When does FortiGate look up routing for new sessions?

FortiGate looks up routing for new sessions specifically on the first packet from the originator and the responder. This process is crucial because it determines how the device will route the traffic based on the session initiation. When the first packet from either end of a communication is received, FortiGate checks the routing table to find the appropriate interface and gateway for the traffic, which is vital for establishing a session. The device uses this information to set up the necessary session and facilitate the ongoing communication between the two endpoints.

To clarify further, packet verification and the establishment of a session occur at different stages. While packet verification ensures the integrity and validity of packets that have either already been seen in an established session or are just being processed, it does not involve routing decisions. Similarly, conversation initiation is a more general term that could refer to any part of the communication process, but the specific routing lookup is tied to the first packet being processed. Thus, the unique role of the first packets in routing makes this choice the right one for this scenario.