5.5 F-TEID Allocation and Release

29.2443GPPInterface between the Control Plane and the User Plane nodesRelease 17TS

5.5.1 General

For EPC and 5GC, F-TEID shall be only allocated by the UP function, see clause 5.8.2.3 of 3GPP TS 23.501 [28].

The UP function shall set the FTUP feature flag in the UP Function Features IE (see clause 8.2.25) and the CP function shall request the UP function to allocate the F-TEID. The UP function shall reject a request to establish a new PDR with an F-TEID allocation in the CP function option, with the cause "Invalid F-TEID allocation option". As an exception, the UP Function shall accept the PFCP Session Establishment Request message with a PDR including an existing F-TEID to re-establish a PFCP session during a restoration procedure as specified in clause 4.3.2 of 3GPP TS 23.527 [40] and clauses 16.1A.4 and 17.1A.4 of 3GPP TS 23.007 [24].

5.5.2 Void

5.5.3 F-TEID allocation in the UP function

The CP function shall request the UP function to allocate the F-TEID by setting the CHOOSE flag in the Local F-TEID IE of the PDR IE (see Table 7.5.2.2-1). The Source Interface IE indicates for which interface the F-TEID is to be assigned.

The CP function may request the UP function to allocate the same F-TEID to several PDRs to be created within one single PFCP Session Establishment Request or PFCP Session Modification Request by:

– setting the CHOOSE flag in the Local F-TEID IE of each PDR to be created with a new F-TEID; and

– setting the CHOOSE ID field of the Local F-TEID IE, for each PDR to be created with the same F-TEID, with the same CHOOSE ID value;

or, if the UP function indicated support of the PDI optimization (see clause 8.2.25), by:

– including the Local F-TEID IE only in the Create Traffic Endpoint IE and by setting the CHOOSE flag in the Local F-TEID IE of this IE; and

– including the Traffic Endpoint ID in all the PDRs to be created with the same F-TEID.

If the PDR(s) is created successfully, the UP function shall return the F-TEID(s) it has assigned to the PDR(s) or to the Traffic Endpoint(s) in the PFCP Session Establishment Response or PFCP Session Modification Response.

Upon receiving a request to remove a PDR or a Traffic Endpoint, or to delete a PFCP session, the UP function shall free the F-TEID(s) that was assigned to the PDR if there is no more PDR with the same F-TEID, to the Traffic Endpoint or to the PFCP Session.

When using redundant GTP-U transmission on N3/N9 interfaces (see clause 5.24.2), the CP function shall request the UP function to allocate the F-TEID for the redundant GTP-U tunnel following the same requirements as specified in this clause, using the "Local F-TEID for Redundant Transmission" IE instead of the "Local F-TEID" IE.