Cisco IOS Wide-Area Networking Configuration Guide - Free Books

Configuring Frame Relay SwitchingConfiguring Frame RelayFigure 25Frame Relay Switched NetworkDTERouter AFrame RelaynetworkDLCI 50DLCI 60NetworkinterfaceDLCI 70Router BDTEFrame Relay DCEswitch implementsthe networkinterfaceDLCI 80DTEImplements theRouter Cuser interface62860Frame Relay switching is supported on the following interface types:• Serial interfaces• ISDN interfacesNoteFrame Relay switching is not supported on subinterfaces.Frame Relay Switching over ISDN B ChannelsFrame Relay switching over ISDN B channels enables you to transport Frame Relay data over ISDN.This feature allows small offices to be hubbed out of larger offices rather than being connected directlyto the core network. The hub router acts as a Frame Relay switch, switching between ISDN and serialinterfaces, as shown in Figure 26.Figure 26Router Used As a Frame Relay Switch over ISDNISDNnetworkRouter acting asa Frame Relay switchFrame RelaynetworkFrame Relayover ISDNFrame Relayover ISDNFrame Relay40081Frame Relay switching over ISDN provides the following functionality:• LMI is supported on ISDN Frame Relay DCE interfaces.• A single BRI/PRI interface can use a combination of switched PVCs and terminated Frame RelayPVCs.• Frame Relay switching supports both leased-line ISDN, on which a B channel is permanentlyconnected, and switched ISDN, on which B channels may be dynamically set up and torn down.20