Cisco IOS Cookbook, 2nd Edition

PPP over Frame Relay

Problem

You want to run use PPP encapsulation over a Frame Relay PVC.

Solution

To configure PPP over Frame Relay, you need to associate the DLCI with a Virtual Template, which will carry the Layer 3 information. Because PPP fundamentally involves a single connection between two devices, it is most natural to use this feature on point-to-point subinterfaces:

Router1#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router1(config)#interface Loopback1
Router1(config-if)#ip address 10.1.200.5 255.255.255.252
Router1(config-if)#exit
Router1(config)#interface Virtual-Template1
Router1(config-if)#ip unnumbered Loopback1
Router1(config-if)#encapsulation ppp
Router1(config-if)#exit
Router1(config)#interface Serial0
Router1(config-if)#no ip address
Router1(config-if)#encapsulation frame-relay
Router1(config-if)#exit
Router1(config)#interface Serial0.1 point-to-point
Router1(config-subif)#frame-relay interface-dlci 104 ppp Virtual-Template1
Router1(config-fr-dlci)#exit
Router1(config-subif)#exit
Router1(config)#end
Router1#

You can also use this feature directly on a physical interface:

Router2#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router2(config)#interface Loopback1
Router2(config-if)#ip address 10.1.200.6 255.255.255.252
Router2(config-if)#exit
Router2(config)#interface Virtual-Template1
Router2(config-if)#ip unnumbered Loopback1
Router2(config-if)#encapsulation ppp
Router2(config-if)#exit Router2(config)# ...