On Latency for Non-Scheduled Traffic in TSN

Although networks based on 802 standards were initially designed to transport best-effort traffic, they now can accommodate all sorts of traffic, including time-sensitive ones. The latter is possible through a group of standards developed and maintained by the Time-Sensitive Networking (TSN) Task Group. This set of protocols ensures bounds and latency guarantees for streams of periodically arriving data. However, no bounds or guarantees are specified for stochastically arriving data. In this work, we propose an approximation for the end-to-end average latency that randomly arriving frames experience in a flow over a TSN path. These are non-scheduled frames arriving at a scheduled network. We based our approximation on a classic model from urban traffic literature called Fixed-Cycle Traffic Light (FCTL). Our approach is effective and extremely fast to compute compared to exact models or simulations.