SSION RESOURCE SETUP REQUEST message. It encapsulates the NAS PDU to be sent to the UE. 3 5G System Overview 20. The gNB configures the DRB(s) for the PDU session using an RRC Reconfiguration message, which also encapsulates the NAS PDU to be sent to the UE. It can also provide other radio configuration such as physical layer, measurements, etc. 21. The UE replies with an RRC Reconfiguration Complete message upon successful com- pletion of the configuration. 22. The gNB indicates the successful completion using the NG-AP PDU SESSION RESOURCE SETUP RESPONSE message. An RRC Reconfiguration message is used to provide most of the UE configurations while the UE is in the CONNECTED state, such as RB configurations, measurement configura- tion, physical layer configuration, etc. Additionally, it can be used to configure dual connectivity. Some part of the configu- rations may be generated by another node, either by the DU in the case of CU/DU split of a gNB or another gNB in the case of dual connectivity. The configuration generated by another node is carried within containers in the RRC Reconfiguration message and can be forwarded transparently by the serving gNB or gNB-CU putting together the final RRC Reconfiguration message sent to the UE. This is to allow the other nodes to support configurations or even to be of different 3GPP releases that may not be sup- ported or comprehended by the serving gNB-CU. Some notable examples are discussed further below. The RLC bearer and physical layer configuration may be put together by the gNB-DU and is provided in the container, CellGroupConfig. The RBConfig carries the SDAP and PDCP configurations and could be provided by the master or secondary gNB-CU in the case of dual connectivity. There are two containers defined in the RRC Reconfiguration message SO that the UE behavior is the same irrespective of whether the RBConfig is originated from the master or secondary cell group. The snippet of the ASN.1 below shows the usage of the containers in the RRC Reconfiguration message.