How to make a straight through Ethernet cable


The ability to make a straight through Ethernet cable can come in handy, whether you need to create a specific Ethernet cable or you need to fix an existing one. You can save money by making your own Ethernet cables in the exact lengths necessitated by your network. With some practice and following the standards laid out by the EIA-TIA, your cables will work nicely and be of a professional quality. In the lab below, I outline the materials and steps necessary in creating a straight through Ethernet cable.

What you will need:

  1. Cat5e Ethernet cable – I recommend purchasing a box of Cat5e cable. You will save money by purchasing your cable in bulk.
  2. RJ-45 connectors
  3. Crimper Tool – capable of crimping 8 wire (RJ-45) and 6 wire (RJ-11). Most tools have built in cutters too.
  4. Stripper Tool
  5. Scissors – I prefer using a scissors
  6. Cable Tester – For testing that your cable connections are good and there are not any open or crossed wires
a scissors, a crimping tool, and a stripping tool

cable testers

 Cat5E Ethernet cable and RJ-45 connectors

Steps to make a straight through Ethernet cable:
  1. Cut a piece of cable to the length you will need. Give a little extra to make room for mistakes.
  2. Strip a half inch to an inch of the outer jacket away from the cable. If you use strippers make sure not to nick the wire pairs and expose the copper, this could introduce crosstalk onto your wires. I prefer to use a scissor and my fingers to tear away the jacket. Then I cut with the scissors to clean up the edge.
  3. Now you need to untwist the wire pairs (not too much, only undo one or two twists) so you can align them according to the EIA-TIA568B wire color sequence. I use my fingers to straighten the wires by bending them back and forth, straightening them as they warm up.

    EIA-TIA 568B Standard

    1 2 3 4 5 6 7 8
    white/orange orange white/green blue white/blue green white/brown brown
  4. I usually have to trim the ends of the wires so they line up and create a straight edge.

  5. Now holding an RJ-45 connector with the tab side facing down, push the 8 wires into the connector, sliding each wire into a groove. While holding the connector tab side down the white/orange wire should be on the far left and the brown wire should be on the far right. It is very important that the wires push all the way up and into the connector so that when the pins are pushed down during crimping they will make contact with the wires. The sleave or jacket of the cable (light blue below) should also be pushed in as far as it can go so it will be held in place once crimped. You may want to pull the wires out and put them back in to make sure they are sliding in correctly, this will also further straighten the wires.
    notice the tab make sure it is facing down push the wires and sleave into the connector

  6. Before crimping, examine the cable and connector from the side. Did the wires slide all the way up in to the proper grooves? Are the colors in the proper order when observed from tab side down? Did the jacket slide all the way into the connector? If not, you may need pull the cable out of the connector, trim the wires or the jacket accordingly, and reinsert.
  7. If everything looks good, using your crimper tool insert the connector and cable into the 8 wire slot and press down tightly. This will cause a piece of plastic in the connector to press down on the jacket and hold the cable in the connector preventing it from accidentally pulling out. Crimping also forces copper pins in the connector to push down and make contact with the separate wires.

  8. You are now finished terminating one end of the cable. Repeat the process on the other end of the cable and when you are done, insert the cable into a cable tester and run a wire test to make sure that none of the wires are accidentally crossed, by not being in the right order, or open by not touching the connector pins. Depending on the cable tester you may need to read the manual to understand the device output.

  9. Lastly, test your cable by using it on your network. Attach the cable to your computer’s NIC and the other end to your switch. Do you see green lights? Open the Network Connections dialogue box in Windows, does it show a properly enabled and active connection on the NIC. You can also look for the status in your system tray network connections icon. If you have an internet connection, can you browse the web? If not can you ping your gateway from a command prompt?

Author: Dan

Dan teaches computer networking and security classes at Central Oregon Community College.

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