针对控制平面连通效能优化的控制器布置方法
A Placement Strategy of Controllers for Optimizing the Connectivity of Control Plane

针对控制器间通信时延大、信息交互困难和全网视角难以维护的问题,提出了一种针对控制平面连通效能优化的控制器布置方法。该方法在保证负载均衡和服务质量的基础上将控制器布置问题建模成为一个K？？center问题,并对指标优化下的控制器布置位置和个数进行了刻画。为求解该模型,设计了相应的基于连通效能的两阶段优化算法:第一阶段通过设置节点的优先级别和搜索范围参数,在确保控制器准确布置的前提下缩小了解的搜索范围,得到了线性松弛下的搜索半径;第二阶段输入第一阶段的结果,通过不断调整指针最终确定控制器的布置位置。仿真结果表明:该方法实现了控制器的最优化部署,减少了控制器间的平均时延,方便了控制层面的信息交互,与CCP方法相比,在保证时延和负载均衡的同时使运算复杂度和连通效能得到了明显改善,在OS3E拓扑中的解搜索范围减小了30％,不同拓扑中的平均连通效能最大减小了15％。
A placement strategy of controllers for optimizing the connectivity of control plan is proposed to decrease communication latency among controllers, to improve the message communication and to remain a global view of the whole network. The controller placement problem is formulated as a K？？center problem based on the load balance and QoS. The number of controllers and their placements are also studied with optimization. A 2？？stage optimization algorithm based on connectivity is designed to solve the model. In the first stage of the algorithm, the node priority and the search variables are set to reduce the search scope and to ensure the accurate placement, until a search diameter is achieved under linear relaxation. The results of the first stage are used as the inputs of the second stage, and the final placement of controllers is obtained through the pointer adjustment. Simulation results show that the proposed strategy realizes the optimization of controller placement, reduces the average inner？？controller latency and improves the communication in the control plane. A comparison with the CCP strategy shows that the strategy decreases the algorithm complexity and improves the connectivity of control plane with the consideration of the latency and load balance. The search scope of the solution space reduces by 30% in OS3E, and the average connectivity for different topologies increases about 15%