What is VRRP?
The Virtual Router Redundancy Protocol (VRRP) is a computer networking protocol that provides for automatic assignment of available Internet Protocol (IP) routers to participating hosts. The protocol achieves this by creation of virtual routers, which are an abstract representation of multiple routers, i.e. master and backup routers, acting as a group.
The default gateway of a participating host is assigned to the virtual router instead of a physical router. If the physical router that is routing packets on behalf of the virtual router fails, another physical router is selected to automatically replace it. This increases the availability and reliability of routing paths via automatic default gateway selections on an IP subnetwork.
You can configure VRRP on several physical routers to establish virtual routers: one router works as a master router and the other as backup routers. If the master router fails or has a lower priority than other backup routers, one of the backup routers will be selected to automatically to replace the master router. The virtual router can be accessed via one virtual IP address without the need of configuring IP addresses on each physical router.