The Experts below are selected from a list of 438 Experts worldwide ranked by ideXlab platform
Mohamed Ould-khaoua - One of the best experts on this subject based on the ideXlab platform.
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A performance model of compressionless routing in k -ary n -cube networks
Performance Evaluation, 2005Co-Authors: Ahmad Khonsari, Mohamed Ould-khaouaAbstract:Several analytical models of fully adaptive routing in wormhole-routed networks have recently been reported in the literature. All these models, however, have been discussed for routing algorithms with deadlock avoidance. Recent studies have revealed that deadlocks are quite rare in the network, especially when enough routing freedom is provided. Thus, the hardware resources, e,g. virtual channels, dedicated for deadlock avoidance are not utilised most of the time. This consideration has motivated researchers to introduce fully adaptive routing algorithms with deadlock-recovery. This paper proposes a new analytical model to predict message latency in k-aryn-cubes with compressionless routing, a fully adaptive algorithm that uses deadlock-recovery. The proposed model uses results from queueing systems with impatient customers to capture the effects of the Timeout Mechanism used in this routing algorithm to deal with message deadlock. The validity of the model is demonstrated by comparing results predicted by the analytical model against those obtained through simulation experiments.
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A Performance Model of Software-Based Deadlock Recovery Routing Algorithm in Hypercubes
Parallel Processing Letters, 2005Co-Authors: Ahmad Khonsari, Hamid Sarbazi-azad, Mohamed Ould-khaouaAbstract:Recent studies have revealed that deadlocks are generally infrequent in the network. Thus the hardware resources, e.g. virtual channels, dedicated for deadlock avoidance are not utilised most of the time. This consideration has motivated the development of novel adaptive routing algorithms with deadlock recovery. This paper describes a new analytical model to predict message latency in hypercubes with a true fully adaptive routing algorithm with progressive deadlock recovery. One of the main features of the proposed model is the use of results from queueing systems with impatient customers to capture the effects of the Timeout Mechanism used in this routing algorithm for deadlock detection. The validity of the model is demonstrated by comparing analytical results with those obtained through simulation experiments.
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Analysis of true fully adaptive routing with software-based deadlock recovery
Journal of Systems and Software, 2004Co-Authors: Ahmad Khonsari, Hamid Sarbazi-azad, Mohamed Ould-khaouaAbstract:Several analytical models of fully adaptive routing (AR) in wormhole-routed networks have recently been reported in the literature. All these models, however, have been discussed for routing algorithms with deadlock avoidance. Recent studies have revealed that deadlocks are quite rare in the network, especially when enough routing freedom is provided. Thus the hardware resources, e.g. virtual channels, dedicated for deadlock avoidance are not utilised most of the time. This consideration has motivated researchers to introduce fully adaptive routing algorithms with deadlock recovery. This paper describes a new analytical model of a true fully AR algorithm with software-based deadlock recovery, proposed in Martinez et al. (Software-based deadlock recovery techniques for true fully AR in wormhole networks, Proc. Int. Conf. Parallel Processing (ICPP'97), 1997, p. 182) for k-ary n-cubes. The proposed model uses the results from queueing systems with impatient customers to capture the effects of the Timeout Mechanism used in this routing algorithm for deadlock detection. Results obtained through simulation experiments confirm that the model predicts message latency with a good degree of accuracy under different working conditions.
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A Performance Model of True Fully Adaptive Routing in Hypercubes
High Performance Computing Systems and Applications, 2003Co-Authors: Ahmad Khonsari, Hamid Sarbazi-azad, Mohamed Ould-khaouaAbstract:Recent studies have revealed that deadlocks are generally infrequent in the network. Thus the hardware resources, e.g. virtual channels, dedicated for deadlock avoidance is not utilized most of the time. This consideration has motivated the development of novel adaptive routing algorithms with deadlock recovery. This paper describes a new analytical model to predict message latency in hyper-cubes with a true fully adaptive routing algorithm with progressive deadlock recovery. One of the main features of the proposed model is the use of results from queuing systems with impatient customers to capture the effects of the Timeout Mechanism used in this routing algorithm for deadlock detection. The validity of the model is demonstrated by comparing analytical Results with those obtained through simulation experiments.
