FGCP HA: active-passive vs active-active, heartbeat links, primary election (monitored ports, uptime, priority, serial, override)

FortiGate Clustering Protocol (FGCP) joins two or more identical FortiGates into one high-availability (HA) cluster that survives the failure of a single unit. To form a cluster the members must match on hardware model and firmware, and share the same HA group ID, group name and password. Hostnames and management IPs stay unique per member. The cluster presents shared virtual MAC and IP addresses so the network sees one device.