Research On The Deployment Of Distributed SDN Controllers And Cross-domain Routing Technology

Software Defined Networking(SDN)is an emerging network architecture that decoups the data plane from the control plane to simplify network configuration and centralized network management.However,in practical applications,traditional SDN controllers manage and control the whole network information in a centralized manner,which is easy to lead to the problem of single point of failure,bringing challenges to network security and network scalability.With the application of SDN in data network,block chain and other fields,distributed controller architecture has become a research hotspot in recent years.Distributed controller architecture deploits multiple controllers in the network,each of which controls the forwarding behavior of switching nodes in the local network domain.One of the major research challenges of distributed controller architectures is to effectively utilize network resources,including control resources and communication resources.Control resources are closely related to the initial deployment of the network.The distribution of controllers determines the allocation of control resources to a large extent,and the allocation of communication resources is mainly reflected in the formulation of routing policies during network operation.Therefore,how to deploy the controller to the appropriate network location to divide the network domain and how to ensure the efficient completion of cross-domain end-to-end communication are the most important problems in distributed controller architecture.Aiming at the problem of controller deployment in distributed SDN network,this thesis designs a controller deployment model based on anycast technology based on anycast communication in IPv6.Firstly,the controller is set as an anycast node,and the switch uses anycast address to find the nearest controller node and establish a control connection with it.Through mathematical abstraction,a preliminary optimization model for the average control delay is established.Then,the controller load and network robustness in the network are analyzed in detail and the model is optimized.Through the redundant deployment of controllers,it is ensured that the switch has a backup controller node at a certain distance apart from the main controller.Finally,a controller deployment solution algorithm based on the bat algorithm is proposed for the above optimization model.Simulation results show that the controller deployment algorithm based on anycast technology can reduce the average network delay,improve network load balance and improve network robustness.Aiming at the problem of cross-domain routing in distributed SDN networks,this thesis proposes a cross-domain routing mechanism based on SRv6.The realization of cross-domain routing requires the cooperation of the control plane and the forwarding plane.For the control plane,in order to ensure compatibility,on the basis of the routing system of the existing controller architecture,this thesis adds cross-domain routing proxy components to complete the collection of path information in adjacent domains to achieve controller coordination; in order to reduce end-to-end delay,This thesis designs a delay detection and propagation mechanism based on virtual network coordinates to ensure that the controller node can know the path delay to other network domains,so as to obtain cross-domain paths with lower delay.For the forwarding plane,this thesis uses the characteristics of SRv6 to re-encapsulate the message to guide the forwarding node to forward the cross-domain path with lower latency.The simulation results under different networks and different data sets show that the SRv6-based cross-domain routing mechanism has good compatibility with traditional SDN networks,and can effectively reduce network cross-domain communication delays.