When you configure a virtual routing ID (VRID), the software automatically uses the MAC address as the MAC address of the virtual router. The first five octets of the address are the standard MAC prefix for VRRP packets. The last octet is the VRID.
When the virtual router becomes the master router, it broadcasts a gratuitous ARP (GARP) request containing the virtual router‘s MAC address for each IP address associated with the virtual router. Hosts use the MAC address of the virtual router in routed traffic they send to their default IP gateway.
You can manually configure a unique virtual MAC address for each IPv4 and IPv6 VRRP instance per VRID. If there is no manually configured virtual MAC address for a VRRP instance, the system automatically assigns one.
The ability to configure a unique virtual MAC address is subject to the following limitations:
Note
A virtual MAC address can be dynamically updated while a VRRP or VRRP-E session is enabled. When the VRRP or VRRP-E virtual MAC address is modified on the master device, expect a traffic drop until the host device receives the GARP or Router Advertisement (RA) containing the updated virtual MAC address from the master VRRP device.