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153
High Speed Switch Scheduling for Local Area Networks
 ACM Transactions on Computer Systems
, 1993
"... Current technology trends make it possible to build communication networks that can support high performance distributed computing. This paper describes issues in the design of a prototype switch for an arbitrary topology pointtopoint network with link speeds of up to one gigabit per second. The s ..."
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Cited by 210 (3 self)
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Current technology trends make it possible to build communication networks that can support high performance distributed computing. This paper describes issues in the design of a prototype switch for an arbitrary topology pointtopoint network with link speeds of up to one gigabit per second. The switch deals in fixedlength ATMstyle cells, which it can process at a rate of 37 million cells per second. It provides high bandwidth and low latency for datagram traffic. In addition, it supports realtime traffic by providing bandwidth reservations with guaranteed latency bounds. The key to the switch's operation is a technique called parallel iterative matching, which can quickly identify a set of conflictfree cells for transmission in a time slot. Bandwidth reservations are accommodated in the switch by building a fixed schedule for transporting cells from reserved flows across the switch; parallel iterative matching can fill unused slots with datagram traffic. Finally, we note that pa...
Effective bandwidths at multiclass queues
 Queueing Systems
, 1991
"... Consider a queue which serves traffic from a number of distinct sources and which is required to deliver a performance guarantee, expressed in terms of the mean delay or the probability the delay exceeds a threshold. For various simple models we show that an effective bandwidth can be associated wit ..."
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Cited by 185 (4 self)
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Consider a queue which serves traffic from a number of distinct sources and which is required to deliver a performance guarantee, expressed in terms of the mean delay or the probability the delay exceeds a threshold. For various simple models we show that an effective bandwidth can be associated with each source, and that the queue can deliver its performance guarantee by limiting the sources served so that their effective bandwidths sum to less than the capacity of the queue. Keywords: large deviations, M/G/1 queue, circuitswitched network, connection acceptance control. 1.
A new approach for allocating buffers and bandwidth to heterogeneous, regulated traffic in an ATM node
 IEEE Journal on Selected Areas in Communications
, 1995
"... AbstractA new approach to determining the admissibility of variable bit rate (VBR) traffic in buffered digital networks is developed. In this approach all traffic presented to the network is assumed to have been subjected to leakybucket regulation, and extremal, periodic, onoff regulated traffic ..."
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Cited by 151 (9 self)
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AbstractA new approach to determining the admissibility of variable bit rate (VBR) traffic in buffered digital networks is developed. In this approach all traffic presented to the network is assumed to have been subjected to leakybucket regulation, and extremal, periodic, onoff regulated traffic is considered; the analysis is based on fluid models. Each regulated traffic stream is allocated bandwidth and buffer resources which are independent of other traffic. Bandwidth and buffer allocations are traded off in a manner optimal for an adversarial situation involving minimal knowledge of other traffic. This leads to a singleresource statisticalmultiplexing problem which is solved using techniques previously used for unbuffered traffic. VBR traffic is found to be divisible into two classes, one for which statistical multiplexing is effective and one for which statistical multiplexing is ineffective in the sense that accepting small losses provides no advantage over requiring lossless performance. The boundary of the set of admissible traffic sources is examined, and is found to be sufficiently linear that an effective bandwidth can be meaningfully assigned to each VBR source, so long as only statisticallymultiplexable sources are considered, or only nonstatisticallymultiplexable sources are considered. If these two types of sources are intermixed, then nonlinear interactions occur and fewer sources can be admitted than a linear theory would predict. A qualitative characterization of the nonlinearities is presented. The complete analysis involves conservative approximations; however, admission decisions based on this work are expected to be less overly conservative than decisions based on alternative approaches. I.
Models of Blocking Probability in AllOptical Networks with and without Wavelength Changers
 IEEE Journal on Selected Areas in Communications
, 1995
"... We introduce a traffic model for circuit switched alloptical networks (AONs) which we then use to calculate the blocking probability along a path for networks with and without wavelength changers. We investigate the effects of path length, switch size, and interference length (the expected number of ..."
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Cited by 143 (0 self)
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We introduce a traffic model for circuit switched alloptical networks (AONs) which we then use to calculate the blocking probability along a path for networks with and without wavelength changers. We investigate the effects of path length, switch size, and interference length (the expected number of hops shared by two sessions which share at least one hop) on blocking probability and the ability of wavelength changers to improve performance. Our model correctly predicts unobvious qualitative behavior demonstrated in simulations by other authors. Keywords: AllOptical Networks, Wavelength Changers, Traffic Models 1 Introduction In an AllOptical Network (AON), the signals remain in the optical domain from the origin to the destination. We consider AONs supporting pointtopoint sessions between users. Without wavelength changers, a session must use the same wavelength on every fiber. With wavelength changers, a session may use a different wavelength on each fiber it occupies. In eith...
Information Theory and Communication Networks: An Unconsummated Union
 IEEE Trans. Inform. Theory
, 1998
"... Information theory has not yet had a direct impact on networking, although there are similarities in concepts and methodologies that have consistently attracted the attention of researchers from both fields. In this paper, we review several topics that are related to communication networks and that ..."
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Cited by 134 (5 self)
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Information theory has not yet had a direct impact on networking, although there are similarities in concepts and methodologies that have consistently attracted the attention of researchers from both fields. In this paper, we review several topics that are related to communication networks and that have an information theoretic flavor, including multiaccess protocols, timing channels, effective bandwidth of bursty data sources, deterministic constraints on datastreams, queueing theory, and switching networks. Keywords Communication networks, multiaccess, effective bandwidth, switching I. INTRODUCTION Information theory is the conscience of the theory of communication; it has defined the "playing field" within which communication systems can be studied and understood. It has provided the spawning grounds for the fields of coding, compression, encryption, detection, and modulation and it has enabled the design and evaluation of systems whose performance is pushing the limits of wha...
