JPL 5G Binding Support Function (BSF) Partner Validated

This service allows the Policy Control Function to register the PDU session binding information for a UE in the BSF by providing the user identity, the DNN, the UE address(es), and the selected PCF address for a certain PDU session to the BSF. The BSF stores this information and keeps mapping the UEs with the PCF instances.

This service operation allows NEF of AF to retrieve the address information of the selected PCF. It takes binding details as an input. The discovery can be based on the UE address, SUPI, DNN, or S-NSSAI and IPv4 address domain.

This service operation allows the PCF to update an existing session binding information for a UE in the BSF by providing information to be updated (such as the UE address/es) for a PDU session, and based on that the BSF updates the session binding information.

In proxy mode, when the BSF receives a request from an AF, it checks whether it has already selected a PCF for the Rx session, then it proxies the request to the corresponding PCF. 

In redirect mode, BSF acts like a Diameter Redirect Agent and sends the route information to the requesting node. The AF contacts the BSF on Rx session establishment to retrieve the PCF address. The BSF (redirect) does not maintain Diameter sessions, therefore, an AF should not send an Rx session modification or termination request to the BSF.