5.8.2.17 Data exposure via Service Based interface

The UPF may expose information by means of UPF Event Exposure service as described in TS 23.502 [3] clause 5.2.26.2, via a service-based interface directly. The NF consumers, which may receive UPF event notifications, are AF/NEF, TSNAF/TSCTSF, SMF and NWDAF/DCCF/MFAF.

When the UPF supports the data exposure via the service based interface, it may register its NF profile to the NRF including the UPF Event Exposure services and the related Event ID(s).

For data collection from UPF (see clause 4.15.4.5 of TS 23.502 [3]), NF consumers can do the subscription to the UPF either directly or indirectly via SMF. As described in clause 4.15.4.5.1 of TS 23.502 [3], for User Data Usage events (i.e. User Data Usage Measures and User Data Usage Trends) or Abnormal traffic pattern event, an NF consumer should subscribe to the UPF Event Exposure service directly if target of data collection is "any UE" or if target of data collection is a UE IP address and if the subscription is not including any of the following parameters: AoI, BSSID/SSID and DNAI. Otherwise, the NF consumer shall subscribe indirectly via SMF.

NOTE 1: Direct subscription to UPF is more efficient, therefore it is recommended that NF consumer subscribes directly to UPF whenever possible.

NOTE 2: The UE IP address is used to discover the PSA UPF serving the particular UE IP address. The NF consumer can only use the UE IP address to discover PSA UPF(s) that serve the corresponding IPv4 address/IPv6 prefix range and register the corresponding information in the NRF.

Upon release of an N4 Session, the UPF implicitly terminates subscriptions for a UE related to the N4 Session. When the N4 Session to the UPF is released and the UPF received the Subscription termination reporting indication, the UPF shall send a notification with a subscription termination indication and an optional cause code to the UPF event consumer. When the N4 Session to the UPF is released, the UPF may report to the consumer any data that has been collected but not sent to the consumer yet, if UPF received the Remaining data reporting indication and/or based on local configuration (see clause 4.15.4.5 of TS 23.502 [3]).

To alleviate the load of UPF due to frequent event notification for data collection related events, the event subscription may include Reporting suggestion information. The Reporting suggestion information includes Reporting urgency information and Reporting window information. Reporting urgency information represents whether this event report can be delay tolerant, i.e. the event report can be delayed. If the Reporting urgency information indicates "delay tolerant", the Reporting window is also provided, which defines the last valid reporting time and UPF shall report the event before that time. If the Reporting suggestion information allows this, the UPF can concatenate several event reports (of the same event) to the same notification endpoint into one notification message.

The UPF may also expose UE information by means of the Nupf_GetUEPrivateIPaddrAndIdentifiers service as described in clause 5.2.26.3 of TS 23.502 [3]. An UPF which is deployed with NAPT (Network Address Port Translation) functionality may support to provide the 5GC UE IP address to NEF based on NEF request containing public IP address and port number using the Nupf_GetUEPrivateIPaddrAndIdentifiers service as described in clause 4.15.10 of TS 23.502 [3] for AF specific UE ID retrieval.

The UPF event exposure service may allow NF consumer to obtain one NATed UE public IP address and Port number for a particular PDU Session, based on the UE private IP address allocated by 5GC. An UPF which is deployed with NAT functionality may support to provide the UE public IP address and port number to consumer based on Nupf_EventExposure_Subscribe request as defined in clause 5.2.26.2.3 of TS 23.502 [3]. For information flow for getting UE public IP address and port number, see clause 6.2.8.2.4 of TS 23.288 [5].