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Switched real-time Ethernet with earliest deadline first scheduling - protocols and traffic handling
Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).ORCID-id: 0000-0002-6526-3931
2002 (engelsk)Inngår i: Parallel and Distributed Computing Practices, ISSN 1097-2803, Vol. 5, nr 1, s. 105-115Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

There is a strong interest of using the cheap and simple Ethernet technology for industrial and embedded systems. This far, however, the lack of real-time services has prevented this change of used network technology. This paper presents enhancements to full-duplex switched Ethernet for the ability of giving throughput and delay guarantees. The switch and the end-nodes control the real-time traffic with Earliest Deadline First (EDF) scheduling on the frame level. No modification to the Ethernet standard is needed in the network that supports both real-time and non-real-time TCP/IP communication. The switch is responsible for admission control where feasibility analysis is made for each link between source and destination. The switch broadcasts Ethernet frames regularly to clock synchronize the end nodes and to implement flow control for non-real-time traffic. We have characterized the performance of the network in terms of channel acceptance ratio by simulations with different number of nodes connected to the switch.

sted, utgiver, år, opplag, sider
Commack, N.Y.: Nova Science Publishers , 2002. Vol. 5, nr 1, s. 105-115
Emneord [en]
real-time Ethernet
HSV kategori
Identifikatorer
URN: urn:nbn:se:hh:diva-2743Lokal ID: 2082/3145OAI: oai:DiVA.org:hh-2743DiVA, id: diva2:239961
Tilgjengelig fra: 2009-08-12 Laget: 2009-08-12 Sist oppdatert: 2018-03-23bibliografisk kontrollert
Inngår i avhandling
1. Enhancing the Performance of Distributed Real-time Systems
Åpne denne publikasjonen i ny fane eller vindu >>Enhancing the Performance of Distributed Real-time Systems
2007 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

Advanced embedded systems can consist of many sensors, actuators and processors that are deployed on one or several boards, while having a demand of interacting with each other and sharing resources. Communication between different components usually has strict timing constraints. There is thus a strong need to provide solutions for time critical communication. This thesis focuses on both the support of real-time services over standard switched Ethernet networks and the improvement of systems' real-time characteristics, such as reducing delay and jitter in processors and on communication links.

Switched Ethernet has been chosen in this work because of its major advantages in industry; it supports higher bit-rates than most other current LAN (Local Area Network) technologies, including field buses, still at a low cost. We propose using a star network topology with a single Ethernet switch. Each node is connected to a separate port of the switch via a full-duplex link, thereby eliminating collisions. A solid real-time communication protocol for switched Ethernet networks is proposed in the thesis, including a real-time layer between the Ethernet layer and the TCP/IP suite. The network has the capability of supporting both real-time and non real-time traffic and assuring adaptation to the surrounding protocol standards.

Most embedded systems work in a dynamic environment, where the precise behavior of the network traffic can usually not be predicted. To support real-time services, we have chosen the Earliest Deadline scheduling algorithm (EDF) because of its optimality, high efficiency and suitability for being used in adaptive schemes. To be able to increase the amount of guaranteed real-time traffic, the notion of Asymmetric Deadline Partitioning Scheme (ADPS) is introduced. ADPS allows distribution of the end-to-end deadline of a message, sent from any source node in the network to any destination node via the switch, into two sub-deadlines, one for each hop according to the load of the physical link that it must traverse.

For the EDF scheduling algorithm, the feasibility test is one of the most important techniques that provides us with information about whether or not the real-time traffic can be guaranteed by the network. With the same computational complexity as the feasibility test, a method has been developed to compute the minimum EDF-feasible deadline for a real-time task. The importance of this method in real-time applications lies in that it can be effectively used to reduce the response times of specific control activities or limit their input-output jitter. To allow more flexibility in the control of delay and jitter in real-time systems, a general approach for reducing task deadlines according to the requirements of individual tasks has been developed. The method allows the user to specify a deadline reduction factor for each task in order to better exploit the available slack according to the tasks' actual requirements.

sted, utgiver, år, opplag, sider
Göteborg: Chalmers university of technology, 2007. s. 156
Serie
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie, ISSN 0346-718X ; 2599
Emneord
Switched Ethernet, Real-Time Communication, EDF scheduling, Reducation of delay and jitter
HSV kategori
Identifikatorer
urn:nbn:se:hh:diva-1986 (URN)2082/2381 (Lokal ID)978-91-7291-918-1 (ISBN)2082/2381 (Arkivnummer)2082/2381 (OAI)
Disputas
2007-05-14, Wigforssalen, Halmstad, 10:15 (engelsk)
Opponent
Veileder
Merknad

Ingår även i serien: Technical report. D / Department of Computer Science and Engineering, Chalmers University of Technology, 1653-1787 ; 28

Tilgjengelig fra: 2008-09-29 Laget: 2008-09-29 Sist oppdatert: 2018-03-23bibliografisk kontrollert
2. Switched Real-Time Ethernet for Industrial Applications
Åpne denne publikasjonen i ny fane eller vindu >>Switched Real-Time Ethernet for Industrial Applications
2003 (engelsk)Licentiatavhandling, med artikler (Annet vitenskapelig)
Abstract [en]

The research reported in this thesis has been focused on developing and analyzing how to support real-time traffic over a switched Ethernet network without any hardware or protocol modifications. The work has resulted in a proposed systems model, supporting both real-time and non real-time traffic. Currently this model is intended for a one-switch network, with no shared media. All added traffic handling to support real-time communication is positioned in a thin layer (RT layer) added between the Ethernet layer and the TCP/IP suite. This assures adaptation to the surrounding protocol standards. The RT layer manages traffic on the basis of virtual connections, denoted as RT channels, as well as packet level scheduling. RT channels are created between end-nodes prior to any occurrence of real-time traffic. Asymmetric deadline partitioning between the links of the RT channels is also proposed, in order to increase the number of possible RT channels.

sted, utgiver, år, opplag, sider
Göteborg: Chalmers tekniska högskola, 2003. s. 16
Serie
Technical report L, ISSN 1651-4963 ; 20
Emneord
Switched Ethernet, Real-time communication, EDF scheduling, Industrial networks
HSV kategori
Identifikatorer
urn:nbn:se:hh:diva-599 (URN)2082/941 (Lokal ID)2082/941 (Arkivnummer)2082/941 (OAI)
Presentation
2003-05-27, Wigforssalen, Kristian IV:s väg, Halmstad, 13:15 (engelsk)
Veileder
Tilgjengelig fra: 2007-04-10 Laget: 2007-04-10 Sist oppdatert: 2018-03-23bibliografisk kontrollert

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