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Journal ArticleDOI

Random early detection gateways for congestion avoidance

01 Aug 1993-IEEE ACM Transactions on Networking (IEEE Press)-Vol. 1, Iss: 4, pp 397-413
TL;DR: Red gateways are designed to accompany a transport-layer congestion control protocol such as TCP and have no bias against bursty traffic and avoids the global synchronization of many connections decreasing their window at the same time.
Abstract: The authors present random early detection (RED) gateways for congestion avoidance in packet-switched networks. The gateway detects incipient congestion by computing the average queue size. The gateway could notify connections of congestion either by dropping packets arriving at the gateway or by setting a bit in packet headers. When the average queue size exceeds a present threshold, the gateway drops or marks each arriving packet with a certain probability, where the exact probability is a function of the average queue size. RED gateways keep the average queue size low while allowing occasional bursts of packets in the queue. During congestion, the probability that the gateway notifies a particular connection to reduce its window is roughly proportional to that connection's share of the bandwidth through the gateway. RED gateways are designed to accompany a transport-layer congestion control protocol such as TCP. The RED gateway has no bias against bursty traffic and avoids the global synchronization of many connections decreasing their window at the same time. Simulations of a TCP/IP network are used to illustrate the performance of RED gateways. >

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TL;DR: In this paper, the authors provide a unified and comprehensive theory of structural time series models, including a detailed treatment of the Kalman filter for modeling economic and social time series, and address the special problems which the treatment of such series poses.
Abstract: In this book, Andrew Harvey sets out to provide a unified and comprehensive theory of structural time series models. Unlike the traditional ARIMA models, structural time series models consist explicitly of unobserved components, such as trends and seasonals, which have a direct interpretation. As a result the model selection methodology associated with structural models is much closer to econometric methodology. The link with econometrics is made even closer by the natural way in which the models can be extended to include explanatory variables and to cope with multivariate time series. From the technical point of view, state space models and the Kalman filter play a key role in the statistical treatment of structural time series models. The book includes a detailed treatment of the Kalman filter. This technique was originally developed in control engineering, but is becoming increasingly important in fields such as economics and operations research. This book is concerned primarily with modelling economic and social time series, and with addressing the special problems which the treatment of such series poses. The properties of the models and the methodological techniques used to select them are illustrated with various applications. These range from the modellling of trends and cycles in US macroeconomic time series to to an evaluation of the effects of seat belt legislation in the UK.

4,252 citations

Journal ArticleDOI
TL;DR: On conventional PC hardware, the Click IP router achieves a maximum loss-free forwarding rate of 333,000 64-byte packets per second, demonstrating that Click's modular and flexible architecture is compatible with good performance.
Abstract: Clicks is a new software architecture for building flexible and configurable routers. A Click router is assembled from packet processing modules called elements. Individual elements implement simple router functions like packet classification, queuing, scheduling, and interfacing with network devices. A router configurable is a directed graph with elements at the vertices; packets flow along the edges of the graph. Several features make individual elements more powerful and complex configurations easier to write, including pull connections, which model packet flow drivn by transmitting hardware devices, and flow-based router context, which helps an element locate other interesting elements. Click configurations are modular and easy to extend. A standards-compliant Click IP router has 16 elements on its forwarding path; some of its elements are also useful in Ethernet switches and IP tunnelling configurations. Extending the IP router to support dropping policies, fairness among flows, or Differentiated Services simply requires adding a couple of element at the right place. On conventional PC hardware, the Click IP router achieves a maximum loss-free forwarding rate of 333,000 64-byte packets per second, demonstrating that Click's modular and flexible architecture is compatible with good performance.

2,595 citations

01 Apr 1999
TL;DR: This document defines TCP's four intertwined congestion control algorithms: slow start, congestion avoidance, fast retransmit, and fast recovery, as well as discussing various acknowledgment generation methods.
Abstract: This document defines TCP's four intertwined congestion control algorithms: slow start, congestion avoidance, fast retransmit, and fast recovery. In addition, the document specifies how TCP should begin transmission after a relatively long idle period, as well as discussing various acknowledgment generation methods.

2,237 citations

Journal ArticleDOI
TL;DR: The existence of fair end-to-end window-based congestion control protocols for packet-switched networks with first come-first served routers is demonstrated using a Lyapunov function.
Abstract: In this paper, we demonstrate the existence of fair end-to-end window-based congestion control protocols for packet-switched networks with first come-first served routers. Our definition of fairness generalizes proportional fairness and includes arbitrarily close approximations of max-min fairness. The protocols use only information that is available to end hosts and are designed to converge reasonably fast. Our study is based on a multiclass fluid model of the network. The convergence of the protocols is proved using a Lyapunov function. The technical challenge is in the practical implementation of the protocols.

