Overview of measurement-based connection admission control methods in ATM networks
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paper_title: A simple multi-QoS ATM buffer management scheme based on adaptive admission control

paper_content:

This paper proposes simple and effective multi-QoS ATM buffer management scheme with admission control. The proposed scheme supports three QoS-service classes by two separate buffers with strict priority and measurement-based as well as individual cell loss rate (CLR)-based admission control. Two guaranteed classes for video and reliable data are multiplexed into a high priority buffer and individual CLR management is employed. We show that the proposed individual CLR management is simple and effective compared to separate buffers with WRR (weighted round robin). One best-effort class is assigned to the low priority buffer, and includes LAN intercommunication using an upper-layer congestion control mechanism. Since measurement-based adaptive admission control is employed for best-effort service, the proposed adaptive admission control achieves high bandwidth efficiency while keeping the target CLR. This multi-QoS management scheme can be applied to future multimedia ATM networks that integrate video, data, and other services.
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paper_title: Traffic Models in Broadband Networks

paper_content:

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. We survey and examine traffic models that are currently used in the literature. Traditional short-range and non-traditional long-range dependent traffic models are presented. The number of parameters needed, parameter estimation, analytical tractability, and ability of traffic models to capture marginal distribution and auto-correlation structure of the actual traffic are discussed.
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paper_title: A call admission control scheme in ATM networks

paper_content:

In an ATM (asynchronous transfer mode) network, call admission control decides whether or not to accept a new call, so as to ensure the service quality of both individual existing calls and of the new call itself. The measure of service quality used for the call admission control considered here is virtual cell loss probability, PV. PV may be formulated simply from the maximum and the average cell rates alone, and it provides a good estimate of cell loss probability without respect to the burst lengths. PV computational complexity increases rapidly with an increase either in the number of call types, K, or in the number of existing calls of individual call types; and for this reason, the author proposes a method for calculating a PV approximation on the upper side, with the aim of achieving real-time call admission control. Its complexity of computation is a linear order of K. Also proposed is a call admission algorithm which utilizes this approximation method and for which, in some cases, the computational complexity is independent of K. >
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paper_title: Connection admission control in ATM networks

paper_content:

A connection admission control scheme based on the Gaussian traffic model is proposed. According to the scheme every call declares only its peak rate. Its statistics are then measured during its holding time. The connection admission criteria is based on traffic measurements and loss probability calculations based on the the Gaussian traffic model. Simulation tests show that the scheme is somewhat more efficient than schemes proposed earlier.
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paper_title: High-speed connection admission control in ATM networks by generating virtual requests for connection

paper_content:

This paper proposes a high-speed connection admission control scheme, named PERB CAC (CAC based on prior estimation for residual bandwidth). This scheme estimates the residual bandwidth in advance by generating a series of virtual requests for connection. When an actual connection request occurs, PERB CAC can instantaneously judge if the required bandwidth is larger than the estimated residual bandwidth, so the connection set-up time can be greatly reduced. Therefore, PERB CAC can realize high-speed connection set-up.
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paper_title: On the theory of general on-off sources with applications in high-speed networks

paper_content:

A general theory of on-off sources is provided. The basic source model is characterized by alternating independent on (burst) and off (silence) periods, which may have general distributions. Other more complex sources are constructed, and their behavior is characterized in terms of the basic source model. Heterogeneous and homogeneous statistical multiplexers fed by such sources are considered. In the heterogeneous environment, a simple result on the tail behavior of the multiplexer queue length distribution in the heavy traffic is provided. In the homogeneous environment, asymptotic results on the tail behavior of the queue length distribution are provided for all levels of utilization. The results for the heterogeneous environment suggest a new call admission control policy for general on-off sources in high-speed networks, which depends only on the first two moments of the on and off periods of individual sources and their respective peak rates. >
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paper_title: Managing bandwidth in ATM networks with bursty traffic

paper_content:

Three approaches to the bandwidth management problem that have been proposed and studied by various groups are reviewed to illustrate three distinctly different approaches and identify their strengths and weaknesses. Based on these approaches, a bandwidth management and congestion control scheme for asynchronous transfer mode (ATM) networks that supports both point-to-point and one-to-many multicast virtual circuits is proposed. It is shown that the method can handle fully heterogeneous traffic and can be effectively implemented. The algorithm for making virtual circuit acceptance decisions is straightforward and fast, and the hardware mechanisms needed to implement buffer allocation and traffic monitoring at the user-network interface have acceptable complexities. It is also shown, through numerical examples, that the approach can achieve reasonable link efficiencies even in the presence of very bursty traffic. No advance reservation required, simplifying the interface between the network and the user and avoiding an initial network round trip delay before data can be transmitted. >
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paper_title: Loss performance analysis of an ATM multiplexer loaded with high-speed on-off sources

paper_content:

