Networking Guide : Cat 5 Wiring Scheme
Straight-through cable is a Cat 5 cable that has similar wiring
in both ends. Both cable ends follow either 568A or 568B. If you
buy a Cat 5 cable, a practical way to check if it is a
straight-through cable is by laying the two ends (connectors) side
by side and verifying the colors order. If the colors in
both ends are in
the same order, it is a straight-trough cable. A straight-through
cable is used to connect a computer to a hub or a switch. It can also be used
to connect two hubs (or switches) if each hub (or switch) has an uplink
(i.e. built-in crossover) port.
Picture: Crossover Cable Wiring
568A on one end, 568B on the other end.
Pins 1, 2, 3, 6 are crossed to pins 3, 6, 1, 2 respectively.
Crossover cable is a Cat 5
cable that has one end following 568A and the other 568B. A
crossover cable is used to connect two computers directly, that's
without a hub or a switch. However some computer models have
auto-crossover (a.k.a. auto-switching or auto-MDI/MDIX) port that lets a computer connect
directly to another computer using a straight-through cable. A crossover cable is
also used to connect two hubs (or switches) if both hubs (or switches) don't have uplink ports.
The wiring inside a crossover cable is illustrated in the picture above.