The NG user plane interface (NG-U) is defined between the NG-RAN node and the UPF. The transport network layer is built on IP transport and GTP-U is used on top of UDP/IP to carry the user plane PDUs between the NG-RAN node and the UPF.

NG-U provides non-guaranteed delivery of user plane PDUs between the NG-RAN node and the UPF.