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student information processing board

Working dorm networks are a necessity for most MIT students, with puzzled students coming out of their rooms the instant the network stops working. This week, we discuss the issue of dorm networks.

Question: What services are available in MIT dorms?

Answer: The current service level in most dorms (with a few exceptions) is one port per pillow (that is, per student) at 10Mbps shared.

The current MIT standard for upgrades and new building construction is 2 ports per pillow at 100Mbps and wireless service. Baker, Sidney Pacific, The Warehouse, and Simmons conform to the standard.

Senior House currently has 100Mbps and wireless service, but only one port per student.

Other dorms may have wireless (via dorm provided, or individual student provided access points), but it is not supported by Information Systems.

Question: Why are the dorm networks occasionally hosed?

Answer: As mentioned in the answer to the above question about dorm speeds, the majority of the dorm networks are older shared 10Mbps networks. These networks can easily become congested because there are just too many machines trying to send too much traffic through the network.

The most common reason for traffic congestion on these networks are file sharing programs. Many file sharing programs are quite aggressive about consuming as much bandwidth as they can and these programs also believe that MIT has a very high speed connection so attempt to retrieve files from MIT with a higher priority than from other locations.

Backing up your hard drive from one machine on the network to another using windows file sharing has also been known to really slow down the dorm networks. If you’d like to back up your computer to another machine on the network, if at all possible, hook the machines up to each other directly using a crossover cable. If that’s not possible, then use a more network friendly protocol like ftp or ssh to transfer your files between machines.

Question: How do I configure file-sharing software to not hose the network?

Answer: The best bet for configuring file sharing programs to not hose the network is to turn off uploading. Sharing your MP3 collection with the world (besides a potential violation of copyright) may make you well liked in your file sharing community, but its effect on the network will make your neighbors unhappy -- and your neighbors know where you sleep!

File sharing programs also have a “supernode” option. What this option does is advertises your machine as the source of all files on your subnet, causing more people to try to download files from your machine and increasing traffic on your network. This option is typically enabled by default and should be turned off.

If your file sharing program allows you to rate limit uploading and downloading, you should set rate limits. What rate limit will work best is highly dependent on the amount of traffic on the network at the time, but 384kbps for downloads and 128kbps for uploads is a reasonable place to start. Keep in mind that if you’re on one of the 10Mbps shared networks, the entire rest of your dorm is contending for that 10Mbps of bandwidth.

Question: What upgrades are planned for the future?

Answer: Housing and Information Systems have announced a project to upgrade the network infrastructure in the dormitories. This project is the culmination of nearly one year’s worth of work and planning since the “Resnet Town Meetings” in the Spring 2002 semester.

The town meetings enabled Information Systems and Housing to hear the students’ concerns and begin preliminary plans for an upgrade. Much of the planning took place over the fall semester. Installing new equipment to support 100Mbps and wireless would require new Telecom rooms, as there was simply no way to squeeze additional equipment into the existing spaces. Housing and Information Systems worked together to identify locations for the new rooms. The process to identify and agree upon locations for these new Telecom rooms was long, however it ensured that the interruption to the students would be minimal.

Each student will have four RJ-45 ports. One port will be reserved for analog phone service. Two ports will be activated for MITnet service at 100Mbps. The fourth port will be reserved for future service. Each dorm will be getting Information Systems’ supported 802.11b wireless service, using access points similar to the ones installed in academic buildings around campus.

The upgrades are currently planned to be done in several phases. Phase I, which is expected to kick off before the end of 2003, will include the following dorms: Next House (W71), East Campus (62 & 64), Bexley (W13), New House (W70). The networks in these buildings are currently not maintainable, and as such are a high priority for upgrades. In the interim, Information Systems has been working in the space obtained thus far to provide some incremental upgrades and short-term solutions for these networks. Once Phase I is underway, additional dorms will be identified and necessary space will be found for the next round of upgrades based on the availability of funding.

Question: What are the issues involved with upgrading the dorm networks?

Answer: The primary issue with upgrading dorm networks is space. The current phone closets are inadequate for new equipment to provide higher speed service. They don't have appropriate space for new equipment, nor do they have appropriate cooling for that equipment.

In a dorm, acquiring space may mean taking away student rooms. Information Systems has been working closely with the Department of Housing to obtain adequate space and minimize disruption to students. Finding appropriate space for new telecommunications rooms can be a lengthy process involving much negotiation and compromise.

The upgrade project also requires substantial funding. The Department of Housing is contributing $900,000, and Information Systems is contributing $2.9 million to Phase I of the upgrade project.

To ask us a question, send e-mail to sipb@mit.edu. We’ll try to answer you quickly, and we might address your question in our next column. Copies of each column and pointers to additional information will be posted on our Web site http://www.mit.edu/~asksipb/.