Frame Relay Continued
Frame relay can operate over both SVCs and PVCs like X.25 but usually operates over PVCs.
PVCs remain connected to the WAN until they are manually removed by network administrator.
Frame relay connections are identified by DLCIs (data link connection identifiers). The DLCI is a local number associated with the IP address at the other end of the frame relay link. The DLCI tells the network how to route the data.
Frame relay also uses the LMI (line management interface) protocol. LMI is a "keep-alive" mechanism that lets the router know that the link is still alive even though data is not currently being transmitted.