Backhaul — N2/N3 and legacy S1/X2 transport

5G Backhaul: N2 and N3 Interfaces

The 5G backhaul carries two primary interfaces between the gNB (or O-CU) and the 5G Core. The N2 interface transports control plane signaling between the gNB and the AMF using NGAP protocol over SCTP. The N3 interface carries user plane data between the gNB and the UPF using GTP-U tunnels over UDP/IP. N2 traffic is lightweight — typically tens of megabits per second per site — but demands high reliability since control plane failures affect all users on the cell. N3 traffic dominates backhaul bandwidth, carrying all subscriber data with volumes matching the aggregate radio throughput of the…