Function of the VRRP advertisement
The current master router sends periodic advertisements to inform the other routers in the VR of its operational status. If the backup VRs fail to receive a master advertisement within the timeout interval, the current master is assumed to be unavailable and a new master is elected from the existing backups. The timeout interval for a VR is three times the advertisement interval configured on the VRs in the network or subnet. In the default VRRP configuration, the advertisement interval is one second and the resulting timeout interval is three seconds.
All VRRP routers belonging to the same VR must be configured with the same advertisement interval. As required in RFC 3768, if a locally configured advertisement interval does not match the interval received in an inbound VRRP packet, the VR drops that packet.
Most IPv6 host configurations learn the default gateway IPv6 address using router advertisements. The VR that becomes the master sends router advertisements for its virtual IP address.