How does vrrp work?
Virtual Router Redundancy Protocol (VRRP) enables you to set up
a group of routers as a default gateway router (VRRP Group) for
backup or redundancy purposes. This way, the PC clients can
actually point to the IP address of the VRRP virtual router as
their default gateway. If one of the master routers in the group
goes down, one of the other routers can take over.
Routers can function as master or backup routers, and you can
actually configure up to 255 virtual routers on a router interface.
Of course, there are platform constraints like router memory, for
instance. Additionally, VRRP is intended for use with IPv4 routers
only.