5.28 Downlink data delivery status with UPF buffering (for 5GC)

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

5.28.1 General

Stage 2 requirements for the support of Downlink data delivery status notification with UPF buffering are specified in clause 5.8.3.2 of 3GPP TS 23.501 [28] and clauses 4.15.3.2.8 and 4.15.3.2.9 of 3GPP TS 23.502 [29].

If the UP function supports the Downlink data delivery status notification with UPF buffering, the UP function shall set the DDDS feature flag in the UP Function Features IE (see clause 8.2.25). If so, the CP function may request the UP function to notify the first buffered DL packet and / or the first discarded DL packet for the traffic matching the downlink PDR by set the BUFF flag, BDPN flag and DDPN flag in the Apply Action IE of the FAR. The CP function may also provide the DL Buffering Duration IE and DL Buffering Suggested Packet Count IE in the related BAR to the UP function.

The UP function shall report the first buffered DL packet for each service data flow identified by a PDR, by sending a PFCP Session Report Request including a Downlink Data Report IE identifying the PDR(s) for which downlink packets have been received. The UP function shall also report the first discarded DL packet for each service data flow identified by a PDR if the DL Buffering Duration or DL Buffering Suggested Packet Count is exceeded. DL Data Status IE shall be included in the Downlink Data Report IE to indicate the report is triggered by the Downlink data delivery status with UPF buffering when the first DL packet is buffered or discarded.

NOTE The CP function can request the UP function to report the first buffered DL packet by setting the BDPN flag and / or the NOCP flag in the Apply Action IE of the FAR. If the BDPN flag is set, the UP function reports the first buffered DL packet for each service data flow identified by a PDR associated to the FAR. If the NOCP flag is set, the UP function reports the first buffered DL packet of any PDR associated to the FAR, i.e. if there are subsequent DL packets (pertaining to different service data flow identified by other PDRs associated to the FAR), there is no new report sent to the CP function.

If the UP function supports the Downlink data delivery status notification with UPF buffering, the CP function may also request the UP function to drop the DL packets directly and send a notification for the traffic matching the downlink PDR by set the DROP flag and DDPN flag in the Apply Action IE of the FAR.

The UP function shall report the dropped DL packets for each service data flow identified by a PDR, by sending a PFCP Session Report Request including a Downlink Data Report IE identifying the PDR(s) for which downlink packets have been received.