MULTI_IP_SUBNET is a guest operating system feature flag, which you can enable when creating the VM by using the command line, a deployment manager template, or Terraform. The following shows the commands:
gcloud compute instances create …
The following shows the deployment manager template:
- type: compute.v1.instance properties: disks: - boot: true guestOsFeatures: - type: MULTI_IP_SUBNET
You can verify that the instance was created using this option by clicking Equivalent REST at the bottom of the VM Instance details page or describing the instance using gcloud commands.
MULTI_IP_SUBNET scheme simplifies configuring routing in FortiGates. It uses the subnet configuration known from on-premise networks, where the interface IP address is configured with the subnet's full netmask, instead of 255.255.255.255. Static route configuration in FortiOS is necessary only for the CIDRs not directly connected to the firewall.