Rede sensível ao tempo: um estudo do mapeamento sistemático

The time sensitive network (TSN) is a technology that aims to provide a whole new level of determinism. It is made up of a set of standards, which are still being developed by the IEEE 802.1 working group. Its goal is to provide a network with extremely small packet loss in addition to calculable latencies and jitter. Because it is fairly recent, there is a certain di culty nding relevant materials for conducting research or developing it. Based on this problem this problem, the objective of this work is to perform a survey, gathering the important information about this new technology. The TSN is a set of several mechanisms. Each of them belongs to the 802.1 standard group. The work done here, talks about eight of the main mechanisms. In this way, a reader who has some level of information about networks, is able to understand the most relevant mechanisms and therefore can understand how the time sensitive network works, and its full potential.A rede sensível ao tempo (TSN) é uma tecnologia que visa fornecer um nível de determinismo totalmente novo. Ela é formada por um conjunto de padrões, os quais ainda estão sendo desenvolvidos pelo grupo de trabalho IEEE 802.1. Eles visam fornecer uma rede com perda de pacotes extremamente pequena alem de latências calculáveis e jitter limitado. Por ser razoavelmente recente, ha uma certa dificuldade de encontrar materiais relevantes para a realização uma pesquisa ou para o desenvolvimento da mesma. Visando essa problemática, o objetivo deste trabalho é realizar um mapeamento sistemático reunindo as informações importantes sobre esta nova tecnologia. A TSN é um conjunto de vários mecanismos. Cada um deles pertence a um padrão do grupo 802.1. O trabalho realizado aqui, fala sobre oito dos principais mecanismos. Deste modo o leitor, que possua algum nível de informação sobre redes, é capaz de compreender os mecanismos mais relevantes e por conseguinte entender como a rede sensível ao tempo funciona e todo o seu potencial

Design of Time-Sensitive Networks For Safety-Critical Cyber-Physical Systems

A new era of Cyber-Physical Systems (CPSs) is emerging due to the vast growth in computation and communication technologies. A fault-tolerant and timely communication is the backbone of any CPS to interconnect the distributed controllers to the physical processes. Such reliability and timing requirements become more stringent in safety-critical applications, such as avionics and automotive. Future networks have to meet increasing bandwidth and coverage demands without compromising their reliability and timing. Ethernet technology is efficient in providing a low-cost scalable networking solution. However, the non-deterministic queuing delay and the packet collisions deny low latency communication in Ethernet. In this context, IEEE 802.1 Time Sensitive Network (TSN) standard has been introduced as an extension of the Ethernet technology to realize switched network architecture with real-time capabilities. TSN offers Time-Triggered (TT) traffic deterministic communication. Bounded Worst-Case end-to-end Delay (WCD) delivery is yielded by Audio Video Bridging (AVB) traffic. In this thesis, we are interested in the TSN design and verification. TSN design and verification are challenging tasks, especially for realistic safety-critical applications. The increasing complexity of CPSs widens the gap between the underlying networks' scale and the design techniques' capabilities. The existing TSN's scheduling techniques, which are limited to small and medium networks, are good examples of such a gap. On the other hand, the TSN has to handle dynamic traffic in some applications, e.g., Fog computing applications. Other challenges are related to satisfying the fault-tolerance constraints of mixed-criticality traffic in resource-efficient manners. Furthermore, in space and avionics applications, the harsh radiation environment implies verifying the TSN's availability under Single Event Upset (SEU)-induced failures. In other words, TSN design has to manage a large variety of constraints regarding the cost, redundancy, and delivery latency where no single design approach fits all applications. Therefore, TSN's efficient employment demands a flexible design framework that offers several design approaches to meet the broad range of timing, reliability, and cost constraints. This thesis aims to develop a TSN design framework that enables TSN deployment in a broad spectrum of CPSs. The framework introduces a set of methods to address the reliability, timing, and scalability aspects. Topology synthesis, traffic planning, and early-stage modeling and analysis are considered in this framework. The proposed methods work together to meet a large variety of constraints in CPSs. This thesis proposes a scalable heuristic-based method for topology synthesis and ILP formulations for reliability-aware AVB traffic routing to address the fault-tolerance transmission. A novel method for scalable scheduling of TT traffic to attain real-time transmission. To optimize the TSN for dynamic traffic, we propose a new priority assignment technique based on reinforcement learning. Regarding the TSN verification in harsh radiation environments, we introduce formal models to investigate the impact of the SEU-induced switches failures on the TSN availability. The proposed analysis adopts the model checking and statistical model checking techniques to discover and characterize the vulnerable design candidates

