Section: 4.4.3.5 N4 PFD management Procedure
Content: This N4 procedure is used by the SMF to provision or remove all PFD(s) belonging to an Application Identifier in the UPF. PFD sets belonging to different Application Identifiers can be managed with the same PFD management request message. The N4 PFD management procedure is a node level procedure, i.e. independent of any PDU Session. Figure 4.4.3.5-1: PFD management in the UPF 1. The SMF is triggered to provision or remove the PFD set belonging to an Application Identifier in the following cases: When the caching timer expires and there's no active PCC rule that refers to the corresponding application identifier, the SMF informs the UPF to remove the PFD(s) identified by the Application Identifier. When a PCC rule is provided for an Application Identifier corresponding to the PFD(s) that are not already provided to the UPF, the SMF shall provide the PFD(s) to the UPF (if there are no PFD(s) cached, the SMF retrieves them from the NEF (PFDF), as described in TS 23.503[ Policy and charging control framework for the 5G System (5GS); Stage 2 ]  [20]). When any update of the PFD(s) is received from NEF (PFDF) and there are still active PCC rules in UPF for the Application Identifier. 2. The SMF sends a PFD management request to the UPF to provision/remove the PFD(s) corresponding to the Application Identifier(s). 3. The UPF updates the PFD(s) according to the request and acknowledges by responding with a PFD management response message.