Software-defined network congestion control algorithm based on stream segmentation

The invention claims a software-defined network congestion control algorithm based on stream segmentation and belongs to the technical field of communication networks. First, an SDN (software-defined network) controller initializes network topology and forwarding paths; the controller monitors traffic of all links by transmitting State-Request information periodically to a switch to query states of the switch and its ports, and then calculates load condition of each path; when the load of one path is greater than a set congestion threshold, a large stream on the path may be split into a plurality of sub-streams, and the controller schedules the sub-streams to the other available paths with light load by issuing corresponding stream tables; the controller queries the state of the switch periodically, and transmits a message of decreasing data packet rate to a source switch when usage of a cache of a target switch is excessive; the algorithm performs path reselection on data streams leading to link congestion a