Algorithm to Balance Load of Controllers in Software-Defined Network

Abstract

This paper proposes an algorithm to resolve the imbalance state in a software-defined network in which orchestrated multiple-controller architecture is applied. In the orchestrated multiple-controller architecture, a super-controller recognizes load of all controllers in the network and run a load balancing process. Controllers process flow requests from switches based on the decision of the super-controller. The load of a controller in this paper includes a propagation delay and the number of packet-in messages, since the controller needs to wait for a response from the instruction requested switch for a flow installation. The load balancing is a technique to efficiently use the resources, to increase throughput, to reduce the response time for a request, and to avoid the imbalance state of all controllers. When the imbalance state is detected by the super-controller, requests of a switch in a controller with the maximum load are transferred to process at another available controller. Load of the maximum controller is reduced. A load balancing algorithm to pair switch and controller is introduced to minimize the maximum load of all controllers. Computer simulation result shows that the proposed algorithm reduces up to 79.11% of the average standard deviation, which indicates the imbalance state, of all controllers, compared to a conventional scheme.