The virtual MAC address of the virtual router.
Although the value of this object can be derived from the
'cVrrpOperationsVrId' object, i.e., 00-00-5E-00-01-(VRID)
for IPv4 and 00-00-5E-00-02-(VRID) for IPv6, it is defined
so that it is easily obtainable by a management application
and can be included in VRRP-related SNMP notifications.