N8 Reference Point (AMF to UDM)

Also known as: N8 reference point, N8 interface

N8 is the 3GPP service-based reference point between the AMF and the UDM, exposing Nudm services for subscription data retrieval, registration status updates and access and mobility subscription management. It is one of the most sensitive interfaces in the 5G core because it fronts long-term subscriber data; TLS with OAuth 2.0 tokens and strict Nudm scope enforcement are required.

Categories: Core NetworkSecurity ControlsProtocols and Standards

N8 in context

The mobile core is where subscriber sessions, mobility and policy live. In 4G it is the EPC (MME, HSS, S/PGW); in 5G it is the Service-Based Architecture with AMF, SMF, UPF, AUSF, UDM and the NRF. Core exposure is the difference between a single-subscriber leak and a fleet-wide breach.

Security controls in telecom span signaling firewalls (SS7/Diameter/GTP screening at the network edge), transport encryption (IPsec, TLS, PRINS), identity and access on OSS/BSS, and monitoring at both the packet and log level. Controls are audited against GSMA FS.11/FS.19/FS.20/FS.36 and, in Europe, NIS2 sectoral rules.

To place N8 in the wider telecom-security picture, review N12, N3IWF, N6, N11, EAP-AKA′ and NAF.