Creating the Second Virtual Network Interface (VNIC)

As you select the previously created public-facing subnet when deploying both FortiMail A/B instances, you will see a private IP is assigned for port1 automatically in FortiMail GUI under System > Network > Interface. When editing this interface, you can modify the Advanced Settings as required, but you must keep the Addressing Mode settings as DHCP.

To use port 1 as a dedicated management interface, you need to add a new port for the Heartbeat between two FortiMail nodes, and the best practice is to locate each port in a different subnet.

Go to Networking > Virtual Cloud Networks and click the name of the previously created VCN, then click Create Subnet. Select Regional as Subnet Type, and Private Subnet as Subnet Access. Keep other settings as default for now, as you will need to modify them later.

Click Create Subnet, and you will find there are two subnets under your VCN now.

Then, go to Compute > Instances > FortiMail instance A, from Resources list, check the Attached VNIC and click Create VNIC. Select the previously created virtual cloud network and subnet, and make sure the option “Skip source/destination check” is enabled, as it is requested for setting target as private in route rules.

Then you can assign a private IP and specify a hostname as optional.

After clicking Save Changes, this VNIC will be displayed in the list. Then go to FortiMail instance B, and repeat this step.