Ethernet cables are used to connect several pieces of a local area network together. Ethernet cables typically come in two varieties: crossover cables and patch cables.
Since crossover cables and patch cables are fundamentally different, each cable has a different function in a local area network.
Category-5, 5e, and 6 cables are assembled according to either the T568A or T568B standard. The T568A standard requires the cable end to terminate the internal coloured wires in this order, as viewed from the top, left to right: green-white, green, orange-white, blue, blue-white, orange, brown-white, brown.
The T568B standard requires the cable ends to terminate the internal coloured wires in this order, as viewed from the top, left to right: orange-white, orange, green-white, blue, blue-white, green, brown-white, brown.
How is a Patch Cable Made?
A patch cable is an Ethernet cable where both ends are wired to one of the specifications (either T568A or T568B, but not both). Since both ends are terminated in the same fashion, a patch cable is often called a "straight-through" cable.
How is a Crossover Cable Made?
A crossover cable is an Ethernet cable where one of the ends is wired according to the T568A specification, whereas the other end is wired according to the T568B specification. This allows the data output pins on one end of the cable to be connected directly to the data input pins on the other end of the cable.
Where is a Patch Cable Used?
A patch cable is used to for connections from computer network adaptors to Ethernet hubs or switches. Patch cables can also be used to connect two Ethernet hubs or switches together.
Where is a Crossover Cable Used?
A crossover cable is often used to connect the network adaptors on two computers directly to each other, without using a network hub or switch as routing device. Some network hubs or switches may require a crossover cable to connect from one hub or switch to another, although this is more common with large hubs and switches (32 ports or more) than with smaller hubs or switches (16 ports or less).