3GPP 23.501 v20.2.0 — the document's own text
8.2.1.3 5G-AN - SMF
Taught in 8. What actually travels on the wire (The 5G system architecture, in depth).

Legend:
- N2 SM information: This is the subset of NG-AP information that the AMF transparently relays between the 5G-AN and the SMF and is included in the NG-AP messages and the N11 related messages.
NOTE 1: From the 5G-AN perspective, there is a single termination of N2 i.e. the AMF.
NOTE 2: For the protocol stack between the AMF and the SMF, see clause 8.2.3.