08-04-2023 10:29 AM - edited 08-04-2023 10:54 AM
Scenario 1:
With passive link state set to shutdown, I would expect the firewalls to hit their flap limit. That scenario would result in failover to firewall 2, back to firewall 1 (due to preempt with higher priority value), then back to firewall 2. Assuming a flap limit of 3, firewall 1 would remain in a suspended state due to 'non-functional loop detected' until admin intervention, while firewall 2 continued to support traffic.
Scenario 2:
As you suggested, setting passive link state to auto would result in a cleaner failover. Firewall 1 would fail to firewall 2 and stay there. Firewall 1 would stay suspended due to monitored link down. Once the link is back up, firewall 1 would renegotiate HA, and should become the active unit since it's configured to preempt with a higher priority value.
Scenario 3:
If a monitored link on each firewall failed (e.g. e1/1 on both firewalls), one of them would become suspended due to non-func loop, regardless of passive link state being shutdown or auto. Recovery would require admin intervention, same as the first scenario.
If there's something I overlooked or didn't take into account, feel free to correct me.
