nfiguration. Therefore, F1AP signaling (e.g. configuration update) is used by gNB-DU and gNB-CU to exchange configuration information, which has been configured in each node by OAM. One example that illustrates the principle described above is the SI. Generally, gNB-DU is responsible for generating MIB and SIB1 system information, while the rest of the system information is controlled by gNB-CU. The information for the MIB and SIB1 is configured by OAM. However, since in certain cases (e.g. SI delivery using dedicated RRC signaling) a gNB-CU needs to know that information, whenever it is changed a gNB-DU propagates that information to the gNB-CU using F1AP signaling. For additional information about OAM support for CU/DU split, see Section 6.5. Addi- tional details related to OAM are specified in 3GPP TS 28.541. 4.2.4 Further Reading Full information about the CU/DU split NG-RAN architecture and related protocols described in this chapter can be found in the 3GPP technical specifications provided below. References 3GPP TS 38.401 is the general stage-2 specification covering all the NG-RAN aspects, including the CU/DU split, and it is a good starting point for an interested reader to under- stand the details beyond what is described in this chapter. Once a reader has familiarized himself with the high-level aspects, we suggest learning the details of the control-plane signaling, defined in 3GPP TS 38.473. To understand the user-plane aspect, a reader must proceed to read both 3GPP TS 38.425 and 3GPP TS 29.281.4 Finally, 3GPP TS 28.541 can be used to gain an understanding of OAM aspects of the CU/DU split, noting that this specifi- cation covers other nodes and architectures as well. References 3GPP Technical Report 38.801 (2017). Study on new radio access technology: Radio access architecture and interfaces. Available at: www.3gpp.org (accessed May 29, 2020). 3GPP Technical Specification 28.541 (2019).Management and orchestration; 5G Network Resource Model (NRM); Stage 2 and stage 3. Available at: www.3gpp.org (ac