5G • Core Network
N3 Interface
N3 Reference Point (NG-U)
User plane reference point between gNodeB and UPF running GTP-U over UDP/IP.
Technical Explanation
N3 transports all user plane data traffic between the radio base station and the 5G Core User Plane Function (UPF). Packets are encapsulated in GTP-U tunnels tagged with TEIDs and QFI headers for per-flow scheduling.
Key Functions
- Transports user plane IP and Ethernet traffic between gNodeB and UPF
- Encapsulates packets using GTP-U tunneling protocol
- Carries 6-bit QFI in extension headers for end-to-end QoS enforcement
Specifications
3GPP TS 23.501, TS 29.281
Interfaces
N3
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