Reserving internal addresses
Reserve six static internal addresses for both FortiGate instances (three per instance). A static internal IP address is required for the heartbeat interface (port3) and recommended for other NICs. The following shows an example command to reserve a private address:
gcloud compute addresses create addr-fgt1-port1 --region=REGION \ --subnet=SUBNET_EXT
Repeat this command six times for all three subnets and both FortiGate instances.