VRRP Fundamentals

Virtual Router Redundancy Protocol (VRRP) is an open-standard First Hop Redundancy Protocol (FHRP) that provides high availability for default gateways.

How VRRP Works

VRRP groups two or more physical routers into a single Virtual Router. This virtual router has its own virtual IP (VIP) and virtual MAC address.

One physical router is elected as the Master, which actively forwards traffic sent to the VIP. The other routers act as Backups. If the Master fails, the Backup with the highest priority takes over the VIP and MAC, ensuring seamless connectivity for end hosts.

VRRP Configuration Example

Here is a basic VRRP configuration on a Cisco IOS device:

Router(config)# interface GigabitEthernet0/0
Router(config-if)# ip address 192.168.1.2 255.255.255.0
Router(config-if)# vrrp 10 ip 192.168.1.1
Router(config-if)# vrrp 10 priority 110
Router(config-if)# vrrp 10 preempt

• vrrp 10 ip 192.168.1.1: Assigns the virtual IP 192.168.1.1 to VRRP group 10.
• vrrp 10 priority 110: Sets the priority (default is 100). Higher priority becomes Master.
• vrrp 10 preempt: Allows a Backup router to take over if its priority becomes higher than the current Master.