UPF

Technical Explanation

The UPF represents the foundational user plane evolution of 5G, replacing the LTE SGW-U and PGW-U. It processes user IP/Ethernet traffic at ultra-high throughput and ultra-low latency. It is controlled exclusively by the SMF over the N4 interface using PFCP. Because the UPF is decoupled from control plane logic, it can be dynamically instantiated at central data centers, regional sites, or far edge/on-premise MEC (Multi-Access Edge Computing) locations for localized traffic breakout.

Key Functions

• Packet routing, packet inspection, and packet forwarding (GTP-U encapsulation/decapsulation)
• Anchor point for Intra/Inter-RAT mobility (PDU Session Anchor - PSA)
• Uplink and Downlink QoS enforcement, rate policing (MBR/GBR), and traffic shaping
• Local breakout (UL CL / Branching Point) to route traffic directly to local edge computing networks
• Buffering of downlink packets and triggering data notification to SMF for paging