Research And Implementation Of Flow Table Matching Algorithm For Software Defined Network Based On DPI

With the deep research in software defined network(SDN) as well as the advance of SDN innovative application, it is a trend to combine SDN and other technologies. Although DPI can parse the key information of packets, it can't make the corresponding strategy to process packets. And the key information of packets is parsed by DPI, and then corresponding strategy is made by SDN. Based on the analysis and research of matching field in SDN flow table and OpenFlow,a new flow table matching algorithm for is proposed in the thesis. And the URL, parsed by DPI, is added into matching field in SDN table. Besides, the URL will be matched by multi-mode matching algorithm based on identifying the application type, which is proposed in this article. By this way, it can effectively use the information of the DPI resolution and also improve the efficiency of packet forwarding.First of all, system design scheme of the table matching algorithm is proposed in the thesis by analysis purpose of the subject and the features of match field of table. In this thesis, by studying the structure of matching field in OpenFlow, the code module in Open vSwitch, and the circulation way of packets in switch, then the process of modifying the matching field is designed. Based on the comparison of 3 classical multi-mode matching algorithms, such as AC, Wu-Manber and SBOM algorithm, AC algorithm and Wu-Manber algorithm are applied in the string matching module. In order to achieve optimization of algorithm performance, this thesis proposes the new improvements of the 2 algorithms.Secondly, according to the design scheme of system, implement the table matching algorithm. The structure of SDN flow table is modified and the string of URL is added into fields matching field. And the multi-mode matching algorithm based on identifying the application type is proposed for the new column in the matching field. The new algorithm consists of the implementation of AC and Wu-Manber algorithm to realize the different length of the URL adaptively choosing corresponding algorithms. After identifying the application type of packets, complete packets forwarding.Finally, the system of the flow table matching algorithm is tested. And Open vSwitch is installed on X86 and OpenDayLight is installed on Windows. Then the system of the flow table matching algorithm is tested. The test results show that packets forwarding are successfully completed when specify the switch port, and the specified application types of packets will be detected in the corresponding switch port.