Troubleshooting Cables

If one of the problems discussed so far isn't the cause of your networking quandary, the next logical suspect is the cabling that connects the workstations. This section discusses cabling, gives you a few pointers for preventing cable problems, and discusses some common cable kinks that can crop up. Although most large-scale cabling operations are performed by third-party cable installers, home setups are usually do-it-yourself jobs. You can prevent some cable problems and simplify your troubleshooting down the road by taking a few precautions and "ounce of prevention" measures in advance:

• First and foremost, always buy the highest-quality cable you can find (for example, Category 5e or Category 6 or higher for twisted-pair cable). With network cabling, you get what you pay for.
• Good-quality cable will be labeled. You should also add your own labels for things such as the source and destination of the cable.
• To avoid electromagnetic interference, don't run cable near electronic devices, power lines, air conditioners, fluorescent lights, motors, and other electromagnetic sources.
• Try to avoid phone lines because the ringer signal can disrupt network data carried over twisted-pair cable.
• To avoid the cable being stepped on accidentally, don't run it under carpet.
• To avoid people tripping over a cable (and possibly damaging the cable connector, the NIC port, or the person doing the tripping!), avoid high-traffic areas when laying the cable.
• If you plan to run cable outdoors, use conduit or another casing material to prevent moisture damage.
• Don't use excessive force to pull or push a cable into place. Rough handling can cause pinching or even breakage.

If you suspect cabling might be the cause of your network problems, here's a list of a few things to check:

• Watch for electromagnetic interference. If you see garbage on a workstation screen or experience random packet loss or temporarily missing nodes, the problem might be electromagnetic interference. Check your cables to make sure that they are at least 6 to 12 inches from any source of electromagnetic interference.
• Check your connections. Loose connections are a common source of cabling woes. Be sure to check every cable connection associated with the workstation that's experiencing network difficulty, including connections to the network adapter, router, switch, and so on.
• Check the lay of the line. Loops of cable could be generating an electrical field that interferes with network communication. Try not to leave your excess cable lying around in coils or loops.
• Inspect the cable for pinching or breaks. A badly pinched cable can cause a short in the wire, which could lead to intermittent connection problems. Make sure that no part of the cable is pinched, especially if the back of the computer is situated near a wall. A complete lack of connection with the network might mean that the cable's copper core has been severed completely and needs to be replaced.