Timing analysis of rate-constrained traffic in TTEthernet using network calculus

Zhao, Luxi; Pop, Paul; Li, Qiao; Chen, Junyan; Huagang, Xiong

doi:10.1007/s11241-016-9265-0

Cited by 60 publications

(34 citation statements)

References 27 publications

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“…A TTEthernet network is a full duplex switched network with time-triggered and event-triggered mechanism. A TTE network can be formally modeled as a directed graph G(V , E), where the set of vertices V comprises the communication nodes (switches and end-systems) and the edges E represent the directional communication links between nodes, similar to Zhao et al [18]. For an edge e i,j with the bandwidth C e i,j (e.g.…”

Section: System Model a Network Modelmentioning

confidence: 99%

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Enhancing Real-Time and Determinacy for Network-Level Schedule in Distributed Mixed-Critical System

Huagang

et al. 2020

IEEE Access

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Time-triggered Ethernet (TTE) is designed as a deterministic real-time network for mixed-critical real-time systems, such as industrial automation, aerospace, and aviation. Due to asynchrony between tasks and the network in end systems (ESes), time-triggered (TT) messages have to spend uncertain time in waiting for being scheduled after they are generated. The waiting time uncertainly increases end to end delays for TT messages and will degrade the real-time and determinacy of TT messages sequentially. The contribution of this paper is to present a new architecture SDTTE to minimize the end to end delays, so as to enhance real-time and determinacy of TT messages. More specifically, a frame-based network model is built to describe distributed network resources. Under the network model, the end to end delay model with asynchrony between tasks and the network is analyzed. To match the generated time with the triggered time for TT messages, the triggered mechanism of the TT traffic in ESes is regarded as event strategy to detect the generated time of TT messages automatically. Based on this, the software defined TTE (SDTTE) is presented to optimize TT schedule online in switches. Furthermore, a simplified algorithm based on Satisfiability Modulo Theories (SMT) is proposed to satisfy real-time computing requirements. Finally, experiments with three network sizes verify the availability of SDTTE and analyze its performance. The results show that end to end delays for TT messages in SDTTE are decreased by about 95% compared with those in TTE. And the delays for rate-constrained and best-effort messages in SDTTE are almost as well as those in TTE. The processing time is less than 10s. In general, SDTTE provides a method to optimize end to end delays for TT messages in TTE, thus SDTTE has more determinacy and real-time than TTE. Meanwhile, SDTTE makes dynamic reconfiguration possible in practice. INDEX TERMS End to end delay, determinacy, real-time, software defined network, time-triggered ethernet.

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Section: System Model a Network Modelmentioning

confidence: 99%

“…However, the queuing delay for a TT message in an end system (ES) has not been considered into the conventional end to end delay [16]- [18]. Indeed, a TT frame might have to wait a full transmission period in the ES before being scheduled out [19].…”

Section: Introduction a Time-triggered Schedule Tablementioning

confidence: 99%

Enhancing Real-Time and Determinacy for Network-Level Schedule in Distributed Mixed-Critical System

Huagang

et al. 2020

IEEE Access

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“…A TTE network is a full duplex switched network with timetriggered and event-triggered mechanism. A TTE network can be formally modeled as a directed graph G(V , E), where the set of vertices V comprises the communication nodes (switches and end systems, SWs and ESes) and the edges E represent the directional communication links between nodes, similar to Zhao [45].…”

Section: Network Architecture a Network Modelmentioning

confidence: 99%

“…In Algorithm 2, D p denotes the worst-case end to end delay, it can be computed by network calculus (NC) using equation (2) (3) [45]. The time window T F p,q limits the update time of common switches SW c .…”

Section: Definition 2: the Rate-constrained Update For Rc Traffic Is mentioning

confidence: 99%

A Mixed-Critical Consistent Update Algorithm in Software Defined Time-Triggered Ethernet Using Time Window