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MASCOTS - Analysis of Timeout-based adaptive wormhole routing
MASCOTS 2001 Proceedings Ninth International Symposium on Modeling Analysis and Simulation of Computer and Telecommunication Systems, 1Co-Authors: Ahmad Khonsari, Hamid Sarbazi-azad, Mohamed Ould-khaouaAbstract:Although many adaptive routing algorithms have been proposed for wormhole-routed networks, it is necessary to have a clear understanding of the factors that affect their potential performance before they can be widely adopted in commercial multicomputers. This paper proposes a new analytical model of an adaptive routing algorithm proposed by Duato (see Future Generation Computer Systems vol.10, no.10, p.45-58, 1994). The main feature of this routing algorithm is the use of a Timeout Mechanism to select a particular class of virtual channels at a given router. This has the advantage of reducing virtual channels multiplexing, leading to improvement in network performance. Simulation experiments reveal that the proposed analytical model predicts message latency with a good degree of accuracy.
Ahmad Khonsari - One of the best experts on this subject based on the ideXlab platform.
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A performance model of compressionless routing in k -ary n -cube networks
Performance Evaluation, 2005Co-Authors: Ahmad Khonsari, Mohamed Ould-khaouaAbstract:Several analytical models of fully adaptive routing in wormhole-routed networks have recently been reported in the literature. All these models, however, have been discussed for routing algorithms with deadlock avoidance. Recent studies have revealed that deadlocks are quite rare in the network, especially when enough routing freedom is provided. Thus, the hardware resources, e,g. virtual channels, dedicated for deadlock avoidance are not utilised most of the time. This consideration has motivated researchers to introduce fully adaptive routing algorithms with deadlock-recovery. This paper proposes a new analytical model to predict message latency in k-aryn-cubes with compressionless routing, a fully adaptive algorithm that uses deadlock-recovery. The proposed model uses results from queueing systems with impatient customers to capture the effects of the Timeout Mechanism used in this routing algorithm to deal with message deadlock. The validity of the model is demonstrated by comparing results predicted by the analytical model against those obtained through simulation experiments.
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A Performance Model of Software-Based Deadlock Recovery Routing Algorithm in Hypercubes
Parallel Processing Letters, 2005Co-Authors: Ahmad Khonsari, Hamid Sarbazi-azad, Mohamed Ould-khaouaAbstract:Recent studies have revealed that deadlocks are generally infrequent in the network. Thus the hardware resources, e.g. virtual channels, dedicated for deadlock avoidance are not utilised most of the time. This consideration has motivated the development of novel adaptive routing algorithms with deadlock recovery. This paper describes a new analytical model to predict message latency in hypercubes with a true fully adaptive routing algorithm with progressive deadlock recovery. One of the main features of the proposed model is the use of results from queueing systems with impatient customers to capture the effects of the Timeout Mechanism used in this routing algorithm for deadlock detection. The validity of the model is demonstrated by comparing analytical results with those obtained through simulation experiments.
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Analysis of true fully adaptive routing with software-based deadlock recovery
Journal of Systems and Software, 2004Co-Authors: Ahmad Khonsari, Hamid Sarbazi-azad, Mohamed Ould-khaouaAbstract:Several analytical models of fully adaptive routing (AR) in wormhole-routed networks have recently been reported in the literature. All these models, however, have been discussed for routing algorithms with deadlock avoidance. Recent studies have revealed that deadlocks are quite rare in the network, especially when enough routing freedom is provided. Thus the hardware resources, e.g. virtual channels, dedicated for deadlock avoidance are not utilised most of the time. This consideration has motivated researchers to introduce fully adaptive routing algorithms with deadlock recovery. This paper describes a new analytical model of a true fully AR algorithm with software-based deadlock recovery, proposed in Martinez et al. (Software-based deadlock recovery techniques for true fully AR in wormhole networks, Proc. Int. Conf. Parallel Processing (ICPP'97), 1997, p. 182) for k-ary n-cubes. The proposed model uses the results from queueing systems with impatient customers to capture the effects of the Timeout Mechanism used in this routing algorithm for deadlock detection. Results obtained through simulation experiments confirm that the model predicts message latency with a good degree of accuracy under different working conditions.
