31 Days Before Your CCNA Exam

Day 2 345Example 2-2Frame Relay Full Mesh with One Subnet: R2R2(config)#interface serial 0/0/0R2(config-if)#encapsulation frame-relayR2(config-if)#ip address 10.1.1.2 255.255.255.0R2(config-if)#no shutdownR2(config-if)#router eigrp 1R2(config-router)#network 10.0.0.0Example 2-3Frame Relay Full Mesh with One Subnet: R2R3(config)#interface serial 0/0/0R3(config-if)#encapsulation frame-relayR3(config-if)#ip address 10.1.1.3 255.255.255.0R3(config-if)#no shutdownR3(config-if)#interface fastethernet 0/0R3(config-if)#ip address 192.168.30.1 255.255.255.0R3(config-if)#no shutdownR3(config-if)#router eigrp 1R3(config-router)#network 10.0.0.0R3(config-router)#network 192.168.30.0This simple configuration takes advantage of the following IOS default settings:■■■■The LMI type is automatically sensed.The (default) encapsulation is Cisco instead of IETF.PVC DLCIs are learned via LMI status messages.Inverse ARP is enabled (by default) and is triggered when the status message declaring thatthe VCs are up is received.Configuring the EncapsulationIf one of the routers in a full mesh, one subnet configuration does not support the Cisco Frame Relayencapsulation, change the encapsulation to IETF on the Cisco routers with the following command:Router(config-if)#encapsulation frame-relay ietfConfiguring the LMI TypeLMI operates between the local router and the local Frame Relay switch. The LMI message typeused by the local Frame Relay switch might need to be hard-coded on the local router, eitherbecause the IOS version does not support autosensing or network administration policy requiresthat the LMI type be documented on the interface for verification and troubleshooting purposes.Assume the Frame Relay switch used by R2 is an ANSI switch. The following command wouldchange the LMI type on R2 to use the ANSI LMI type:R2(config)#interface serial 0/0/0R2(config-if)#frame-relay lmi-type ansiThe LMI setting is a per-physical-interface setting, even if subinterfaces are used, so the framerelaylmi-type command is always a subcommand under the physical interface.