command ties the Hot Standby priority of the router to the availability of its
interfaces. It is useful for tracking interfaces that are not configured for
the Hot Standby Router Protocol (HSRP). Only IP interfaces are tracked. A
tracked interface is up if IP on that interface is up. Otherwise, the tracked
interface is down.
When a tracked
interface goes down, the Hot Standby priority decreases by 10. If an interface
is not tracked, its state changes do not affect the Hot Standby priority. For
each group configured for Hot Standby, you can configure a separate list of
interfaces to be tracked.
priority-decrement argument specifies by how much
to decrement the Hot Standby priority when a tracked interface goes down. When
the tracked interface comes back up, the priority is incremented by the same
tracked interfaces are down and
priority-decrement values have been configured,
these configured priority decrements are cumulative. If tracked interfaces are
down, but none of them were configured with priority decrements, the default
decrement is 10 and it is cumulative.
command must be used in conjunction with this command
on all routers in the group whenever the best available router should be used
to forward packets. If the hsrp preempt
command is not used, then the active router stays
active, regardless of the current priorities of the other HSRP routers.
In the following
example, Ten Gigabit Ethernet interface 0/2/0/1 tracks interface 0/1/0/1 and
0/3/0/1. If one or both of these two interfaces go down, the Hot Standby
priority of the router decreases by 10. Because the default Hot Standby
priority is 100, the priority becomes 90 when one of the tracked interfaces
goes down and the priority becomes 80 when both go down.
RP/0/0/CPU0:router(config)# router hsrp
RP/0/0/CPU0:router(config-hsrp)# interface TenGigE 0/2/0/1
RP/0/0/CPU0:router(config-hsrp-if)# hsrp track TenGigE 0/1/0/1
RP/0/0/CPU0:router(config-hsrp-if)# hsrp track TenGigE 0/3/0/1
RP/0/0/CPU0:router(config-hsrp-if)# hsrp preempt
RP/0/0/CPU0:router(config-hsrp-if)# hsrp ipv4 220.127.116.11