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A Performance Model of True Fully Adaptive Routing in Hypercubes
High Performance Computing Systems and Applications, 2003Co-Authors: Ahmad Khonsari, Hamid Sarbazi-azad, Mohamed Ould-khaouaAbstract:Recent studies have revealed that deadlocks are generally infrequent in the network. Thus the hardware resources, e.g. virtual channels, dedicated for deadlock avoidance is not utilized most of the time. This consideration has motivated the development of novel adaptive routing algorithms with deadlock recovery. This paper describes a new analytical model to predict message latency in hyper-cubes with a true fully adaptive routing algorithm with progressive deadlock recovery. One of the main features of the proposed model is the use of results from queuing systems with impatient customers to capture the effects of the Timeout Mechanism used in this routing algorithm for deadlock detection. The validity of the model is demonstrated by comparing analytical Results with those obtained through simulation experiments.
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MASCOTS - Analysis of Timeout-based adaptive wormhole routing
MASCOTS 2001 Proceedings Ninth International Symposium on Modeling Analysis and Simulation of Computer and Telecommunication Systems, 1Co-Authors: Ahmad Khonsari, Hamid Sarbazi-azad, Mohamed Ould-khaouaAbstract:Although many adaptive routing algorithms have been proposed for wormhole-routed networks, it is necessary to have a clear understanding of the factors that affect their potential performance before they can be widely adopted in commercial multicomputers. This paper proposes a new analytical model of an adaptive routing algorithm proposed by Duato (see Future Generation Computer Systems vol.10, no.10, p.45-58, 1994). The main feature of this routing algorithm is the use of a Timeout Mechanism to select a particular class of virtual channels at a given router. This has the advantage of reducing virtual channels multiplexing, leading to improvement in network performance. Simulation experiments reveal that the proposed analytical model predicts message latency with a good degree of accuracy.
Jia Wang - One of the best experts on this subject based on the ideXlab platform.
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The taming of the shrew: mitigating low-rate TCP-targeted attack
IEEE Transactions on Network and Service Management, 2010Co-Authors: Chia-wei Chang, Jia WangAbstract:A Shrew attack, which uses a low-rate burst carefully designed to exploit TCP's retransmission Timeout Mechanism, can throttle the bandwidth of a TCP flow in a stealthy manner. While such an attack can significantly degrade the performance of all TCP-based protocols and services including Internet routing (e.g., BGP), no existing scheme clearly solves the problem in real network scenarios. In this paper, we propose a simple protection Mechanism, called SAP (Shrew Attack Protection), for defending against a Shrew attack. Rather than attempting to track and isolate Shrew attackers, SAP identifies TCP victims by monitoring their drop rates and preferentially admits those packets from the victims with high drop rates to the output queue. This is to ensure that well-behaved TCP sessions can retain their bandwidth shares. Our simulation results indicate that under a Shrew attack, SAP can prevent TCP sessions from closing, and effectively enable TCP flows to maintain high throughput. SAP is a destination-port-based Mechanism and requires only a small number of counters to find potential victims, which makes SAP readily implementable on top of existing router Mechanisms.
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The Taming of the Shrew: Mitigating Low-Rate TCP-Targeted Attack
2009 29th IEEE International Conference on Distributed Computing Systems, 2009Co-Authors: Chia-wei Chang, Jia WangAbstract:A Shrew attack, which uses a low-rate burst carefully designed to exploit TCP's retransmission Timeout Mechanism, can throttle the bandwidth of a TCP flow in a stealthy manner. While such an attack can significantly degrade the performance of all TCP-based protocols and services including Internet routing (e.g., BGP), no existing scheme clearly solves the problem in real network scenarios. In this paper, we propose a simple protection Mechanism, called SAP (Shrew Attack Protection), for defending against a Shrew attack. Rather than attempting to track and isolate Shrew attackers, SAP identifies TCP victims by monitoring their drop rates and preferentially admits those packets from victims with high drop rates to the output queue. This is to ensure that well-behaved TCP sessions can retain their bandwidth shares. Our simulations indicate that under a Shrew attack, SAP can prevent TCP sessions from closing, and effectively enable TCP flows to maintain high throughput. SAP is a destination-port-based Mechanism and requires only a small number of counters to find potential victims, which makes SAP readily implementable on top of existing router Mechanisms.
