VRRP Timer tips

The default timer for VRRP advertisements by the Master Router is 1 seconds.
The holdtime is 3 times this and is a default around 6 seconds.

VRRP timers must either be the same in the Group or routers "set to learn" these timers. Because if a VRRP Backup router receives a VRRP Advertisement w/ different timer then the one it has configured, the packed will be discarded. This will cause both routers to think they are Masters!

If routers are set the "learn timers", then the adv.time learned from the vrrp adv.packet will override the one in the config.

(config-if)# vrrp 1 timers learn

If you want to use timers in msec, this must be defined in all the vrrp group routers because when using msec timers, learning the timers from the master feature will not work.

R1(config-if)#vrrp 1 timer adv msec 200
R1(config-if)#vrrp 1 timer learn
% cannot learn timer values when millisecond timers are configured
R1(config-if)#

Note: In VRRP, a sub-second hello timer results in a hello timer of 1 second being sent. So if you set msec timer on one router and a non-default non-learning vrrp on another, they won't talk to each other!


Ref: VRRP @ Cisco
Very good investigation of the topic: (HSRP,VRRP,GLBP timers)