Policy routing allows you to specify an interface to route traffic. This is useful when you need to route certain types of network traffic differently than you would if you were using the routing table. You can use the incoming traffic's protocol, source or destination address, source interface, or port number to determine where to send the traffic.
When a packet arrives, the FortiGate starts at the top of the policy route list and attempts to match the packet with a policy. For a match to be found, the policy must contain enough information to route the packet. At a minimum, this requires the outgoing interface to forward the traffic, and the gateway to route the traffic to. If one or both of these are not specified in the policy route, then the FortiGate searches the routing table to find the best active route that corresponds to the policy route. If no routes are found in the routing table, then the policy route does not match the packet. The FortiGate continues down the policy route list until it reaches the end. If no matches are found, then the FortiGate does a route lookup using the routing table.
The following topics include information about policy routes: