Research On SDN Multi-controller Placement And Dynamic Switch Migration Mechanism

Software Defined Network(SDN)is a new emerging network architecture.Compared to traditional IP networks,the architecture decouples the control layer from the forwarding device and concentrates it into controllers.This modification achieves great improvement in openness and flexible management of the network.As a new type of architecture,SDN still has many technical problems remain unsolved.A new multi-controller deployment scheme and dynamic switch migration algorithm are proposed in this paper after the study on how to improve the scalability of SDN.This paper analyzed several key factors that could influence the network scalability according to the research on the basic principles of data transmission and path request in SDN data plane.The advantages and disadvantages of different multi-controller deployment schemes were tested by carrying out extensive numerical simulations.Besides,a new dynamic switch migration mechanism is proposed to improve the performance of the network by adjusting the mapping relations among controllers and switches.Firstly,the general principles of data-packet transmitting is studied with the modified Jackson model applied to the SDN network.In order to do further research into controllers'capacity,the processing delay distribution and load distribution in the network are theoretically analyzed under different request rates and service rates.The effectiveness of the modified model is verified through the simulations carried out by MATLAB.Secondly,a new De-Marginalization(DM)algorithm is designed to improve the defects of the existing schemes used in multi-controller deployment,such as k-center and k-median algorithms.By applying DM algorithm,the best control nodes combination is established during the iteration of optimizing the connectivity and stability of the network.The optimized deployment schemes has been validated by evaluating the concerned statistics collected in the simulations.Finally,a dynamic switch migration solution based on the Self-Optimizing Mechanism(SOM)is designed to make full use of the resource of SDN controllers,as well as improving the load balance degree among those controllers.By comparing the relevant parameters of each domain,the proposed mechanism can quickly select appropriate target switches and migrating destinations.One of the advantages is that it achieved flexible management of SDN control plane by local dynamic adjustment.Simulation results verified that the proposed mechanism can enhance the balance among controllers,and reduce the flow setup latency,while the computation complexity during the migrating process is kept at a reasonable level.