NGAP (NG Application Protocol)

Also known as: NG Application Protocol, N2 Application Protocol

NGAP is the 3GPP signalling protocol between the 5G gNB and the AMF over the N2 reference point, defined in TS 38.413. It carries UE context management, mobility, PDU session management triggers, NAS transport and paging. NGAP runs over SCTP and is a primary attack surface for RAN-to-core exposure; it is also the 5G analogue of LTE's S1AP.

Categories: Radio Access NetworkCore NetworkSignaling

NGAP 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 NGAP in the wider telecom-security picture, review 5G SA, AMF, Base Station (BS), Capacity Planning, CAPEX and CSCF — each entry cross-references back to this page so you can walk the topic in either direction.

Related terms

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