Large Deviations, the Shape of the Loss Curve, and Economies of Scale in Large Multiplexers
, 1995
"... We analyse the queue Q L at a multiplexer with L inputs. We obtain a large deviation result, namely that under very general conditions lim L!1 L \Gamma1 log P[Q L ? Lb] = \GammaI (b) provided the offered load is held constant, where the shape function I is expressed in terms of the cumulant ..."
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Cited by 117 (12 self)
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We analyse the queue Q L at a multiplexer with L inputs. We obtain a large deviation result, namely that under very general conditions lim L!1 L \Gamma1 log P[Q L ? Lb] = \GammaI (b) provided the offered load is held constant, where the shape function I is expressed in terms of the cumulant generating functions of the input traffic. This provides an improvement on the usual effective bandwidth approximation P[Q L ? b] e \Gammaffib , replacing it with P[Q L ? b] e \GammaLI(b=L) . The difference I(b) \Gamma ffi b determines the economies of scale which are to be obtained in large multiplexers. If the limit = \Gamma lim t!1 t t (ffi) exists (here t is the finite time cumulant of the workload process) then lim b!1 (I(b) \Gamma ffi b) = . We apply this idea to a number of examples of arrivals processes: heterogeneous superpositions, Gaussian processes, Markovian additive processes and Poisson processes. We obtain expressions for in these cases. is zero for independent arrivals, but positive for arrivals with positive correlations. Thus economies of scale are obtainable for highly bursty traffic expected in ATM multiplexing.
Fundamental Bounds and Approximations for ATM Multiplexers with Applications to Video Teleconferencing
, 1995
"... The main contributions of this paper are twofold. First, we prove fundamental, similarly behaving lower and upper bounds, and give an approximation based on the bounds, which is effective for analyzing ATM multiplexers, even when the traffic has many, possibly heterogeneous, sources and their model ..."
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Cited by 108 (12 self)
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The main contributions of this paper are twofold. First, we prove fundamental, similarly behaving lower and upper bounds, and give an approximation based on the bounds, which is effective for analyzing ATM multiplexers, even when the traffic has many, possibly heterogeneous, sources and their models are of high dimension. Second, we apply our analytic approximation to statistical models of video teleconference traffic, obtain the multiplexing system's capacity as determined by the number of admissible sources for given cell loss probability, buffer size and trunk bandwidth, and, finally, compare with results from simulations, which are driven by actual data from coders. The results are surprisingly close. Our bounds are based on Large Deviations theory. The main assumption is that the sources are Markovian and timereversible. Our approximation to the steady state buffer distribution is called "ChernoffDominant Eigenvalue" since one parameter is obtained from Chernoff's theorem and t...
Local Area Network Traffic Characteristics, with Implications for Broadband Network Congestion Management
"... This paper examines the phenomenon of congestion in order to better understand the congestion management techniques that will be needed in highspeed, cellbased networks. The first step of this study is to use high timeresolution local area network (LAN) traffic data to explore the nature of LAN t ..."
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Cited by 95 (0 self)
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This paper examines the phenomenon of congestion in order to better understand the congestion management techniques that will be needed in highspeed, cellbased networks. The first step of this study is to use high timeresolution local area network (LAN) traffic data to explore the nature of LAN traffic variability. Then, we use the data for a tracedriven simulation of a connectionless service that provides LAN interconnection. The simulation allows us to characterize what congestion might look like in a highspeed, cellbased network. The most
Effects of Wavelength Routing and Selection Algorithms on Wavelength Conversion Gain in WDM Optical Networks
 IEEE/ACM Transactions on Networking
, 1998
"... Wavelength division multiplexing technology is emerging as the transmission and switching mechanism for future optical mesh networks. In these networks, it is desired that a wavelength can be routed without electrical conversions. Two technologies are possible for this purpose: Wavelength Selective ..."
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Cited by 81 (2 self)
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Wavelength division multiplexing technology is emerging as the transmission and switching mechanism for future optical mesh networks. In these networks, it is desired that a wavelength can be routed without electrical conversions. Two technologies are possible for this purpose: Wavelength Selective CrossConnects (WSXC), and Wavelength Interchanging CrossConnects (WIXC) which involve wavelength conversion. It is believed that wavelength converters may improve the blocking performance, but there is a mix of results in the literature on the amount of this performance enhancement. In this paper, we use two metrics to quantify the wavelength conversion gain: the reduction in blocking probability and the increase in maximum utilization, compared to a network without converters. We study effects of wavelength routing and selection algorithms on these measures for mesh networks. We use the Overflow Model to analyze the blocking probability for wavelength selective mesh networks using the Fir...
Traffic Models in Broadband Networks
, 1997
"... Traffic models are at the heart of any performance evaluation of telecommunications networks. An accurate estimation of network performance is critical for the success of broadband networks. Such networks need to guarantee an acceptable quality of service (QoS) level to the users. Therefore, traff ..."
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Cited by 74 (0 self)
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Traffic models are at the heart of any performance evaluation of telecommunications networks. An accurate estimation of network performance is critical for the success of broadband networks. Such networks need to guarantee an acceptable quality of service (QoS) level to the users. Therefore, traffic models need to be accurate and able to capture the statistical characteristics of the actual traffic. In this article we survey and examine traffic models that are currently used in the literature. Traditional shortrange and nontraditional longrange dependent traffic models are presented. Number of parameters needed, parameter estimation, analytical tractability, and ability of traffic models to capture marginal distribution and autocorrelation structure of actual traffic are discussed. n Figure 1. Finite state model for voice. This research was supported in part by the National Science Foundation under grant NCR9396299. This article is based on Georgia Tech technical report G...