Command:

standby preempt or priority

Mode:

Router(config-if)#


Syntax:

standby [group-number] priority priority [preempt [delay delay]]

standby [group-number] [priority priority] preempt [delay delay]

no standby [group-number] priority priority [preempt [delay delay]]

no standby [group-number] [priority priority] preempt [delay delay]


Syntax Description:

group-number

(Optional) Group number on the interface to which the other arguments in this command apply.

priority priority

(Optional) Priority value that prioritizes a potential Hot Standby router. The range is 1 to 255, where 1 denotes the lowest priority and 255 denotes the highest priority. The default priority value is 100. The router in the HSRP group with the highest priority value becomes the active router.

preempt

(Optional) The router is configured to preempt, which means that when the local router has a Hot Standby priority higher than the current active router, the local router should attempt to assume control as the active router. If preempt is not configured, the local router assumes control as the active router only if it receives information indicating that there is no router currently in the active state (acting as the designated router).

delay delay

(Optional) Time in seconds. The delay argument causes the local router to postpone taking over the active role for delay seconds since that router was last restarted. The range is 0 to 3600 seconds (1 hour). The default is 0 seconds (no delay).

 


Command Description:

To configure Hot Standby Router Protocol (HSRP) priority, preemption, and preemption delay, use the standby interface configuration command. To restore the default values, use the no form of this command.

When using this command, you must specify at least one keyword (priority or preempt) or you can specify both.

When group number 0 is used, no group number is written to NVRAM, providing backward compatibility.

The assigned priority is used to help select the active and standby routers. Assuming preemption is enabled, the router with the highest priority becomes the designated active router. In case of ties, the primary IP addresses are compared, and the higher IP address has priority.

Note that the device's priority can change dynamically if an interface is configured with the standby track command and another interface on the router goes down.

When a router first comes up, it does not have a complete routing table. If it is configured to preempt, it will become the active router, yet it is unable to provide adequate routing services. This problem is solved by configuring a delay before the preempting router actually preempts the currently active router.

The assigned priority has a higher priority than the authentication string specified in the standby authentication command. A router with a higher HSRP priority will ignore the authentication string.


Example:

In the following example, the router has a priority of 120 (higher than the default value) and will wait for 300 seconds (5 minutes) before attempting to become the active router:

Router(config)#interface fastethernet 0

Router(config-if)#standby ip 172.19.108.254
Router(config-if)#standby priority 120 preempt delay 300

Misconceptions:
None

Related commands:
standby track

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