Frame Relay - 8 : Virtual Circuits

The paths between sites are actually called virtual circuits, which we'll talk more about when we learn about the ATM protocol. As a matter of fact, ATM, ISDN and frame relay are all related standards that share a lot of features.

There are two types of virtual circuits in frame relay: permanent virtual circuits, or PVCs, and switched virtual circuits, or SVCs.

PVCs are set up statically, and this means they must be manually created and broken down.

The SVCs can be dynamically set up and deleted as the traffic requires.
Today most frame relay services use PVC connections. This isn't because they are better, but because businesses do not often change physical location, so SVC services are not required.