Logically Centralized Path Computation In SDN Network

Network programming is the core idea in the software-defined networks, to quickly determine the behavior of the network in real time by the software, real-time reconstruction of the network to optimize network resources utilization is the biggest target in software defined networks. This thesis is done in the context of software-defined networks.Nowadays the network has become more complex and diverse than it at the birth of the Internet. Network hardware and software status in the world’s countries vary, with a complex and diverse forms. Large-scale network may involves large networks composed of heterogeneous networks, large-scale network may consist of a plurality of carrier networks. In this paper, large-scale network composed of subregions. OpenFlow is a technology in software-defined networks. OpenFlow network managed by a controller, Open Flow is in a centralized control way. For the drawbacks of centralized control, this thesis presented a way to computing the path in large large-scale network, to resolve the big network scale problem and the heterogeneous network problems. Among these networks which serve as the manager is that the routing framework described in this article and the routing calculation information exchange method.This paper describes the complete multi-domain routing implementation process in detail, including data acquisition, calculation and execution. OpenFlow network centralized control by the controller, the heterogeneous network managed by different controllers for customized management. Making the large network into multiple levels of multiple regions, each region both independent management and mutual cooperation. First, we proposed a network load balancing and congestion avoidance algorithms for a single LAN which under high load conditions, and then compare with other routing algorithm. The algorithm works out the paths result and put into the offline alternative paths, the path calculation module will select the right path in real-time, in order to improve backup options’ success rate and speed up the response speed of the system. Then, the regions use the routing information exchange process to complete the path computing in layered large-scale network through gathering routing information, routing algorithm calculation, and deploy the path in the network. Specifically, the upper controller coordinate the behavior of the subregions, the routing management work done by the highest level controller-based guidance stepwise down to the lowest level controller, eventually forming domain autonomy, inter-domain interoperability in accordance with standard communication in the large-scale network. Then we verified the correctness and feasibility of routing information exchange process by experiment. Consider the complexity of path computation limitations in the network and more competition at resources among businesses in large public network, the computational complexity shortcomings. We proposed virtual network mapping scheme, in the virtual network service exclusive virtual network resources, route calculation is simple. This paper designed a two-stage virtual network mapping algorithm, and then compared with other virtual network mapping algorithm. And then this paper extended it to inter-domain mapping algorithm, use inter-domain path computation to map inter-domain links. Finally this article completely designed the path calculation methods in large-scale network.