Switch - Networking
A switch is a device that makes decisions on the routing of traffic. Like a hub and a bridge, a switch can connect different network protocols, like 10Base-T and 100Base-T. However, a switch makes decisions based upon the layer 2 packets as they are passed through the device. In the telephone networks, switches are used to connect virtual circuits within the phone network.
A switch may also include the function of the router, a device or program that can determine the route and specifically what adjacent network point the data should be sent to. In general, a switch is a simpler and faster mechanism than a router, which requires knowledge about the network and how to determine the route. Some newer switches also perform the routing functions of layer 3, the Network layer. Layer 3 switches are also sometimes called IP switches.