N11 Interface
The N11 interface is the reference point between the Access and Mobility Management Function (AMF) and SMF.
To request a new session, both the UE and the gNB use the Next Generation Application Protocol (NGAP) to carry Non Access Stratum (NAS) messages across the N1 or N2 interface. AMF receives these requests and handles the connectivity and mobility management. Then, the AMF forwards the session management related requirements over the N11 interface to the SMF. The AMF identifies the SMF that can handle the connection request by querying the Network Repository Function (NRF).
The messages that SMF receives over the N11 interface are the requests to add, modify, or delete a PDU session across the user plane.