I. Introduction
In Recent years, Internet of Things (IoT) has become an indispensable and important infrastructure to provide intelligent life, such as intelligent transportation system and smart home [1]. The increase of network users promotes the rapid development of IoT. As a special paradigm of IoT, industrial IoT (IIoT) is a novel term that provides ubiquitous connections for sensors, automated guided vehicles, machines, and industrial robots [2]. The applications of IIoT can improve industrial productivity and efficiency obviously [2], [3]. Software-defined network (SDN) improves network controllability by the separation of the data and control planes. Without introducing new link layer protocols, the SDN can be compatible with existing industrial communication protocols, and it is flexible to modify and reconstruct the network based on various qualities of service requirements of IIoT users. Hence, the SDN can improve the efficiency of IIoT and reduce network complexity significantly [4]–[6]. The structure diagram of the SDN-enabled IIoT network is shown in Fig. 1.