Automatic monitoring method of network topology

An automatic monitoring method of network topology, which utilizes a controller for looking for the network topology and cooperates with a plurality of routing rules to produce the optimal packet transmission path that is written into a flow table corresponding to nodes of optimal transmission paths, so as to transmit each packet flow to a destination interface according to the optimal transmission path, if the node or link is interrupted, an automatic restore procedure will determine whether to take backup path or re-arrange the optimal transmission path, such that the packet flow still able to act the most efficient path, thus reducing the costs of network resources and maintaining the network system.