The performance of an asynchronous transfer mode (ATM) multiplexer whose input consists of the superposition of a multiplicity of homogeneous on-off sources modeled by a two-state Markovian process is studied. The approach is based on the approximation of the actual input process by means of a suitably chosen two-state Markov modulated Poisson process (MMPP), as a simple and effective choice for the representation of superposition arrival streams. To evaluate the cell loss performance, a new matching procedure that leads to accurate results compared to simulation is developed. The application limits of the proposed method are also discussed. The outstanding physical meaning of this procedure permits a deep insight into the multiplexer performance behavior as the source parameters and the multiplexer buffer size are varied. >
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paper_title: On the asymptotic behavior of heterogeneous statistical multiplexer with applications

paper_content:

The author combines a heterogeneous statistical multiplexer in heavy traffic with different characteristics in discrete time which is representative of the asynchronous transfer mode (ATM) environment at the cell level. An exact formulation of the queuing model for the multiplexer is presented. Using spectral decomposition method and asymptotic analysis, it is shown that for fixed source average utilization and peak rate, as the burst size of the individual sources increase the tail behavior of the distribution of the number of cells queued in the multiplexer has a simple characterization. This characterization provides a simple approximation of the queuing behavior of the multiplexer, where the impact of each source is quite evident. The accuracy of this approximation is examined. Some applications are considered where both buffer sizing and admission control are discussed. >
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paper_title: Call admission control in an ATM network using upper bound of cell loss probability

paper_content:

Call admission control in ATM networks without monitoring network load is proposed. Traffic parameters specified by users are employed to obtain the upper bound of cell loss probability, thereby determining call admission. A cell loss probability standard is guaranteed to be satisfied under this control without assumptions of a cell arrival process. Implementation of this control to quickly evaluate cell loss probability after acceptance of a new call is discussed. The result is also applicable to ATM network dimensioning based on traffic parameters. >
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paper_title: Adaptive Connection Admission Control Using Real-time Traffic Measurements in ATM Networks

paper_content:

The invention disclosed is a device capable of sensing and recording the total thermal energy received by an object in a given location. The device can sense the energy received from any direction by any source of thermal energy. The sensors are attached to a recorder so that variations over time can be observed.
---
paper_title: A Framework for Bandwidth Management in ATM Networks--Aggregate Equivalent Bandwidth Estimation Approach

paper_content:

A unified framework for traffic control and bandwidth management in ATM networks is proposed. It bridges algorithms for real-time and data services. The central concept of this framework is adaptive connection admission. It employs an estimation of the aggregate equivalent bandwidth required by connections carried in each output port of the ATM switches. The estimation process takes into account both the traffic source declarations and the connection superposition process measurements in the switch output ports. This is done in an optimization framework based on a linear Kalman filter. To provide a required quality of service guarantee, bandwidth is reserved for possible estimation error. The algorithm is robust and copes very well with unpredicted changes in source parameters, thereby resulting in high bandwidth utilization while providing the required quality of service. The proposed approach can also take into account the influence of the source policing mechanism. The tradeoff between strict and relaxed source policing is discussed.
---
paper_title: A simple bandwidth management strategy based on measurements of instantaneous virtual path utilization in ATM networks

paper_content:

A new connection admission control method based on actual virtual path traffic measurements is proposed to achieve high bandwidth efficiency for various types of traffic. The proposed method is based on the measurement of instantaneous virtual path utilization, which is defined as the total cell rate of the active virtual channels normalized by the virtual path capacity. A low-pass filter is used to determine the instantaneous virtual path utilization from crude measurements. A smoothing coefficient formula is derived as a function of the peak rate of the virtual channel. The residual bandwidth is derived from the maximum instantaneous utilization observed during a monitoring period. Simulation shows that the proposed method achieves statistical multiplexing gains of up to 80% of the limit possible with optimum control for similar traffic sources. It can be implemented with very simple hardware. The admission decision is simple: the requested bandwidth is compared with the residual bandwidth. This method is therefore well suited for practical asynchronous transfer mode switching systems.
---
paper_title: A Decision-Theoretic Approach to Call Admission Control in ATM Networks

paper_content:

