An apparatus comprising: logical nodes including a gNB central unit, gNB-CU, and a gNB distributed unit, gNB-DU, the gNB-CU comprising a gNB-CU control plane, gNB-CU-CP, for control-plane functionality, a gNB-CU user plane, gNB-CU-CP, for user-plane functionality, the gNB-CU-CP configured to communicate with the gNB-CU-UP over an E1 interface, the gNB-CU-UP configured to communicate user plane messages with the gNB-DU over an F1 user-plane interface, F1-U, the gNB-CU-CP configured to communicate control plane messages with the gNB-DU over an F1 application protocol, F1-AP, used on an F1 control plane interface, F1-C, wherein the apparatus is configured to: transmit or receive first messages according to an E1 application protocol, E1-AP, the first messages including: a GNB-CU-UP E1 setup request message from the gNB-CU-UP to the gNB-CU-CP, wherein the E1 setup request message includes a gNB-CU-UP ID that is at least a local ID; a radio bearer configuration message from the gNB-CU-CP to the gNB-CU-UP over the E1 interface to configure one or more data radio bearers, DRBs, wherein the radio bearer configuration message includes a user equipment ID and a DRB ID; a reset message over the E1 interface from the gNB-CU-UP to the gNB-CU-CP or from the gNB-CU-CP to the gNB-CU-UP; an error indication message over the E1 interface from the gNB-CU-UP to the gNB-CU-CP indicating a cause of the error; transmit or receive second messages according to the F1-AP, the second messages including: a UE context setup request message from the gNB-CU-CP to the gNB-DU over the F1-C, wherein the UE context setup message is configured to include quality-of-service parameters; a UE context modify message from the gNB-CU-CP to the gNB-DU over the F1-C, wherein the UE context modify message is configured to include quality-of-service parameters; a UE context release message from the gNB-CU-CP to the gNB-DU over the F1-C; and an uplink radio-resource control, RRC, message including a PDCP-PDU from the gNB-DU to the gNB-CU-CP over the F1-C. transmit or receive first messages according to an E1 application protocol, E1-AP, the first messages including: a GNB-CU-UP E1 setup request message from the gNB-CU-UP to the gNB-CU-CP, wherein the E1 setup request message includes a gNB-CU-UP ID that is at least a local ID; a radio bearer configuration message from the gNB-CU-CP to the gNB-CU-UP over the E1 interface to configure one or more data radio bearers, DRBs, wherein the radio bearer configuration message includes a user equipment ID and a DRB ID; a reset message over the E1 interface from the gNB-CU-UP to the gNB-CU-CP or from the gNB-CU-CP to the gNB-CU-UP; an error indication message over the E1 interface from the gNB-CU-UP to the gNB-CU-CP indicating a cause of the error; a GNB-CU-UP E1 setup request message from the gNB-CU-UP to the gNB-CU-CP, wherein the E1 setup request message includes a gNB-CU-UP ID that is at least a local ID; a radio bearer configuration message from the gNB-CU-CP to the gNB-CU-UP over the E1 interface to configure one or more data radio bearers, DRBs, wherein the radio bearer configuration message includes a user equipment ID and a DRB ID; a reset message over the E1 interface from the gNB-CU-UP to the gNB-CU-CP or from the gNB-CU-CP to the gNB-CU-UP; an error indication message over the E1 interface from the gNB-CU-UP to the gNB-CU-CP indicating a cause of the error; transmit or receive second messages according to the F1-AP, the second messages including: a UE context setup request message from the gNB-CU-CP to the gNB-DU over the F1-C, wherein the UE context setup message is configured to include quality-of-service parameters; a UE context modify message from the gNB-CU-CP to the gNB-DU over the F1-C, wherein the UE context modify message is configured to include quality-of-service parameters; a UE context release message from the gNB-CU-CP to the gNB-DU over the F1-C; and an uplink radio-resource control, RRC, message including a PDCP-PDU from the gNB-DU to the gNB-CU-CP over the F1-C. a UE context setup request message from the gNB-CU-CP to the gNB-DU over the F1-C, wherein the UE context setup message is configured to include quality-of-service parameters; a UE context modify message from the gNB-CU-CP to the gNB-DU over the F1-C, wherein the UE context modify message is configured to include quality-of-service parameters; a UE context release message from the gNB-CU-CP to the gNB-DU over the F1-C; and an uplink radio-resource control, RRC, message including a PDCP-PDU from the gNB-DU to the gNB-CU-CP over the F1-C.