Multi-active handling procedure

The multi-active handling procedure includes detection, collision handling, and failure recovery.

Detection

MAD identifies each IRF fabric with a domain ID and an active ID (the member ID of the master). If multiple active IDs are detected in a domain, MAD determines that an IRF collision or split has occurred.

For more information about the MAD mechanisms and their application scenarios, see "MAD mechanisms."

Collision handling

When MAD detects a multi-active collision, it sets all IRF fabrics except one to the Recovery state. The fabric that is not placed in Recovery state can continue to forward traffic. The Recovery-state IRF fabrics are inactive and cannot forward traffic.

LACP MAD and BFD MAD use the following process to handle a multi-active collision:

  1. Compare the number of members in each fabric.

  2. Set all fabrics to the Recovery state except the one that has the most members.

  3. Compare the member IDs of the masters if all IRF fabrics have the same number of members.

  4. Set all fabrics to the Recovery state except the one that has the lowest numbered master.

  5. Shut down all network ports and interfaces in the Recovery-state fabrics except for the following ports and interfaces:

    • IRF physical interfaces.

    • Ports and interfaces you have specified with the mad exclude interface command.

In contrast, ARP MAD and ND MAD do not compare the number of members in fabrics. These MAD mechanisms use the following process to handle a multi-active collision:

  1. Compare the member IDs of the masters in the IRF fabrics.

  2. Set all fabrics to the Recovery state except the one that has the lowest numbered master.

  3. Take the same action on the network ports and interfaces in Recovery-state fabrics as LACP MAD and BFD MAD.

Failure recovery

To merge two split IRF fabrics, first repair the failed IRF link and remove the IRF link failure.