568-A CAT-5 Cable End Diagram This is the less common type CAT-5 end in use.  Both 568 end types use the same physical cable and plug, but a different cable pin-out configuration.

568-B CAT-5 Cable End Diagram This is the more common type of CAT-5 end in use today.  Again, both types of CAT-5 cable end (568-A and 568-B) use the same physical cable and plug, but a different cable pin-out configuration.

Notes for wiring diagrams above:

1. For patch cables, 568-B wiring is by far, the most common method.
2. There is no difference in connectivity between 568B and 568A cables. Either wiring should work fine on any system*. (*see notes below)
3. For a straight through cable, wire both ends identical.
4. For a crossover cable, wire one end 568A and the other end 568B.
5. Do not confuse pair numbers with pin numbers. A pair number is used for reference only (eg: 10BaseT Ethernet uses pairs 2 & 3). The pin numbers indicate actual physical locations on the plug and jack.