Chapter 6
Virtual Router Redundancy Protocol
When an end station is statically configured with the address of the router that will handle its routed traffic, a single point of failure is introduced into the network. If the router goes down, the end station is unable to communicate. Since static configuration is a convenient way to assign router addresses, Virtual Router Redundancy Protocol (VRRP) was developed to provide a backup mechanism.
VRRP eliminates the single point of failure associated with static default routes by enabling a backup router to take over from a “master” router without affecting the end stations using the route. The end stations will use a “virtual” IP address that will be recognized by the backup router if the master router fails. Participating routers use an election protocol to determine which router is the master router at any given time. A given port may appear as more than one virtual router to the network, also, more than one port on a 7000 Series Managed Switch may be configured as a virtual router. Either a physical port or a routed VLAN may participate.
v1.1, May 2006