When making a cable, just remember, only 4 pins of RJ-45 cable is used which is pin 1,2,3,6. (read from left to right when you holding a cable connector).
Pin 1 = Tx+
Pin 2 = Tx-
Pin 3 = Rx+
Pin 6 = Rx-
If you make a straight-through cable, make sure you are using the same color in sequence for both end of connector. You can use the standard color sequence but not 100% required.
If you make a cross-over cable, just make sure using this rule to connect both ends.
PIN 1 connect to PIN 3
PIN 2 connect to PIN 6
see this
http://www.littlewhitedog.com/content-8.html