This paper describes a simple and robust ATM call admission control, and develops the theoretical background for its analysis. Acceptance decisions are based on whether the current load is less than a precalculated threshold, and Bayesian decision theory provides the framework for the choice of thresholds. This methodology allows an explicit treatment of the trade-off between cell loss and call rejection, and of the consequences of estimation error. Further topics discussed include the robustness of the control to departures from model assumptions, its performance relative to a control possessing precise knowledge of all unknown parameters, the relationship between leaky bucket depths and buffer requirements, and the treatment of multiple call types. >
---
paper_title: Call admission control in an ATM network using upper bound of cell loss probability

paper_content:

Call admission control in ATM networks without monitoring network load is proposed. Traffic parameters specified by users are employed to obtain the upper bound of cell loss probability, thereby determining call admission. A cell loss probability standard is guaranteed to be satisfied under this control without assumptions of a cell arrival process. Implementation of this control to quickly evaluate cell loss probability after acceptance of a new call is discussed. The result is also applicable to ATM network dimensioning based on traffic parameters. >
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paper_title: Equivalent capacity and its application to bandwidth allocation in high-speed networks

paper_content:

The authors propose a computationally simple approximate expression for the equivalent capacity or bandwidth requirement of both individual and multiplexed connections, based on their statistical characteristics and the desired grade-of-service (GOS). The purpose of such an expression is to provide a unified metric to represent the effective bandwidth used by connections and the corresponding effective load of network links. These link metrics can then be used for efficient bandwidth management, routing, and call control procedures aimed at optimizing network usage. While the methodology proposed can provide an exact approach to the computation of the equivalent capacity, the associated complexity makes it infeasible for real-time network traffic control applications. Hence, an approximation is required. The validity of the approximation developed is verified by comparison to both exact computations and simulation results. >
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paper_title: Effectiveness of dynamic bandwidth management mechanisms in ATM networks

paper_content:

The leaky bucket, a credit management system that allows cells to enter the network only if sufficient credit is available, is considered. Motivation for an in-depth study of dynamic control algorithms, to avoid congestion in high-speed networks under time varying traffic statistics, is provided. The need for real-time traffic measurements and dynamic control actions for long-lived connections is demonstrated. In particular, it is shown through simulations that implementing access control algorithms based on the bandwidth allocation procedures only at connection setup is not sufficient for congestion-free operation of the network. It is further shown that if the bandwidth allocation and the leaky bucket parameters are not dynamically adjusted, the performances of the connections depend on their initial parameters and can be very undesirable as the traffic parameters change over time. Moreover, if corrective actions are not taken, congestion may build up in the network even in the presence of leaky buckets. The simple dynamic approach proposed limits the congestion periods in the network to the time scales of the connection-level controls. Therefore, the probability of many connections sending excess traffic into the network at the same time is greatly reduced, alleviating the congestion problem. >
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paper_title: Effective bandwidth of general Markovian traffic sources and admission control of high speed networks

paper_content:

A prime instrument for controlling congestion in high-speed broadband ISDN (BISDN) networks is admission control, which limits call and guarantees a grade of service determined by delay and loss probability in the multiplexer. It is shown, for general Markovian traffic sources, that it is possible to assign a notational effective bandwidth to each source which is an explicitly identified, simply computing quantity with provably correct properties in the natural asymptotic regime of small loss probabilities. It is the maximal real eigenvalue of a matrix which is directly obtained from the source characteristics and the admission criterion, and for several sources it is simply additive. Both fluid and point process models are considered, and parallel results are obtained. Numerical results show that the acceptance set for heterogeneous classes of sources is closely approximated and conservatively bounded by the set obtained from the effective bandwidth approximation. >
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paper_title: Fundamental Bounds and Approximations for ATM Multiplexers with Applications to Video Teleconferencing

paper_content:

The main contributions of this paper are two-fold. 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 time-reversible. Our approximation to the steady-state buffer distribution is called Chenoff-dominant eigenvalue since one parameter is obtained from Chernoffs theorem and the other is the system's dominant eigenvalue. Fast, effective techniques are given for their computation. In our application we process the output of variable bit rate coders to obtain DAR(1) source models which, while of high dimension, require only knowledge of the mean, variance, and correlation. We require cell-loss probability not to exceed 10/sup -6/, trunk bandwidth ranges from 45 to 150 Mb/s, buffer sizes are such that maximum delays range from 1 to 60 ms, and the number of coder-sources ranges from 15 to 150. Even for the largest systems, the time for analysis is a fraction of a second, while each simulation takes many hours. Thus, the real-time administration of admission control based on our analytic techniques is feasible. >
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paper_title: Real-time cell loss ratio estimation and its applications to ATM traffic controls

paper_content:

