Formal Timing Analysis of Non-Scheduled Traffic in Automotive Scheduled TSN Networks

Fedor Smirnov1, Michael Glaß2, Felix Reimann3 and Jürgen Teich1
1Hardware/Software Co-Design, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Germany.
2Institute of Embedded Systems/Real-Time Systems, Ulm University, Germany.
3Audi Electronics Venture GmbH, Germany.


To cope with requirements for low latency, the upcoming Ethernet standard Time-Sensitive Networking (TSN) provides enhancements for scheduled traffic, enabling mixedcriticality networks where critical messages are sent according to a system-wide schedule. While these networks provide a completely predictable behavior of the scheduled traffic by construction, timing analysis of the critical non-scheduled traffic with hard deadlines remains an unsolved issue. State-of-the-art analysis approaches consider the interference that unscheduled messages impose on each other, but there is currently no approach to determine the worst-case interference that can be imposed by scheduled traffic, the so-called schedule interference (SI), without relying on restrictions of the shape of the schedule. Considering all possible interference scenarios during each calculation of the SI is impractical, as it results in an explosion of the computation time. As a remedy, this paper proposes a) an approach to integrate the analysis of the worst-case SI into state-of-the-art timing analysis approaches and b) preprocessing techniques that reduce the computation time of the SI-calculation by several orders of magnitude without introducing any pessimism.

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