Straight Cable

There are two types of network cables commonly used in PC networks - Straight-through and cross-over.

Cross-over: A cross-over cable is used to connect two computers via their NICs, without using a hub or switch. (Note: You can only connect two computers at one time, connecting three or more will require a hub or switch of some sort).

Straight-through: A straight-through network cable is just what the name implies, a cable that passes data straight through from one end to another. Straight-through cables are used for a variety of connections. (e.g. connecting a computer to a hub or switch, connecting a computer to a cable/ISDN/DSL modem, and linking switches and hubs together.)

Let's start with a straight-through cable and then we'll get fancy with a cross-over cable.

Cutting, Stripping, And Sorting The Wires

Cut a piece of Cat 5 as long as you need. When you cut, remember the old saying: Measure twice, cut once. Make sure the cut on each end is clean and straight.

Strip about an inch of the insulation off the cable. Cut it back nice and square. Some crimping tools such as the one used in this article come with a built-in wire stripper. You put the cable in to a stop on one side of the cutter. It will cut the jacket the right length to make a perfect crimp. It is extremely important that you only cut the plastic insulation/jacket and not the wire. Damaging one of the 8 wires, even if you just nick it or partially cut it, will ruin your cable.

Untwist the wires. You'll notice that there are 4 pairs of multi-colored wires inside. Sort the pairs by color. You should end up with wires color coded as follows: blue/blue-white, orange/orange-white, green/green-white, brown/brown-white.

Note: Some Cat 5 cable skimps on the color-coding and you will have to keep the track of which wire was wrapped around which. If at all possible, check the cable before you buy and make sure the color-coding is easy to recognize. If not, you'll be cursing up a storm later and wish you would have spent the extra 5 bucks on the better cable.

Now align the wires in the following order from left to right. The order is important since there is a wiring standard defined by the Telecommunications Industry Association (TIA) http://www.tiaonline.org. It's called the EIA/TIA-568 Commercial Building Telecommunications Wiring Standard, and you can find more information on it here: http://www.digital-delivery.com/Standards.htm#s5

Get the wires lined up and nice and straight. Then clip off the top millimeter so that they are all the same length and stick out about half an inch from the insulated part.