5G • Core Network
N4 Interface
N4 Reference Point (PFCP)
Control/User plane separation interface between SMF and UPF running PFCP protocol.
Technical Explanation
The N4 interface implements 3GPP Control and User Plane Separation (CUPS). The SMF programs packet handling rules into the UPF using the Packet Forwarding Control Protocol (PFCP): Packet Detection Rules (PDR), Forwarding Action Rules (FAR), and QoS Enforcement Rules (QER).
Key Functions
- Decouples Session Management Function from high-speed User Plane Function
- Runs Packet Forwarding Control Protocol (PFCP) over UDP port 8805
- Programs packet routing, QoS policing, and charging rules into UPF hardware
Specifications
3GPP TS 23.501, TS 29.244
Interfaces
N4
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