Section: 10.9.1 EN-DC
Content: The eNB to Master Node change procedure is used to transfer context data from a source eNB to a target MN that adds an SN during the handover. Figure 10.9.1-1: eNB to Master Node change Figure 10.9.1-1 shows an example signaling flow for eNB to Master Node change: 1. The source eNB starts the handover procedure by initiating the X2 Handover Preparation procedure. 2. The target MN sends SgNB Addition Request to the target SN. 3. The target SN replies with SgNB Addition Request Acknowledge. If data forwarding is needed, the target SN provides forwarding addresses to the target MN. NOTE 0: Void. 4. The target MN includes within the Handover Request Acknowledge message a transparent container to be sent to the UE as an E-UTRA RRC message, including a NR RRC configuration message which also includes the SCG configuration, to perform the handover, and may also provide forwarding addresses to the source eNB. 5. The source eNB triggers the UE to apply the new configuration. 6/7. The UE synchronizes to the target MN and replies with RRCConnectionReconfigurationComplete message. 8. If configured with bearers requiring SCG radio resources, the UE synchronizes to the target SN. NOTE 0: The order the UE performs Random Access towards the target MN (step 6) and performs the Random Access procedure towards the target SN (step 8) is not defined. 9. If the RRC connection reconfiguration procedure was successful, the target MN informs the target SN. 10. For bearers using RLC AM, the source eNB sends the SN Status Transfer message, which the target MN forwards then to the target SN, if needed. 11. Data forwarding from the source eNB takes place. 12-15. The target MN initiates the S1 Path Switch procedure. NOTE 1: If new UL TEIDs of the S-GW are included, the target MN performs MN initiated SN Modification procedure to provide them to the target SN. 16. The target MN initiates the UE Context Release procedure towards the source eNB. NOTE 2: Void. NOTE 3: Void.