High availability with two FortiGates

1. Setting up registration and licensing

Make sure both FortiGates are running the same FortiOS firmware version. Register and apply licenses to the new FortiGate unit before adding it to the HA cluster.

This includes licensing for FortiCare Support, IPS, AntiVirus, Web Filtering, Mobile Malware, FortiClient, FortiCloud, and additional virtual domains (VDOMs).

All FortiGates in the cluster must have the same level of licensing for FortiGuard, FortiCloud, FortiClient, and VDOMs. FortiToken licenses can be added at any time because they are synchronized to all cluster members.

You can also install any third-party certificates on the primary FortiGate before forming the cluster. Once the cluster is formed, third-party certificates are synchronized to the backup FortiGate.

2. Configuring the primary FortiGate for HA

On the primary FortiGate, go to System > Settings and change the Host name to identify this as the primary FortiGate in the HA cluster.

Go to System > HA and set the Mode to Active-Passive. Set the Device priority to a higher value than the default (in the example, 250) to make sure this FortiGate will always be the primary FortiGate. Also, set a Group name and Password.

Make sure that two Heartbeat interfaces (in the example, port3 and port4) are selected and the Heartbeat Interface Priority for each is set to 50.

Since the backup FortiGate is not available, when you save the HA configuration, the primary FortiGate will form a cluster of one FortiGate but will keep operating normally.

If there are other FortiOS HA clusters on your network, you may need to change the cluster group ID using this CLI command.

config system ha
    set group-id 25
end

3. Connecting the backup FortiGate

Connect the backup FortiGate to the primary FortiGate and the network, as shown in the network diagram at the top of the recipe.

Making these network connections will disrupt traffic so you should do this when the network is not processing much traffic. If possible, make direct Ethernet connections between the heartbeat interfaces of the two FortiGate units.

Switches must be used between the cluster and the Internet, and between the cluster and the internal networks, 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.

4. Configuring the backup FortiGate for HA

Connect to the backup FortiGate GUI and go to System > Settings and change the Host name to identify this as the backup FortiGate.

Go to System > HA and duplicate the HA configuration of the primary FortiGate (except for the Device priority): set Mode to Active-Passive, and set the Device Priority to a lower value than the default to make sure this FortiGate will always be the backup FortiGate. Also, set the same Group name and Password as the primary FortiGate.

Make sure that the same two Heartbeat interfaces (port3 and port4) are selected and the Heartbeat Interface Priority for each is set to 50.

If you changed the cluster group id of the primary FortiGate, change the cluster group ID for the backup FortiGate to match, using this CLI command.

config system ha
    set group-id 25
end

When you save the HA configuration of the backup FortiGate, if the heartbeat interfaces are connected, the FortiGates will find each other and form an HA cluster. Network traffic may be disrupted for a few seconds while the cluster is negotiating.

5. Viewing the status of the HA cluster

Connect to the GUI of the primary FortiGate. The HA Status widget shows the cluster mode (Mode) and group name (Group).

It also shows the host name of the primary FortiGate (Master), which you can hover over to verify that the cluster is synchronized and operating normally. You can click on the widget to change the HA configuration or view a list of recently recorded cluster events, such as members joining or leaving the cluster.

6. Results

Traffic is now passing through the primary FortiGate. However, if the primary FortiGate becomes unavailable, traffic should fail over and the backup FortiGate will process traffic.

A failover also causes the primary and backup FortiGate to reverse roles, even when both FortiGates are available again.

To test HA failover, from a PC on the internal network, ping an IP address on the Internet (in the example, 8.8.8.8).

After a moment, power off the primary FortiGate. You will see a momentary pause in the ping results, until traffic fails over to the backup FortiGate, allowing the ping traffic to continue.

7. (Optional) Upgrading the firmware for the HA cluster

Upgrading the firmware on the primary FortiGate automatically upgrades the firmware on the backup FortiGate. Both FortiGates are updated with minimal traffic disruption.

Always review the Release Notes and Supported Upgrade Paths before installing new firmware.