Abstract

Till Steinbach, Hyung-Taek Lim, Franz Korf, Thomas C. Schmidt, Daniel Herrscher, Adam Wolisz,
Beware of the Hidden! How Cross-traffic Affects Quality Assurances of Competing Real-time Ethernet Standards for In-Car Communication,
In: 2015 IEEE Conference on Local Computer Networks (LCN), p. 1–9, IEEE Press : Piscataway, NJ, USA, October 2015.
[pdf][BibTeX][Abstract] LCN Best Paper Award

Abstract: Real-time Ethernet is expected to become the core technology of future in-car communication networks. Following its current adoption in subsystems for info- and entertainment, broadband Ethernet promises new features in the core of upcoming car series. Its full potential will enfold when deploying Ethernet-based backbones that consolidate all automotive domains on a single physical layer at increased bandwidth but reduced complexity and cost. In such a backbone, traffic with a variety of real-time requirements and best-effort characteristics will share the same physical infrastructure. However, certain applications like online diagnosis, data- or firmware updates, and access to off-board backends will introduce bursty high traffic loads to the sensitive core of the cars communication network. In this work, we analyze the robustness against cross-traffic of real-time Ethernet protocols. Based on a realistic in-car scenario, we demonstrate that background cross-traffic can have significant impact on in-car backbone networks–-even for real-time protocols with strict prioritization. By comparing the real-time approaches Ethernet AVBs asynchronous credit based shaping with the time-triggered and rate-constrained traffic classes of Time-triggered Ethernet (AS6802) we quantify how different media access policies suffer from low priority bursts of applications such as diagnosis, online updates or backend-based services. Our simulation study of a realistic in-car backbone design and traffic model reveals that in a realistic in-car network design, cross-traffic may increase end-to-end latency by more than 500% while the jitter can become 14 times higher than for a network without background tasks. We discuss ways to mitigate these degrading effects.

Themes: Time-Sensitive Networking

 

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