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SVC stands for switched virtual circuit, is a packet switching method that refers to the setting up of a temporary circuit, or path, for purposes of data transmission in a frame relay network environment. In doing this, the SVC may access numerous disparate circuit resources to enable the transmission of data. An SVC is only maintained for the duration of the data session. After that point, it is no longer utilized. In terms of appearance, SVCs appear to users as a single physical circuit; however, they are a shared pool of circuit resources used to support multiple users as they require the connections. Additionally, these circuits are only available to the user.

A good working example of a basic SVC is a telephone call. A telephone link is created during a call, as it is established when the call begins. When the call ends, the link vanishes. So, the link, or SVC uses a temporary connection to convey information. Then, when the information is completely conveyed, the connection, the SVC, disappears.

SVC, and virtual circuits in general, offer a number of advantages including:
– All packets take the same route and are therefore delivered in order.
– The overhead in each packet is smaller, since packets don’t have to contain the full address
– The Connection is more reliable—network resources are distributed at call setup so that even during congestion, provided a call has been setup, the packets will (or should be able) to get through
– Easier billing since records are generated per call and not per packet.

Additional Reading
What are E-SBCs?
What is Demarcation Point?
VoIP vs Landline