133 research outputs found
Delay Analysis of AVB traffic in Time-Sensitive Networks (TSN)
International audienceFuture autonomous vehicles and ADAS (Advanced Driver Assistance Systems) need real-time audio and video transmission together with control data traac (CDT). Audio/video stream delay analysis has been largely investigated in AVB (Audio Video Bridging) context, but not yet with the presence of the CDT in the new TSN context. In this paper we present a local delay analysis of AVB frames under hierarchical scheduling of credit-based shaping and time-aware shaping on TSN switches. We present the eeects of time aware shaping on AVB traac, how it changes the relative order of transmission of frames leading to bursts and worst case scenarios for lower priority streams. We also show that these bursts are upper-bounded by the Credit-Bases Shaper, hence the worst-case transmissions delay of a given stream is also upper-bounded. We present the analysis to compute the worst case delay for a frame, as well as the feasibility condition necessary for the analysis to be applied. Our methods (analysis and simulation) are applied to an automotive use case, which is deened within the Eurostars RETINA project, and where both control data traac and AVB traac must be guaranteed. CCS CONCEPTS • Computer systems organization →Embedded systems; • Networks →Network reliability
Simulation of Mixed Critical In-vehicular Networks
Future automotive applications ranging from advanced driver assistance to
autonomous driving will largely increase demands on in-vehicular networks. Data
flows of high bandwidth or low latency requirements, but in particular many
additional communication relations will introduce a new level of complexity to
the in-car communication system. It is expected that future communication
backbones which interconnect sensors and actuators with ECU in cars will be
built on Ethernet technologies. However, signalling from different application
domains demands for network services of tailored attributes, including
real-time transmission protocols as defined in the TSN Ethernet extensions.
These QoS constraints will increase network complexity even further.
Event-based simulation is a key technology to master the challenges of an
in-car network design. This chapter introduces the domain-specific aspects and
simulation models for in-vehicular networks and presents an overview of the
car-centric network design process. Starting from a domain specific description
language, we cover the corresponding simulation models with their workflows and
apply our approach to a related case study for an in-car network of a premium
car
Software-Defined Networks Supporting Time-Sensitive In-Vehicular Communication
Future in-vehicular networks will be based on Ethernet. The IEEE
Time-Sensitive Networking (TSN) is a promising candidate to satisfy real-time
requirements in future car communication. Software-Defined Networking (SDN)
extends the Ethernet control plane with a programming option that can add much
value to the resilience, security, and adaptivity of the automotive
environment. In this work, we derive a first concept for combining
Software-Defined Networking with Time-Sensitive Networking along with an
initial evaluation. Our measurements are performed via a simulation that
investigates whether an SDN architecture is suitable for time-critical
applications in the car. Our findings indicate that the control overhead of SDN
can be added without a delay penalty for the TSN traffic when protocols are
mapped properly.Comment: To be published at IEEE VTC2019-Sprin
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
Design Optimization of Cyber-Physical Distributed Systems using IEEE Time-sensitive Networks (TSN)
In this paper we are interested in safety-critical real-time applications implemented on distributed architectures supporting the Time-SensitiveNetworking (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 Time-Triggered (TT) communication based on schedule tables, Audio-Video-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
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
Improved Delay Bound for a Service Curve Element with Known Transmission Rate
Network calculus is often used to prove delay bounds in deterministic
networks, using arrival and service curves. We consider a FIFO system that
offers a rate-latency service curve and where packet transmission occurs at
line rate without pre-emption. The existing network calculus delay bounds take
advantage of the service curve guarantee but not of the fact that transmission
occurs at full line rate. In this letter, we provide a novel, improved delay
bound which takes advantage of these two features. Contrary to existing bounds,
ours is per-packet and depends on the packet length. We prove that it is tight.Comment: 4 pages, 2 figure
A Survey of Scheduling in Time-Sensitive Networking (TSN)
TSN is an enhancement of Ethernet which provides various mechanisms for
real-time communication. Time-triggered (TT) traffic represents periodic data
streams with strict real-time requirements. Amongst others, TSN supports
scheduled transmission of TT streams, i.e., the transmission of their packets
by edge nodes is coordinated in such a way that none or very little queuing
delay occurs in intermediate nodes. TSN supports multiple priority queues per
egress port. The TAS uses so-called gates to explicitly allow and block these
queues for transmission on a short periodic timescale. The TAS is utilized to
protect scheduled traffic from other traffic to minimize its queuing delay. In
this work, we consider scheduling in TSN which comprises the computation of
periodic transmission instants at edge nodes and the periodic opening and
closing of queue gates.
In this paper, we first give a brief overview of TSN features and standards.
We state the TSN scheduling problem and explain common extensions which also
include optimization problems. We review scheduling and optimization methods
that have been used in this context. Then, the contribution of currently
available research work is surveyed. We extract and compile optimization
objectives, solved problem instances, and evaluation results. Research domains
are identified, and specific contributions are analyzed. Finally, we discuss
potential research directions and open problems.Comment: 34 pages, 19 figures, 9 tables 110 reference
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