Results 1 
8 of
8
A ControlTheoretic Approach to Flow Control
, 1991
"... This paper presents a controltheoretic approach to reactive flow control in networks that do not reserve bandwidth. We assume a roundrobinlike queue service discipline in the output queues of the network’s switches, and propose deterministic and stochastic models for a single conversation in a ne ..."
Abstract

Cited by 380 (7 self)
 Add to MetaCart
This paper presents a controltheoretic approach to reactive flow control in networks that do not reserve bandwidth. We assume a roundrobinlike queue service discipline in the output queues of the network’s switches, and propose deterministic and stochastic models for a single conversation in a network of such switches. These models motivate the PacketPair rate probing technique, and a provably stable ratebased flow control scheme. A Kalman state estimator is derived from discretetime state space analysis, but there are difficulties in using the estimator in practice. These difficulties are overcome by a novel estimation scheme based on fuzzy logic. We then present a technique to extract and use additional information horn the system to develop a continuoustime system model. This is used to design a wuisnt of the control law that is also provably stable, and, in addition, takes control action as rapidly as possible. Finally, practical issues such as correcting parameter drift and cmmlination with window flow control are described.
Analysis Of A Fluid Approximation To Flow Control Dynamics
 In Proc. IEEE INFOCOM '92
, 1992
"... We consider a flow control mechanism that dynamically regulates the rate of data flow into a network based on feedback information about the network state. Such mechanisms have been introduced recently in a variety of networks including the Internet, and have been advocated for future highspeed net ..."
Abstract

Cited by 26 (6 self)
 Add to MetaCart
We consider a flow control mechanism that dynamically regulates the rate of data flow into a network based on feedback information about the network state. Such mechanisms have been introduced recently in a variety of networks including the Internet, and have been advocated for future highspeed networks. We first model the flow control mechanism by a discretespace stochastic process and define appropriate performance measures for transient and steadystate regimes. However, the model does not appear to be analytically tractable and we study it through simulation. We then simplify it to a continuousspace deterministic (or fluid) model for which we can easily derive closedform solutions. We find the analytical results for the fluid model to agree well with the simulation results obtained using the discretespace model. Both models explicitly consider delay of the feedback information, thus making them relevant for highspeed networks. 1 Introduction In a computer network, packets g...
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 ..."
Abstract

Cited by 8 (5 self)
 Add to MetaCart
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...
Transient Analysis of Manufacturing Systems Performance
, 1994
"... Studies in performance evaluation of automated manufacturing systems, using simulation or analytical models, have always emphasized steadystate or equilibrium performance in preference to transient performance. In this study, we present several situations in manufacturing systems where transient an ..."
Abstract

Cited by 4 (0 self)
 Add to MetaCart
Studies in performance evaluation of automated manufacturing systems, using simulation or analytical models, have always emphasized steadystate or equilibrium performance in preference to transient performance. In this study, we present several situations in manufacturing systems where transient analysis is very important. Manufacturing systems and models in which such situations arise include: systems with failure states and deadlocks, unstable queueing systems, and systems with fluctuating or nonstationary workloads. Even in systems where equilibrium exists, transient analysis is important in studying issues such as accumulated performance rewards over finite intervals, first passage times, sensitivity analysis, settling time computation, and deriving the behavior of queueing models as they approach equilibrium. In certain systems, convergence to steadystate is so slow that only transient analysis can throw light on the system performance. In this paper, we focus on transient analysis of Markovian models of manufacturing systems. After presenting several illustrative manufacturing situations where transient analysis has significance, we discuss two problems for demonstrating the importance of transient analysis. The first problem is concerned with the computation of distribution of time to absorption in Markov models of manufacturing systems with deadlocks or failures, and the second problem shows the relevance of transient analysis to a multiclass manufacturing system with significant setup times. We also briefly discuss computational aspects of transient analysis.
Fast TimeDependent Evaluation of MultiService Networks
 Computer Networks and ISDN Systems  Special Issue on Modeling of Wired and Wireless ATM. http://www.ccs.neu.edu/home/matta/publications.html
"... We present a numericalanalytical method to evaluate multiservice networks with adaptive routing, scheduling and admission controls. We apply our method to connectionoriented networks supporting different types of realtime connections. The network dynamics is described by difference equations whi ..."
Abstract

