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262
Admission Control for Statistical QoS: Theory and Practice
, 1999
"... In networks that support Quality of Service (QoS), an admission control algorithm determines whether or not a new traffic flow can be admitted to the network such that all users will receive their required performance. Such an algorithm is a key component of future multiservice networks as it deter ..."
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Cited by 106 (12 self)
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In networks that support Quality of Service (QoS), an admission control algorithm determines whether or not a new traffic flow can be admitted to the network such that all users will receive their required performance. Such an algorithm is a key component of future multiservice networks as it determines the extent to which network resources are utilized and whether the promised QoS parameters are actually delivered. Our goals in this paper are threefold. First, we describe and classify a broad set of proposed admission control algorithms. Second, we evaluate the accuracy of these algorithms via experiments using both onoff sources and long traces of compressed video; we compare the admissible regions and QoS parameters predicted by our implementations of the algorithms with those obtained from tracedriven simulations. Finally, we identify the key aspects of an admission control algorithm necessary for achieving a high degree of accuracy and hence a high statistical multiplexing gain...
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 105 (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...
Squeezing The Most Out Of ATM
, 1996
"... Even though ATM seems to be clearly the wave of the future, one performance analysis indicates that the combination of stringent performance requirements (e.g., 10  9 cell blocking probabilities), moderatesize buffers and highly bursty traffic will require that the utilization of the network be ..."
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Cited by 72 (10 self)
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Even though ATM seems to be clearly the wave of the future, one performance analysis indicates that the combination of stringent performance requirements (e.g., 10  9 cell blocking probabilities), moderatesize buffers and highly bursty traffic will require that the utilization of the network be quite low. That performance analysis is based on asymptotic decay rates of steadystate distributions used to develop a concept of effective bandwidths for connection admission control. However, we have developed an exact numerical algorithm that shows that the effectivebandwidth approximation can overestimate the target small blocking probabilities by several orders of magnitude when there are many sources that are more bursty than Poisson. The bad news is that the appealing simple connectionadmissioncontrol algorithm using effective bandwidths based solely on tailprobability asymptotic decay rates may actually not be as effective as many have hoped. The good news is that the statistical multiplexing gain on ATM networks may actually be higher than some have feared. For one example, thought to be realistic, our analysis indicates that the network actually can support twice as many sources as predicted by the effectivebandwidth approximation. That discrepancy occurs because for a large number of bursty sources the asymptotic constant in the tail probability exponential asymptote is extremely small. That in turn can be explained by the observation that the asymptotic constant decays exponentially in the number of sources when the sources are scaled to keep the total arrival rate fixed. We also show that the effectivebandwidth approximation is not always conservative. Specifically, for sources less bursty than Poisson, the asymptotic constant grows exponentially in the numbe...
Asymptotic results for multiplexing subexponential onoff processes
 Advances in Applied Probability
, 1998
"... Consider an aggregate arrival process AN obtained by multiplexing N OnOff processes with exponential Off periods of rate λ and subexponential On periods τon. As N goes to infinity, with λN → Λ, AN approaches an M/G/ ∞ type process. Both for finite and infinite N, we obtain the asymptotic characteri ..."
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Cited by 70 (19 self)
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Consider an aggregate arrival process AN obtained by multiplexing N OnOff processes with exponential Off periods of rate λ and subexponential On periods τon. As N goes to infinity, with λN → Λ, AN approaches an M/G/ ∞ type process. Both for finite and infinite N, we obtain the asymptotic characterization of the arrival process activity period. Using these results we investigate a fluid queue with the limiting M/G/ ∞ arrival process A ∞ t and capacity c. When On periods are regularly varying (with noninteger exponent), we derive a precise asymptotic behavior of the queue length random variable QP t observed at the beginning of the arrival process activity periods P[Q P t +ρ−c> x] ∼ Λr P[τ c−ρ x/(r+ρ−c) on> u]du x → ∞, where ρ = EA ∞ t < c; r (c ≤ r) is the rate at which the fluid is arriving during an On period. The asymptotic (time average) queuedistributionlower boundis obtained undermoregeneral assumptions on On periods than regular variation. In addition, we analyze a queueing system in which one OnOff process, whose On period belongs to a subclass of subexponential distributions, is multiplexed with independent exponential processes with aggregate expected rate Eet. This system is shown to be asymptotically equivalent to the same queueing system with the exponential arrival processes being replaced by their total mean value Eet.
Call Admission Control Schemes: A Review
"... Over the last few years, a substantial number of call admission control (CAC) schemes have been proposed for ATM networks. In this article, we review the salient features of some of these algorithms. Also, we quantitatively compare the performance of three of these schemes. ..."
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Cited by 62 (1 self)
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Over the last few years, a substantial number of call admission control (CAC) schemes have been proposed for ATM networks. In this article, we review the salient features of some of these algorithms. Also, we quantitatively compare the performance of three of these schemes.
Providing EndtoEnd Statistical Performance Guarantees with Bounding Interval Dependent Stochastic Models
 In ACM Sigmetrics'94
, 1994
"... This paper demonstrates a new, efficient, and general approach for providing endtoend performance guarantees in integrated services networks. This is achieved by modeling a traffic source with a family of bounding intervaldependent (BIND) random variables and by using a ratecontrolled service di ..."
