The Experts below are selected from a list of 81129 Experts worldwide ranked by ideXlab platform
Yannhang Lee - One of the best experts on this subject based on the ideXlab platform.
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emerging cots architecture support for real time tsn ethernet
ACM Symposium on Applied Computing, 2019Co-Authors: James A Coleman, Sara Almalih, Alexander Slota, Yannhang LeeAbstract:The IEEE family of standards referred to as Time Sensitive Networking (TSN) is gaining popularity in many real-time embedded applications, including industrial automation and automotive. Based on a synchronized clock at the Network layer, the TSN standards aim at deterministic behavior of Message communication over an Ethernet. However, the data access time between a CPU and its Network interface may be affected by the contention for shared resources and buses at each node. Any jitter on this final segment of the communication path can have a negative impact on clock synchronization and Network Message transmission. In this paper, we investigate the potential performance impacts to real-time TSN Ethernet caused by the level of precision to which the Network clock and the CPU clock is synchronized as well as the magnitude of transmission jitter under various load conditions. Specifically, we look into the emerging architecture features in x86 systems that are considered to be commercial-off-the-shelf (COTS) platforms for embedded applications. We show that the latest generation of COTS hardware significantly reduces the jitters of clock synchronization between the software visible clock and the Network, as well as reducing the jitter from when software attempts to transmit an Ethernet frame to when it actually appears on the wire. As a consequence, a significant performance improvement for software applications utilizing real-time TSN Ethernet can be attained in the emerging COTS systems.
Leandros Tassiulas - One of the best experts on this subject based on the ideXlab platform.
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mobility support through caching in content based publish subscribe Networks
Grid Computing, 2010Co-Authors: Vasilis Sourlas, Georgios S Paschos, Paris Flegkas, Leandros TassiulasAbstract:In a publish/subscribe (pub/sub) Network, Message delivery is guaranteed for all connected subscribers at publish time. However, in a dynamic mobile scenario where users join and leave the Network, it is important that content published at the time they are disconnected is still delivered when they reconnect from a different point. In this paper, we enhance the caching mechanisms in pub/sub Networks to enable client mobility. We build our mobility support with minor changes in the caching scheme while preserving the main principles of loose coupled and asynchronous communication of the pub/sub communication model. We also present a new proactive mechanism to reduce the overhead of duplicate responses. The evaluation of our proposed scheme is performed via simulations and testbed measurements.
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caching in content based publish subscribe systems
Global Communications Conference, 2009Co-Authors: Vasilis Sourlas, Georgios S Paschos, Paris Flegkas, Leandros TassiulasAbstract:In a publish/subscribe Network, Message delivery is guaranteed for all active subscribers at publish time. However, in a dynamic scenario where users join and leave the Network, a user may be interested in content published before the subscription time. In this paper, we introduce mechanisms that enable caching in such Networks, while maintaining the main principle of loose-coupled and asynchronous communication. Furthermore we investigate two caching policies; caching in all candidate brokers (basic caching) which yields high survivability and low delay and caching in leaf brokers (leaf caching) which maintains low overhead and querying complexity. The comparison is performed via simulations and testbed measurements and insights are given for future work.
David K Y Yau - One of the best experts on this subject based on the ideXlab platform.
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Exploiting Power Grid for Accurate and Secure Clock Synchronization in Industrial IoT
2016 IEEE Real-Time Systems Symposium (RTSS), 2016Co-Authors: Sreejaya Viswanathan, Rui Tan, David K Y YauAbstract:Desynchronized clocks among nodes in industrial Internet of Things (IoT) can degrade system performance and even lead to safety incidents. Clock synchronization protocols based on Network Message exchanges, though widely used in current industrial systems, are susceptible to delay attacks against the packet transmission. This vulnerability cannot be solved by conventional security measures such as encryption, and remains an open problem. This paper proposes to use the sine voltage waveform of a utility power grid to synchronize "things" connected to the same grid. Our experiments demonstrate that minute fluctuations of the voltage's cycle length encode fine-grained global time information in a city-scale utility grid. Based on this key result, we develop a clock synchronization approach that achieves sub-ms accuracy and is provably secure against packet delay attacks. Implementation results show that our approach achieves an average synchronization error of 0.1 ms between two IoT nodes that are 10 km apart. When the proposed system is deployed within the same floor of a building, the error reduces to 10 us.
James A Coleman - One of the best experts on this subject based on the ideXlab platform.
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emerging cots architecture support for real time tsn ethernet
ACM Symposium on Applied Computing, 2019Co-Authors: James A Coleman, Sara Almalih, Alexander Slota, Yannhang LeeAbstract:The IEEE family of standards referred to as Time Sensitive Networking (TSN) is gaining popularity in many real-time embedded applications, including industrial automation and automotive. Based on a synchronized clock at the Network layer, the TSN standards aim at deterministic behavior of Message communication over an Ethernet. However, the data access time between a CPU and its Network interface may be affected by the contention for shared resources and buses at each node. Any jitter on this final segment of the communication path can have a negative impact on clock synchronization and Network Message transmission. In this paper, we investigate the potential performance impacts to real-time TSN Ethernet caused by the level of precision to which the Network clock and the CPU clock is synchronized as well as the magnitude of transmission jitter under various load conditions. Specifically, we look into the emerging architecture features in x86 systems that are considered to be commercial-off-the-shelf (COTS) platforms for embedded applications. We show that the latest generation of COTS hardware significantly reduces the jitters of clock synchronization between the software visible clock and the Network, as well as reducing the jitter from when software attempts to transmit an Ethernet frame to when it actually appears on the wire. As a consequence, a significant performance improvement for software applications utilizing real-time TSN Ethernet can be attained in the emerging COTS systems.
Wm. Arthur Conklin - One of the best experts on this subject based on the ideXlab platform.
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State Based Network Isolation for Critical Infrastructure Systems Security
2015 48th Hawaii International Conference on System Sciences, 2015Co-Authors: Wm. Arthur ConklinAbstract:The collision of information technology (IT) and operational technology (OT) Networks has resulted in some significant security challenges. Cyber attacks are now taking place against critical infrastructures and the nature of industrial automation control systems equipment in OT Networks makes traditional IT security measures more difficult if not impossible to employ. A new method of system isolation based on system state vice Network traffic restrictions is presented as a means to protect critical systems from conventional IT based attacks. This new method of protection functions by isolating systems from the Network, yet moving data in form of state transfer vice Network Message. This method improves reliability and provides a means of protection from most current IT based attack vectors.