How to Calculate a Virtual MAC Address

• NGFW Firewall
• High Availability

Details

In Layer 3 mode, a virtual MAC address is created for the configured floating IP address and ARP load sharing IP address interfaces.

The format of the virtual MAC is 00-1B-17:00: xx: yy, where;

•    00-1B-17: The vendor ID  (This value may be different depending on PAN-OS version or Platform)
•    00: Fixed at 00
•    xx: The value representation is as follows
  
•    yy: The interface ID

When a new active device takes over, Gratuitous ARPs are sent from each of the connected interfaces of the functional device. This informs the connected Layer-2 switches of the new location for the virtual MAC addresses.