VRRP Configuration

A default gateway is a critical resource for connectivity. However, it's prone to a single point of failure. Thus, redundancy for the default gateway is required. If WAN backhaul is available, and a router failure occurs, then the access point should act as a router and forward traffic on to its WAN link.

Define an external Virtual Router Redundancy Protocol (VRRP) configuration when router redundancy is required in a network requiring high availability.

Central to the configuration of VRRP is the election of a VRRP master. A VRRP master (once elected) performs the following functions:

• Responds to ARP requests

• Forwards packets with a destination link layer MAC address equal to the virtual router MAC address

• Rejects packets addressed to the IP address associated with the virtual router, if it is not the IP address owner

• Accepts packets addressed to the IP address associated with the virtual router, if it is the IP address owner or accept mode is true.

Those nodes that lose the election process enter a backup state. In the backup state they monitor the master for any failures, and in case of a failure one of the backups, in turn, becomes the master and assumes the management of the designated virtual IPs. A backup does not respond to an ARP request, and discards packets destined for a virtual IP resource.