notes: Backup Interface

Tracks the local line protocol of "primary" interface.

- If the line is up, the "backup" interface is in standby.
- If the line is down, the "backup" interface is out of standby and UP.
- The command "backup interface {int}" is placed on the primary interface, specifying the backup interface.
- Delay-Timers can be used with the backup command.
- Fallover, specifies the delay before the standby link gets brought up after the primary link failed.
- Failback, specifies the delay after the primary link came back up before bringing down the secondary interface.

Note: This solution could have the same black-hole pitfall that floating statics have.
- One solution is to use a tunnel interface and configure the backup command on the tunnel
- The backup command cannot be used on frame-relay physical interfaces. (no way to detect when back up)

optional commands:

backup delay

backup load

- allows backup based on a load value

config-set:


R4:

ip route 150.1.5.0 255.255.255.0 Serial0/1
ip route 150.1.5.0 255.255.255.0 155.1.0.5
!
interface Serial0/0.1 point-to-point
backup delay 3 60
backup interface Serial0/1


verification:

show backup

debug backup