软件定义网络中基于效率区间的负载均衡在线优化算法

An Efficient Online Algorithm for Load Balancing in Software Defined Networks Based on Efficiency Range

在大型复杂软件定义网络中,为提高网络负载均衡,减少控制器与交换机间的传播时延,该文提出一种基于效率区间的负载均衡在线优化算法。在初始静态网络中,通过贪心算法选择初始控制器集合,并以其为根节点构建M棵改进代价的最小生成树(MST),确定初始M个负载均衡的子网;当网络流量发生变化时,通过广度优先搜索(BFS)调整子网间交换机映射关系使其满足效率区间,保证任意时刻网络的负载均衡。算法均以网络连通性为基础,且均以传播时延为目标重新更新控制器集合。仿真实验表明,该算法在保证任意时刻网络负载均衡的同时,可以保证较低的传播时延,与Pareto模拟退火算法、改进的K-Means算法等相比,可以使网络负载均衡情况平均提高40.65%。

Due to the limitation of individual controller’s processing capacity in large-scale complex Software Defined Networks (SDN), an efficient online algorithm for load balancing among controllers based on efficiency range is proposed to improve load balancing among controllers and reduce the propagation delay between a controller and the switch. In the initial static network, the initial set of controllers is selected by a greedy algorithm, then M improved Minimum Spanning Trees (MST) rooted at the initial set of controllers are constructed, so initial M subnets with load balancing are determined. With the dynamic changes of load, for the purpose of making the controller work within efficiency range at any time, several switches in different subnets are reassigned by Breadth First Search (BFS). The initial set of controllers is updated for minimizing propagation delay in the algorithms’ last step. The algorithm is based on the connectivity of intra-domain and inter-domain. Simulation results show that the proposed algorithms not only guarantee the load balancing among controllers, but also guarantee the lower propagation delay. As to compare to PSA algorithm, optimized K-Means algorithm, etc., it can make Network Load Balancing Index (NLBI) averagely increase by 40.65%.