PFCP (Packet Forwarding Control Protocol)

Also known as: Packet Forwarding Control Protocol, Sx, N4 Protocol

PFCP is the 3GPP protocol (TS 29.244) between control and user plane functions on the Sxa/Sxb/Sxc interfaces (EPC CUPS) and the N4 interface in 5G. It lets the SMF program forwarding, QoS and usage-reporting rules into the UPF, and lets the SGW-C program the SGW-U. Exposed PFCP endpoints are a critical attack surface: manipulation can redirect user traffic, disable lawful intercept or exfiltrate session data.

Categories: Core NetworkProtocols and Standards

PFCP in context

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.

Telecom security is written into standards from 3GPP, GSMA, ETSI, IETF and ITU-T. Understanding which body owns which specification, and how they interlock, is essential for both design and audit work.

To place PFCP in the wider telecom-security picture, review N4, PCF, DoT, SMF, ZIP and RANAP: each entry cross-references back to this page so you can walk the topic in either direction.

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