The global flow table based on the software-defined networking

With the rapid development of SDN, its security problem is increasingly outstanding. Because of the openness and intelligence of SDN, the flow can be dispatched and controlled globally by the network controller. However there is not a mechanism that provides a clear visibility of the distribution, path and traffic of the whole network flows for the security equipment. Now many security detection methods need to know the distribution and behaviors of the global flows. So the paper proposes a new mechanism named global flow table and corresponding algorithms to realize the global flows' collection, the whole network flow path computation and global flows storing. This method can provide both the global details of the whole network topology and the key information of per flow mentioned above conveniently and directly for the security equipment. And we also design a structure to store the details of all flows. Then we analyze the time performance of the algorithm theoretically. The experimental result verifies the theoretical analysis and concludes that the algorithm has a good time performance. The primary affecting factors of the algorithm are the number of the flow tables and the ratio of the links to the switches.