Network Troubleshooting: Cable Connections
The cables that connect client computers to the rest of the network are finicky beasts. They can break at a moment’s notice, and “break,” doesn’t necessarily mean “to physically break in two.” Although some broken cables look like someone got to the cable with pruning shears, most cable problems aren’t visible to the naked eye.
Twisted-pair cable: If your network uses twisted-pair cable, you can quickly tell whether the cable connection to the network is good by looking at the back of your computer. Look for a small light located near where the cable plugs in; if this light is glowing steadily, the cable is good.
If the light is dark or it’s flashing intermittently, you have a cable problem (or a problem with the network card or the hub or switch that the other end of the cable is plugged in to).
If the light isn’t glowing steadily, try removing the cable from your computer and reinserting it. This action may cure the weak connection.
Patch cable: Hopefully, your network is wired so that each computer is connected to the network with a short (six feet or so) patch cable. One end of the patch cable plugs into the computer, and the other end plugs into a cable connector mounted on the wall. Try quickly disconnecting and reconnecting the patch cable. If that doesn’t do the trick, try to find a spare patch cable that you can use.
Switches: Switches are prone to having cable problems, too — especially switches that are wired in a “professional manner,” involving a rat’s nest of patch cables. Be careful whenever you enter the lair of the rat’s nest. If you need to replace a patch cable, be very careful when you disconnect the suspected bad cable and reconnect the good cable in its place.