e to establish the UE con- text in the gNB-DU. In this message, it may also encapsulate the RRC Security Mode Command message. 12. The gNB-DU sends the RRC Security Mode Command message to the UE. 13. The gNB-DU sends the UE Context Setup Response message to the gNB-CU-CP. 14. The gNB-CU-CP sends the E1AP Bearer Context Modification Request message to the gNB-CU-UP, with a list of PDU sessions to modify, including F1-U DL TEID and the transport layer address received from the gNB-DU. This step is necessary since it is the gNB-DU that allocates the F1-U downlink transport layer addresses. 15. Similar to step 10, if the procedure is successful, the gNB-CU-UP sends the E1AP Bearer Context Modification Response message to the gNB-CU-CP. The message carries the list of successfully modified PDU sessions, together with the list of DRBs for each PDU session and their parameters. 16. The UE responds with the RRC Security Mode Complete message. 17. The gNB-DU encapsulates the RRC message in the F1AP UL RRC Message Transfer message and sends it to the gNB-CU-CP. 18. The gNB-CU-CP generates the RRC Connection Reconfiguration message and encap- sulates it in the F1AP DL RRC Message Transfer message. 19. The gNB-DU sends the RRC Connection Reconfiguration message to the UE. 20. The UE sends the RRC Connection Reconfiguration Complete message to the gNB-DU. 21. The gNB-DU encapsulates the RRC message in the F1AP UL RRC Message Transfer message and sends it to the gNB-CU-CP. 22. The gNB-CU-CP sends the Initial UE Context Setup Response message to the AMF. 4.4.3.2 OAM Aspects It is generally assumed that a gNB-CU-CP and a gNB-CU-UP have independent man- agement interfaces and are managed by the OAM somewhat separately. Therefore, in the beginning, the peer nodes are not aware of each other's configuration and certain E1AP procedures have been defined to allow both nodes to exchange relevant configuration infor- mation. For example, once the gNB-CU-UP is reconfigured, parameters such as the NR CGI Support List, Slice Support List