The digital transformation of industry requires industrial control networks provide high flexibility and determinacy. Time-sensitive software-defined networking that combines time-sensitive networking and software-defined networking is a new network paradigm which provides both real-time transmission feature and network flexibility. During network updates, the transmission consistency needs to be maintained. However, previous mechanisms mostly target on the proper schedule transition, which cannot guarantee no frame loss and also introduces extra update overhead. The article proposes a novel flow schedule generation model which guarantees no frame loss during network updates even with the basic two-phase update mechanism and introduces no extra update overhead. Two algorithms are designed for the model to adapt to different application scenarios: the offline algorithm poses better schedulability, whereas the online one consumes less time with slightly decreased schedulability. The experiments on two real-world industrial networks demonstrate our mechanism achieves zero frame loss without extra update overhead compared to existing methods, and the online algorithm saves 40% execution time with at most 10% schedulability decrease when the bandwidth utilization is less than 50%.

The emerging momentum of digital transformation of industry, i.e. Industry 4.0, poses strong demands for integrating industrial control networks, and Ethernet to enable the real-time Internet of Things (RT-IoT). Time-triggered (TT) networks provide a cost-efficient integrated solution while RT-IoT arouses the reconfiguration challenges: the network has to be flexible enough to adapt to changes and yet provides deterministic transmission persistently during network reconfiguration. Software defined network benefits the flexible industrial control by configuring the rules handling frames. However, previous reconfiguration mechanisms are mostly oriented to the context of data centers and wide area networks and thus do not consider the deterministic transmission in TT networks. This paper focuses on the reconfiguration (i.e., updates) for the deterministic transmission. To minimize the overhead during updates, namely the minimum number of loss frames and the minimum duration time of updates, we first establish an update theory based on the dependence relationship derived by the conflicts during updates. In addition then the reconfiguration problem is modeled with the dependence graph built by the relationship. On such a basis, we present a reconfiguration mechanism and its implementation to solve the problem. Finally, we evaluate the proposed reconfiguration mechanism in two real industrial network topologies. The experimental results demonstrate that compared with previous methods, our mechanism significantly reduces the number of loss frames and achieves zero loss in almost all cases.