Protocol Dictionary (Protocol)¶
A dictionary for looking up the main protocols used in 5GC by their layer, role, upper/lower relationships, and purpose.
Related: Interface Dictionary / Message Dictionary / Registration chapter
Protocol List¶
| Protocol | Layer/Role | Upper/Lower | Main Purpose | Spec |
|---|---|---|---|---|
| NAS (Non-Access Stratum) | Control signaling between UE⇔AMF. Includes 5GMM (mobility management) / 5GSM (session management) | Upper: application/session layer / Lower: RRC (radio), NGAP (N2) | UE-to-core control such as registration, authentication, and session requests | TS 24.501 |
| NGAP (NG Application Protocol) | Control between (R)AN⇔AMF (N2 application layer) | Upper: carries NAS-PDU / Lower: SCTP | NG Setup, UE-associated signalling, context management | TS 38.413 |
| SCTP | Transport for N2 (reliable message-oriented transfer) | Upper: NGAP / Lower: IP | Transport of NGAP signaling | RFC 4960 (port 38412) |
| HTTP/2 | Transport for SBI (Service Based Interface) | Upper: SBI API (JSON, etc.) / Lower: TCP (TLS-protected) | Service-based communication between NFs | RFC 7540 / TS 29.500 |
| TLS | Protection of SBI communication (confidentiality, integrity, authentication) | Upper: HTTP/2 / Lower: TCP | Encryption and protection of SBI messages | TS 33.501 |
| GTP-U | User plane encapsulation (GTP User Plane) | Upper: user data / Lower: UDP/IP | User data transfer over N3/N9 | TS 29.281 |
| PFCP (Packet Forwarding Control Protocol) | N4 session control | Upper: SMF-UPF control / Lower: UDP/IP | Setting and controlling UPF forwarding rules (PDR/FAR, etc.) | TS 29.244 |
About the SCTP Port Number
The SCTP destination port for N2 (NGAP) is 38412 as the registered value (TS 38.412).