How to Diagnose Network Issues

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Basic Troubleshooting

So, your computer seems fine, but your "Tetris Online" game won't open. Perhaps you don't have a network connection. Here's a couple of things you can do to help determine the nature of the problem. First, open a web browser, like Firefox, Netscape, Safari, or Internet Explorer. Try something basic, like

Don't see anything? Get a "Server not found" or "The page cannot be displayed" error message? Look to see if you have a network link signal. Many systems will show a green "link light" nearby the network connector on the back or side of your computer. MacBook users will have to check the Network Page in System Preferences ("Show Network Status") to see if your connection is active or if the machine thinks the "cable is unplugged." Windows XP can also give you an indication if the cable is unplugged or not, try opening the Network Connections Control Panel to see what's there. Make sure no connections are marked as "Disabled," if so, you can change that setting right there in System Preferences or the Control Panel.

Wireless trouble? Try connecting to the ObieWiFi network again. If no networks are listed, try disabling your wireless interface and re-enabling it again. Some laptops have a physical switch to do this, the rest of us will use the Network Preferences or control panel. Our wireless covers most of the campus pretty well, but you might have found one of the few remaining spots where the signal is too weak. Try testing things in a different location.

Network cable unplugged? Try unplugging and reconnecting each end of the cable, at your computer and at the wall. If that doesn't fix the problem, the next step is to disconnect your cable and your roommate's cable at the wall jacks and swap them. If your problem is fixed, and your roommate now has the problem, then it's clear the problem is ours. Please use the working computer to send an email to our Help Desk or call us at 58197. We'll need to know your residence hall and room number, as well as the number or letters describing the wall jack which isn't working.

What, you weren't successful in sending the problem to your roommate? If it's convenient, try swapping cables with your roommate. Network cables have eight tiny wires in them, and after some weeks of having bunks set on them and being generally twisted up and stepped on, some of those wires can break. Looks are deceiving, a bad cable doesn't have to be the nastiest looking one in the room. New Ethernet cables can be obtained at the Computer Store in Mudd A-Level.

Okay, if you're still with me, you appear to have a problem with your computer or specifically with our network and your computer. You'll need to call for help.

Information we would like to know

  • We need to know how to find you: Residence Hall, room number, phone number and/or email, please.
  • We need to know the problem symptoms, and the results of the tests you've performed already, including the ones above.
  • It's really helpful to know the IP address and MAC address of the computer, if you can get them.
    • In Windows, the command line is quickest
      • Click Start, select Run, type in "cmd" and click OK.
      • In the (usually black) window, please type "ipconfig /all" and press the Enter key
      • Lots of information comes back. Please send the text from every "Physical Address" and "IP Address" line you see.
    • In Macintosh, use the Network panel in System Preferences. Show each interface in turn (probably Built-in Ethernet and AirPort), and click on the TCP/IP button for the IP Address, and the Ethernet button for the Ethernet ID.
  • Finally, please tell us when it's convenient or best for us to reach you. Someone will be in touch with you promptly.

Testing Your Connection

If you have a network connection, but it seems to be amazingly sluggish, you may still have a problem with your computer and not with the network. To help us determine the location of network slowdowns, we've located several Network Diagnostic Tools around the campus network. You can run a connection test with any of these servers:

Network Diagnostic Tools around campus
South Firelands Language Houses
Campus Mudd Central Peters Hall Severance Hall
North Burton
Between us and the World
On our router At our edge In Columbus, our ISP
On Abilene, the Internet 2 Network
Indianapolis New York Seattle
Sunnyvale, CA | Washington, DC
Other available servers
Argonne National Lab U of Michigan, Flint UC Santa Cruz
Stanford NSF, Arlington, VA Jefferson Accelerator Lab
Swiss Education Network | U of Hawaii


For a rough indicator of off-campus performance, many of us consult the bandwidth speedometer at Speakeasy. Mostly we choose the Chicago server, for comparison. You'll need the Flash plug-in for your browser for this test to display properly.