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ICDCS - The Taming of the Shrew: Mitigating Low-Rate TCP-Targeted Attack
2009 29th IEEE International Conference on Distributed Computing Systems, 2009Co-Authors: Chia-wei Chang, Seungjoon Lee, Bill Lin, Jia WangAbstract:A Shrew attack, which uses a low-rate burst carefully designed to exploit TCP's retransmission Timeout Mechanism, can throttle the bandwidth of a TCP flow in a stealthy manner. While such an attack can significantly degrade the performance of all TCP-based protocols and services including Internet routing (e.g., BGP), no existing scheme clearly solves the problem in real network scenarios. In this paper, we propose a simple protection Mechanism, called SAP (Shrew Attack Protection), for defending against a Shrew attack. Rather than attempting to track and isolate Shrew attackers, SAP identifies TCP victims by monitoring their drop rates and preferentially admits those packets from victims with high drop rates to the output queue. This is to ensure that well-behaved TCP sessions can retain their bandwidth shares. Our simulations indicate that under a Shrew attack, SAP can prevent TCP sessions from closing, and effectively enable TCP flows to maintain high throughput. SAP is a destination-port-based Mechanism and requires only a small number of counters to find potential victims, which makes SAP readily implementable on top of existing router Mechanisms.
Hamid Sarbazi-azad - One of the best experts on this subject based on the ideXlab platform.
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A Performance Model of Software-Based Deadlock Recovery Routing Algorithm in Hypercubes
Parallel Processing Letters, 2005Co-Authors: Ahmad Khonsari, Hamid Sarbazi-azad, Mohamed Ould-khaouaAbstract:Recent studies have revealed that deadlocks are generally infrequent in the network. Thus the hardware resources, e.g. virtual channels, dedicated for deadlock avoidance are not utilised most of the time. This consideration has motivated the development of novel adaptive routing algorithms with deadlock recovery. This paper describes a new analytical model to predict message latency in hypercubes with a true fully adaptive routing algorithm with progressive deadlock recovery. One of the main features of the proposed model is the use of results from queueing systems with impatient customers to capture the effects of the Timeout Mechanism used in this routing algorithm for deadlock detection. The validity of the model is demonstrated by comparing analytical results with those obtained through simulation experiments.
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Analysis of true fully adaptive routing with software-based deadlock recovery
Journal of Systems and Software, 2004Co-Authors: Ahmad Khonsari, Hamid Sarbazi-azad, Mohamed Ould-khaouaAbstract:Several analytical models of fully adaptive routing (AR) in wormhole-routed networks have recently been reported in the literature. All these models, however, have been discussed for routing algorithms with deadlock avoidance. Recent studies have revealed that deadlocks are quite rare in the network, especially when enough routing freedom is provided. Thus the hardware resources, e.g. virtual channels, dedicated for deadlock avoidance are not utilised most of the time. This consideration has motivated researchers to introduce fully adaptive routing algorithms with deadlock recovery. This paper describes a new analytical model of a true fully AR algorithm with software-based deadlock recovery, proposed in Martinez et al. (Software-based deadlock recovery techniques for true fully AR in wormhole networks, Proc. Int. Conf. Parallel Processing (ICPP'97), 1997, p. 182) for k-ary n-cubes. The proposed model uses the results from queueing systems with impatient customers to capture the effects of the Timeout Mechanism used in this routing algorithm for deadlock detection. Results obtained through simulation experiments confirm that the model predicts message latency with a good degree of accuracy under different working conditions.
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A Performance Model of True Fully Adaptive Routing in Hypercubes
High Performance Computing Systems and Applications, 2003Co-Authors: Ahmad Khonsari, Hamid Sarbazi-azad, Mohamed Ould-khaouaAbstract:Recent studies have revealed that deadlocks are generally infrequent in the network. Thus the hardware resources, e.g. virtual channels, dedicated for deadlock avoidance is not utilized most of the time. This consideration has motivated the development of novel adaptive routing algorithms with deadlock recovery. This paper describes a new analytical model to predict message latency in hyper-cubes with a true fully adaptive routing algorithm with progressive deadlock recovery. One of the main features of the proposed model is the use of results from queuing systems with impatient customers to capture the effects of the Timeout Mechanism used in this routing algorithm for deadlock detection. The validity of the model is demonstrated by comparing analytical Results with those obtained through simulation experiments.