The asymptotics of cell-loss ratio (CLR) in the regime of large buffers are characterized by two parameters, the asymptotic constant and asymptotic decay rate. Both parameters can be expanded in powers of one minus the link utilization (heavy traffic expansion). Thus, once the coefficients in this expansion are obtained, the CLR can be very easily estimated from the measured link utilization by using CLR asymptotics. This paper proposes an algorithm for estimating these coefficients in real time. For this purpose, the notion of state-space representation for a single-server queue is introduced: the elements of the state vector are the coefficients in the expansion of the asymptotic constant and asymptotic decay rate. Bayesian regression analysis is applied to estimate the state vector based on the buffer measurement. Our approach does not require any models describing the statistics of the traffic other than the asymptotic behavior of the CLR in the regime of large buffers. In addition, it allows us to estimate the effective bandwidth of the aggregated process easily, so it is applicable to a wide range of ATM traffic control methods, such as connection admission control and VP bandwidth control. We describe how this method of CLR estimation will be applied to connection admission control and VP bandwidth control by using results from simulation experiments.
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paper_title: Effectiveness of dynamic bandwidth management mechanisms in ATM networks

paper_content:

The leaky bucket, a credit management system that allows cells to enter the network only if sufficient credit is available, is considered. Motivation for an in-depth study of dynamic control algorithms, to avoid congestion in high-speed networks under time varying traffic statistics, is provided. The need for real-time traffic measurements and dynamic control actions for long-lived connections is demonstrated. In particular, it is shown through simulations that implementing access control algorithms based on the bandwidth allocation procedures only at connection setup is not sufficient for congestion-free operation of the network. It is further shown that if the bandwidth allocation and the leaky bucket parameters are not dynamically adjusted, the performances of the connections depend on their initial parameters and can be very undesirable as the traffic parameters change over time. Moreover, if corrective actions are not taken, congestion may build up in the network even in the presence of leaky buckets. The simple dynamic approach proposed limits the congestion periods in the network to the time scales of the connection-level controls. Therefore, the probability of many connections sending excess traffic into the network at the same time is greatly reduced, alleviating the congestion problem. >
---
paper_title: Effective bandwidth of general Markovian traffic sources and admission control of high speed networks

paper_content:

A prime instrument for controlling congestion in high-speed broadband ISDN (BISDN) networks is admission control, which limits call and guarantees a grade of service determined by delay and loss probability in the multiplexer. It is shown, for general Markovian traffic sources, that it is possible to assign a notational effective bandwidth to each source which is an explicitly identified, simply computing quantity with provably correct properties in the natural asymptotic regime of small loss probabilities. It is the maximal real eigenvalue of a matrix which is directly obtained from the source characteristics and the admission criterion, and for several sources it is simply additive. Both fluid and point process models are considered, and parallel results are obtained. Numerical results show that the acceptance set for heterogeneous classes of sources is closely approximated and conservatively bounded by the set obtained from the effective bandwidth approximation. >
---
paper_title: A Decision-Theoretic Approach to Call Admission Control in ATM Networks

paper_content:

This paper describes a simple and robust ATM call admission control, and develops the theoretical background for its analysis. Acceptance decisions are based on whether the current load is less than a precalculated threshold, and Bayesian decision theory provides the framework for the choice of thresholds. This methodology allows an explicit treatment of the trade-off between cell loss and call rejection, and of the consequences of estimation error. Further topics discussed include the robustness of the control to departures from model assumptions, its performance relative to a control possessing precise knowledge of all unknown parameters, the relationship between leaky bucket depths and buffer requirements, and the treatment of multiple call types. >
---
paper_title: Loss performance analysis of an ATM multiplexer loaded with high-speed on-off sources

paper_content:

The performance of an asynchronous transfer mode (ATM) multiplexer whose input consists of the superposition of a multiplicity of homogeneous on-off sources modeled by a two-state Markovian process is studied. The approach is based on the approximation of the actual input process by means of a suitably chosen two-state Markov modulated Poisson process (MMPP), as a simple and effective choice for the representation of superposition arrival streams. To evaluate the cell loss performance, a new matching procedure that leads to accurate results compared to simulation is developed. The application limits of the proposed method are also discussed. The outstanding physical meaning of this procedure permits a deep insight into the multiplexer performance behavior as the source parameters and the multiplexer buffer size are varied. >
---
paper_title: Adaptive Connection Admission Control Using Real-time Traffic Measurements in ATM Networks

paper_content:

