Cisco IOS Cookbook, 2nd Edition

Setting Up Frame Relay with Point-to-Point Subinterfaces

Problem

You want to configure Frame Relay services so that each PVC is assigned to a separate subinterface.

Solution

Probably the cleanest way to set up a Frame Relay network is to use point-to-point subinterfaces. If you have a host site that connects to two or more branches through a Frame Relay WAN, you could configure the central host router like this:

Central#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Central(config)#interface Serial0
Central(config-if)#description Frame-Relay host circuit
Central(config-if)#no ip address
Central(config-if)#encapsulation frame-relay
Central(config-if)#exit
Central(config)#interface Serial0.1 point-to-point
Central(config-subif)#description PVC to first branch - DLCI 101
Central(config-subif)#ip address 192.168.1.5 255.255.255.252
Central(config-subif)#frame-relay interface-dlci 101 
Central(config-fr-dlci)#exit
Central(config-subif)#exit
Central(config)#interface Serial0.2 point-to-point
Central(config-subif)#description PVC to second branch - DLCI 102
Central(config-subif)#ip address 192.168.1.9 255.255.255.252
Central(config-subif)#frame-relay interface-dlci 102 
Central(config-fr-dlci)#exit
Central(config-subif)#exit
Central(config)#end
Central#

And all of the branches would follow the same basic configuration, but with different IP addresses and DLCI numbers:

Branch1#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Branch1(config)# ...