Research On Software Defined Networking Controller Scalability

Software Defined Networking, known as SDN, is a novel architecture that decouples the control plane from the data plane, and opens a programmable network in a centralized way. In the SDN network, SDN controller, known as networking operating system, is the key part of SDN.It offers northbound interface for the upper-layer applications, and manages all the network devices through the southbound interface Openflow protocol.SDN achieves a flexible and highly efficient management over the network, making the network more programmable and extensible. SDN controller plays a significant part of the future carrier network, however,its current architecture, core function modules, open interfaces and protocols are not enough to support these features. For example, innovative services-oriented carrier network proposes that it should satisfy the critical requirement in low-delay transmission and on-demand dynamic network construction. Openflow has been widely accepted and becomes the de facto standard of the SDN southbound interface, but OpenFlow is hard to support all of carrier network, such as optical networks. Apart from that, different controllers have different northbound APIs, which limit the scalability of network services and applications. In this paper, we conduct a comprehensive research on SDN controller scalability, specific tasks are as follows:(1) Propose a common SDN controller scalability model, analyze its key technology, including core functionality modules and its extension,Openflow protocol evolution and Openflow extension, restful API and so on.(2) Research on the core functionality modules of the SDN controller which reflects the key features of future network innovative services,propose a method that combining network construction with routing to extend the core function. Besides, we put the core function extended SDN(Ex-SDN) controller together with Coordinate Controller for the multiple domains architecture design and routing analysis.(3) Develop the Ex-SDN controller software based on the Opendaylight controller which supports scale-free network construction and route extensions. Develop the function visualization Web APP,providing the portal to view and operate the network topology, network construction, flow pre-configuration and so on. Build Mininet simulation environment to simulate Optically-routed network(ORN) topology,analysis the average number of hopes and network delay controlled by Ex-SDN controller and Opendaylight controller. Experimental results show that the Ex-SDN controller has improved greatly in the decline of the average number of hops and network delay. The conclusion network construction and route extension modules worked, and it verified the core function scalability of the SDN controller.