VRRP and neighbor discovery for IPv6

Neighbor Discovery (ND) is the IPv6 equivalent of the IPv4 ARP for layer 2 address resolution, and uses IPv6 ICMP messages to do the following:

  • Determine the link-layer address of neighbors on the same VLAN interface.

  • Verify that a neighbor is reachable.

  • Track neighbor (local) routers.

Neighbor Discovery enables functions such as the following:

  • Router and neighbor solicitations and discovery

  • Detecting address changes for devices on a VLAN

  • Identifying a replacement for a router or router path that has become unavailable

  • Duplicate address detection (DAD)

  • Router Advertisement processing

  • Neighbor reachability

  • Autoconfiguration of unicast addresses

  • Resolution of destination addresses

  • Changes to link-layer addresses.

An instance of Neighbor Discovery is triggered on a device when a new or changed IPv6 address is detected. VRRPv3 provides a faster failover to a backup router by not using standard ND procedures. A failover to a backup router can occur in approximately three seconds without any interaction with hosts and with a minimum of VRRPv3 traffic.