Rethinking the Use of Network Cycle in Time-Sensitive Networking (TSN) Flow Scheduling

Time-Sensitive Networking (TSN) is an emerging network architecture that provides bounded latency and reliable network services for time-sensitive applications. Since time-triggered flows in TSN are typically periodic, a concept of network cycle is widely used in both standards and academic researches. However, although network cycle has gained popularity, its rationale has not yet been analyzed systematically. In this paper, we mathematically evaluate the performance of several flow scheduling algorithms in terms of flow schedulability with and without employing network cycle. We observe that only when the network cycle is set to a proper value can the performance of flow scheduling be significantly improved. To better evaluate the scheduling effect, a novel assessment metric and a goal-based optimization algorithm are introduced. Our experiment results show that the network cycle-based algorithm can achieve a considerable improvement (40% - 170% improvement in the number of scheduled flows) compared to the ones with network cycle disabled.