In a re-allocation process of a first user plane function network element to a second user plane function network element, a session management function network element sends a respective session modification request to each anchor user plane function network element of a plurality of anchor user plane function network elements, where each session modification request includes information about the second user plane function network element; and indicates to only a first anchor user plane function network element in the plurality of anchor user plane function network elements to send an end marker; or sends the end marker to only the first anchor user plane function network element.