Just some Frame Relay notes I’ve made in my studies.
PVC Status Messages- Active - Working Inactive - remote problem - problem on the other side Deleted - Local problem (problem on the immediate device) \\\\\ Three types of LMI: Cisco -default propreitary ANSI Q933A LMI Autosense used from the DTE side to determine the LMI type coming from the frame-relay provider. It sends out the three LMI messages and the LMI type based on what it recieves back.3 LMIs not recieved is the default for a time out and connection to be considered down. router#show frame LMI - shows what type of LMI is being used, how many enq. has been sent and recieved. \\\\\ DLCI - Data Link Connection Identifier. Frame Relay's Layer 2 address. Locally Significant only. Not advertised to other routers. Assigned by the frame relay provider. iARP - Inverse ARP - Dynamic Mapping - Router's service to learn the discover the FRcircuit dynamically and create frame-map statements. Enabled by default. Frame map statements: Always map the local DLCI to the remote IP address. commands: router(config-if)#encapsulation frame-relay - to turn frame relay on an interface. (Cisco or ietf are your encapsulation options. router#show frame map - show frame relay map statements created statically or via iARP router(config-if)#no frame-relay inverse-arp - turn off iARP (disable dynamic mapping) router(config-if)#frame map ip x.x.x.x(remote router) xxx(local dlci) broadcast(to send out routing updates for routing protocols since FR is an NBMA network) Split Horizon - Rule that routes learned on an interface are not to be sent out that same interface. Split Horizon is a routing loop prevention rule. Problem in frame-relay using point to point connections. router(config-if)#no ip split horizon - turns off the split horizon rule. Point to Multipoint is a way to prevent this. This is done by creating logical subinterfaces off a physical interface. router(config)#interface serial 0/0.### specify point to point or multipoint. Congestion notification values: FECN - Forward Explicit Congestion Notification BECN - Backward Explicit Congestion Notification DE - Discard Eligible router#show frame pvc - will show you pvc interfaces, will display in/out FECN and BECN values