The invention disclosed is a device capable of sensing and recording the total thermal energy received by an object in a given location. The device can sense the energy received from any direction by any source of thermal energy. The sensors are attached to a recorder so that variations over time can be observed.
---
paper_title: Equivalent capacity and its application to bandwidth allocation in high-speed networks

paper_content:

The authors propose a computationally simple approximate expression for the equivalent capacity or bandwidth requirement of both individual and multiplexed connections, based on their statistical characteristics and the desired grade-of-service (GOS). The purpose of such an expression is to provide a unified metric to represent the effective bandwidth used by connections and the corresponding effective load of network links. These link metrics can then be used for efficient bandwidth management, routing, and call control procedures aimed at optimizing network usage. While the methodology proposed can provide an exact approach to the computation of the equivalent capacity, the associated complexity makes it infeasible for real-time network traffic control applications. Hence, an approximation is required. The validity of the approximation developed is verified by comparison to both exact computations and simulation results. >
---
paper_title: A Framework for Bandwidth Management in ATM Networks--Aggregate Equivalent Bandwidth Estimation Approach

paper_content:

A unified framework for traffic control and bandwidth management in ATM networks is proposed. It bridges algorithms for real-time and data services. The central concept of this framework is adaptive connection admission. It employs an estimation of the aggregate equivalent bandwidth required by connections carried in each output port of the ATM switches. The estimation process takes into account both the traffic source declarations and the connection superposition process measurements in the switch output ports. This is done in an optimization framework based on a linear Kalman filter. To provide a required quality of service guarantee, bandwidth is reserved for possible estimation error. The algorithm is robust and copes very well with unpredicted changes in source parameters, thereby resulting in high bandwidth utilization while providing the required quality of service. The proposed approach can also take into account the influence of the source policing mechanism. The tradeoff between strict and relaxed source policing is discussed.
---
paper_title: A simple bandwidth management strategy based on measurements of instantaneous virtual path utilization in ATM networks

paper_content:

A new connection admission control method based on actual virtual path traffic measurements is proposed to achieve high bandwidth efficiency for various types of traffic. The proposed method is based on the measurement of instantaneous virtual path utilization, which is defined as the total cell rate of the active virtual channels normalized by the virtual path capacity. A low-pass filter is used to determine the instantaneous virtual path utilization from crude measurements. A smoothing coefficient formula is derived as a function of the peak rate of the virtual channel. The residual bandwidth is derived from the maximum instantaneous utilization observed during a monitoring period. Simulation shows that the proposed method achieves statistical multiplexing gains of up to 80% of the limit possible with optimum control for similar traffic sources. It can be implemented with very simple hardware. The admission decision is simple: the requested bandwidth is compared with the residual bandwidth. This method is therefore well suited for practical asynchronous transfer mode switching systems.
---
paper_title: A Decision-Theoretic Approach to Call Admission Control in ATM Networks

paper_content:

This paper describes a simple and robust ATM call admission control, and develops the theoretical background for its analysis. Acceptance decisions are based on whether the current load is less than a precalculated threshold, and Bayesian decision theory provides the framework for the choice of thresholds. This methodology allows an explicit treatment of the trade-off between cell loss and call rejection, and of the consequences of estimation error. Further topics discussed include the robustness of the control to departures from model assumptions, its performance relative to a control possessing precise knowledge of all unknown parameters, the relationship between leaky bucket depths and buffer requirements, and the treatment of multiple call types. >
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paper_title: Link capacity allocation and network control by filtered input rate in high-speed networks

paper_content:

We study link capacity allocation for a finite buffer system to transmit multimedia traffic. The queueing process is simulated with real video traffic. Two key concepts are explored in this study. First, the link capacity requirement at each node is essentially captured by its low-frequency input traffic (filtered at a properly selected cut-off frequency). Second, the low-frequency traffic stays intact as it travels through a finite-buffer system without significant loss. Hence, one may overlook the queueing process at each node for network-wide traffic flow in the low-frequency band. We propose a simple, effective method for link capacity allocation and network control using on-line observation of traffic flow in the low-frequency band. The study explores a new direction for measurement-based traffic control in high-speed networks. >
---
paper_title: Effectiveness of dynamic bandwidth management mechanisms in ATM networks

paper_content:

