New tools tame Napster traffic

Traffic shapers offer relief from new 'Net apps.

By Carolyn Duffy Marsan
Network World, 06/05/00

New traffic-shaping devices promise to prevent Napster and similar bandwidth hogs from overwhelming campus and corporate networks, an advancement early adopters say will loosen bans on these increasingly popular Internet applications.

Among the colleges recently lifting restrictions to Napster are Plattsburgh State University, Buffalo State College, Williams College, College of St. Benedict and St. John's University, which have all purchased network traffic shapers to classify and control Napster and other network applications. Napster lets users share digital music files over the Internet.

The experience colleges have had taming Napster offers an important lesson to corporate network managers facing similar threats from other bandwidth-intensive applications such as Gnutella, iMesh, Freenet and CuteMX. All these applications let users swap large files including music, images and software over the Internet, creating heavy, bursty traffic patterns on LANs and Internet connections.

"This Napster class of applications can be bandwidth-intensive for small periods of time," explains John McConnell, a Boulder, Colo., consultant specializing in network bandwidth management. "From a network administrator's point of view, you don't know when loads are coming, how long they will last and what the demand is going to be. . . . If you allow these applications to have uncontrolled access and utilization, you can start starving out your business processes."

That's what happened to Plattsburgh State University, which began blocking Napster last November after the application saturated its outbound Internet bandwidth. Located in upstate New York, the university has two T-1 lines that provide Internet access to dormitory and administrative networks.

Network manager Hap Wheeler recently purchased two Packeteer PacketShapers for about $10,000 each to control the amount of bandwidth Napster can consume on each network. Wheeler plans to unblock Napster in the fall for the 2,600 students who live on campus.

"What the Packeteer device allows me to do is automatically classify applications . . . to get a list of incoming and outgoing traffic so I can set priorities," Wheeler explains.

Wheeler used PacketShaper to place the highest priority on traffic from the university's online research applications. Below that he rated HTTP traffic for general Web surfing and AOL traffic for e-mail services. Further down were incoming file transfers. The lowest priority was given to bandwidth-intensive file-sharing applications such as Napster, iMesh, CuteMX and Gnutella.

Setting up the PacketShaper was easy, Wheeler says. You just point and click using a Web-based interface to first monitor all network traffic and then set up classifications.

"I didn't think of getting a bandwidth management device before Napster," Wheeler says. "With applications like Napster, you can't solve the problem by throwing bandwidth at it" because users will keep consuming all the available bandwidth.

Napster is already accessible again at the College of St. Benedict and at St. John's University, both in St. Cloud, Minn. The two colleges share a computer network with two T-1 lines for Internet access and a total of 4,000 users. John Muggli, who manages the network, tried to block Napster at the firewall but was only partially successful because Napster traffic reroutes itself to get to its destination. So this spring he bought a PacketShaper to limit the bandwidth available to Napster.

"When Napster started getting popular, the librarians started complaining," Muggli says. "They run all of their applications over the Web. Their card catalog system is off-site, so they couldn't do their work."

Muggli used the PacketShaper to limit Napster to one-tenth of the network's overall bandwidth, or a few hundred kilobytes per second. He also created a "suspicious" class of traffic that includes other file-sharing applications and limited their bandwidth.

"It's been working fairly well," Muggli says. "The students were happy to still be able to access Napster although it is slow. They just turn it on in the morning, set it up to download a file, go to class and whatever they are targeting is there when they get back to the dorm."

Students at the two colleges should see Napster speed up in the fall, as Muggli plans to add two more T-1s to the campus network. "We were planning on upgrading our lines this summer anyway, but I think the PacketShaper will help us control the bandwidth," Muggli says. "Without something like this, we could buy more and more T-1s, and they'd just keep filling up."

Some colleges are continuing to block Napster because of copyright concerns but are using traffic shapers to control other bandwidth-intensive multimedia applications. For example, Texas Christian University installed an Allot Communications Net Enforcer between the firewall and router on its network, which has four T-1 lines and supports 5,000 students, faculty and staff.

Senior network engineer Jim Mayne says he bought the $12,000 Allot device in the spring, when the university discovered that 60% to 70% of its traffic was related to MP3 music files. He used the device to give the highest priority to faculty, staff and laboratory traffic, granting these users a guaranteed minimum bandwidth. He set e-mail, telnet and news traffic as the next priority down. To the dormitory Web traffic, he assigned the lowest priority and set bandwidth at 128K bit/sec.

"Napster is currently blocked, and it will stay that way," Mayne says. "We blocked it originally because of the need to gain our bandwidth back, but we'll continue to block it until there's some clear position about its legality."

This summer Mayne is increasing his Internet connection to handle up to 12M bit/sec, almost double the current bandwidth. He says the extra bandwidth plus the Allot traffic shaper put him in a good position to manage Gnutella, iMesh and other multimedia applications next fall.

"These new applications create a distributed computing environment across the globe," Mayne says. "It's going to be tremendous in terms of its possibilities, but it's going to be a real headache for people trying to maintain their network properties."