wireless. The challenge is capacity,'' explains Noblet.

These are heavy users. Students do language lab classes from their own room using video over IP, for example, and Noblet admits that heavy use of video on the network presents a real capacity challenge.

''802.11a is good for this, because it provides a lot of bandwidth. Also, it's orthogonal, which is good for a campus with a lot of reflections and interference.'' The problem with 802.11a is that you get a much shorter range out of it. Noblet estimates it provides full rate only if you're within 120 feet of the base station.

So the college is looking at other technologies, too (just as WISPs across the country are experimenting with everything new). ''We're experimenting with mesh technology,'' says Noblet. He feels it's especially useful for a problem some colleges face. When the incoming class is larger than expected, the college builds temporary student housing. If you need to hook up temporary buildings quickly, mesh is a great way to do it.

However, APs in such buildings need to have power. Noblet would love to be able to supply power through microwave, just as other APs get power over Ethernet, but the technology is not yet available.

The toughest problem of a larger network is management. ''The network is open. Visitors can plug in and log on. Authentication does not solve virus problems. We have to authenticate and patch users before they log on.''

For permanent off campus housing, not the temporary structures, Noblet prefers to run fiber above ground along utility poles. ''They have an obligation to allow us to run fiber on the poles, but they're in no hurry,'' he complains. ISPs across the nation know exactly what that's like. In a few cases, Noblet has been forced to turn on DSL circuits while waiting for the fiber paperwork to go through.

Given all of these constraints, it may seem surprising that Noblet is expanding the network at all. But as every service provider is finding, there are more applications for IP every day. It may not be true everywhere that if you build it they will come, but if you're a college and you're offering free, high quality service, you will find that service used to the limit.

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