backup interface

To enable an interface or link as a backup connection make use of the following 2 commands

backup interface x
backup delay a b

where a is the delay in seconds before activating the backup connection and b is the delay in seconds before the prinary interface is re-instated

This configuration is applied to the PRIMARY interface. Verification can be done via the show backup command.

R5#s backup
Primary Interface Secondary Interface Status
----------------- ------------------- ------
Serial2/0.513 Serial2/1 normal operation

Also use the show interface on the secondary/backup interface to display the standby status.

R5#s int s2/1
Serial2/1 is standby mode, line protocol is down