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28
Experimental Assessment of Endtoend Behavior on Internet
 PROC. IEEE INFOCOM '93
, 1993
"... Over the last decade Internet has grown by orders of magnitude in size. Many of the protocols that were designed several years ago are still in use. It is not clear if the assumptions made in the design of control schemes still hold, particularly when we consider endtoend behavior of paths in the ..."
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Cited by 79 (2 self)
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Over the last decade Internet has grown by orders of magnitude in size. Many of the protocols that were designed several years ago are still in use. It is not clear if the assumptions made in the design of control schemes still hold, particularly when we consider endtoend behavior of paths in the network, today. This paper describes a simple experiment designed to capture endtoend behavior of the Internet. The measurements indicate that the IP level service provided in the network yields high losses, duplicates and reorderings of packets. In addition, the roundtrip transit delay varies significantly. These measurements indicate that the network may have several problems which still need to be analysed in order to improve the efficiency of protocols and control mechanisms that it uses.
PacketPair Flow Control
 IEEE/ACM Transactions on Networking
, 1994
"... This paper presents the packetpair ratebased feedback flow control scheme. This scheme is designed for networks where individual connections do not reserve bandwidth and for the available bitrate (besteffort) component of integrated networks. We assume a roundrobinlike queue service discipline ..."
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Cited by 53 (2 self)
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This paper presents the packetpair ratebased feedback flow control scheme. This scheme is designed for networks where individual connections do not reserve bandwidth and for the available bitrate (besteffort) component of integrated networks. We assume a roundrobinlike queue service discipline in the output queues of the network's switches, and propose a linear stochastic model for a single conversation in a network of such switches. These model motivates the PacketPair rate probing technique, which forms the basis for provably stable discrete and continuous time ratebased flow control schemes. We present a novel state estimation scheme based on fuzzy logic. We then address several practical concerns: dealing with system startup, retransmission and timeout strategy, and dynamic setpoint probing. We present a finite state machine as well as source code for a model implementation. The dynamics of a single source, the interactions of multiple sources, and the behavior of packetpai...
Robust rate control for ABR sources
 In Proceedings of IEEE INFOCOM
, 1998
"... Abstract — The paper considers the design of explicit ratebased flow control for ABR sources in an ATM network. The goal is to share the available capacity “fairly ” among many sources while maintaining queue length at a bottleneck node at a desired level. This problem is formulated as a stochastic ..."
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Cited by 40 (11 self)
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Abstract — The paper considers the design of explicit ratebased flow control for ABR sources in an ATM network. The goal is to share the available capacity “fairly ” among many sources while maintaining queue length at a bottleneck node at a desired level. This problem is formulated as a stochastic control problem, and in this framework ratecontrol mechanisms are developed, which stabilize the queue length even thou,gh different sources may have different roundtrip delays to the bottleneck node. Various robustness properties of the solution are illustrated through simulation experiments.
Resource sharing of TCP connections with different round trip times
 in: Proceedings of IEEE Infocom
, 2000
"... Abstract The performance of TCP connections sharing a common link and the resulting link usage depends on the various round trip times along the connections. Expressions exist for these values only in the homogenous case and heuristics for the general case give uncertain results. In this paper we ..."
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Cited by 33 (0 self)
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Abstract The performance of TCP connections sharing a common link and the resulting link usage depends on the various round trip times along the connections. Expressions exist for these values only in the homogenous case and heuristics for the general case give uncertain results. In this paper we first derive an exact expression (in the setting of fluid models) for the window evolution of TCP connections with different round trip delays. We next apply this result in a particular context to derive expressions for the maximum window sizes and the throughputs of TCP connections as well the idle periods and the utilization of the shared link. We show a bias in favor of connections with short round trip delays persists even for large buffer sizes. First and second order approximations in buffer size are given respectively for small and large buffers. These expressions show that for small buffers small round trip times predominate in global performances while the opposite is true for large buffers. I.
