5.11 User plane inactivity detection and reporting

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

5.11.1 General

This clause specifies the support of user plane inactivity detection and reporting.

5.11.2 User plane inactivity detection and reporting per PDN connection or PDU session

Clause 5.4.4.1 of 3GPP TS 23.401 [14] requires the PGW to initiate the release of an inactive emergency PDN connection.

Clauses 4.3.7 and 4.3.2.2.2 of 3GPP TS 23.502 [29] require the SMF to be able to initiate the deactivation of the UP connection of an existing PDU session without user plane activity for a given inactivity period, except for the H-SMF for the home routed roaming scenario or except for an always-on PDU session as described in clause 5.6.8 of 3GPP TS 23.501 [28].

Clauses 4.3.5.7, 4.23.9.4 and 4.23.9.5 of 3GPP TS 23.502 [29] requires the SMF to be able to initiate the deactivation of the UP connection of an existing PDU session in source UL CL or source UPF (e.g. PSA2) if no active traffic over the N9 forwarding tunnel is detected and reported by the Source UL CL. Clause 4.23.9.4 of 3GPP TS 23.502 [29] also requires the SMF to release the N9 forwarding tunnel of an existing PDU session in the target UL CL/BP if no active traffic over the N9 forwarding tunnel is detected and reported by the Source UL CL.

Clause 7.2.5.3 of 3GPP TS 23.247 [72] requires the MB-SMF to be able to initiate the deactivation of an MBS session without user plane activity.

The CP function may request the UP function to detect and report when no user plane packets are received for a PFCP session, by provisioning the User Plane Inactivity Timer IE in the PFCP Session Establishment Request or PFCP Session Modification Request.

Upon being provisioned with this IE, the UP function shall monitor the user plane activity of the PFCP session and report any user plane inactivity exceeding the duration indicated by this IE by sending a PFCP Session Report Request with the Report Type set to UPIR (User Plane Inactivity Report). The UP function shall then continue to process any further user plane packets as instructed by the rules provisioned for the PFCP session, until receiving any new instruction from the CP function.

5.11.3 User plane inactivity detection and reporting per PDR

Clause 4.23.9.5 of 3GPP TS 23.502 [29] requires the target I-SMF to be able to initiate the release of the N9 forwarding tunnel of an existing PDU session in the target UL CL/BP if no active traffic over the N9 forwarding tunnel is detected and reported by the target UL CL/BP.

When both the CP function and the UP function support the UPIDP feature (see clause 8.2.25), the CP function may request the UP function to detect and report when no user plane packets are received for one or more PDRs, by provisioning a URR including the User Plane Inactivity Timer IE and by associating this URR with the PDR(s) in a PFCP Session Establishment Request or PFCP Session Modification Request.

Upon being provisioned with this URR, the UP function shall monitor the user plane activity of all the PDR(s) associated with the URR and report user plane inactivity when no traffic has been received for any PDR(s) associated with the URR for the duration indicated in the User Plane Inactivity Timer IE by sending a PFCP Session Report Request with the Report Type set to USAR (Usage Report) and with the Usage Report Trigger IE set to UPINT (User Plane Inactivity Timer).