Abstract: In a logically centralized but physically distributed multi-controller software-defined networking (SDN) environment, the placement of controllers directly impacts network performance, including latency and load balancing. Therefore, the multiple controllers placement (MCP) problem is a crucial issue in SDN. Based on this analysis, a heuristic SDN MCP mechanism that integrates the genetic algorithm (GA) and k-medoid clustering algorithm, termed the GA-K-Medoids MCP mechanism, is proposed. This mechanism aims to minimize the propagation delay between controllers and switches, as well as among controllers. The performance of the proposed MCP mechanism is evaluated using two common network topologies, Internet2 OS3E and Palmetto, and compared with other mechanisms. Simulation results demonstrate that the GA-K-Medoids MCP can provide an effective and low-latency controller placement solution for multi-controller SDN.

Key words: software-defined networking(SDN), evolutionary algorithm(EA), multiple controllers placement（MCP）