DiscreteTime Analysis of Adaptive Rate Control Mechanisms
 In Proc. 5th Int. Conference on Data and Communications
, 1994
"... We analyze the performance of a generic feedback flow control mechanism which captures the properties of several such mechanisms recently proposed in the literature. These mechanisms dynamically regulate the rate of data flow into a network based on feedback information about the network state. They ..."
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Cited by 26 (4 self)
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We analyze the performance of a generic feedback flow control mechanism which captures the properties of several such mechanisms recently proposed in the literature. These mechanisms dynamically regulate the rate of data flow into a network based on feedback information about the network state. They are used in a variety of networks and they have been advocated for upcoming highspeed networks. However, they are difficult to model realistically. In this paper, we present a stochastic discretetime approach that yields models which are realistic and yet tractable and computationally easy to solve. For our generic mechanism, the feedback consists of an exponentially averaged estimate of the bottleneck service rate and queue size. We obtain a model described by nonlinear stochastic difference equations. We find the conditions under which these equations converge to a steadystate and we characterize the speed of convergence to steadystate. We then consider a linearized version of the mo...
Optimal Rate Control For High Speed Telecommunication Networks
 34th IEEE Conference on Decision and Control
, 1995
"... We present in this paper two approaches for designing controllers that dynamically regulate the rate of data flow into a network based on feedback state information. They result in controllers that are similar to ones that have been advocated for both endtoend and hopbyhop congestion control in ..."
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Cited by 24 (14 self)
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We present in this paper two approaches for designing controllers that dynamically regulate the rate of data flow into a network based on feedback state information. They result in controllers that are similar to ones that have been advocated for both endtoend and hopbyhop congestion control in highspeed networks. Many existing control protocols have been developed on growing available experience, using adhoc techniques that did not come as a result of a controltheoretical study. This is due to the high complexity of the controlled systems, that are typically decentralized, have nonlinear dynamics, and may only use partial noisy delayed information. Some attempts have been made in recent years to use control theory to design flow controllers with, however, no explicit objective functions to be minimized; moreover, the class of control policies in existing theoretical work is quite restricted. In this paper we formulate explicitly some cost criteria to be minimized, related to p...
On the effect and control of selfsimilar network traffic: A simulation perspective
, 1997
"... Thispaperpresentsadiscussionofsimulationrelated issuesarisinginthestudyofselfsimilarnetwork tra#cwithrespecttoitse#ectandcontrol.Selfsimilartra #chasbeenshowntobeanubiquitous phenomenonarisingindiversenetworkingcontexts withpotentiallyadversee#ectsonnetworkperformance. Inmanyinstances,anexperiment ..."
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Cited by 19 (3 self)
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Thispaperpresentsadiscussionofsimulationrelated issuesarisinginthestudyofselfsimilarnetwork tra#cwithrespecttoitse#ectandcontrol.Selfsimilartra #chasbeenshowntobeanubiquitous phenomenonarisingindiversenetworkingcontexts withpotentiallyadversee#ectsonnetworkperformance. Inmanyinstances,anexperimentalorempirical approachneedstobetakentoe#ectivelyevaluate theperformanceimpactofsophisticatedcontrolalgorithmsactingatvariouslayersintheprotocolstack underselfsimilartra#cconditions.Simulatingorexperimentallyimplementingsuchenvironmentsisnon  trivialduetothefactthat,ingeneral,thecharacteristicsoftheobservedtra #cisitselfinfluencedbythe actionsofthecontrolalgorithmsunderstudy.To whatdegreeselfsimilaritymanifestsitselfinnetwork tra#cmaydependonthepropertiesoftheprotocols employed,andtracebasedsimulationsthatrelyon tra#cmeasurementstodrivesimulationsfailtocapturethisdynamicaspect. Wediscussanapproachtoevaluatingcontrolprotocolsunderself similartra#cconditionsbasedon asimple,robustapplicationlevelcausalmechanism oftra#cselfsimilaritywhichisgroundedinboth empiricalUNIXfilesystemresearchandanalytic tra#cmodelsinvolvingcertainrenewalprocesses. Wepresentahighleveldiscussionconcentratingon simulationrelatedissues,withspecificresearchresultssummarizedorpointedtointhereferences. 1
Performance Modeling of TCP/IP in a WideArea Network
, 1997
"... We examine the problem of evaluating the performance of TCP connections over wide area networks. Our approach combines experimental and analytic methods, and proceeds in three steps. First, we have used measurements taken over Renater to provide a basis for the chosen analytic model. This model tur ..."
