Backup using Backup Interfaces

R1 is connected to R2 via 2 links, one of the two links will be active if the first on goes down:



!
hostname r1
!
interface Loopback0
 ip address 1.1.1.1 255.255.255.255
!
interface FastEthernet1/0
 ip address 192.168.12.1 255.255.255.0
!

interface FastEthernet2/0

 backup delay 3 60

 backup interface FastEthernet1/0

 ip address 192.168.112.1 255.255.255.0

!

ip route 2.2.2.2 255.255.255.255 192.168.12.2

ip route 2.2.2.2 255.255.255.255 192.168.112.2

!

!

hostname r2

!

interface Loopback0

 ip address 2.2.2.2 255.255.255.255

!

interface FastEthernet1/0

 ip address 192.168.12.2 255.255.255.0

!

interface FastEthernet2/0

 ip address 192.168.112.2 255.255.255.0

!

ip route 1.1.1.1 255.255.255.255 192.168.12.1

ip route 1.1.1.1 255.255.255.255 192.168.112.1

!

FastEthernet2/0: 

Backup interface FastEthernet1/0, failure delay 3 sec, secondary disable delay 60 sec,

r1(config-if)#backup ?      

  active     Configure an interface as an active backup

  delay      Delays before backup line up or down transitions

  interface  Configure an interface as a backup

  load       Load thresholds for line up or down transitions