The leaky bucket, a credit management system that allows cells to enter the network only if sufficient credit is available, is considered. Motivation for an in-depth study of dynamic control algorithms, to avoid congestion in high-speed networks under time varying traffic statistics, is provided. The need for real-time traffic measurements and dynamic control actions for long-lived connections is demonstrated. In particular, it is shown through simulations that implementing access control algorithms based on the bandwidth allocation procedures only at connection setup is not sufficient for congestion-free operation of the network. It is further shown that if the bandwidth allocation and the leaky bucket parameters are not dynamically adjusted, the performances of the connections depend on their initial parameters and can be very undesirable as the traffic parameters change over time. Moreover, if corrective actions are not taken, congestion may build up in the network even in the presence of leaky buckets. The simple dynamic approach proposed limits the congestion periods in the network to the time scales of the connection-level controls. Therefore, the probability of many connections sending excess traffic into the network at the same time is greatly reduced, alleviating the congestion problem. >
---
paper_title: A call admission control scheme in ATM networks

paper_content:

In an ATM (asynchronous transfer mode) network, call admission control decides whether or not to accept a new call, so as to ensure the service quality of both individual existing calls and of the new call itself. The measure of service quality used for the call admission control considered here is virtual cell loss probability, PV. PV may be formulated simply from the maximum and the average cell rates alone, and it provides a good estimate of cell loss probability without respect to the burst lengths. PV computational complexity increases rapidly with an increase either in the number of call types, K, or in the number of existing calls of individual call types; and for this reason, the author proposes a method for calculating a PV approximation on the upper side, with the aim of achieving real-time call admission control. Its complexity of computation is a linear order of K. Also proposed is a call admission algorithm which utilizes this approximation method and for which, in some cases, the computational complexity is independent of K. >
---
paper_title: A Framework for Bandwidth Management in ATM Networks--Aggregate Equivalent Bandwidth Estimation Approach

paper_content:

A unified framework for traffic control and bandwidth management in ATM networks is proposed. It bridges algorithms for real-time and data services. The central concept of this framework is adaptive connection admission. It employs an estimation of the aggregate equivalent bandwidth required by connections carried in each output port of the ATM switches. The estimation process takes into account both the traffic source declarations and the connection superposition process measurements in the switch output ports. This is done in an optimization framework based on a linear Kalman filter. To provide a required quality of service guarantee, bandwidth is reserved for possible estimation error. The algorithm is robust and copes very well with unpredicted changes in source parameters, thereby resulting in high bandwidth utilization while providing the required quality of service. The proposed approach can also take into account the influence of the source policing mechanism. The tradeoff between strict and relaxed source policing is discussed.
---
paper_title: A simple bandwidth management strategy based on measurements of instantaneous virtual path utilization in ATM networks

paper_content:

A new connection admission control method based on actual virtual path traffic measurements is proposed to achieve high bandwidth efficiency for various types of traffic. The proposed method is based on the measurement of instantaneous virtual path utilization, which is defined as the total cell rate of the active virtual channels normalized by the virtual path capacity. A low-pass filter is used to determine the instantaneous virtual path utilization from crude measurements. A smoothing coefficient formula is derived as a function of the peak rate of the virtual channel. The residual bandwidth is derived from the maximum instantaneous utilization observed during a monitoring period. Simulation shows that the proposed method achieves statistical multiplexing gains of up to 80% of the limit possible with optimum control for similar traffic sources. It can be implemented with very simple hardware. The admission decision is simple: the requested bandwidth is compared with the residual bandwidth. This method is therefore well suited for practical asynchronous transfer mode switching systems.
---
paper_title: Managing bandwidth in ATM networks with bursty traffic

paper_content:

Three approaches to the bandwidth management problem that have been proposed and studied by various groups are reviewed to illustrate three distinctly different approaches and identify their strengths and weaknesses. Based on these approaches, a bandwidth management and congestion control scheme for asynchronous transfer mode (ATM) networks that supports both point-to-point and one-to-many multicast virtual circuits is proposed. It is shown that the method can handle fully heterogeneous traffic and can be effectively implemented. The algorithm for making virtual circuit acceptance decisions is straightforward and fast, and the hardware mechanisms needed to implement buffer allocation and traffic monitoring at the user-network interface have acceptable complexities. It is also shown, through numerical examples, that the approach can achieve reasonable link efficiencies even in the presence of very bursty traffic. No advance reservation required, simplifying the interface between the network and the user and avoiding an initial network round trip delay before data can be transmitted. >
---
paper_title: A Decision-Theoretic Approach to Call Admission Control in ATM Networks

paper_content:

