The Experts below are selected from a list of 39 Experts worldwide ranked by ideXlab platform
Leandros Tassiulas - One of the best experts on this subject based on the ideXlab platform.
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Push Forward Link-Level Sc for Network-Wide Perfor
1996Co-Authors: Leandros TassiulasAbstract:A Virtual Circuit Network with arbitrary topology is considered. The traffic streams follow prespecified routes, different in general for each stream, to reach their destination. A fluid traffic model is adopted and a processor sharing service discipline is considered. A policy is proposed for setting adaptively the fractions of the transmission capacity, which is allocated to the different traffic streams in the processor sharing discipline at each link. The amount of traffic arrived at the originating node of each link is measured for each stream. The fraction of the link capacity allocated to each stream is set to be proportional to the measured traffic. The traffic is measured continuously and the fractions are updated regularly based on the most recent traffic measurements. It is shown that eventually, the transmission capacity allocated to each stream converges to a quantity proportional to the average rate of the stream. Hence, if the capacity condition is satisfied, sufficient fractions of the capacity are allocated at each link for each stream. End-to-end performance guarantees are provided, if the traffic is regulated, The policy is distributed since each link adjusts the service fractions based on observations of the traffic arriving at its originating node only. Furthermore, it is adaptive since no information on the traffic characteristics is needed for the application of the policy.
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Push forward link-level scheduling for Network-wide performance
IEEE ACM Transactions on Networking, 1996Co-Authors: Leandros TassiulasAbstract:A Virtual Circuit Network with arbitrary topology is considered. The traffic streams follow prespecified routes, different in general for each stream, to reach their destination. A fluid traffic model is adopted and a processor sharing service discipline is considered. A policy is proposed for setting adaptively the fractions of the transmission capacity, which is allocated to the different traffic streams in the processor sharing discipline at each link. The amount of traffic arrived at the originating node of each link is measured for each stream. The fraction of the link capacity allocated to each stream is set to be proportional to the measured traffic. The traffic is measured continuously and the fractions are updated regularly based on the most recent traffic measurements. It is shown that eventually, the transmission capacity allocated to each stream converges to a quantity proportional to the average rate of the stream. Hence, if the capacity condition is satisfied, sufficient fractions of the capacity are allocated at each link for each stream. End-to-end performance guarantees are provided, if the traffic is regulated. The policy is distributed since each link adjusts the service fractions based on observations of the traffic arriving at its originating node only. Furthermore, it is adaptive since no information on the traffic characteristics is needed for the application of the policy.
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INFOCOM - Link-level scheduling for Network-level performance
Proceedings of INFOCOM '94 Conference on Computer Communications, 1Co-Authors: Leandros TassiulasAbstract:A service discipline for the link transmission scheduling in a Virtual Circuit Network with arbitrary topology is proposed. The scheduling of each link is based on the traffic at its origin node only. It is performed in two levels operating in different time scales. In the slower time scale the fraction of the link capacity to be allocated to the different streams is updated such that it remains proportional to the traffic of each stream that has arrived at the origin node of the link. In the faster time scale the link capacity is shared, such that the fractions of the capacity allocated by the bandwidth allocation policy are honored. A fluid traffic model is considered and processor sharing service is assumed. The policy is analyzed and it is shown that the existence of rates of the arrival streams guarantees that the allocated bandwidth at each stream will converge to a value larger than the link load. When the arrival streams are regulated to satisfy certain burstiness constraints, then the backlog at each Network node is bounded as well. >
A.a. Hagin - One of the best experts on this subject based on the ideXlab platform.
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ICDCS - Performability, reliability, and survivability of communication Networks: system of methods and models for evaluation
14th International Conference on Distributed Computing Systems, 1Co-Authors: A.a. HaginAbstract:This paper presents a system of methods and models for evaluating the performability, reliability, and survivability of a communication Network. All proposed models and methods are shown to be interdependent by way of indexes and parameters of the basic Network properties. Indexes for these Network properties are found for each message-exchanging terminal pair and for the entire Network. Steady-state availability, MTBF (mean time between failures), and MTTR (mean time to repair) are computed for reliability analysis of the Network with limited repair. Survivability indexes are found for the Network exposed to multiple external (adverse) influences that cause a gradual structural degradation of the Network. Models are proposed for the performability evaluation of unreliable Virtual Circuit Network X.25/X.75 with routing adapted to Network element failures. Some numerical results of comparative analysis of Network performability for adaptive and static routings are presented. >
