A decomposition approach for SMT-based schedule synthesis for time-triggered networks

Pozo, Francisco del; Steiner, Wilfried; Rodríguez-Navas, Guillermo; Hansson, Hans

doi:10.1109/etfa.2015.7301436

Cited by 45 publications

(22 citation statements)

References 24 publications

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“…The same author has proposed an SMT-solver approach to introduce periodic evenly-spaced slots into the static schedules to help reduce RC delays in [36]. More recent work has shown how the SMTbased approach can be extended to handle very large systems [29]. Suethanuwong [37] proposes a scheduling approach of the TT traffic, ignoring RC traffic, that introduces equally distributed available time slots for BE traffic.…”

Section: Brief Review Of Related Workmentioning

confidence: 99%

Design optimisation of cyber‐physical distributed systems using IEEE time‐sensitive networks

Pop

Raagaard

Craciunas

et al. 2016

IET cyber-phys. syst.

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129

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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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Section: Brief Review Of Related Workmentioning

confidence: 99%

Design optimisation of cyber‐physical distributed systems using IEEE time‐sensitive networks

Pop

Raagaard

Craciunas

et al. 2016

IET cyber-phys. syst.

Self Cite

129

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“…Updating schedules to accommodate new messages may trigger re-validation and re-certification activities, which are costly. In addition, as the number of frames increases (systems may have tens of thousands of frames, even millions of frames [9]), the ESes and NSes will run out of memory for the required schedule tables. Although methods such as [9] can handle a large number of TT frames, they are not able to integrate the schedulability analysis of RC frames.…”

Section: Problem Formulationmentioning

confidence: 99%

“…The algorithm assigns higher priorities to traffic flows that have more stringent timing requirements. For TTEthernet, researchers have proposed approaches to synthesize the communication schedules [9,3]. Their methods are able to handle up to 100,000 TT frames, but ignore RC frames.…”

Section: Related Workmentioning

confidence: 99%

Traffic class assignment for mixed-criticality frames in TTEthernet

Gavriluţ

Pop

2016

SIGBED Rev.

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In this paper we are interested in mixed-criticality applications, which have functions with different timing requirements, i.e., hard real-time (HRT), soft real-time (SRT) and functions that are not time-critical (NC). The applications are implemented on distributed architectures that use the TTEthernet protocol for communication. TTEthernet supports three traffic classes: Time-Triggered (TT), where frames are transmitted based on static schedule tables; Rate Constrained (RC), for dynamic frames with a guaranteed bandwidth and bounded delays; and Best Effort (BE), for which no timing guarantees are provided. HRT messages have deadlines, whereas for SRT messages we capture the quality-of-service using "utility functions". Given the network topology, the set of application messages and their routing, we are interested to determine the traffic class of each message, such that all HRT messages are schedulable and the total utility for SRT messages is maximized. For the TT frames we decide their schedule tables, and for the RC frames we decide their bandwidth allocation. We propose a Tabu Search-based metaheuristic to solve this optimization problem. The proposed approach has been evaluated using several benchmarks, including two realistic test cases.

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“…We assume that each message m P M has a first path πm on which it is scheduled, where a path is a complete route from the node sending m to the destination (or target) of m. Thus a schedule only schedules m on links that πm traverses. Such an assumption has been used often in practice in order to find schedules in large networks [26,23]. We allow the switches on πm to have a second path to the target of m, which can be thought of as a fallback path; systems using slight variations of this protocol can be found in the literature [29,21].…”

Section: Introductionmentioning

confidence: 99%

“…Different techniques have been adopted for synthesis of time-triggered schedules for medium size systems, such as constraint programming (CP) solvers [25], integer linear programming (ILP) solvers [14], and satisfiability modulo theory (SMT) solvers [18]. For systems or larger size, SMT solvers have been combined with iterative/segmentation techniques yielding good results [11,4,26,23,12], even if compared to ILP.…”

Section: Introductionmentioning

confidence: 99%

Synthesizing time-triggered schedules for switched networks with faulty links

Avni

Guha

Rodríguez-Navas

2016

Proceedings of the 13th International Conference on Embedded Software

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Time-triggered (TT) switched networks are a deterministic communication infrastructure used by real-time distributed embedded systems. These networks rely on the notion of globally discretized time (i.e. time slots) and a static TT schedule that prescribes which message is sent through which link at every time slot, such that all messages reach their destination before a global timeout. These schedules are generated offline, assuming a static network with fault-free links, and entrusting all error-handling functions to the end user. Assuming the network is static is an over-optimistic view, and indeed links tend to fail in practice. We study synthesis of TT schedules on a network in which links fail over time and we assume the switches run a very simple error-recovery protocol once they detect a crashed link. We address the problem of finding a pk, qresistant schedule; namely, one that, assuming the switches run a fixed error-recovery protocol, guarantees that the number of messages that arrive at their destination by the timeout is at least , no matter what sequence of at most k links fail. Thus, we maintain the simplicity of the switches while giving a guarantee on the number of messages that meet the timeout. We show how a pk, q-resistant schedule can be obtained using a CEGAR-like approach: find a schedule, decide whether it is pk, q-resistant, and if it is not, use the witnessing fault sequence to generate a constraint that is added to the program. The newly added constraint disallows the schedule to be regenerated in a future iteration while also eliminating several other schedules that are not pk, q-resistant. We illustrate the applicability of our approach using an SMT-based implementation.

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A decomposition approach for SMT-based schedule synthesis for time-triggered networks

Cited by 45 publications

References 24 publications

Design optimisation of cyber‐physical distributed systems using IEEE time‐sensitive networks

Design optimisation of cyber‐physical distributed systems using IEEE time‐sensitive networks

Traffic class assignment for mixed-criticality frames in TTEthernet

Synthesizing time-triggered schedules for switched networks with faulty links

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