MULTI_IP_SUBNET scheme

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 …

--guest-os-features MULTI_IP_SUBNET

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.

The 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.