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Guaranteeing Hard Real-Time Requirements of In-Vehicle Multihop Communication Over COTS Ethernet Hardware
ISSN: 0148-7191, e-ISSN: 2688-3627
Published April 12, 2011 by SAE International in United States
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Automakers currently use Ethernet for fast batch transfers when updating software in ECUs in a vehicle. But Ethernet is also planned for real-time traffic as well; in the short term future for streaming of video and audio and potentially in the long term also for Drive-by-wire functions.
Ethernet today uses the same frame format as the original Ethernet from the 1970s did but except from that it bears little resemblance to its original form. Ethernet today uses switches and hence the argument often raised against its use for carrying hard real-time traffic - that the shared medium can cause unbounded delay due to collisions - is not applicable today. In addition, normal Ethernet switches today support prioritization of traffic which allows an engineer to assign a high priority to urgent time-critical traffic so that its queuing delay is not affected by lower priority (supposedly less time-critical) traffic.
Although the high bit-rate and the ability to control queuing delays thanks to prioritization are attractive for carrying real-time traffic, this alone cannot guarantee that real-time requirements are fulfilled. It is necessary to prove with mathematical rigor that given a traffic model and given the topology and configuration of the network, all real-time requirements will be met. Such proof techniques are known for the CAN bus and they have been adopted in design tools. Such proofs are also known for star networks based on switched Ethernet for simple traffic models but no design tool is currently based on them.
Therefore, in this paper, we list desired functionalities of a tool for proving that timing requirements are fulfilled. It should sport the ability to analyze multihop traffic over switched Ethernet networks and allow designers great freedom in how flows are described in order to reduce pessimism of the analysis due to modeling.
CitationLext, J., Bröhne, L., and Andersson, B., "Guaranteeing Hard Real-Time Requirements of In-Vehicle Multihop Communication Over COTS Ethernet Hardware," SAE Technical Paper 2011-01-1038, 2011, https://doi.org/10.4271/2011-01-1038.
- Gumbrich, S., “Embedded systems overhaul -It's time to tune up for the future of the automotive industry,” IBM Business Consulting Services, 2004, Available at http://www-05.ibm.com/de/automotive/downloads/embedded_systems_overhaul.pdf.
- CAN Specification. Version 2.0. 1991, Robert Bosch GmbH, www.semiconductors.bosch.de/pdf/can2spec.pdf.
- Mok, A. K. and Ward, S.: Distributed broadcast channel access. Computer Networks, 3:327-335, 1979.
- Davis, R. I., Burns, A., Bril, R. J., Lukkien, J. J., “Controller Area Network (CAN) schedulability analysis: Refuted, revisited and revised,” Real-Time Systems, Volume 35, Issue 3, April 2007, Pages 239 - 272.
- Pereira, N., Andersson, B. and Tovar, E., “WiDom: A Dominance Protocol for Wireless Medium Access,” IEEE Transactions on Industrial Informatics, Volume 3, Issue 2, May 2007 Page(s):120 - 130.
- Kopetz, H. and Grünsteidl, G.: TTP - A Time-Triggered Protocol for Fault-Tolerant Real-Time Systems. FTCS 1993: 524-533.
- Thomsen, T. and Drenkhahn, G., “Ethernet for AUTOSAR,” Available at http://www.autosar.org/download/conferencedocs/07_Elektrobit_Ethernet_for_Autosar.pdf.
- AVnu Alliance, Available at http://www.avnu.org/audiences#automotive.
- “Beyond FlexRay: BMW airs Ethernet plans,” Available at http://www.eetimes.com/electronics-blogs/other/4200470/Beyond-FlexRay-BMW-airs-Ethernet-plans.
- Reichart, Dr. G.Former Vice President, Body and Safety Electronics, Driver Assistance, Wiring Harness BMW Group, “AUTOSAR and beyond - Some comments on automotive HW/SW-Architectures & Processes,” Available at http://www.mentor.com/events/transconf/detroit/presentations/upload/detroit-10-2.pdf.
- Micrel data sheet for KSZ8873, Available at http://www.micrel.com/_PDF/Ethernet/datasheets/KSZ8873MLL_FLL_RLL_DS.pdf.
- Press release: “Dongbu HiTek to Manufacture Automotive Ethernet ICs”, 2010-07-22, Available at http://www.dongbuhitek.com/eng/Mediaroom/board_detail.asp?BoardId=Media&Idx=265.
- SMSC data sheet for LAN89303, Available at http://www.smsc-ais.com/AIS/download.php?id=449&filename=LAN89303AM DS Rev. 1.1 (08-03-10).pdf.
- Westermo data sheet for RFI-10P, Available at http://www.westermo.com/dman/Document.phx/Datasheets/Ethernet/English/rfi-10+datasheet+ENG.pdf.
- Westermo, RedFox User guide, Available at http://www.westermo.com/dman/Document.phx/Manuals/Ethernet/Ethernet+Switches/RedFox+Manual.pdf.
- Westermo New June 2010, Available at http://www.westermo.com/dman/Document.phx/Media+Archive/Brochures/News+Brochures/westermo_news_1006_SE.pdf?folderId=%2FMedia+Archive%2FBrochures%2FNews+Brochures&cmd=download.
- Marvell 88E6092, Available at http://www.marvell.com/products/switching/linkstreet/marvell_linkstreet_88E6092_product_brief.pdf.
- Tindell, K. and Clark, J., “Holistic schedulability analysis for distributed hard real-time systems,” Microprocessing and Microprogramming Volume 40, Issue 2-3, April, Pages 117-134, 1994.
- AUTOSAR. http://www.autosar.org/.
- Wireshark website. www.wireshark.org.
- IEEE 1616a-2010. http://bmsmail3.ieee.org:80/u/17205/248373.