5G • Core Network
CUPS
Control and User Plane Separation
The architectural principle decoupling control plane signaling from user plane data traffic to allow independent scaling and edge deployment.
Technical Explanation
Introduced in 3GPP Release 14 for 4G and perfected in 5G, CUPS decouples control plane functions (AMF, SMF, PCF) from user plane forwarding (UPF). Controlled by the Packet Forwarding Control Protocol (PFCP) over the N4 interface, CUPS allows operators to scale compute-intensive control functions centrally in regional data centers while pushing lightweight, high-speed UPFs to the network edge next to cell towers for ultra-low latency and local traffic breakout.
Key Functions
- Independent scalability of throughput (UPF) and signaling capacity (SMF/AMF)
- Deployment of UPF near the network edge without relocating control logic
- Standardized PFCP protocol on the N4 interface for multi-vendor interoperability
- Drastic reduction of transport backhaul costs via local data offload
Specifications
3GPP TS 23.214, TS 23.501, TS 29.244
Interfaces
N4 (PFCP between SMF and UPF)
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