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Makin' cables

LAN Party How To - Part 2: Building the LAN
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Ready-made Ethernet cables can be purchased in most any length you'll need or made yourself. Manufactured cables are a convenient option, however there are a few reasons you might consider making them yourself:

Building the cabling is usually cheaper Having complete control of the length of the cable allows you to better size the cables to fit the venue's configuration. Having less spare cable at the end of the cable reduces the likelihood of a foot getting caught in it and jerked, possibly causing a serious accident Shorter / correctly-sized cables also provide better signal strength It's usually difficult to locate pre-made cabling that uses solid core wire You're likely going to need to repair a cable at some point, so you might as well get used to learning how they are made

To make your own Ethernet cables, you will need the following items:

Spool of the appropriate type of cable as described above - usually sold in boxes of 1000 feet A supply of RJ-45 Ethernet plugs - we like to call these "crystals" A basic knife or other cutting tool for cutting the right length of cable from the spool An RJ-45 crimping tool either with appropriate jacket-shaving blade or two separate tools A UTP cable tester or known-good network connector for testing

The assembly process goes like this:

Pull the desired length of cable from the spool
You can either measure by physically running the box from the first location to the desired destination, or measure the actual distance and use the footage markers on the jacket of the cable. (You know, the number that's on the outside of the jacket that you never paid attention to before?) If you decide to pull from one location to the other, be sure to add a few extra feet to account for things like distance from floor to switch, corners, etc.

Cut the cable from the spool
Nothing special here, just need to make sure everything is cut nice and neat.

Strip the PVC jacket about an inch from the end of the cable
An inch will expose enough wire to be more easily managed by big fingers.

Fan out the 4 separate colored pairs
This makes identification easier as you match colors.

Carefully arrange the wires in the proper order
95% of the time, you will be making a straight-through type cable. The only time you need a crossover cable is when uplinking switches that don't have uplink ports or a feature called Auto MDI-X that automatically cross-connects the transmit and receive wire pairs on any port as needed.

Figure 6 shows the RJ45 connector pinouts for 568A and 568B standards. It doesn't matter which one you choose as long as you manufacture all cables using the same standard.


Figure 6: UTP RJ-45 connector pinouts
(click image to enlarge)

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