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In this paper we are interested in safety-critical real-time applications implemented on distributed architectures supporting the TimeSensitive Networking (TSN) standard. The ongoing standardization of TSN is an IEEE effort to bring deterministic real-time capabilities into the IEEE 802.1 Ethernet standard supporting safety-critical systems and guaranteed Quality-of-Service. TSN will support TimeTriggered (TT) communication based on schedule tables, AudioVideo-Bridging (AVB) flows with bounded end-to-end latency as well as Best-Effort messages. We first present a survey of research related to the optimization of distributed cyber-physical systems using real-time Ethernet for communication. Then, we formulate two novel optimization problems related to the scheduling and routing of TT and AVB traffic in TSN. Thus, we consider that we know the topology of the network as well as the set of TT and AVB flows. We are interested to determine the routing of both TT and AVB flows as well as the scheduling of the TT flows such that all frames are schedulable and the AVB worst-case end-to-end delay is minimized. We have proposed an Integer Linear Programming (ILP) formulation for the scheduling problem and a Greedy Randomized Adaptive Search Procedure (GRASP)-based heuristic for the routing problem. The proposed approaches have been evaluated using several test cases.

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Mixed-criticality and high availability distributed systems, like those on large industrial deployments, strongly rely on deterministic communication in order to guarantee the realtime behavior. The time-triggered paradigm -as in TTEthernetguarantees the deterministic delivery of messages with fixed latency and limited jitter. We look closely at industrial deployments in which production as well as consumption of messages is carried out within software tasks running on distributed embedded nodes (i.e. end-systems). We present an approach to minimize the end-to-end latency of such tasks, respecting their precedence constraints as well as the scheduled communication in an underlying switched TTEthernet network. The approach is based on and validated by a large industrial use-case for which we analyze a test bed implementing our solution. * The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement n o 610640 (DREAMS).

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Document VersionPublisher's PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publicationCitation for published version (APA): Sokolova, A., Craciunas, S. S., Kirsch, C. M., Payer, H., & Röck, H. (2009). Programmable temporal isolation through variable-bandwidth servers. In Proceedings Fourth IEEE International Symposium on Industrial Embedded Systems (SIES 2009, Lausanne, Switzerland, July 8-10, 2009 General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Abstract-We introduce variable-bandwidth servers (VBS) for scheduling and executing processes under programmable temporal isolation. A VBS is an extension of a constant-bandwidth server where throughput and latency of process execution can not only be controlled to remain constant across different competing workloads but also to vary in time as long as the resulting bandwidth stays below a given bandwidth cap. We have designed and implemented a VBS-based EDF-style constant-time scheduling algorithm, a constant-time admission test, and four alternative queue management plugins which influence the scheduling algorithm's overall temporal and spatial complexity. Experiments confirm the theoretical bounds in a number of microbenchmarks and demonstrate that the scheduler can effectively manage in constant time any number of processes up to available memory while maintaining response times of individual processes within a bounded range. We have also developed a small-footprint, bare-metal virtual machine that uses VBS for temporal isolation of multiple, concurrently running processes executing real code. I. INTRODUCTIONVirtualization has always been a fascinating topic in sys...