Building the routing table

In the factory default configuration, the FortiGate unit routing table contains a single static default route. You can add routing information to the routing table by defining additional static routes.

It is possible that the routing table is faced with several different routes to the same destination—the IP addresses of the next-hop router specified in those routes or the FortiGate interfaces associated with those routes may vary. In this situation, the “best” route is selected from the table.

The FortiGate unit selects the “best” route for a packet by evaluating the information in the routing table. The “best” route to a destination is typically associated with the shortest distance between the FortiGate unit and the closest gateway, also known as a next-hop router. In some cases, the next best route may be selected if the best route is unavailable.

The FortiGate unit installs the best available routes in the unit’s forwarding table, which is a subset of the unit’s routing table. Packets are forwarded according to the information in the forwarding table.