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Multi-Hop Real-Time Communication over Switched Ethernet Technology
Mälardalen University, School of Innovation, Design and Engineering. Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. (IS (Complex Real-Time Embedded Systems))ORCID iD: 0000-0003-3469-1834
2014 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Switched Ethernet technology has been introduced to be exploited in real-time communication systems due to its features such as its high throughput and wide availability, hence being a cost-effective solution. Many real-time switched Ethernet protocols have been developed, preserving the profits of traditional Ethernet technology, to overcome the limitations imposed by using commercially available (COTS) switches. These limitations mainly originate from the non-deterministic behavior of the Ethernet switches inherent in the use of FIFO queues and a limited number of priority levels.

 

In our research we focus on two particular real-time communication technologies, one based on COTS Ethernet switches named the FTT-SE architecture and the other using a modified Ethernet switch called the HaRTES architecture. Both architectures are based on a master-slave technique supporting different and temporally isolated traffic types including real-time periodic, real-time sporadic and non-real-time traffic. Also, they provide mechanisms implementing adaptivity as a response to the requirements imposed by dynamic real-time applications. Nevertheless, the two mentioned architectures were originally developed for a simple network consisting of a single switch, and they were lacking support for multi-hop communication. In industrial applications, multi-hop communication is essential as the networks comprise a high number of nodes, that is far beyond the capability of a single switch.

 

In this thesis, we study the challenges of building multi-hop communication using the FTT-SE and the HaRTES architectures. We propose different architectures to provide multi-hop communication while preserving the key characteristics of the single-switch architecture such as timeliness guarantee, resource efficiency, adaptivity and dynamicity. We develop a response time analysis for each proposed architecture and we compare them to assess their corresponding benefits and limitations. Further, we develop a simulation tool to evaluate the solutions.

Place, publisher, year, edition, pages
Västerås: Mälardalen University , 2014.
Series
Mälardalen University Press Licentiate Theses, ISSN 1651-9256 ; 184
National Category
Embedded Systems Communication Systems
Research subject
Computer Science
Identifiers
URN: urn:nbn:se:mdh:diva-26121ISBN: 978-91-7485-168-7 (print)OAI: oai:DiVA.org:mdh-26121DiVA: diva2:756463
Presentation
2014-11-18, Delta, Mälardalens högskola, Västerås, 13:30 (English)
Opponent
Supervisors
Available from: 2014-10-20 Created: 2014-10-17 Last updated: 2014-11-12Bibliographically approved
List of papers
1. Performance Analysis of Master-Slave Multi-Hop Switched Ethernet Networks
Open this publication in new window or tab >>Performance Analysis of Master-Slave Multi-Hop Switched Ethernet Networks
2013 (English)In: Proceedings of the 8th IEEE International Symposium on Industrial Embedded Systems, SIES 2013, 2013, 280-289 p.Conference paper, Published paper (Refereed)
Abstract [en]

There is an increasing trend towards using switched Ethernet in real-time distributed systems due to features like absence of collisions and high throughput. Nevertheless, a few problems persist, in particular related to priority inversion and limited length in queues. In this paper we focus on a protocol which uses a master-slave technique over standard switched Ethernet in order to overcome such problems, namely FTT-SE protocol. We present an improved response time analysis for such a network and we compare, analytically and with simulations, the results achieved with Network Calculus on a worst-case scenario. We show that our proposed response time analysis gives tighter bounds compared to Network Calculus. Moreover, we compare the performance of different solutions to scale the FTT-SE protocol with respect to the bandwidth utilization. Finally, we propose a new architecture to improve the average performance of master-slave switched Ethernet networks.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:mdh:diva-21348 (URN)10.1109/SIES.2013.6601501 (DOI)2-s2.0-84885416264 (Scopus ID)9781479906581 (ISBN)
Conference
8th IEEE International Symposium on Industrial Embedded Systems (SIES13), Porto, Portugal, June 19-21, 2013
Projects
PRESS - Predictable Embedded Software Systems
Available from: 2013-09-18 Created: 2013-09-11 Last updated: 2016-11-01Bibliographically approved
2. Response time analysis of multi-hop HaRTES Ethernet Switch networks
Open this publication in new window or tab >>Response time analysis of multi-hop HaRTES Ethernet Switch networks
Show others...
2014 (English)In: IEEE Int. Workshop Factory Commun. Syst. Proc. WFCS, 2014Conference paper, Published paper (Refereed)
Abstract [en]

In this paper we focus on micro-segmented switched-Ethernet networks with HaRTES switches. HaRTES switches provide synchronous and asynchronous real-time traffic scheduling, dynamic Quality-of-Service adaptation and transparent integration of real-time and non-real-time nodes. Herein we investigate the challenges of connecting multiple HaRTES switches in order to build multi-hop communication and we propose a method, named Distributed Global Scheduling, to handle the traffic forwarding in such an architecture while preserving the unique properties of the single HaRTES switch case. Moreover, we develop a response time analysis for the method. We also evaluate the level of pessimism embodied in the anal-ysis. Finally, we show the applicability of the proposed method in an industrial setting by applying it in an automotive case study.

