A virtual circuit (VC) is a communications arrangement in which data from a source user may be passed to a destination user over more than one real communications circuit during a single period of communication, but the switching is hidden from the users.
Switched virtual circuits (SVC) are generally setup on a per-call basis and are disconnected when the call is terminated; however, a permanent virtual circuit (PVC) can be established as an option to provide a dedicated circuit link between two facilities.
A virtual circuit network switched virtual circuit (SVC) is a virtual circuit that is dynamically established on demand and is torn down when transmission is complete. Plain old telephone service (POTS) and ISDN telephone calls on the PSTN can be regarded as a simple form of switched virtual circuit. SVCs are used in situations where data transmission is sporadic. In ATM terminology, this is known as a switched virtual connection.
A permanent virtual virtual circuit circuit (PVC) is a virtual circuit established for repeated use between the same data terminal equipments (DTE). In a PVC, the long-term association is identical to the data transfer phase of a virtual call. Permanent virtual circuits eliminate the need for repeated call set-up and clearing.
See also: DLCI
Electronics Topics
The field of electronics is the study and use of systems that operate by controlling the flow of electrons or other electrically charged particles in devices such as thermionic valves and semiconductors. The design and construction of electronic circuits to solve practical problems is part of the fields of electronic engineering, and the hardware design side of computer engineering. The study of new semiconductor devices and their technology is sometimes considered as a branch of physics.
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