AIS AI2524 user manual Configure a Backup Interface for a Subinterface

Chapter 13: AI2524 Frame Relay Configuration Steps

Example: Transparent Bridging Using Subinterfaces

In this example, Frame Relay DLCIs 42, 64, and 73 are to be used as separate point-to-point links with transparent bridging running over them. The bridging spanning tree algorithm views each PVC as a sep- arate bridge port, and a frame arriving on the PVC can be relayed back out a separate PVC. Be sure that routing is not enabled when config- uring transparent bridging using subinterfaces.

interface serial 0 encapsulation frame-relay interface serial 0.1 point-to-point bridge-group 1

frame-relay interface-dlci 42 interface serial 0.2 point-to-point bridge-group 1

frame-relay interface-dlci 64 interface serial 0.3 point-to-point bridge-group 1

frame-relay interface-dlci 73

Configure a Backup Interface for a Subinterface

Both point-to-point and multipoint Frame Relay subinterfaces can be configured with a backup interface. This approach allows individual PVCs to be backed up in case of failure rather than depending on th entire Frame Relay connection to fail before the backup takes over. You can configure a subinterface for backup on failure only, not for backup based on loading of the line.

If the serial interface has a backup interface, it will have precedenc over the subinterface's backup interface in the case of completeloss o connectivity with the Frame Relay network. As a result, a subinterface backup is activated only if the serial interface is up, or if the serial in- terface is down and does not have a backup interface defined. If a sub- interface has failed while its backup is in use, and then the serial interface goes down, the subinterface backup stays connected.

Beginning in global configuration mode, configure a backup interface for a Frame Relay subinterface:

1.Specify the interface. interface serial number

2.Configure Frame Relay encapsulation. encapsulation frame-relay

August 1997	Page 13-27
2524UM