This paper describes a simple and robust ATM call admission control, and develops the theoretical background for its analysis. Acceptance decisions are based on whether the current load is less than a precalculated threshold, and Bayesian decision theory provides the framework for the choice of thresholds. This methodology allows an explicit treatment of the trade-off between cell loss and call rejection, and of the consequences of estimation error. Further topics discussed include the robustness of the control to departures from model assumptions, its performance relative to a control possessing precise knowledge of all unknown parameters, the relationship between leaky bucket depths and buffer requirements, and the treatment of multiple call types. >
---
paper_title: On the relevance of long-range dependence in network traffic

paper_content:

There is much experimental evidence that network traffic processes exhibit ubiquitous properties of self-similarity and long-range dependence, i.e., of correlations over a wide range of time scales. However, there is still considerable debate about how to model such processes and about their impact on network and application performance. In this paper, we argue that much previous modeling work has failed to consider the impact of two important parameters, namely the finite range of time scales of interest in performance evaluation and prediction problems, and the first-order statistics such as the marginal distribution of the process. We introduce and evaluate a model in which these parameters can be controlled. Specifically, our model is a modulated fluid traffic model in which the correlation function of the fluid rate matches that of an asymptotically second-order self-similar process with given Hurst parameter up to an arbitrary cutoff time lag, then drops to zero. We develop a very efficient numerical procedure to evaluate the performance of a single-server queue fed with the above fluid input process. We use this procedure to examine the fluid loss rate for a wide range of marginal distributions, Hurst (1950) parameters, cutoff lags, and buffer sizes. Our main results are as follows. First, we find that the amount of correlation that needs to be taken into account for performance evaluation depends not only on the correlation structure of the source traffic, but also on time scales specific to the system under study. For example, the time scale associated with a queueing system is a function of the maximum buffer size. Thus, for finite buffer queues, we find that the impact on loss of the correlation in the arrival process becomes nil beyond a time scale we refer to as the correlation horizon. This means, in particular, that for performance-modeling purposes, we may choose any model among the panoply of available models (including Markovian and self-similar models) as long as the chosen model captures the correlation structure of the source traffic up to the correlation horizon. Second, we find that loss can depend in a crucial way on the marginal distribution of the fluid rate process. Third, our results suggest that reducing loss by buffering is hard for traffic with correlation over many time scales. We advocate the use of source traffic control and statistical multiplexing instead.
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paper_title: The importance of long-range dependence of VBR video traffic in ATM traffic engineering: myths and realities

paper_content:

There has been a growing concern about the potential impact of long-term correlations (second-order statistic) in variable-bit-rate (VBR) video traffic on ATM buffer dimensioning. Previous studies have shown that video traffic exhibits long-range dependence (LRD) (Hurst parameter large than 0.5). We investigate the practical implications of LRD in the context of realistic ATM traffic engineering by studying ATM multiplexers of VBR video sources over a range of desirable cell loss rates and buffer sizes (maximum delays). Using results based on large deviations theory, we introduce the notion of Critical Time Scale (CTS). For a given buffer size, link capacity, and the marginal distribution of frame size, the CTS of a VBR video source is defined as the number of frame correlations that contribute to the cell loss rate. In other words, second-order behavior at the time scale beyond the CTS does not significantly affect the network performance. We show that whether the video source model is Markov or has LRD, its CTS is finite, attains a small value for small buffer, and is a non-decreasing function of buffer size. Numerical results show that (i) even in the presence of LRD, long-term correlations do not have significant impact on the cell loss rate; and (ii) short-term correlations have dominant effect on cell loss rate, and therefore, well-designed Markov traffic models are effective for predicting Quality of Service (QOS) of LRD VBR video traffic. Therefore, we conclude that it is unnecessary to capture the long-term correlations of a real-time VBR video source under realistic ATM buffer dimensioning scenarios as far as the cell loss rates and maximum buffer delays are concerned.
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paper_title: Long-range dependence in variable-bit-rate video traffic

paper_content:

We analyze 20 large sets of actual variable-bit-rate (VBR) video data, generated by a variety of different codecs and representing a wide range of different scenes. Performing extensive statistical and graphical tests, our main conclusion is that long-range dependence is an inherent feature of VBR video traffic, i.e., a feature that is independent of scene (e.g., video phone, video conference, motion picture video) and codec. In particular, we show that the long-range dependence property allows us to clearly distinguish between our measured data and traffic generated by VBR source models currently used in the literature. These findings give rise to novel and challenging problems in traffic engineering for high-speed networks and open up new areas of research in queueing and performance analysis involving long-range dependent traffic models. A small number of analytic queueing results already exist, and we discuss their implications for network design and network control strategies in the presence of long-range dependent traffic. >
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paper_title: Queue Response to Input Correlation Functions: Discrete Spectral Analysis

paper_content:

