HSRP w/ Interface Tracking
Per Cisco documentation:
"Interface tracking allows you to specify another interface on the router for the HSRP process to monitor in order to alter the HSRP priority for a given group."
The track statement assigns a value that the priority will be decreased if the interface being tracked goes down.
Example config on 4461 router
RTR_1(config)#do sh run inter te 0/0/4
interface TenGigabitEthernet0/0/4
description Downlink_to_LAN
ip address 10.10.208.2 255.255.255.0
standby 208 ip 10.10.208.1
standby 208 priority 125
standby 208 preempt
RTR_1(config)#track 1 interface te 0/0/5 line-protocol
The line above says "Watch this interface"
!
RTR_1(config)#inter ten 0/0/4
RTR_1(config-if)#standby 208 track 1 decrement 100
Now, on RTR-2
interface TenGigabitEthernet0/0/4
description Downlink_to_LAN
ip address 10.10.208.3 255.255.255.0
standby 208 ip 10.10.208.1
standby 208 preempt
Note: "Preempt" is required on RTR-2 in order to take over for a lower priority HSRP peer, which RTR-1 would become after the "decrement" is put in place, during a link-down event.
Now when 0/0/5 on RTR-1 or the upstream switch to RTR-1 goes down, RTR-2 will take over as the HSRP virtual IP .1, but when 0/0/5 on RTR-1 goes back into an "UP" state, RTR-1 will go back to being the HSRP .1
Per Cisco documentation:
"Interface tracking allows you to specify another interface on the router for the HSRP process to monitor in order to alter the HSRP priority for a given group."
The track statement assigns a value that the priority will be decreased if the interface being tracked goes down.
Example config on 4461 router
RTR_1(config)#do sh run inter te 0/0/4
interface TenGigabitEthernet0/0/4
description Downlink_to_LAN
ip address 10.10.208.2 255.255.255.0
standby 208 ip 10.10.208.1
standby 208 priority 125
standby 208 preempt
RTR_1(config)#track 1 interface te 0/0/5 line-protocol
The line above says "Watch this interface"
!
RTR_1(config)#inter ten 0/0/4
RTR_1(config-if)#standby 208 track 1 decrement 100
Now, on RTR-2
interface TenGigabitEthernet0/0/4
description Downlink_to_LAN
ip address 10.10.208.3 255.255.255.0
standby 208 ip 10.10.208.1
standby 208 preempt
Note: "Preempt" is required on RTR-2 in order to take over for a lower priority HSRP peer, which RTR-1 would become after the "decrement" is put in place, during a link-down event.
Now when 0/0/5 on RTR-1 or the upstream switch to RTR-1 goes down, RTR-2 will take over as the HSRP virtual IP .1, but when 0/0/5 on RTR-1 goes back into an "UP" state, RTR-1 will go back to being the HSRP .1