A Simulation Model for Investigating Clock Synchronization Issues in Time-Sensitive Networks

The IEEE 802.1 Time-Sensitive Networking (TSN) task force has set guidelines for IEEE 802.3 networks allowing deterministic realtime communication over Ethernet. To execute deterministic time-triggered scheduling operations, the network nodes need to be synchronized. One application of time synchronization is distributed data acquisition for the Wendelstein 7-X nuclear fusion experiment. Both the system control and the scientific evaluation of the experiments need measurement timestamps with accuracies in the nanosecond range. The TSN standard IEEE 802.1AS has specified the generalized Precision Time Protocol (gPTP) which executes the synchronization process. However, there are some issues that are not addressed in the standard such as the impact of clock skew and drift of network nodes on the number of resynchronizations needed to maintain the required synchronization accuracy. This paper introduces an OMNeT++ simulation model, which can be used to investigate clock synchronization issues in time-sensitive networks

Zeitsynchronisation in drahtgebundenen Rechnernetzen

Ausgehend von einer Analyse des Standes der Technik werden neuartige Verfahren für die Zeitsynchronisation in drahtgebundenen Netzwerken vorgestellt. Unter anderem wird, zum ersten Mal im Bereich der Zeitsynchronisation, eine Kombination aus Linearer Optimierung und Broadcast-Nachrichten vorgestellt, was eine Verbindung der jeweiligen Genauigkeits- und Skalierbarkeitsvorteile ermöglicht. Weiterhin wird, ebenfalls zum ersten Mal im Bereich der Zeitsynchronisation, eine Kombination aus Linearer Optimierung und Temperaturkompensation vorgestellt.Based on an analysis of the state of the art, several new time synchronization methods for wired networks are proposed. Among others, for the first time in the synchronization domain, a combination of linear programming and broadcast messages is proposed, which allows combining the respective accuracy and scalability advantages. Moreover, this thesis proposes combining linear programming and temperature compensation, also for the first time in the field of time synchronization

A Comprehensive Review on Time Sensitive Networks with a Special Focus on Its Applicability to Industrial Smart and Distributed Measurement Systems

The groundbreaking transformations triggered by the Industry 4.0 paradigm have dramati-cally reshaped the requirements for control and communication systems within the factory systems of the future. The aforementioned technological revolution strongly affects industrial smart and distributed measurement systems as well, pointing to ever more integrated and intelligent equipment devoted to derive accurate measurements. Moreover, as factory automation uses ever wider and complex smart distributed measurement systems, the well-known Internet of Things (IoT) paradigm finds its viability also in the industrial context, namely Industrial IoT (IIoT). In this context, communication networks and protocols play a key role, directly impacting on the measurement accuracy, causality, reliability and safety. The requirements coming both from Industry 4.0 and the IIoT, such as the coexistence of time-sensitive and best effort traffic, the need for enhanced horizontal and vertical integration, and interoperability between Information Technology (IT) and Operational Technology (OT), fostered the development of enhanced communication subsystems. Indeed, established tech-nologies, such as Ethernet and Wi-Fi, widespread in the consumer and office fields, are intrinsically non-deterministic and unable to support critical traffic. In the last years, the IEEE 802.1 Working Group defined an extensive set of standards, comprehensively known as Time Sensitive Networking (TSN), aiming at reshaping the Ethernet standard to support for time-, mission-and safety-critical traffic. In this paper, a comprehensive overview of the TSN Working Group standardization activity is provided, while contextualizing TSN within the complex existing industrial technological panorama, particularly focusing on industrial distributed measurement systems. In particular, this paper has to be considered a technical review of the most important features of TSN, while underlining its applicability to the measurement field. Furthermore, the adoption of TSN within the Wi-Fi technology is addressed in the last part of the survey, since wireless communication represents an appealing opportunity in the industrial measurement context. In this respect, a test case is presented, to point out the need for wirelessly connected sensors networks. In particular, by reviewing some literature contributions it has been possible to show how wireless technologies offer the flexibility necessary to support advanced mobile IIoT applications

Development of an SDN control plane for Time-Sensitive Networking (TSN) endpoints

Objectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructur

Time Sensitive Networking - Sviluppo di un ambiente di test

In ambito industriale si hanno processi real-time, le cui azioni devono avvenire entro un intervallo di tempo. Non rispettare una scadenza può avere conseguenze disastrose. Questi processi possono essere portati avanti da più dispositivi, i quali necessitano di comunicazioni deterministiche per parlare tra di loro. Ethernet offre ottime prestazioni e ha dimostrato di poter stare al passo delle innovazioni tecnologiche, ma sono necessarie modifiche per potere garantire una comunicazione deterministica. Gli standard per le Time Sensitive Network(TSN) permettono di utilizzare Ethernet come protocollo real-time. \`E stato definito un ambiente di test per reti TSN, atto a replicare utilizzi industriali, per verificare il funzionamento degli standard TSN

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