The authors explore a new concept of spectral characterization of wide-band input process in high speed networks. It helps them to localize wide-band sources in a subspace, especially in the low-frequency band, which has a dominant impact on queueing performance. They choose simple periodic-chains for the input rate process construction. Analogous to input functions in signal processing, they use elements of DC, sinusoidal, rectangular pulse, triangle pulse, and their superpositions, to represent various input correlation properties. The corresponding input power spectrum is defined in the discrete-frequency domain. In principle, a continuous spectral function of stationary random input process can be asymptotically approached by its discrete version as one sufficiently reduces the discrete-frequency intervals. An understanding of the queue response to the input spectrum will provide a great deal of knowledge to develop advanced network traffic measurement theory, and help to introduce effective network resource allocation policies. The new relation between queue length and input spectrum is a fruitful starting point for further research. >
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paper_title: Queue Response to Input Correlation Functions: Continuous Spectral Analysis

paper_content:

Queueing performance in a richer, heterogeneous input environment is studied. A unique way to understand the effect of second- and higher-order input statistics on queues is offered, and new concepts of traffic measurement, network control, and resource allocation are developed for high-speed networks in the frequency domain. The technique applies to the analysis of queue response to the individual effects of input power spectrum, bispectrum, trispectrum, and input-rate steady-state distribution. The study provides clear evidence that of the four input statistics, the input power spectrum is most essential to queueing analysis. Furthermore, input power in the low-frequency band has a dominant impact on queueing performance, whereas high-frequency power to a large extent can be neglected. >
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paper_title: Link capacity allocation and network control by filtered input rate in high-speed networks

paper_content:

We study link capacity allocation for a finite buffer system to transmit multimedia traffic. The queueing process is simulated with real video traffic. Two key concepts are explored in this study. First, the link capacity requirement at each node is essentially captured by its low-frequency input traffic (filtered at a properly selected cut-off frequency). Second, the low-frequency traffic stays intact as it travels through a finite-buffer system without significant loss. Hence, one may overlook the queueing process at each node for network-wide traffic flow in the low-frequency band. We propose a simple, effective method for link capacity allocation and network control using on-line observation of traffic flow in the low-frequency band. The study explores a new direction for measurement-based traffic control in high-speed networks. >
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paper_title: A low-pass filter design for ATM traffic measurement and its application to bandwidth management

paper_content:

A low-pass filter (LPF) for ATM traffic measurement is presented and an admission control method based on it is proposed. Instantaneous rate is estimated with the LPF and the maximum instantaneous rate (MIR) observed over the monitoring period is used to determine the residual bandwidth in the method. Hence we call it the MIR method. We developed an analytical model to investigate the performance of the MIR method. We confirmed that the MIR method regulates the number of connections properly even for connections with long holding time. In addition, the MIR method is robust against long range dependent traffic, which degrades the robustness of many previously proposed methods. Because the MIR method does not assume any mathematical model and can be implemented with simple hardware, it is well suited for practical ATM switching systems.
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Title: Overview of measurement-based connection admission control methods in ATM networks

Section 1: Introduction
Description 1: Introduce the concept of ATM networks and the necessity of connection admission control (CAC) methods.

Section 2: Connection Admission Control CAC-Related Issues
Description 2: Discuss CAC-related issues, including switch architecture, burst traffic model, traffic descriptor, and requirements for effective CAC methods.

Section 3: Overview of CAC Methods
Description 3: Provide an overview of CAC methods and present a taxonomy to classify the various approaches.

Section 4: Taxonomy
Description 4: Explain the taxonomy used to classify CAC methods, detailing the distinctions between rate-sharing multiplexing (RSM) methods, rate-envelope multiplexing (REM) methods, CLR methods, and effective bandwidth (EB) methods.

Section 5: Brief Overview of Proposed Methods
Description 5: Offer a brief survey of proposed CAC methods, categorized based on the taxonomy introduced earlier, and highlight specific methods and their key features.

Section 6: Description of Measurement-Based Admission Control Methods
Description 6: Examine the need for measurement-based CAC methods and provide detailed descriptions of selected measurement-based methods.

Section 7: Comparison
Description 7: Compare the discussed measurement-based CAC methods based on various criteria such as bandwidth efficiency, implementation complexity, and dependency on traffic models.

Section 8: Closing Remarks
Description 8: Summarize the findings and discuss the potential of measurement-based CAC methods in high-speed backbone ATM networks.