Section: 8.9.2 Bearer context setup over F1-U
Content: Figure 8.9.2-1 shows the procedure used to setup the bearer context in the gNB-CU-UP. Figure 8.9.2-1: Bearer context setup over F1-U 0. Bearer context setup (e.g., following an SGNB ADDITION REQUEST message from the MeNB) is triggered in gNB-CU-CP. 1. The gNB-CU-CP sends a BEARER CONTEXT SETUP REQUEST message containing UL TNL address information for S1-U or NG-U, and if required, DL TNL address information for X2-U to setup the bearer context in the gNB-CU-UP. For NG-RAN, the gNB-CU-CP decides flow-to-DRB mapping and sends the generated SDAP and PDCP configuration to the gNB-CU-UP. NOTE: In case of Conditional Handover or Conditional PSCell Addition/Change, the BEARER CONTEXT SETUP REQUEST message indicates to ignore the included security context and not to initiate sending downlink packets until the UE successfully accesses. Up to implementation, the gNB-CU-CP may request to establish bearer context as if a regular HO was requested. 2. The gNB-CU-UP responds with a BEARER CONTEXT SETUP RESPONSE message containing the UL TNL address information for F1-U, and DL TNL address information for S1-U or NG-U, and if required, UL TNL address information for X2-U or Xn-U. NOTE: The indirect data transmission for split bearer through the gNB-CU-UP is not precluded. 3. F1 UE context setup procedure is performed to setup one or more bearers in the gNB-DU. 4. The gNB-CU-CP sends a BEARER CONTEXT MODIFICATION REQUEST message containing the DL TNL address information for F1-U or Xn-U, and PDCP status. NOTE: In case the indirect path indication is received in step 4, the gNB-CU-UP may not discard the DL data based on the Downlink Data Delivery Status frame received from the gNB-DU. During the inter-gNB indirect-to-direct or indirect-to-indirect path switching, the source gNB-CU-UP forwards the buffered DL data to the target gNB as specified in TS 38.300[ NR; NR and NG-RAN Overall description; Stage-2 ]  [2]. 5. The gNB-CU-UP responds with a BEARER CONTEXT MODIFICATION RESPONSE message.