Abstract: With the development of network, a single controller cannot meet the control needs of a large number of switches, which needs to be handled by multiple controllers. This paper uses the improved k-means++ algorithm to divide the topological graph into an undirected graph and the shortest path problem of the undirected graph. The graph is divided by the weight of the edge, and the weight is weighted by link bandwidth and transmission delay. The load balance and cost of the two methods are compared to obtain the multi-controller deployment strategy. Subsequently, by adopting a traffic balanc- ing strategy for multiple paths in the network, the data is reasonably distributed on different paths, so that the network traffic is distributed more evenly and the network performance is higher. Experimental verification shows that when multiple paths are available for data packets, the transmission path can be selected reasonably to balance the load of each path in the network. 

Key words: SDN, load balancing, multi-controller deployment, k-means++ algorithm