Series
IEEE International Workshop on Factory Communication Systems - Proceedings, WFCS
National Category
Engineering and Technology Computer and Information Science
Identifiers
urn:nbn:se:mdh:diva-25722 (URN)10.1109/WFCS.2014.6837579 (DOI)000356767300004 ()2-s2.0-84903977537 (Scopus ID)9781479932351 (ISBN)
Conference
10th IEEE Workshop on Factory Communication Systems, WFCS 2014, 5 May 2014 through 7 May 2014, Toulouse
Available from: 2014-07-28 Created: 2014-07-25 Last updated: 2015-07-16Bibliographically approved
3. Reduced Buffering Solution for Multi-Hop HaRTES Switched Ethernet Networks
Open this publication in new window or tab >>Reduced Buffering Solution for Multi-Hop HaRTES Switched Ethernet Networks
Show others...
2014 (English)In: The 20th IEEE International Conference on embedded and Real-Time Computing Systems and Applications RTCSA'14, 2014, Article number 6910504- p.Conference paper, Published paper (Refereed)
Abstract [en]

In the context of switched Ethernet networks, multi-hop communication is essential as the networks in industrial applications comprise a high amount of nodes, that is far beyond the capability of a single switch. In this paper, we focus on multi-hop communication using HaRTES switches. The HaRTES switch is a modified Ethernet switch that provides real-time traffic scheduling, dynamic Quality-of-Service and temporal isolation between real-time and non-real-time traffic. Herein, we propose a method, called Reduced Buffering Scheme, to conduct the traffic through multiple HaRTES switches in a multi-hop HaRTES architecture. In order to enable the new scheduling method we propose to modify the HaRTES switch structure. Moreover, we develop a response time analysis for the new method. We also compare the proposed method with a method previously proposed, called Distributed Global Scheduling, based on their traffic response times. We show that, the new method forwards all types of traffic including the highest, the medium and the lowest priority, faster than the previous method in most of the cases. Furthermore, we show that the new method performs even better for larger networks compared with the previous one.

Keyword
Switched Ethernet, Real-Time Communication, Multi-hop communication
National Category
Engineering and Technology
Identifiers
urn:nbn:se:mdh:diva-25189 (URN)10.1109/RTCSA.2014.6910504 (DOI)000352610400008 ()2-s2.0-84908626169 (Scopus ID)978-1479939534 (ISBN)
Conference
20th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications, RTCSA 2014; Chongqing; China; 20 August 2014 through 22 August 2014
Projects
PRESS - Predictable Embedded Software Systems
Available from: 2014-06-05 Created: 2014-06-05 Last updated: 2015-12-23Bibliographically approved
4. Implementing a Clock Synchronization Protocol on a Multi-Master Switched Ethernet Network
Open this publication in new window or tab >>Implementing a Clock Synchronization Protocol on a Multi-Master Switched Ethernet Network
2013 (English)Conference paper, Published paper (Refereed)
Abstract [en]

The interest to use Switched Ethernet technologies in real-time communication is increasing due to its absence of collisions when transmitting messages. Nevertheless, using COTS switches affect the timeliness guarantee inherent in potentially overflowing internal FIFO queues. In this paper we focus on a solution, called the FTT-SE protocol, which is developed based on a master-slave technique. Recently, an extension of the FTT-SE protocol has been proposed where the transmission of messages are controlled using multiple master nodes. In order to guarantee the correctness of the protocol, the masters should be timely synchronized. Therefore, in this paper we investigate using a clock synchronization protocol, based on the IEEE 1588 standard, among master nodes and we study the effects of this protocol on the network performance. In addition, we present a formal verification of this solution by means of model checking to prove the correctness of the FTT-SE protocol when the clock synchronization protocol is applied.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:mdh:diva-21365 (URN)10.1109/ETFA.2013.6647957 (DOI)2-s2.0-84890679568 (Scopus ID)9781479908622 (ISBN)
Conference
18th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA13), 10-13 September 2013, Cagliari, Italy
Projects
PRESS - Predictable Embedded Software Systems
Available from: 2013-09-17 Created: 2013-09-11 Last updated: 2016-11-01Bibliographically approved
5. SEtSim: A Modular Simulation Tool for Switched Ethernet Networks
Open this publication in new window or tab >>SEtSim: A Modular Simulation Tool for Switched Ethernet Networks
2014 (English)Report (Other academic)
Abstract [en]

Using high bandwidth network technologies in real-time applications, for example in automotive systems, is rapidly increasing. In this context, switched Ethernet-based protocols are becoming more popular due to their features such as providing a collision-free domain for transmission of messages. Moreover, switched Ethernet is a mature technology. Several protocols based on switched Ethernet have been proposed over the years, tuned for time critical applications. However, research for improving the features and performance of these protocols is still on-going. In order to evaluate the performance of early stage proposed protocols, the mathematical analysis and/or experiments are required. However, performing an experiment for complex network topologies with a large set of messages is not effortless. Therefore, using a simulation based approach for evaluating a protocol's performance and/or properties is highly useful. As a response to this we have, based on Simulink, developed a simulator, called SEtSim, for switched Ethernet networks. SEtSim currently supports different network topologies of the FTT-SE protocol, a master-slave protocol designed for standard Ethernet switches, as well as Ethernet AVB protocol. However, the kernel of SEtSim is designed such that it is possible to add and integrate other switched Ethernet-based protocols. In this paper, we describe the design of SEtSim and we show its scalability.

Place, publisher, year, edition, pages
Sweden: Mälardalen Real-Time Research Centre, Mälardalen University, 2014
Series
MRTC Reports, ISSN 1404-3041
Keyword
Switched Ethernet, Real-Time Networks, Simulation, Evaluation, Simulink, The FTT-SE Protocol, The Ethernet AVB
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:mdh:diva-26036 (URN)MDH-MRTC-292/2014-1-SE (ISRN)
Projects
PRESS - Predictable Embedded Software Systems
Available from: 2014-09-30 Created: 2014-09-30 Last updated: 2014-10-20Bibliographically approved

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