Inter-MN RRC Resume without MN initiated SN change is used to transfer UE context data from a source MN to a target MN while the UE context at the SN is kept. During the procedure, the target MN may decide not to keep the SN.
If the RRC connection reconfiguration procedure was successful, the target MN initiates the Xn Retrieve UE Context Confirm procedure and indicates to the source MN whether the UE context in the SN is kept or not.
The source MN sends SN Release Request message to the SN including a Cause indicating MCG mobility. The SN acknowledges the release request. The source MN indicates to the SN that the UE context in the SN is kept, if it receives the indication from the target MN. If the indication as the UE context kept in the SN is included, the SN keeps the UE context.
If received in step 10, the source MN sends the Xn-U Address Indication message to the SN to transfer data forwarding information. More than one data forwarding addresses may be provided if the PDU session is split in the target side.
The target MN initiates the Path Switch procedure. If the target MN includes multiple DL TEIDs for one PDU session in the Path Switch Request message, multiple UL TEID of the UPF for the PDU session should be included in the Path Switch Ack message in case there is TEID update in UPF.
Upon reception of the UE Context Release message from source MN, the SN releases C-plane related resources associated to the UE context towards the source MN. Any ongoing data forwarding may continue. The SN shall not release the UE context associated with the target MN if the UE context kept indication was included in the SN Release Request message in step 11.