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Sunday, June 27, 2010

Ethernet Cable: Color-Code Standards

The information listed here is to assist Network Administrators in the color coding of Ethernet cables. Please be aware that modifying Ethernet cables improperly may cause loss of network connectivity.

Straight-Through Ethernet Cable


Crossover Ethernet Cable

Ethernet Cable Instructions:
  1. Pull the cable off the reel to the desired length and cut. If you are pulling cables through holes, its easier to attach the RJ-45 plugs after the cable is pulled. The total length of wire segments between a PC and a hub or between two PC's cannot exceed 100 Meters (328 feet) for 100BASE-TX and 300 Meters for 10BASE-T.
  2. Start on one end and strip the cable jacket off (about 1") using a stripper or a knife. Be extra careful not to nick the wires, otherwise you will need to start over.
  3. Spread, untwist the pairs, and arrange the wires in the order of the desired cable end. Flatten the end between your thumb and forefinger. Trim the ends of the wires so they are even with one another, leaving only 1/2" in wire length. If it is longer than 1/2" it will be out-of-spec and susceptible to crosstalk. Flatten and insure there are no spaces between wires.
  4. Hold the RJ-45 plug with the clip facing down or away from you. Push the wires firmly into the plug. Inspect each wire is flat even at the front of the plug. Check the order of the wires. Double check again. Check that the jacket is fitted right against the stop of the plug. Carefully hold the wire and firmly crimp the RJ-45 with the crimper.
  5. Check the color orientation, check that the crimped connection is not about to come apart, and check to see if the wires are flat against the front of the plug. If even one of these are incorrect, you will have to start over. Test the Ethernet cable.

Ethernet Cable Tips:
  • A straight-thru cable has identical ends.
  • A crossover cable has different ends.
  • A straight-thru is used as a patch cord in Ethernet connections.
  • A crossover is used to connect two Ethernet devices without a hub or for connecting two hubs.
  • A crossover has one end with the Orange set of wires switched with the Green set.
  • Odd numbered pins are always striped, even numbered pins are always solid colored.
  • Looking at the RJ-45 with the clip facing away from you, Brown is always on the right, and pin 1 is on the left.
  • No more than 1/2" of the Ethernet cable should be untwisted otherwise it will be susceptible to crosstalk.
  • Do not deform, do not bend, do not stretch, do not staple, do not run parallel with power cables, and do not run Ethernet cables near noise inducing components.

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