A software-defined networking, SDN, system for implementing data forwarding, wherein the SDN system comprises an SDN control device and n switching devices, a first switching device is a switching device connected to a source end of data, an n th switching device is a switching device connected to a destination end of the data, and n≥3; wherein: the first switching device is configured to request a forwarding rule from the SDN control device, wherein the request carries characteristic information of the data; the first switching device is further configured to: receive a first forwarding rule returned by the SDN control device, wherein the first forwarding rule comprises information about a path from the first switching device to the n th switching device, the information containing signposts of switching devices on the path, and a reactive flow entry comprising a match condition: the characteristic information of the data and an execution action: encapsulating the information about the path from the first switching device to the n th switching device and sending, to a port on which a second switching device is connected to the first switching device, the data in which the information about the path is encapsulated; and send, to the second switching device, the data and the information about the path from the first switching device to the n th switching device according to the first forwarding rule; and the second switching device is configured to: receive the data and the information about the path from the first switching device to the n th switching device that are sent by the first switching device; query, according to a signpost of a third switching device in the information about the path from the first switching device to the n th switching device, a second forwarding rule stored in the second switching device; obtain a port, on the second switching device, which connects the second switching device to the third switching device; and forward the data to the third switching device through said port. the first switching device is configured to request a forwarding rule from the SDN control device, wherein the request carries characteristic information of the data; the first switching device is further configured to: receive a first forwarding rule returned by the SDN control device, wherein the first forwarding rule comprises information about a path from the first switching device to the n th switching device, the information containing signposts of switching devices on the path, and a reactive flow entry comprising a match condition: the characteristic information of the data and an execution action: encapsulating the information about the path from the first switching device to the n th switching device and sending, to a port on which a second switching device is connected to the first switching device, the data in which the information about the path is encapsulated; and send, to the second switching device, the data and the information about the path from the first switching device to the n th switching device according to the first forwarding rule; and the second switching device is configured to: receive the data and the information about the path from the first switching device to the n th switching device that are sent by the first switching device; query, according to a signpost of a third switching device in the information about the path from the first switching device to the n th switching device, a second forwarding rule stored in the second switching device; obtain a port, on the second switching device, which connects the second switching device to the third switching device; and forward the data to the third switching device through said port.