Network, Computer and Programming Resources

Network - VC (Virtual Circuit)

In long-distance communications, a virtual circuit is a temporary connection between two points. This type of circuit will appear as a dedicated line to the user, but will actually be using packet switching to accomplish transmissions. The virtual circuit is maintained as long as the connection exists. A different virtual circuit may be established each time a call is made. Virtual circuits are used in contrast to leased lines, in which a dedicated connection between two particular points is always available. X.25 and frame relay both use virtual circuits. In the X.25 environment, a virtual circuit is a logical connection between a DTE (computer) and a DCE (digital service unit, modem, or multiplexer). This type of connection can be a switched virtual circuit (SVC) or a permanent virtual circuit (PVC). The SVC can connect to a different DTE at the other end each time. The PVC always connects to the same DTE at the other end.