41 research outputs found
Time-Sensitive Networking for Industrial Automation: Challenges, Opportunities, and Directions
With the introduction of Cyber-Physical Systems (CPS) and Internet of Things
(IoT) into industrial applications, industrial automation is undergoing
tremendous change, especially with regard to improving efficiency and reducing
the cost of products. Industrial automation applications are often required to
transmit time- and safety-critical data to monitor and control industrial
processes, especially for critical control systems. There are a number of
solutions to meet these requirements (e.g., priority-based real-time schedules
and closed-loop feedback control systems). However, due to their different
processing capabilities (e.g., in the end devices and network switches),
different vendors may come out with distinct solutions, and this makes the
large-scale integration of devices from different vendors difficult or
impossible. IEEE 802.1 Time-Sensitive Networking (TSN) is a standardization
group formed to enhance and optimize the IEEE 802.1 network standards,
especially for Ethernet-based networks. These solutions can be evolved and
adapted into a cross-industry scenario, such as a large-scale distributed
industrial plant, which requires multiple industrial entities working
collaboratively. This paper provides a comprehensive review on the current
advances in TSN standards for industrial automation. We present the
state-of-the-art IEEE TSN standards and discuss the opportunities and
challenges when integrating each protocol into the industry domains. Finally,
we discuss some promising research about applying the TSN technology to
industrial automation applications
Quantitative Performance Comparison of Various Traffic Shapers in Time-Sensitive Networking
Owning to the sub-standards being developed by IEEE Time-Sensitive Networking
(TSN) Task Group, the traditional IEEE 802.1 Ethernet is enhanced to support
real-time dependable communications for future time- and safety-critical
applications. Several sub-standards have been recently proposed that introduce
various traffic shapers (e.g., Time-Aware Shaper (TAS), Asynchronous Traffic
Shaper (ATS), Credit-Based Shaper (CBS), Strict Priority (SP)) for flow control
mechanisms of queuing and scheduling, targeting different application
requirements. These shapers can be used in isolation or in combination and
there is limited work that analyzes, evaluates and compares their performance,
which makes it challenging for end-users to choose the right combination for
their applications. This paper aims at (i) quantitatively comparing various
traffic shapers and their combinations, (ii) summarizing, classifying and
extending the architectures of individual and combined traffic shapers and
their Network calculus (NC)-based performance analysis methods and (iii)
filling the gap in the timing analysis research on handling two novel hybrid
architectures of combined traffic shapers, i.e., TAS+ATS+SP and TAS+ATS+CBS. A
large number of experiments, using both synthetic and realistic test cases, are
carried out for quantitative performance comparisons of various individual and
combined traffic shapers, from the perspective of upper bounds of delay,
backlog and jitter. To the best of our knowledge, we are the first to
quantitatively compare the performance of the main traffic shapers in TSN. The
paper aims at supporting the researchers and practitioners in the selection of
suitable TSN sub-protocols for their use cases
Pre-Shaping Bursty Transmissions under IEEE802.1Q as a Simple and Efficient QoS Mechanism
International audienceThe automotive industry is swiftly moving towards Ethernet as the high-speed communication network for in-vehicle communication. There is nonetheless a need for protocols that go beyond what standard Ethernet has to offer in order to provide additional QoS to demanding applications such as ADAS systems or audio/video streaming. The main protocols currently considered for that purpose are IEEE802.1Q, AVB with the Credit Based Shaper mechanism (IEEE802.1Qav) and TSN with its Time-Aware Shaper (IEEE802.1Qbv). AVB/CBS and TSN/TAS both provide efficient QoS mechanisms and they can be used in a combined manner, which offers many possibilities to the designer. Their use however requires dedicated hardware and software components, and clock synchronization in the case of TAS. Previous studies have also shown that the efficiency of these protocols depends much on the application at hand and the value of the configuration parameters. In this work, we explore the use of "pre-shaping" strategies under IEEE802.1Q for bursty traffic such as audio/video streams as a simple and efficient alternative to AVB/CBS and TSN/TAS. Pre-shaping means inserting on the sender side "well-chosen" pauses between successive frames of a burst (e.g., a camera frame), all the other characteristics of traffic remaining unchanged. We show on an automotive case-study how the use of pre-shaping for audio/video streams leads to a drastic reduction of the communication latencies for the best-effort streams while enabling to meet the timing constraints for the rest of the traffic. We then discuss the limitations of the pre-shaping mechanism and future works needed to facilitate its adoption
Latency Analysis of Multiple Classes of AVB Traffic in TSN with Standard Credit Behavior using Network Calculus
Time-Sensitive Networking (TSN) is a set of amendments that extend Ethernet
to support distributed safety-critical and real-time applications in the
industrial automation, aerospace and automotive areas. TSN integrates multiple
traffic types and supports interactions in several combinations. In this paper
we consider the configuration supporting Scheduled Traffic (ST) traffic
scheduled based on Gate-Control-Lists (GCLs), Audio-Video-Bridging (AVB)
traffic according to IEEE 802.1BA that has bounded latencies, and Best-Effort
(BE) traffic, for which no guarantees are provided. The paper extends the
timing analysis method to multiple AVB classes and proofs the credit bounds for
multiple classes of AVB traffic, respectively under frozen and non-frozen
behaviors of credit during guard band (GB). They are prerequisites for
non-overflow credits of Credit-Based Shaper (CBS) and preventing starvation of
AVB traffic. Moreover, this paper proposes an improved timing analysis method
reducing the pessimism for the worst-case end-to-end delays of AVB traffic by
considering the limitations from the physical link rate and the output of CBS.
Finally, we evaluate the improved analysis method on both synthetic and
real-world test cases, showing the significant reduction of pessimism on
latency bounds compared to related work, and presenting the correctness
validation compared with simulation results. We also compare the AVB latency
bounds in the case of frozen and non-frozen credit during GB. Additionally, we
evaluate the scalability of our method with variation of the load of ST flows
and of the bandwidth reservation for AVB traffic