If one or more FPCs in the primary FortiGate-6000 fails, the cluster renegotiates and the FortiGate-6000 with the most operating FPCs becomes the primary FortiGate-6000. An FPC failure can occur if an FPC shuts down due to a software crash or hardware problem, or if the FPC is manually shut down.
FPCs also shut down if one or more FortiGate-6000 power cables is disconnected. A FortiGate-6000 can continue to operate some disconnected power cables, but the system will experience reduced performance because fewer FPCs will be available to process traffic.
After the primary FortiGate-6000 experiences an FPC failure, the FortiGate-6000 with the most operating FPCs becomes the new primary FortiGate-6000. The new primary FortiGate-6000 sends gratuitous arp packets out all of its connected interfaces to inform attached switches to send traffic to it. Sessions then resume with the new primary FortiGate-6000.
If the secondary FortiGate-6000 experiences an FPC failure, its status in the cluster does not change. However, in future negotiations the FortiGate-6000 with an FPC failure is less likely to become the primary FortiGate-6000.