An administrator is troubleshooting a Stateful High Availability (HA) pair of Cisco Secure Firewall 4100 series devices managed by FMC. The units are failing to form an HA state, and logs indicate a state mismatch on the control link. Which underlying cause is most likely preventing the HA synchronization?
Trap 1: The MTU on the data interfaces differs by 4 bytes.
Data interface MTU differences do not prevent the control link from forming, though they can affect packet passing later.
Trap 2: The stateful HA control link is configured across a routed switch…
While direct connection is recommended, routed switched paths are supported provided latency and MTU requirements are met.
Trap 3: The management IP addresses on the active and standby units are…
Active and standby units must have unique management IP addresses assigned to their respective management interfaces.
- A
The MTU on the data interfaces differs by 4 bytes.
Why wrong: Data interface MTU differences do not prevent the control link from forming, though they can affect packet passing later.
- B
The stateful HA control link is configured across a routed switch interface instead of a direct cross-over cable.
Why wrong: While direct connection is recommended, routed switched paths are supported provided latency and MTU requirements are met.
- C
The management IP addresses on the active and standby units are identical.
Why wrong: Active and standby units must have unique management IP addresses assigned to their respective management interfaces.
- D
One unit is running a slightly different maintenance patch release of FTD than its peer.
FMC enforces strict version matching; even a minor patch level mismatch between primary and secondary units will cause HA initialization to fail.