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Cited by 59 (17 self)
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This paper demonstrates a new, efficient, and general approach for providing endtoend performance guarantees in integrated services networks. This is achieved by modeling a traffic source with a family of bounding intervaldependent (BIND) random variables and by using a ratecontrolled service discipline inside the network. The traffic model stochastically bounds the number of bits sent over time intervals of different length. The model captures different source behavior over different time scales by making the bounding distribution an explicit function of the interval length. The service discipline, RCSP, has the priority queueing mechanisms necessary to provide performance guarantees in integrated services networks. In addition, RCSP provides the means for efficiently extending the results from a single switch to a network of arbitrary topology. These techniques are derived analytically and then demonstrated with numerical examples. 1 This research was supported by the National ...
A study of networks simulation efficiency: Fluid simulation vs. packetlevel simulation
, 2001
"... Abstract—Network performance evaluation through traditional packetlevel simulation is becoming increasingly difficult as today’s networks grow in scale along many dimensions. As a consequence, fluid simulation has been proposed to cope with the size and complexity of such systems. This study focuses ..."
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Cited by 56 (1 self)
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Abstract—Network performance evaluation through traditional packetlevel simulation is becoming increasingly difficult as today’s networks grow in scale along many dimensions. As a consequence, fluid simulation has been proposed to cope with the size and complexity of such systems. This study focuses on analyzing and comparing the relative efficiencies of fluid simulation and packetlevel simulation for several network scenarios. We use the “simulation event ” rate to measure the computational effort of the simulators and show that this measure is both adequate and accurate. For some scenarios, we derive analytical results for the simulation event rate and identify the major factors that contribute to the simulation event rate. Among these factors, the “ripple effect ” is very important since it can significantly increase the fluid simulation event rate. For a tandem queueing system, we identify the boundary condition to establish regions where one simulation paradigm is more efficient than the other. Flow aggregation is considered as a technique to reduce the impact of the “ripple effect ” in fluid simulation. We also show that WFQ scheduling discipline can limit the “ripple effect”, making fluid simulation particularly well suited for WFQ models. Our results show that tradeoffs between parameters of a network model determines the most efficient simulation approach. Keywords—fluid simulation, performance evaluation, traffic model I.
Buffer Overflow Asymptotics For A Buffer Handling Many Traffic Sources
 Journal of Applied Probability
, 1995
"... As a model for an ATM switch we consider the overflow frequency of a queue that is served at a constant rate and in which the arrival process is the superposition of N traffic streams. We consider an asymptotic as N !1 in which the service rate Nc and buffer size Nb also increase linearly in N . In ..."
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Cited by 54 (0 self)
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As a model for an ATM switch we consider the overflow frequency of a queue that is served at a constant rate and in which the arrival process is the superposition of N traffic streams. We consider an asymptotic as N !1 in which the service rate Nc and buffer size Nb also increase linearly in N . In this regime, the frequency of buffer overflow is approximately exp(\GammaN I(c; b)), where I(c; b) is given by the solution to an optimization problem posed in terms of timedependent logarithmic moment generating functions. Experimental results for Gaussian and Markov modulated fluid source models show that this asymptotic provides a better estimate of the frequency of buffer overflow than ones based on large buffer asymptotics. ATM SWITCHES; BUFFER OVERFLOW ASYMPTOTICS; EFFECTIVE BANDWIDTHS; LARGE DEVIATIONS; MARKOV MODULATED FLUID AMS 1991 SUBJECT CLASSIFICATION: PRIMARY 60K30, SECONDARY 60F10, 60K25, 68M20, 90B10, 90B22 1. Switches handling many bursty sources In a high speed data com...
Analysis, Approximations and Admission Control of a MultiService Multiplexing System with Priorities
 In Proc. IEEE INFOCOM '95
, 1995
"... We consider an ATM system with an architecture which is designed to accommodate users with very different quality of service requirements. In the base case with only two services, sources which require low loss belong to a High Priority class, and share a FCFS buffer, which has priority access to th ..."
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Cited by 53 (3 self)
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We consider an ATM system with an architecture which is designed to accommodate users with very different quality of service requirements. In the base case with only two services, sources which require low loss belong to a High Priority class, and share a FCFS buffer, which has priority access to the trunk. A Low Priority class of sources with typically less stringent requirements on loss have a separate FCFS buffer, which receives the timevarying, residual bandwidth, if any, of the trunk. By administering admission control and restricting the combination of sources to an admissible set, the service guarantees for both classes may be satisfied. The sources are bursty and stochastic fluid models are used to handle burstscale congestion effects. Our contributions are: (i) we develop simple, fast and robust analytic approximations for the queue distributions in the two buffers; (ii) for admission control, we calculate the admissible set by using our analytic approximations and find that...
Admission Control and Routing in ATM Networks using Inferences from Measured Buffer Occupancy
, 1995
"... We address the issue of call acceptance and routing in ATM networks. Our goal is to design an algorithm that guarantees bounds on the fraction of cells lost by a call. The method we propose for call acceptance and routing does not require models describing the traffic. Each switch estimates the addi ..."
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Cited by 51 (10 self)
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We address the issue of call acceptance and routing in ATM networks. Our goal is to design an algorithm that guarantees bounds on the fraction of cells lost by a call. The method we propose for call acceptance and routing does not require models describing the traffic. Each switch estimates the additional fraction of cells that would be lost if new calls were routed through the switch. The routing algorithm uses these estimates. The estimates are obtained by monitoring the switch operations and extrapolating to the situation where more calls are routed through the switch. The extrapolation is justified by a scaling property. To reduce the variance of the estimates, the switches calculate the cell loss that would occur with virtual buffers. A way to choose the sizes of the virtual buffers in order to minimize the variance is discussed. Thus, the switches constantly estimate their spare capacity. Simulations were performed using Markov fluid sources to test the validity of our approach. ...