VRRP and Interface Tracking

Unanswered Question
May 15th, 2009


If we have two routers configured in VRRP.

RA- as master fa0/0 = /24, VRRP 10 priority 110, VRRP 10 preempt.

VRRP 10 track 1 dec 25.

( track 1 int s0/0 line-protocol)

and Reouter B as backup router

fa0/0 = / 24,

VRRP 10 priority 100, VRRP 10 preempt.

With this command configuration, that means IP address of the Virtual router is same as that of physical address configured on Router A ( fa 0/0).

In this case when s0/0 on Router A goes down, priority of Router A should decerment by 25 ( new priority = 85) so the router B should start forwarding.

Will it work as expected or in thi case it will not work due to Virtual address is same as that of physical IP address of router A fa0/0.

Please share the experience.

Here is the VRRP configuration link:


Thanks in advance


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Giuseppe Larosa Fri, 05/15/2009 - 08:07

Hello Subodh,

it should work because it is the way VRRP works.

VRRP doesn't use a separate ip address for the VIP so when the backup router takes role it should emulate the VIP both at L3 and at L2 sending a gratuitos ARP to update switches cam tables.

also VRRP use special MAC address for emulation at layer2.

Hope to help


bapatsubodh Fri, 05/15/2009 - 09:30


Thanks Giuseppe,

I was just wondering that if we refer to the Cisco Documentation given in the link. It says that owner priority will always remain to 255. This is confusing to me. That is why I thought about having a virtual IP address. ( just like HSRP ). Please let me know your views.

thanks again


Giuseppe Larosa Fri, 05/15/2009 - 09:36

Hello Subdoh,

it also says:

Customizing the behavior of VRRP is optional. Be aware that as soon as you enable a VRRP group, that group is operating. It is possible that if you first enable a VRRP group before customizing VRRP, the router could take over control of the group and become the virtual router master before you have finished customizing the feature. >>Therefore, if you plan to customize VRRP, it is a good idea to do so before enabling VRRP.

So it may be a question of the order of commands

Hope to help



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