A communications method, apparatus, and system to implement handover between session management network elements, where a target session management network element sends a first message to a source session management network element based on the information about the source session management network element received. After receiving the first message from the target intermediate session management network element, the source session management network element indicates, based on the first message, a source intermediate user plane network element to establish a forwarding tunnel. As such, the forwarding tunnel between the source intermediate user plane network element and a target intermediate user plane network element is established, and the source intermediate user plane network element can forward data to the target intermediate user plane network element through the forwarding tunnel.