Design And Implementation Of A Highly Available SDN Multi-controller Architecture

As the trend of next generation network,software defined network proposes to decouple control plane from forwarding plane,and integrates control plane of network devices into a central one and provides programming interfaces.Network administrators can customize network behaviors with these interfaces.Compared to traditional networks,the centralized controller brings great flexibility and operability.In the meantime,many new problems spring up along with the single controller mechanism.Among them,one of which that cannot be ignored is the high availability of the centralized control plane.For example,single controller's performance bottleneck together with the controller's single point of failure have posed rigorous challenges to the high availability of SDN control plane.This paper focuses on the design and implementation of a multi-controller architecture under software defined network.That is,using multiple controllers cooperating together to improve availability of the control plane.We review the design concepts of existing multi-controller architectures from the beginning,and propose a new multi-controller architecture named HACon.HACon is built through hierarchical architecture model as well as controller grouping and controller master/slave mechanism.The Global network is divided into separate autonomous domains,each of which is managed by a different controller.All controllers cooperate with each other forming a load balance group abbreviated as LBG.Each one in LBG selects m controllers from the others as backups,and form a fault-tolerant group abbreviated as FTG.FTG introduces master/slave scheme to realize fault-tolerant mechanism.Number of controllers participated in the network is reduced by combining LBG and FTG together.Hence,network resource utilization is increased while improving the availability of the control plane.This paper concentrates on the discussion of the high availability of SDN control plane.We implement a hierarchical multi-controller architecture based on existing hardware and network protocols.Experiments show that the main advantages of HACon are as follows: 1.effectively improves the scalability of the control plane;2.facilitates fault tolerance of the control plane,thereby greatly enhances the availability of the control plane.