The connection through the Frame Relay network between two DTEs is called a virtual circuit (VC). Virtual circuits may be established dynamically by sending signaling messages to the network. In this case they are called switched virtual circuits (SVCs). However, SVCs are not very common. Generally permanent virtual circuits (PVCs) that have been preconfigured by the carrier are used. The switching information for a VC is stored in the memory of the switch.

Because it was designed to operate on high-quality digital lines, Frame Relay provides no error recovery mechanism. If there is an error in a frame it is discarded without notification.

The FRAD or router connected to the Frame Relay network may have multiple virtual circuits connecting it to various end points. This makes it a very cost-effective replacement for a mesh of access lines. With this configuration, each end point needs only a single access line and interface. More savings arise as the capacity of the access line is based on the average bandwidth requirement of the virtual circuits, rather than on the maximum bandwidth requirement.

The various virtual circuits on a single access line can be distinguished because each VC has its own Data Link Channel Identifier (DLCI). The DLCI is stored in the address field of every frame transmitted. The DLCI usually has only local significance and may be different at each end of a VC.

Interactive Media Activity Drag and Drop: Frame Relay Terminology When the student has completed this activity, the student will be able to correctly identify frame relay terminology.

Web Links Frame Relay http://www.cisco.com/univercd/cc/ td/doc/cisintwk/ito_doc/frame.htm