Huagang

et al. 2020

IEEE Access

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Software Defined Networking (SDN) presents a tremendous opportunity for developing abstract management of network updates. However, network updates introduce challenges in terms of consistency. Many consistent update algorithms are proposed for Ethernet, but there is seldom update algorithm for distributed time-triggered system to satisfy requirements of strict real-time and mixed-critical. The contribution of this paper is to present a distributed update mechanism and a mixed-critical update algorithm for the time-triggered (TT) and rate-constrained (RC) traffics to reduce the memory space complexity, computational time complexity, update time, and keep per-packet consistent strictly. More specifically, consistent update is defined and some basic update algorithms are described. And then a packetbased network model is built to describe network resources. Subsequently, the update mechanism is changed for the TT and RC traffics. Meanwhile, a mixed-critical update algorithm, which contains a time windowbased update and a rate-constrained update for TT and RC traffics respectively, is proposed. Whether the mixed-critical update algorithm is consistent updates or not is proved logically. Finally, experiments analyzed the performance of the mixed-critical update algorithm, compared with four conventional updates. The results show that there is no black hole, loop and inconsistent path for the mixed-critical update algorithm. The most important thing is that the memory space complexity is reduced by 19.93% at least, compared with two-phase update. Meanwhile, the computational time complexity and update time are reduced by 17.14% and 7.96% respectively, compared with time-based update. The mixed-critical update algorithm provides a method to optimize policy update tasks for distributed time-triggered system, so as to improve the ability of system reconfiguration. INDEX TERMS Consistent update, distributed time-triggered system, software defined networking, space complexity, time complexity.

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“…Many industrial wired and wireless networks have been proposed to handle these high-requirement scenarios, e.g., WIA-FA [4], WIA-PA [5], RT-WiFi [6], WirelessHP [7], WirelessHART [8], TTEthernet [9], and time sensitive networks (TSNs) [10]. However, there is still no single network framework that can guarantee all industrial requirements.…”

Section: Introductionmentioning

confidence: 99%

Real-Time Scheduling of Massive Data in Time Sensitive Networks With a Limited Number of Schedule Entries

et al. 2020

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Time sensitive networks support deterministic schedules over Ethernet networks. Due to their high determinism, high reliability and high bandwidth, they have been considered as a good choice for the backbone network of industrial internet of things. In industrial applications, the backbone network connects multiple industrial field networks together and has to carry massive real-time packets. However, the off-theshelf time-sensitive network (TSN) switches can deterministically schedule no more than 1024 real-time flows due to the limited number of schedule table entries. The excess real-time flows have to be delivered by best-effort services because the switch only supports the two scheduling services. The best-effort services can reduce average delay, but cannot guarantee the hard real-time constraints of industrial applications. To make the limited number of schedule table entries support more real-time flows, first, we relax scheduling rules to reduce the requirement for schedule table entries and formulate the process of transmitting packets as a satisfiability modulo theories (SMT) specification. Then, we divide the SMT specification into multiple optimization modulo theories (OMT) specifications so that the execution time of solvers can be reduced to an acceptable range. Second, we propose fast heuristic algorithms that combine schedule tables and packet injection control to eliminate scheduling conflicts. Finally, we conduct extensive evaluations. The evaluation results indicate that, compared to existing algorithms, our proposed algorithm requires only one-twentieth the number of schedule entries to schedule the same flow set. INDEX TERMS Industrial Internet of Things, massive data, real-time scheduling, time sensitive networks.

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Timing analysis of rate-constrained traffic in TTEthernet using network calculus

Cited by 60 publications

References 27 publications

Enhancing Real-Time and Determinacy for Network-Level Schedule in Distributed Mixed-Critical System

Enhancing Real-Time and Determinacy for Network-Level Schedule in Distributed Mixed-Critical System

A Mixed-Critical Consistent Update Algorithm in Software Defined Time-Triggered Ethernet Using Time Window

Real-Time Scheduling of Massive Data in Time Sensitive Networks With a Limited Number of Schedule Entries

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