Crossover cable
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The term crossover cable has two usages:
- a electrical cable that connects two devices directly (output of one to input of the other), also called a crosslink,
- It also allows devices to communicate without a switch, hub, or router. Cross-Over cables are used to connect two computers directly through NICs without the use of a Hub or Switch or to uplink two or more hubs, switches or routers.
- such a cable that changes between two different wirings, particularly an Ethernet crossover cable.
[edit] Examples
 A null modem cable. |
Other technologies use different pairs to transmit data, so crossover cables for them have different configurations to swap the transmit and receive pairs:
- Twisted pair Token ring uses T568B pairs 1 and 3 (the same as T568A pairs 1 and 2), so a crossover cable to connect two Token Ring interfaces must swap these pairs, connecting pins 4, 5, 3, and 6 to 3, 6, 4, and 5 respectively.
- A T1 cable uses T568B pairs 1 and 2, so to connect two T1 CSU/DSU devices back-to-back requires a crossover cable that swaps these pairs. Specifically, pins 1, 2, 4, and 5 are connected to 4, 5, 1, and 2 respectively.
- A 56K DDS cable uses T568B pairs 02 and 04, so a crossover cable for these devices swaps those pairs (pins 01, 02, 07, and 08 are connected to 07, 08, 01, and 02 respectively).
