A method for improving service reliability includes deciding, by a session function entity in a network, to initiate establishment of at least two transmission paths between a terminal and the user plane function entity, and instructing the terminal or the user plane function entity to transmit same data on the at least two paths. The user plane function allocates, based on a notification of the session function entity, user plane resources to the at least two transmission paths, and transmits the same data with the terminal on the at least two transmission paths. A core network initiates the establishment of the at least two transmission paths to the terminal. Two access devices may independently establish the at least two transmission paths.