What is the difference between HSRP preempt and VRRP preempt

To decide an Active/Master Router, We have to enable preempt, configure priorities and Configure highest IP address on the Routers in the HSRP or VRRP group. In case of VRRP, Router which owns the IP address for the VRRP group is always becomes a Master Router.

I thought the only the difference between HSRP and VRRP in case of preempt is Preempt ON by default in VRRP. The Router which is configured with the maximum configurable priority value of 254 in VRRP, that Router would become the master Router. This is not always true. There are some of the rules influence the Master and Preempt in VRRP, Find the difference between HSRP and VRRP in case preempt and Active/Master Router.

Difference between HSRP Preempt and VRRP Preempt

a)   In VRRP preempt enabled by default, In HSRP Preempt disabled by default.

b)   In VRRP, In case priority is equal between Routers, Highest IP address Router will preempt but In HSRP, there are equal priority Routers then the one which is active Router remains active when the standby (former active) Router comes back.

c)   The maximum VRRP and HSRP priority value is 255

d)    The maximum VRRP priority value that you can manually configure on the router is 254, In HSRP is maximum configurable priority is 255.

e)   Only one router can have a VRRP priority setting of 255. In HSRP multiple Routers can have a priority setting of 255.

f)    The Router that “owns the IP address” for the group automatically gets a VRRP priority setting of 255. There is no option to configure Virtual IP address of HSRP group as physical address to any Router in HSRP group.

Difference Between HSRP and VRRP Priority for Preemption

Cisco-Router (config)#int fa0/1

Cisco-Router(config-if)#vrrp 1 pri

Cisco-Router(config-if)#vrrp 1 priority ?

  <1-254>  Priority level

Cisco-Router(config-if)#standby 1 pri

Cisco-Router(config-if)#standby 1 priority ?

  <0-255>  Priority value

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  1. Kanth says:

    Heres some pointers that good to remember.

    Cisco Hot-Standby Router Protocol (HSRP):
    Created by Cisco, for Cisco in 1994
    Uses a default hello timer of 3 seconds with a hold timer of 10 seconds

    Virtual Router Redundancy Protocol (VRRP)
    Created by the IETF in 1999
    Works between multiple vendors
    Has faster timers than HSRP by default – hello of 1 second, hold timer of 3 seconds

    kanth

  2. Markus says:

    Hi!
    I did some testing too and came to the following conclusion which also makes sense in my eyes:

    HSRP:
    – preemption is disabled by default
    – when there are equal priority values then the one who is active remains active when the standby (former active) router comes back

    VRRP:
    – preemption enabled by default
    – with equal priority values the higher ip address wins
    – vrrp does not preempt when preemption is disabled even the higher ip address router does not preempt.

    How did you came to the conclusion with the last fact?

    Regards!
    Markus

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