| 1. |
- Danielsson, Jakob, et al.
(författare)
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Performance Evaluation of Network Convergence Time Measurement Techniques
- 2017
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Ingår i: International Conference on Emerging Technologies And Factory Automation ETFA'17. - 9781509065059 ; , s. 1-7
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Konferensbidrag (refereegranskat)abstract
- In this paper we evaluate solutions that provide measurements for the network convergence time in switched Ethernet networks when links failures happen. We evaluate three solutions to measure the network convergence time in a faulty situation. Compared to the commercially available solutions, our proposals are cost-effective, portable, and open source. Thus, they are easy to deploy on many testbeds. We show the performance of the solutions by measuring different metrics including jitter, network convergence time and packet loss during the network recovery time. Our measurements indicate that it is possible to accurately measure the network convergence time using a packet sender which does not suffer interference from the overlying operating system. Furthermore, we noticed that the packet sniffer TShark did not suffer from kernel interrupts from overlying operating systems.
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| 2. |
- Al-Dulaimy, Auday, et al.
(författare)
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Fault Tolerance in Cloud Manufacturing : An Overview
- 2023
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Ingår i: Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering, LNICST. - : Springer Science and Business Media Deutschland GmbH. - 9783031318900 ; , s. 89-101
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Konferensbidrag (refereegranskat)abstract
- Utilizing edge and cloud computing to empower the profitability of manufacturing is drastically increasing in modern industries. As a result of that, several challenges have raised over the years that essentially require urgent attention. Among these, coping with different faults in edge and cloud computing and recovering from permanent and temporary faults became prominent issues to be solved. In this paper, we focus on the challenges of applying fault tolerance techniques on edge and cloud computing in the context of manufacturing and we investigate the current state of the proposed approaches by categorizing them into several groups. Moreover, we identify critical gaps in the research domain as open research directions. © 2023, ICST Institute for Computer Sciences, Social Informatics and Telecommunications Engineering.
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| 3. |
- Ashjaei, Mohammad, et al.
(författare)
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A Compact Approach to Clustered Master-Slave Ethernet Networks
- 2012
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Ingår i: IEEE International Workshop on Factory Communication Systems - Proceedings, WFCS. - 9781467315739 ; , s. 157-160
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Konferensbidrag (refereegranskat)abstract
- Ethernet switches are increasingly used in real-time distributed systems as a technical solution to guarantee the timeliness in communications. However, there are still limitations related to real-time behavior caused by the limited number of priority levels and the possibility of memory overruns with consequent message losses. These limitations can be eliminated using a master/slave technique such as proposed by the FTT paradigm. This led to the FTT-SE protocol that schedules transmissions centrally in a master node. While this protocol has already been well studied and investigated for small networks with a single switch, its extension to larger networks is still an open issue. In this paper we propose a compact clustered solution to scale the FTT-SE protocol to networks of multiple switches by organizing the network in sub-networks composed of one master and one switch each and which can be connected directly, without bridges. This paper also shows how the timeliness of the traffic can still be enforced. The validation is currently on-going.
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| 4. |
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| 5. |
- Ashjaei, Mohammad, et al.
(författare)
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Dynamic reconfiguration in HaRTES switched ethernet networks
- 2016
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Ingår i: IEEE International Workshop on Factory Communication Systems - Proceedings, WFCS. - 9781509023394
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Konferensbidrag (refereegranskat)abstract
- The ability of reconfiguring a system during runtime is essential for dynamic real-time applications in which resource usage is traded online for quality of service. The HaRTES switch, which is a modified Ethernet switch, holds this ability for the network resource, and at the same time it provides hard real-time support for both periodic and sporadic traffic. Although the HaRTES switch technologically caters this ability, a protocol to actually perform the dynamic reconfiguration is missing in multi-hop HaRTES networks. In this paper we introduce such a protocol that is compatible with the traffic scheduling method used in the architecture. We prove the correctness of the protocol using a model checking technique. Moreover, we conduct a set of simulation experiments to show the performance of the protocol and we also show that the reconfiguration process is terminated within a bounded time.
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| 6. |
- Ashjaei, Mohammad, et al.
(författare)
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Dynamic Reconfiguration in Multi-Hop Switched Ethernet Networks
- 2014
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Ingår i: ACM SIGBED Review. Special Issue on 6th Workshop on Adaptive and Reconfigurable Embedded Systems (APRES 2014). - : Association for Computing Machinery (ACM). - 1551-3688. ; 11:3, s. 62-65
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Tidskriftsartikel (refereegranskat)abstract
- The FTT-SE protocol provides adaptive real-time communication on Ethernet networks. To assure a continued real-time behavior, FTT-SE integrates admission control with a quality-of-service mechanism, which screen all adaptation and reconfiguration requests, accepting only those that do not compromise the system timeliness. The adaptability and reconfigurability have been deeply studied in the case of single switch FTT-SE architectures, whereas the extension of that for the multi-hop FTT-SE architecture was not yet investigated. Therefore, in this paper we study the challenges of enabling dynamic reconfiguration in multi-hop FTT-SE networks, we propose two methods (one centralized and one distributed) and we present a qualitative comparison between them.
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| 7. |
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| 8. |
- Ashjaei, Mohammad, et al.
(författare)
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End-to-end Resource Reservations in Distributed Embedded Systems
- 2016
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Ingår i: Proceedings - 2016 IEEE 22nd International Conference on Embedded and Real-Time Computing Systems and Applications, RTCSA 2016. ; , s. 1-11
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Konferensbidrag (refereegranskat)abstract
- The resource reservation techniques provide effective means to lower the software complexity, ensure predictability and allow flexibility during the development and execution of complex distributed embedded systems. In this paper we propose a new end-to-end resource reservation model for distributed embedded systems. The model is comprehensive in such a way that it supports end-to-end resource reservations on distributed transactions with various activation patterns that are commonly used in industrial control systems. The model allows resource reservations on processors and real-time network protocols. We also present timing analysis for the distributed embedded systems that are developed using the proposed model. The timing analysis computes the end-to-end response times as well as delays such as data age and reaction delays. The presented analysis also supports real-time networks that can autonomously initiate transmissions. Such networks are not supported by the existing analyses. We also include a case study to show the usability of the model and end-to-end timing analysis with resource reservations.
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| 9. |
- Ashjaei, Mohammad, et al.
(författare)
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Evaluation of dynamic reconfiguration architecture in multi-hop switched ethernet networks
- 2014
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Ingår i: 19th IEEE International Conference on Emerging Technologies and Factory Automation, ETFA 2014. - 9781479948468 ; , s. Article number 7005322-
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Konferensbidrag (refereegranskat)abstract
- On-the-fly adaptability and reconfigurability are recently becoming an interest in real-time communications. To assure a continued real-time behavior, the admission control with a quality-of-service mechanism is required, that screen all adaptation and reconfiguration requests. In the context of switched Ethernet networks, the FTT-SE protocol provides adaptive real-time communication. Recently, we proposed two methods to perform the online reconfiguration in multi-hop FTT-SE architectures. However, the methods lack the experimental evaluation. In this paper, we evaluate both methods in terms of the reconfiguration time.
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| 10. |
- Ashjaei, Mohammad, et al.
(författare)
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Implementing a Clock Synchronization Protocol on a Multi-Master Switched Ethernet Network
- 2013
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Konferensbidrag (refereegranskat)abstract
- 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.
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