Crossover cable

A null modem cable.

A crossover cable connects two devices of the same type, for example DTE-DTE or DCE-DCE, usually connected asymmetrically (DTE-DCE), by a modified cable called a crosslink.[1] Such a distinction between devices was introduced by IBM.

The crossing of wires in a cable or in a connector adaptor allows:

  • connecting two devices directly, output of one to input of the other,
  • letting two terminal (DTE) devices communicate without an interconnecting hub knot, i.e. PCs,
  • linking two or more hubs, switches or routers (DCE) together, possibly to work as one wider device.

In contrast, a straight-through cable uses direct wiring to connect complementary devices, e.g. a PC to a switch.

  1. ^ Dean, Tamara (2010). Network+ Guide to Networks. Delmar. p. 657.