PFCP CP and UP match identification is similar to that used by GTPv1. For GTPv1, the tunnel endpoint ID (TEID) is the primary method of matching UP tunnels to CP sessions. In PFCP this is commonly known as the Fully Qualified TEID or F-TEID and has the same use and function as TEID in GTP-C/U.
FortiOS Carrier uses the F-TEID as the primary match criteria for CP to UP messages.
CP communication with UP (for example, PGW-C to PWG-U) can include a Forwarding Action Rule (FAR). A FAR can consist of up to 5 different instructions, including the DROP action, which is notified by the CP to the UP using the DROP flag. For example, the CP may periodically instruct the UP to drop packets for situations when the session is no longer valid.