Dartmouth students experiencing network difficulties over the past few weeks may themselves be causing the problem. According to Computing Services, laptop computers running Windows XP that are connected to the Internet through both the wireless and cable networks are crashing residence cluster connections when a "network bridging" feature is enabled.
Bill Brawley, director of user communications at Computing Services, said that the problem begins when a laptop with Windows XP switches between the wireless Internet card and an Ethernet cable connection.
"There are two sort of network interfaces then," Brawley said. "The bridge feature is handy on a home network, but on our network it bridges those two devices and sets up a loop in which packets travel between the networks, sort of a feedback loop. This messes up both networks for the whole building."
Fixing the problem is quite simple, Brawley said, when the user is aware of the difficulty: one simply disengages the network bridging feature. However, with Windows XP it is easy to turn the device on inadvertently, so the culprit computer's owner may not even be aware of what is causing their lack of connection.
"If you download America Online, it gets turned on during the download process," Brawley said. "It also gets turned on if you do a software restoration or run 'network setup wizard.' It turns on by default."
Microsoft was unable to comment about possible glitches with XP and the network bridging feature.
For students who purchased a laptop from Dartmouth, this feature was not enabled, but it can be turned back on if a student does one of the above activities with the computer.
In order to determine if network bridging is enabled and could cause these difficulties, a student should look in the computer's system tray for "active system connection." After clicking on this icon with the right mouse button, network bridging will show up in a pop-up menu. If there is a check next to the word, it is enabled, and one must simply remove the check.
Addressing this problem hinges on student's awareness that their computers could be causing network difficulties, and Brawley said that he is trying to get the word out.
"A lot of it has to do with educating users," Brawley said. "I have a draft notice on my computer and will give it to [the Office of Residential Life] and post it on a web page, maybe post bulletins in dorms."
While some users still don't know of the potential problem, network technicians have had to do guesswork in order to repair the system.
"First, we look for the machine causing the problem, but because it is with laptops, the student has often gone to class," Brawley said.
"Hopefully the owner will be there and we can talk to them, but if we find the computer closed but not turned off, we unplug it and leave a note that asks them to call the help desk."
In the process of restoring cluster's connections, sometimes it is necessary to restart the building network server or wireless access ports, and occasionally one of the networks must be shut down.
"We would rather have one working network than two that don't work," Brawley said. "If we have to take down a network in an area to fix it, we will do that."
Ariel Dowling '05, who lives in the River apartments, said that she had no Internet connection for the first couple of days, and that she has lost connection "a bunch of times" since then.
"With so many courses online, you can't do anything without the Internet," Dowling said.
