An Analysis ofSDNControllers Software

Abstract

Multi‐controllers can effectively improve the scalability and stability of the control plane in software‐defined networking (SDN) and is becoming a promising solution in large‐scale networks. In this article, we present a research survey for multi‐controller SDN control plane. We categorize the multi‐controller research into two aspects: homogeneous control plane and heterogeneous control plane. For homogeneous control plane, the network uses multiple same types of controllers to achieve the integrative control of the network. The homogeneous structure provides convenience for unified management and maintenance, but poses four critical problems: extending the number of controllers; processing load variance resulting in load imbalance on controllers; unreasonable placement causing low availability; conflicting strategy going against consistency. Heterogeneous multi‐controller SDN control plane that employs different types of controllers has been recently proposed to improve the utilization of control resource and the operation security of control plane. However, due to the increasing number of backdoors and various programming languages, the heterogeneous structure suffers from diverse vulnerabilities and incompatibility problems of different types of controllers. Thus, security and convergence of heterogeneous controllers become two important research topics. We present the research challenges and existing solutions of the aforementioned problems and further propose some promising future researches.