Cited by 2 (1 self)
 Add to MetaCart
We present a numericalanalytical method to evaluate multiservice networks with adaptive routing, scheduling and admission controls. We apply our method to connectionoriented networks supporting different types of realtime connections. The network dynamics is described by difference equations which can be solved for both transient and steadystate performances. Results indicate that our method is computationally much cheaper than discreteevent simulation, and yields accurate performance measures. Connection routing algorithms are usually evaluated individually in terms of steadystate performance measures. In this paper, we also use our timedependent evaluation method to compare several connection routing schemes in terms of instantaneous measures. Our results show that a routing scheme which defines the cost of a path as the sum of measured link utilizations yields more stable behavior and lower connection blocking probability over a wide range of workload parameters and network...
ZIteration: Efficient Estimation of Instantaneous Measures in TimeDependent MultiClass Systems
 In Proceedings of SIGMETRICS/Performance '95
, 1994
"... 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 numericalanalytical method, referred to as Ziteration, to estimate instantaneous ( ..."
Abstract

Cited by 2 (0 self)
 Add to MetaCart
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 numericalanalytical method, referred to as Ziteration, to estimate instantaneous (and steadystate) probability measures of timedependent systems. The key idea is to approximate the relationship between certain instantaneous measures by the relationship between their steadystate counterparts, and use this approximation to solve dynamic flow equations. We show the generality of the Ziteration by applying it to an integrated communication network, a parallel database server, and a distributed batch system. Validations against exact numerical solutions and discreteevent simulations show the accuracy and computational advantages of the Ziteration. Preliminary version appeared in ACM SIGMETRICS/PERFORMANCE '95. This work is supported in part by ARPA and Philips Labs und...
NONSTATIONARY ERLANG LOSS QUEUES AND NETWORKS
, 2004
"... The nonstationary Erlang loss model is a queueing system consisting of a finite number of servers and no waiting room with a nonstationary arrival process or a timedependent service rate. The Erlang loss model is commonly used to model and evaluate many communication systems. Often, these types of ..."
Abstract

Cited by 1 (0 self)
 Add to MetaCart
The nonstationary Erlang loss model is a queueing system consisting of a finite number of servers and no waiting room with a nonstationary arrival process or a timedependent service rate. The Erlang loss model is commonly used to model and evaluate many communication systems. Often, these types of service systems encounter a change in the arrival rate over time while the service rate remains either constant or changes very little over time. In view of this, the focus in this research is the nonstationary Erlang loss queues and network with timedependent arrival rate and constant service rate. We developed an iterative scheme referred to as the fixed point approximation (FPA) in order to obtain the timedependent blocking probability and other measures for a singleclass nonstationary Erlang loss queue and a nonstationary multirate Erlang loss queue. The FPA method was compared against exact numerical results, and two other methods, namely, MOL and PSA, for various nonstationary Erlang loss queues with sinusoidal arrival rates. Although we used sinusoidal functions to model the timedependent arrival rate, the solution can be obtained for any arrival rate function. Experimental results demonstrate that the FPA
Integrated Services Networks
"... Integrated services networks, such asATM (Asynchronous Transfer Mode) networks, are expected to operate at gigabit per second rates and provide various virtualcircuit and datagram services. For this purpose, new control algorithms (e.g. scheduling, admission, routing) have been proposed. The algori ..."
Abstract
 Add to MetaCart
Integrated services networks, such asATM (Asynchronous Transfer Mode) networks, are expected to operate at gigabit per second rates and provide various virtualcircuit and datagram services. For this purpose, new control algorithms (e.g. scheduling, admission, routing) have been proposed. The algorithms are often adaptive, resulting in complex timedependent interactions. This renders traditional evaluation tools ine ective � analytical approaches are typically too coarse, and simulation approaches are often too expensive. The goal of our research istodevelop accurate analytical models that account for the interaction and timedependent nature of the control algorithms, while at the same time being inexpensive or easy to solve. This would allow the rapid and tractable evaluation of di erent design alternatives. In this dissertation, we develop both dynamic models and quasistatic models of integrated networks. Dynamic models can be used to evaluate both virtualcircuit and datagram services. We solve dynamic models using a new iterative method, referred to as the Ziteration. Our method is both accurate and fast. It permits the jointevaluation of various scheduling, admission, and routing schemes used in integrated networks. We showresults comparing dynamic routing schemes on a network with NSFNETbackbone topology. Wealso illustrate the applicability of the Ziteration to other highperformance systems. Quasistatic models are suitable for evaluating datagram services for which the quasistatic assumption is reasonable. We analyze a quasistatic model of a datagram network o ering di erent classes of service. We apply the Liapunov function method to derive stability conditions for the routes of the di erent tra c classes. We show howwith scheduling support for routing, the routes of the tra c classes can be isolated, thereby improving the overall network performance. Fast Evaluation and Dynamic Control of