SMF: Session Management Function

The SMF — Session Controller

The Session Management Function owns the entire PDU session lifecycle from establishment through modification to release. When a UE requests data connectivity, the AMF forwards the request to an appropriate SMF via N11. The SMF then allocates an IP address for the UE using either DHCPv4, DHCPv6, or static assignment from a configured pool. It selects the most suitable UPF based on the data network name, UE location, and network slice, and then programs that UPF with forwarding rules via PFCP on the N4 interface. The SMF is the brain that controls how user data flows through the network.