Two different types of RJ45 patch cable are used to connect Ethernet units: a straight cable and a crossed cable. In the straight cable all the wires are paired one-to-one, while in the crossed cable several wires have different pin positions at each end of the cable. The devices you need to connect determine which cable you have to use. When connecting a device to a hub, switch or router, use a straight cable. Connecting two units directly often requires a crossed cable.