L. Tassiulas - One of the best experts on this subject based on the ideXlab platform.
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Cut-through switching, pipelining, and scheduling for Network evacuation
IEEE ACM Transactions on Networking, 1999Co-Authors: L. TassiulasAbstract:A general model of a Virtual Circuit Network consisting of a number of servers and a number of traffic classes is considered. A traffic class is identified by the sequence of servers that should be visited and the corresponding service rates before a message (customer) of the class leaves the Network. The following cases are distinguished: (1) the messages need nonpreemptive service; (2) the service of a message can be preempted at any time; (3) pipelining of the service in a sequence of servers is allowed; and (4) pipelining is not allowed. All of these cases arise in different transmission switching techniques and scheduling schemes. A fluid model that emerges when both preemption and pipelining are allowed is considered. Scheduling schemes in the fluid model are compared with corresponding ones in the Network with nonpreemptive service and no pipelining. The problem of evacuating the Network from an initial backlog without further arrival is identified in the fluid model. Based on that, a policy with nearly optimal evacuation time is identified for the store-and-forward case. Finally, scheduling with deadlines is considered and it is shown that in the fluid model, the evacuation problem is equivalent to a linear programming problem. The evacuation times under different work-conserving policies are considered in specific examples.
T.a. Tsiligirides - One of the best experts on this subject based on the ideXlab platform.
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Research: Numerical analysis of some basic fluid communication models via parallel block methods
Computer Communications, 1996Co-Authors: T.a. TsiligiridesAbstract:In this work we propose a general method for the solution of some basic delayed feedback schemes used in long haul, high speed data transport. In such cases, simple batch Poisson models do not describe packet delays well, while the propagation delay is now becoming a major factor. Two basic Virtual Circuit Networks of balanced form are examined; the single-hop Network which aggregates many Virtual Circuits in parallel, and the multi-hop Virtual Circuit Network having M nodes in tandem. Using well known adaptive algorithms to dynamically adjust the window size, the above Networks are presented as linear systems of some delay differential equations in which the rate of transmission and the queue occupancy are modelled as fluids. Although these systems are locally unstable (in a Liapounov sense), we identify the appropriate scale for the parameters so that the systems will perform near their optimal theoretical values for a wide range of speeds. In addition, we propose a general method for their numerical solution which in reality are large and complex. The approach is based on parallel block methods that are used to solve the systems of the ordinary differential equations in which the original systems of the delay differential equations have been transformed. The basic theory underlying the parallel block methods is developed and numerical stability of low order is deduced.
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Solution method of some delay feedback schemes used in rate-based flow control analysis of high speed data channels
Proceedings of MILCOM '96 IEEE Military Communications Conference, 1Co-Authors: T.a. Tsiligirides, G.j. Mousadis, M.p. BekakosAbstract:A solution method of a first order, delay differential system, modelling a class of rate-based, feedback control schemes, used in long haul high speed data transport is derived and discussed. In such Networks the traffic pattern varies often unpredictably, while the large propagation delay is becoming a major factor. Our focus is on two basic Virtual Circuit Networks of balanced form; the multi-hop Virtual Circuit Network having M nodes in tandem and the single-hop Virtual Circuit Network which aggregates many Virtual Circuits with various propagation delays and individual windows over the single hop. Using well known adaptive algorithms to dynamically adjust the window size, the above Networks are presented as linear systems of some delay differential equations in which the rate of transmission and the queue occupancy are modelled as fluids. However, such schemes are locally unstable in a Lyapunov sense. We derived a numerical method for solving the resulting delay differential systems and we identify the appropriate scaling for the parameters so as to make the above schemes perform near their optimal theoretical values for a wide range of speeds. The analytical results so obtained are in a complete agreement with those already derived by simulation and reported in the literature. As it appears, oscillations are controlled to acceptably small magnitudes and therefore, such methods may be used as a powerful tool for optimum performance, by means of stabilizing the channel output and achieving fairness.
J. Yanagi - One of the best experts on this subject based on the ideXlab platform.
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An ATM system architecture for seamless Network evolution
Proceedings of GLOBECOM '93. IEEE Global Telecommunications Conference, 1Co-Authors: N. Endo, Akihiko Takase, S. Gouhara, Setsuo Takahashi, J. YanagiAbstract:The paper discusses the ATM Network evolution from various points of view including the evolution of ATM services, service interface, and connection management. The key issues for the ATM Network evolution are the assurance of independent progress of the core transport system separated from adaptation functions for existing and future telecommunication services, the integration of user service interface, and the enhancement of connection management from semi-permanent Virtual path Network to the switched Virtual Circuit Network. The node architecture is proposed based on multiplexer/cross-connect and self-routing switch configuration, which provides the smooth evolution from the cross-connect Network to the switched Network. The traffic management schemes on the node system are also studied. >
