VRRP (Virtual Router Redundancy Protocol) is a standard based First Hop Redundancy Protocol. It eliminates the single point of failure by using multiple optional devices. Traffic prefers going through the selected Master device. You can reaach the related rfc here.
The configuration of Virtual Router Redundancy Protocol is like another First Hop Redundancy Protocol, Cisco proprietary HSRP. There are only small differences in configuration and operation. We will talk about these difference below.
The devices that are configured with VRRP, have two roles. These roles are:
The Active or selected device that the traffic will flow through has the role Master.
The remainning devices has the role Backup.
There is one Master,but there can be one more Backups.
Here, the principle is similar to HSRP. If the Master go down, then one of the Backups takes the Master role.
In Virtual Router Redundancy Protocol, preempt feature is enabled by default. What was preempt? Preempt is the process of “taking the Master role back”. If the failedd Master come back, it can take its role back again. This is enabled by default.