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Cited by 13 (3 self)
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We examine the problem of evaluating the performance of TCP connections over wide area networks. Our approach combines experimental and analytic methods, and proceeds in three steps. First, we have used measurements taken over Renater to provide a basis for the chosen analytic model. This model turns out to be a shared bottleneck model, in which a finite buffer queue is shared by two connections, one being the reference TCP connection, and the other representing the exogenous traffic (i.e. all the other connections). This model is unlike previous models which did not explicitly consider the impact of exogenous traffic on the reference TCP connection. Second, we use fluid modeling to analyze the behavior of the reference TCP connection. We identify two modes of operation. For each mode, we derive closedform expressions for the average throughput and delay as a function of buffering, roundtrip delay, and characteristics of exogenous traffic. Third, we use simulation to validate the m...
ZIteration: A Simple Method for Throughput Estimation in TimeDependent MultiClass Systems
 In ACM SIGMETRICS /PERFORMANCE '95
, 1995
"... Multipleclass multipleresource (MCMR) systems, where each class of customers requires a particular set of resources, are common. These systems are often analyzed under steadystate conditions. We describe a simple method, referred to as Ziteration, to estimate both transient and steadystate perf ..."
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Cited by 11 (5 self)
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Multipleclass multipleresource (MCMR) systems, where each class of customers requires a particular set of resources, are common. These systems are often analyzed under steadystate conditions. We describe a simple method, referred to as Ziteration, to estimate both transient and steadystate performances of such systems. The method makes use of results and techniques available from queueing theory, network analysis, dynamic flow theory, and numerical analysis. We show the generality of the Ziteration by applying it to an ATM network, a parallel disk system, and a distributed batch system. Validations against discreteevent simulations show the accuracy and computational advantages of the Ziteration. 1 Introduction We consider a general multipleclass multipleresource (MCMR) system. We have a set R of resources and a set C of customer classes. The nature of a resource depends on the system being modeled; for example, it may be computer memory, floor space, transmission capacity, e...
Congestion control for differentiatedservices using nonlinear control theory
 In Proceedings of the Sixth IEEE Symposium on Computers and Communications
, 2001
"... The growing demand of computer usage requires efficient ways of managing network traffic in order to avoid or at least limit the level of congestion in cases where increases in bandwidth are not desirable or possible. Using nonlinear control theory we developed and analysed a generic Integrated Dyn ..."
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Cited by 9 (6 self)
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The growing demand of computer usage requires efficient ways of managing network traffic in order to avoid or at least limit the level of congestion in cases where increases in bandwidth are not desirable or possible. Using nonlinear control theory we developed and analysed a generic Integrated Dynamic Congestion Control (IDCC) scheme for controlling traffic using information on the status of each queue in the network. The IDCC scheme is based on a nonlinear model of the network that is generated using fluid flow considerations. The methodology used is general and independent of technology, as for example TCP/IP or ATM. We assume a differentiatedservices network framework and formulate our control strategy in the same spirit as IP DiffServ for three types of services: Premium Service, Ordinary Service, and Best Effort Service. The three differentiated classes of traffic operate at each output port of a router/switch. An IDCC scheme is designed for each output port, and a powerful, simple to implement controller is designed and analysed. The IDCC methodology has been applied to an ATM network. We use OPNET simulations to demonstrate that the proposed control methodology achieves the desired behaviour of the network, and possesses important attributes, such as: stable and robust behaviour, high utilisation with bounded delay and loss performance, and good steady state and transient behaviour.