Section: 4.3.6.4 Transferring an AF request targeting an individual UE address to the relevant PCF
Content: Figure 4.3.6.4-1: Handling an AF request targeting an individual UE address to the relevant PCF Depending on the AF deployment (see clause 6.2.10 of TS 23.501[ System architecture for the 5G System (5GS) ]  [2]), the AF may send the AF request to PCF directly, in which case step 1 is skipped, or via the NEF. 1. [Conditional] If the AF sends the AF request via NEF, the AF sends Nnef_TrafficInfluenceCreate/Update/Delete Request targeting an individual UE address to the NEF. This request corresponds to an AF request to influence traffic routing to a local network and/or to a service function chain that targets an individual UE address. When NEF receives an AF request from AF, the NEF ensures the necessary authorization control and as described in clause 4.3.6.1, mapping from the information provided by the AF into information needed by the 5GC. The NEF responds to the AF. 2. [Conditional] AF/NEF consumes Nbsf_Management_Discovery service operation (providing at least the UE address) to find out the address of the relevant PCF if the PCF address is not available on the NEF based on local configuration, otherwise step 1 is skipped. NOTE 1: The AF/NEF finds the BSF based on local configuration or using the NRF. 3. BSF provides the PCF address in the Nbsf_Management_Discovery response to AF/NEF. 4. If step 1 was performed, NEF invokes the Npcf_PolicyAuthorization service to the PCF to transfer the AF request. If an AF sends the AF request directly to the PCF, AF invokes Npcf_PolicyAuthorization service and the PCF responds to the AF. To support the AF instance change, the Npcf_PolicyAuthorization_Create (initiated by target AF) or Npcf_PolicyAuthorization_Update (initiated by source AF or target AF) service operation may be used. NOTE 2: If the source AF transfers the application context to the target AF, then target AF may create new subscription via Npcf_PolicyAuthorization_Create or update existing subscription via Npcf_PolicyAuthorization_Update. However, whether and how the application context transfer is done is out of this specification. 5. The PCF authorizes the AF request. If the PCF determines that the requirements can't be authorized, it rejects the AF request. Once the PCF authorizes the AF request, the PCF updates the SMF with corresponding new PCC rule(s) with PCF initiated SM Policy Association Modification procedure as described in clause 4.16.5.2. The PCF includes the Traffic Steering Policy ID(s) for AF influence on traffic routing Enforcement Control information and/or N6-LAN Traffic Steering Enforcement Control information in the relevant PCC rule as defined in clause 6.3.1 of TS 23.503[ Policy and charging control framework for the 5G System (5GS); Stage 2 ]  [20]. The PCF may, optionally, use service experience analytics per UP path, as defined in clause 6.4.3 of TS 23.288[ Architecture enhancements for 5G System (5GS) to support network data analytics services ]  [50], to provide a an updated list of DNAI(s) to the SMF. If Npcf_PolicyAuthorization_Update service operation is invoked, the PCF is required to update the subscription resource. The Npcf_PolicyAuthorization_Update service operation may include an updated notification target address. The updated subscription resource is used by the target AF. When a PCC rule is received from the PCF, the SMF may take appropriate actions, when applicable, to reconfigure the User plane of the PDU Session. In the case of AF influence on traffic routing, examples of actions are: - The SMF may consider service experience analytics and/or DN Performance analytics per UP path (i.e. including UPF and/or DNAI and/or AS instance) as defined in clauses 6.4.3 and 6.14.3, respectively, of TS 23.288[ Architecture enhancements for 5G System (5GS) to support network data analytics services ]  [50] before taking any actions. - Determining a target DNAI and adding, replacing or removing UPF(s) in the data path, e.g. to act as UL CL, Branching Point and/or PDU Session Anchor e.g. as described in clause 4.3.5. - Allocate a new Prefix to the UE (when IPv6 multi-Homing applies). - Updating the UPF regarding the target DNAI with AF influence on traffic routing control parameters as described in clause 5.6.7.1 of TS 23.501[ System architecture for the 5G System (5GS) ]  [2]. - Subscribe to notifications from the AMF for an Area of Interest via Namf_EventExposure_Subscribe service operation. - Determining whether to relocate PSA UPF considering the user plane latency requirements provided by the AF (see clause 6.3.6 of TS 23.548[ 5G System Enhancements for Edge Computing; Stage 2 ]  [74]). In the case of AF influence on Service Function Chaining, the SMF may take appropriate actions to enforce the N6-LAN traffic steering control: - Provide N6-LAN traffic steering control parameters to UPF as described in clause 5.6.16 of TS 23.501[ System architecture for the 5G System (5GS) ]  [2].