Feature Description

The SMF is one of the control plane NFs that provide the Session Management service in the 5G core network. The SMF manages the PDU session lifecycle through the following session management procedures:

  • PDU Session Establishment

  • PDU Session Modification

  • PDU Session Release

This chapter describes the policy and user plane management features.

  • Policy Management—Policy Control Function (PCF) or the local configuration controls the policies managed on SMF. The PCF sends Policy and Charging Control (PCC) rules along with the applicable QoS and charging information to the SMF. The SMF uses this information to define QoS flows and apply QoS enforcement (via User Plane Function (UPF) and charging towards Charging Function (CHF). The PCC rules can be configured locally as well. The locally configured policy rules are labelled as static or predefined rules.

  • User Plane Management—The user plane management on SMF includes selection of UPF and maintaining per session and node level user plane data. The SMF performs Path management of the UPF nodes. At a per session level, SMF publishes the Packet Detection Rules (PDRs), QoS Enforcement Rules (QERs), Forwarding Action Rules (FARs), and Usage Reporting Rules (URRs) to the UPF. Then, the SMF enforces the policy rules received from PCF or configured locally.