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MASCOTS - Analysis of Timeout-based adaptive wormhole routing
MASCOTS 2001 Proceedings Ninth International Symposium on Modeling Analysis and Simulation of Computer and Telecommunication Systems, 1Co-Authors: Ahmad Khonsari, Hamid Sarbazi-azad, Mohamed Ould-khaouaAbstract:Although many adaptive routing algorithms have been proposed for wormhole-routed networks, it is necessary to have a clear understanding of the factors that affect their potential performance before they can be widely adopted in commercial multicomputers. This paper proposes a new analytical model of an adaptive routing algorithm proposed by Duato (see Future Generation Computer Systems vol.10, no.10, p.45-58, 1994). The main feature of this routing algorithm is the use of a Timeout Mechanism to select a particular class of virtual channels at a given router. This has the advantage of reducing virtual channels multiplexing, leading to improvement in network performance. Simulation experiments reveal that the proposed analytical model predicts message latency with a good degree of accuracy.
Chia-wei Chang - One of the best experts on this subject based on the ideXlab platform.
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The taming of the shrew: mitigating low-rate TCP-targeted attack
IEEE Transactions on Network and Service Management, 2010Co-Authors: Chia-wei Chang, Jia WangAbstract:A Shrew attack, which uses a low-rate burst carefully designed to exploit TCP's retransmission Timeout Mechanism, can throttle the bandwidth of a TCP flow in a stealthy manner. While such an attack can significantly degrade the performance of all TCP-based protocols and services including Internet routing (e.g., BGP), no existing scheme clearly solves the problem in real network scenarios. In this paper, we propose a simple protection Mechanism, called SAP (Shrew Attack Protection), for defending against a Shrew attack. Rather than attempting to track and isolate Shrew attackers, SAP identifies TCP victims by monitoring their drop rates and preferentially admits those packets from the victims with high drop rates to the output queue. This is to ensure that well-behaved TCP sessions can retain their bandwidth shares. Our simulation results indicate that under a Shrew attack, SAP can prevent TCP sessions from closing, and effectively enable TCP flows to maintain high throughput. SAP is a destination-port-based Mechanism and requires only a small number of counters to find potential victims, which makes SAP readily implementable on top of existing router Mechanisms.
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The Taming of the Shrew: Mitigating Low-Rate TCP-Targeted Attack
2009 29th IEEE International Conference on Distributed Computing Systems, 2009Co-Authors: Chia-wei Chang, Jia WangAbstract:A Shrew attack, which uses a low-rate burst carefully designed to exploit TCP's retransmission Timeout Mechanism, can throttle the bandwidth of a TCP flow in a stealthy manner. While such an attack can significantly degrade the performance of all TCP-based protocols and services including Internet routing (e.g., BGP), no existing scheme clearly solves the problem in real network scenarios. In this paper, we propose a simple protection Mechanism, called SAP (Shrew Attack Protection), for defending against a Shrew attack. Rather than attempting to track and isolate Shrew attackers, SAP identifies TCP victims by monitoring their drop rates and preferentially admits those packets from victims with high drop rates to the output queue. This is to ensure that well-behaved TCP sessions can retain their bandwidth shares. Our simulations indicate that under a Shrew attack, SAP can prevent TCP sessions from closing, and effectively enable TCP flows to maintain high throughput. SAP is a destination-port-based Mechanism and requires only a small number of counters to find potential victims, which makes SAP readily implementable on top of existing router Mechanisms.
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ICDCS - The Taming of the Shrew: Mitigating Low-Rate TCP-Targeted Attack
2009 29th IEEE International Conference on Distributed Computing Systems, 2009Co-Authors: Chia-wei Chang, Seungjoon Lee, Bill Lin, Jia WangAbstract:A Shrew attack, which uses a low-rate burst carefully designed to exploit TCP's retransmission Timeout Mechanism, can throttle the bandwidth of a TCP flow in a stealthy manner. While such an attack can significantly degrade the performance of all TCP-based protocols and services including Internet routing (e.g., BGP), no existing scheme clearly solves the problem in real network scenarios. In this paper, we propose a simple protection Mechanism, called SAP (Shrew Attack Protection), for defending against a Shrew attack. Rather than attempting to track and isolate Shrew attackers, SAP identifies TCP victims by monitoring their drop rates and preferentially admits those packets from victims with high drop rates to the output queue. This is to ensure that well-behaved TCP sessions can retain their bandwidth shares. Our simulations indicate that under a Shrew attack, SAP can prevent TCP sessions from closing, and effectively enable TCP flows to maintain high throughput. SAP is a destination-port-based Mechanism and requires only a small number of counters to find potential victims, which makes SAP readily implementable on top of existing router Mechanisms.
