5G Reference Points

In telecom networks, 5G Reference Points such as N1, N2, N3, N4, N6, N9, and N11 define logical interfaces between the UE, RAN, and core Network Functions. N1 is the NAS link between UE and AMF, N2 carries control plane between RAN and AMF, N3 carries user plane between RAN and UPF, N4 is the SMF-to-UPF interface, N6 connects UPF to data networks, N9 interconnects UPFs, and N11 links AMF and SMF.

Categories: Radio Access NetworkCore NetworkSignaling

5G Reference Points in context

The radio access network is where mobile devices attach to the operator's infrastructure. Attacks in this layer include IMSI catching, rogue base stations and downgrade attacks; defenses rest on mutual authentication, integrity-protected signaling and Open RAN supply-chain hygiene.

The mobile core carries subscriber sessions, mobility and policy. 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.

To place 5G Reference Points in the wider telecom-security picture, review IPsec, SC, Service-Based Architecture (SBA) Security, TCAP, Patch Management and NGAP: each entry cross-references back to this page so you can walk the topic in either direction.

Related terms

Related topic hubs

  • 5G Security 5G SBA, SEPP, SUCI, 5G-AKA, N32 and service-based interface security.
  • GTP Security GTP-C/GTP-U threats across S5/S8, N3/N9 and GRX/IPX borders under GSMA FS.20.
  • Signaling Firewall Unified SS7/Diameter/GTP/SMS signaling firewall framework.
  • Roaming Security IPX/GRX interconnect risk, home-routed vs local-breakout, SEPP.

More from the TelcoSec Glossary

Browse the full TelcoSec Glossary, the Ultimate Guide to Mobile Network Security, or the P1 Arsenal of telecom-security tools.