Here are some common RJ45 Network Connections.

To make a straight through cable use the same configuration at each end. If you want to make a crossover cable, fit one end off as a 568A and the other as a 568B.

Straight through cables are generally used from a switch or router to a computer / laptop. Cross over cables are used for computer to computer connections when not using a switch or router. They are also used for connecting one switch or router to another switch or router.

In summary: Use a crossover cable to connect LIKE devices. For un-like devices use a straight through cable.

This is the 568A standard.

This is the 568B standard.

 

 

 

This is a Crossover cable.
It has a 568A one end and a 568B at the other, The Green and Orange pairs are swapped. This type of patch cable is used when connectng "LIKE" devices to each other.