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V(irtual) R(outer) R(edundancy) P(rotocol)
The Virtual Router Redundancy Protocol (VRRP) is designed to eliminate the single point of failure inherent in the static default routed environment by automatically
providing alternate router paths.
As specified by RFC 2338, VRRP uses an election protocol that dynamically assigns responsibility for a virtual router to one of the VRRP routers on a LAN. The VRRP router controlling the IP address(es) associated with a virtual router is called the Master, and forwards packets sent to these IP addresses.
The election process provides dynamic failover of the forwarding responsibility should the Master become unavailable.
The Virtual Router associated with a given alternate path supported by VRRP uses the same IP address and MAC address as the routers for other paths. As a result, the host's gateway information does not change, no matter
what path is used. Because of this, VRRP-based redundancy significantly reduces administrative overhead when compared to redundancy schemes that require hosts to be configured with multiple default gateways.
Figure above illustrates a simple, two-node Virtual Router using VRRP. The routers in the diagram have been configured as VRRP Routers. They form a Virtual Router.
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