Active/Passive Cluster ID and the Virtual MAC Address
An active/passive FireCluster uses a virtual MAC address, calculated based on the Cluster ID and the interface numbers. If you configure more than one active/passive FireCluster on the same subnet, it is important to know how to set the Cluster ID to avoid a possible virtual MAC address conflict.
How the Virtual MAC Address is Calculated
The virtual MAC addresses for interfaces on an active/passive FireCluster start with 00:00:5E:00:01. The sixth octet of the MAC address is set to a value that is equal to the interface number plus the Cluster ID.
For example, for a FireCluster with the Cluster ID set to 1, the virtual MAC addresses are:
Interface 0: 00:00:5E:00:01:01
Interface 1: 00:00:5E:00:01:02
Interface 2: 00:00:5E:00:01:03
If you add a second FireCluster to the same subnet, you must make sure to set the Cluster ID to a number that is different enough from the Cluster ID of the first FireCluster to avoid a virtual MAC address conflict. For example, if the first FireCluster has 5 interfaces, you must set the Cluster ID of the second FireCluster at least 5 higher than the Cluster ID for the first FireCluster.
For example, if the second FireCluster has the Cluster ID set to 6, the virtual MAC addresses are:
Interface 0: 00:00:5E:00:01:06
Interface 1: 00:00:5E:00:01:07
Interface 2: 00:00:5E:00:01:08
It is also possible that the FireCluster virtual MAC addresses can conflict with HSRP and VRRP configured devices on your network.