Virtual Router Redundancy Protocol definition
The Virtual Router Redundancy Protocol is a network protocol that allows administrators to create virtual routers by combining multiple physical routers into a single group with one IP address. These virtual routers provide high availability and failover capabilities on IP networks — if one router within the group fails, another router can seamlessly take over.
How Virtual Router Redundancy Protocol works
The Virtual Router Redundancy Protocol creates a virtual router — a logical entity that represents a group of routers. The virtual router is associated with a virtual IP address that serves as the default gateway for hosts on the network. This IP address is shared among the routers in the group.
Within any given Virtual Router Redundancy Protocol group, one router will be elected as the “master” router based on established priority (or, in case of a tie, based on the highest IP address). The master router is responsible for actively forwarding traffic to and from the virtual IP address. The other routers in the group will be “backup routers,” spending most of their time on standby.
All routers in the group periodically send “advertisement messages” with their availability and status. Backup routers constantly monitor the master router’s advertisement messages for signs of failure. If they determine that the master router is unable to operate, they elect a new master router among themselves and take over the old one’s MAC and IP address.