Further, when the second node is donor node 2 (or a central unit of donor node 2, or a control-plane part of a central unit of donor node 2) in FIG. 6C, the above process may further include that: the second node sends an address update message to donor node 1 (or a central unit of donor node 1, or a control-plane part of a central unit of donor node 1, or a user-plane part of a central unit of donor node 1) in the figure. The information serves to inform the donor node 1 (or the central unit of donor node 1, or the control-plane part of the central unit of donor node 1, or the user-plane part of the central unit of donor node 1) to use the updated information for data transmission. Specifically, it further includes the steps of: