Chapter 18 Troubleshooting : Life of a Packet : Packet flow : Routing
  
Routing
The routing step determines the outgoing interface to be used by the packet as it leaves the FortiGate unit. In the previous step, the FortiGate unit determined the real destination address, so it can now refer to its routing table and decide where the packet must go next.
Routing also distinguishes between local traffic and forwarded traffic and selects the source and destination interfaces used by the security policy engine to accept or deny the packet.