2,161 citations


Cites background from "Random early detection gateways for..."

  • ...Many researchers have observed that, when using TCP, connections with a long round-trip time that go through many bottlenecks have a smaller transmission rate that the other connections [10, 12, 20]....

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Proceedings ArticleDOI
01 Oct 1998
TL;DR: In this article, the authors developed a simple analytic characterization of the steady state throughput, as a function of loss rate and round trip time for a bulk transfer TCP flow, i.e., a flow with an unlimited amount of data to send.
Abstract: In this paper we develop a simple analytic characterization of the steady state throughput, as a function of loss rate and round trip time for a bulk transfer TCP flow, i.e., a flow with an unlimited amount of data to send. Unlike the models in [6, 7, 10], our model captures not only the behavior of TCP's fast retransmit mechanism (which is also considered in [6, 7, 10]) but also the effect of TCP's timeout mechanism on throughput. Our measurements suggest that this latter behavior is important from a modeling perspective, as almost all of our TCP traces contained more time-out events than fast retransmit events. Our measurements demonstrate that our model is able to more accurately predict TCP throughput and is accurate over a wider range of loss rates.

2,145 citations

References
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Proceedings ArticleDOI
01 Oct 1992
TL;DR: This paper considers the support of real-time applications in an Integrated Services Packet Network (ISPN), and proposes an ISPN architecture that supports two distinct kinds of real time service: guaranteed service, which involves pre-computed worst-case delay bounds, and predicted service which uses the measure performance of the network in computing delay bounds.
Abstract: This paper considers the support of real-time applications in an Integrated Services Packet Network (ISPN). We first review the characteristics of real-time applications. We observe that, contrary to the popular view that real-time applications necessarily require a fixed delay bound, some real-time applications are more flexible and can adapt to current network conditions. We then propose an ISPN architecture that supports two distinct kinds of real-time service: guaranteed service, which is the traditional form of real-time service discussed in most of the literature and involves pre-computed worst-case delay bounds, and predicted service which uses the measure performance of the network in computing delay bounds. We then propose a packet scheduling mechanism that can support both of these real-time services as well as accommodate datagram traffic. We also discuss two other aspects of an overall ISPN architecture: the service interface and the admission control criteria.

919 citations

Book ChapterDOI
01 Jan 1994
TL;DR: In this article, the Bienayme-Chebyshev inequality for random variables with finite rnean and variance was shown to hold for n independent, identically distributed random variables.
Abstract: If S is a random variable with finite rnean and variance, the Bienayme-Chebyshev inequality states that for x > 0, $$\Pr \left[ {\left| {S - ES} \right| \geqslant x{{{(\operatorname{var} S)}}^{{1/2}}}} \right] \leqslant {{x}^{{ - 2}}}$$ (1) If S is the surn of n independent, identically distributed random variables, then, by the central limit theorem*, as n → ∞, the probability on the left approaehes 2Ф( - x), where Ф(x) is the standard normal distribution function. For x large, Ф( - x) behaves as const. x -1 exp( - x2/2).

809 citations

Proceedings ArticleDOI
01 Aug 1991
TL;DR: A control-theoretic approach to reactive flow control in networks that do not reserve bandwidth is presented, and a technique to extract and use additional information from the system to develop a continuous-time system model is presented.
Abstract: This paper presents a control-theoretic approach to reactive flow control in networks that do not reserve bandwidth. We assume a round-robin-like 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 Packet-Pair rate probing technique, and a provably stable rate-based flow control scheme. A Kalman state estimator is derived from discrete-time 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 from the system to develop a continuous-time system model. This is used to design a variant 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 coordination with window flow control are described.

790 citations


"Random early detection gateways for..." refers background in this paper

  • ...In an alternate approach, some congestion control mechanisms that use variants of Fair Queueing [20] or hop-byhop flow control schemes [22] propose that the gateway scheduling algorithm make use of per-connection state for every active connection....

    [...]

  • ...Some of these proposed mechanisms are designed to work with current gateways [15, 23, 31, 33, 34], while other mechanisms are coupled with gateway scheduling algorithms that require perconnection state in the gateway [20, 22]....

    [...]

Journal ArticleDOI
01 Jan 1984

771 citations

Book
01 Jan 1975

654 citations