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Time-Sensitive Networking (TSN) extends Ethernet bridging with features for deterministic transmission. Periodic streams may be scheduled such that their frames hardly interfere in bridges. Additionally, the Time-Aware Shaper (TAS) can keep egress ports free from other traffic when scheduled traffic arrives. TAS scheduling determines transmission starts of scheduled streams at end stations and configures the TAS in bridges. Most TAS scheduling algorithms disregard jitter and synchronization errors at end stations and bridges, race conditions from simultaneously arriving frames with same egress ports, and hardware-based configuration limits of the TAS. We call the resulting schedules tight schedules (TS). However, all these challenges apply to real hardware bridges. Therefore, we present an algorithm using event times with uncertainty to compute efficient robust schedules (ERS) that respect these constraints. We also propose a repair for existing scheduling approaches and call their output naïve robust schedules (NRS). We evaluate and compare their bandwidth usage and stream admission with those of TS. ERS are more efficient than NRS, and the performance gap between ERS and TS quantifies the price for robust schedules. Moreover, the presented algorithm for ERS computes significantly faster than four well-known methods for TS, and it can solve larger problem instances.

Time-Sensitive Networking (TSN) is an enhancement of Ethernet which provides various mechanisms for real-time communication. Time-triggered (TT) traffic represents periodic data streams with strict real-time requirements. Amongst others, TSN supports scheduled transmission of TT streams, i.e., the transmission of their frames by end stations is coordinated in such a way that none or very little queuing delay occurs in intermediate nodes. TSN supports multiple priority queues per egress port. The TAS uses so-called gates to explicitly allow and block these queues for transmission on a short periodic timescale. The TAS is utilized to protect scheduled traffic from other traffic to minimize its queuing delay. In this work, we consider scheduling in TSN which comprises the computation of periodic transmission instants at end stations and the periodic opening and closing of queue gates. In this paper, we first give a brief overview of TSN features and standards. We state the TSN scheduling problem and explain common extensions which also include optimization problems. We review scheduling and optimization methods that have been used in this context. Then, the contribution of currently available research work is surveyed. We extract and compile optimization objectives, solved problem instances, and evaluation results. Research domains are identified, and specific contributions are analyzed. Finally, we discuss potential research directions and open problems.