Scheduling & routing time-triggered traffic in time-sensitive networks

The application of recent advances in computing, cognitive and networking technologies in manufacturing has triggered the so-called fourth industrial revolution, also referred to as Industry 4.0. Smart and flexible manufacturing systems are being conceived as a part of the Industry 4.0 initiative to meet the challenging requirements of the modern day manufacturers, e.g., production batch sizes of one. The information and communication technologies (ICT) infrastructure in such smart factories is expected to host heterogeneous applications ranging from the time-sensitive cyber-physical systems regulating physical processes in the manufacturing shopfloor to the soft real-time analytics applications predicting anomalies in the assembly line. Given the diverse demands of the applications, a single converged network providing different levels of communication guarantees to the applications based on their requirements is desired. Ethernet, on account of its ubiquity and its steadily growing performance along with shrinking costs, has emerged as a popular choice as a converged network. However, Ethernet networks, primarily designed for best-effort communication services, cannot provide strict guarantees like bounded end-to-end latency and jitter for real-time traffic without additional enhancements. Two major standardization bodies, viz., the IEEE Time-sensitive Networking (TSN) Task Group (TG) and the IETF Deterministic Networking (DetNets) Working Group are striving towards equipping Ethernet networks with mechanisms that would enable it to support different classes of real-time traffic. In this thesis, we focus on handling the time-triggered traffic (primarily periodic in nature) stemming from the hard real-time cyber-physical systems embedded in the manufacturing shopfloor over Ethernet networks. The basic approach for this is to schedule the transmissions of the time-triggered data streams appropriately through the network and ensure that the allocated schedules are adhered with. This approach leverages the possibility to precisely synchronize the clocks of the network participants, i.e., end systems and switches, using time synchronization protocols like the IEEE 1588 Precision Time Protocol (PTP). Based on the capabilities of the network participants, the responsibility of enforcing these schedules can be distributed. An important point to note is that the network utilization with respect to the time-triggered data streams depends on the computed schedules. Furthermore, the routing of the time-triggered data streams also influences the computed transmission schedules, and thus, affects the network utilization. The question however remains as to how to compute transmission schedules for time-triggered data streams along with their routes so that an optimal network utilization can be achieved. We explore, in this thesis, the scheduling and routing problems with respect to the time-triggered data streams in Ethernet networks. The recently published IEEE 802.1Qbv standard from the TSN-TG provides programmable gating mechanisms for the switches enabling them to schedule transmissions. Meanwhile, the extensions specified in the IEEE 802.1Qca standard or the primitives provided by OpenFlow, the popular southbound software-defined networking (SDN) protocol, can be used for gaining an explicit control over the routing of the data streams. Using these mechanisms, the responsibility of enforcing transmission schedules can be taken over by the end systems as well as the switches in the network. Alternatively, the scheduling can be enforced only by the end systems or only by the switches. Furthermore, routing alone can also be used to isolate time-triggered data streams, and thus, bound the latency and jitter experienced by the data streams in absence of synchronized clocks in the network. For each of the aforementioned cases, we formulate the scheduling and routing problem using Integer Linear Programming (ILP) for static as well as dynamic scenarios. The static scenario deals with the computation of schedules and routes for time-triggered data streams with a priori knowledge of their specifications. Here, we focus on computing schedules and routes that are optimal with respect to the network utilization. Given that the scheduling problems in the static setting have a high time-complexity, we also present efficient heuristics to approximate the optimal solution. With the dynamic scheduling problem, we address the modifications to the computed transmission schedules for adding further or removing already scheduled time-triggered data streams. Here, the focus lies on reducing the runtime of the scheduling and routing algorithms, and thus, have lower set-up times for adding new data streams into the network

Zuverlässige und herstellerübergreifende Medizingeräteinteroperabilität: Beiträge zur IEEE 11073 SDC-Normenfamilie

Medizingeräte im Krankenhaus sind heute fast ausschließlich isolierte Insellösungen. Sie stellen nach außen keine Informationen und Interaktionsmöglichkeiten bereit - oder nur innerhalb ihres geschlossenen Ökosystems. Daher führt diese Arbeit in die neue IEEE 11073 Service-oriented Device Connectivity (SDC)-Normenfamilie ein, die eine herstellerübergreifende Interoperabilität ermöglicht. Es werden drei Anwendungsbereiche betrachtet: zuverlässige Fernauslösung von Gerätefunktionalitäten, dynamische Assoziierung von Fernsteuerungselementen und -operationen und verteilte Alarmierungssysteme.Medical devices in today's hospitals are almost always isolated systems, which do not transmit information to or interact with external devices. At the most, this is possible within closed company ecosystems. Thus, this work introduces the new IEEE 11073 Service-oriented Device Connectivity (SDC) family of standards, which provides manufacturer-independent interoperability. Three fields of application are considered: safe activation of a device's functionality, dynamic association of a random number of remote-control elements and remote-controllable operations, and distributed alarm systems