X-Over Cable

An abbreviation for “crossover cable,” this is a type of cable designed to connect two devices directly together that would normally have a hub between. This comes up often with Ethernet cables. Ethernet RJ-45 connectors are normally wired for the paradigm where everything runs through a hub. When two devices are connected directly together the wiring is backward and does not match up. So there are “crossover cables” where the middle four of the eight wires are reversed from one end to the other. This is the type of cable required to connect two computers with Ethernet directly together without the need for a hub or switch. Crossover cables are also found in other domains, such as parallel cables for computers. Here they are commonly known as “Null Modem” cables.