Connect the primary and backup FortiGates to each other and to your network as shown. Making these connections disrupts network traffic as you disconnect and re-connect cables.
Switches must be used between the cluster and the ISPs and between the cluster and the internal network as shown in the network diagram. You can use any good quality switches to make these connections. You can also use one switch for all of these connections as long as you configure the switch to separate traffic from the different networks.
The example shows the recommended configuration of direct connections between the lan4 heartbeat interfaces and between the lan5 heartbeat interfaces.
When the heartbeat interfaces are connected, the FortiGates find each other and negotiate to form a cluster. The primary FortiGate synchronizes its configuration to the backup FortiGate. The cluster forms automatically with minimal or no additional disruption to network traffic.
The cluster will have the same IP addresses as the primary FortiGate had. You can log into the cluster by logging into the primary FortiGate CLI or GUI using one of the original IP addresses of the primary FortiGate.