A Survey on Controller Placement in Software-Defined Networks

Software-defined networks (SDNs) are an emerging area in computer networks, enabling efficient resource management in the network by decomposing data and control plans. In SDNs, network controllers acting as the network operating systems, are responsible for serving application programs. Since a control plan consists of several controllers, the placement of network controllers is a challenging issue in complex networks. While the literature has explored the number of controllers and their placement in the network, several fundamental parameters remain unexplored. Therefore, this topic remains open for more investigations. In this paper, we survey the work in the literature on controller placement in SDNs and introduce the research challenges in this area. Additionally, we present potential future research directions to advance this field.