With the interfaces configured, now the FortiGate units can be configured for OSPF on those interfaces. All routers are part of the backbone 0.0.0.0 area, so there is no inter‑area communications needed.

For a simple configuration there will be no authentication, no graceful restart or other advanced features, and timers will be left at their defaults. Also the costs for all interfaces will be left at 10, except for the modem and ISP interfaces where cost will be used to load balance traffic. Nearly all advanced features of OSPF are only available from the CLI.

The network that is defined covers all the subnets used in this example - 10.11.101.0, 10.11.102.0, and 10.11.103.0. All routes for these subnets will be advertised. If there are other interfaces on the FortiGate units that you do not want included in the OSPF routes, ensure those interfaces use a different subnet outside of the 10.11.0.0 network. If you want all interfaces to be advertised you can use an OSPF network of 0.0.0.0 .

Each router will configure:

This section includes: