Research And Implementation Of SDN Network Measurement System

With the rapid development of computer information technology and the increment of network scale, the performance of network has become the first concern of Internet users. The research and development of network measurement technology can help network managers and researchers to know network performance in time for troubleshooting and to understand more about network behavior. With the emergence and rise of Software-Defined Networking (SDN), the research of SDN network measurement is getting more and more attention. Compared with traditional IP network, SDN framework seperates control logic from data plane, the controller is able to intensively manage flow forwarding in the data plane, which is an advantage for the innovation of network measurement. As the mainstream protocol of SDN southbound interface, OpenFlow have the enabling conditions to achieve measurement functions in SDN environment. However, OpenFlow protocol still needs improvement in order to obtain more detailed packet-level information.The thesis first introduces SDN framework and OpenFlow as well as the concept of network measurement. The thesis summarizes current SDN network measurement research in three contexts:performance balance, resource utilization and real-time measurement. On this basis, the thesis proposes a centralized controlled SDN network measurement system basd on OpenFlow protocol. The system is able to collect link parameters and flow information from the network to achieve measurement functions on network topology, link performance and flow status. The main work is as follows:(1) The thesis makes use of the framework of switch counters and message format such as PACKT_IN and STATS_REQUEST. Through the active detection and passive flow collection, the thesis achieves functions such as topology measurement and delay measurement.(2) In view of the existence about traffic sampling deficiencies, the thesis proposed a sampling measurement method based on OpenFlow extension. On the data plane, the switch is able to sample specified flows through flow table matching by using new sampling action. On the control plane, the thesis designs sampling rules based on multiple flow tables and group table. The controller is able to collect and analyze traffic samples and achieves measurement functions on specified flows or links.(3) The thesis learns about Ryu controller and Open vSwitch platform. Event-handling mechanism and service-binding mechanism of Ryu, and the secondary developing method of Open vSwitch is elaborated. The thesis implements the system on related platforms and carries on the function test to validate the usability of measurement modules. Finally, the thesis proposes further improvement of the system, and the future research directions are also discussed.