Random early detection gateways for congestion avoidance
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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Posted Content•
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
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
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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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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11 Apr 1988
TL;DR: In this paper, the authors compare the concept of congestion with that of flow control and congestion control, and identify a number of possible alternatives for congestion avoidance are identified from these a few are selected for study.
Abstract: The authors compare the concept of congestion with that of flow control and congestion control A number of possible alternatives for congestion avoidance are identified From these a few are selected for study The criteria for selection and goals for these schemes are described In particular, the authors wanted the scheme to be globally efficient, fair, dynamic, convergent, robust, distributed, configuration-independent, etc They model the network and the user policies for congestion avoidance as a feedback control system The key components of a generic congestion-avoidance scheme are congestion detection, congestion feedback, feedback selector, signal filter, decision function, and increase/decrease algorithms >
217 citations
Dissertation•
01 Aug 1989
TL;DR: A new channel scheduling method called the Virtual Clock mechanism is developed to regulate packet flows in the Flow Network, and provides firewalls among flows, as in a TDM system, but with the statistical multiplexing advantages of packet switching.
Abstract: : This dissertion present a new architecture, the Flow Network, for packet switching network protocols. The Flow Network can provide users high quality, guaranteed service in terms of average latency and throughput. Rather than an end-point control with a stateless network model, the Flow Network design emphasizes regulation of packet traffic by the network. Rather than window flow control, the Flow Network controls the average transmission rate of individual users. Rather than relying on feedback control, the Flow Network requires users to reserve resources. An abstract entity, a flow, is defined to represent users's data transmission requests. A flow is associated with a specific set of service requirements, which allows application to express their requirement in a quantitive manner. This specification enables the network to check whether adequate resources are available before accepting new transmission requests. It also serves as a contract between the network and the user: it is used as a measure that the network service should meet, as well as a constraint that the user's transmission behavior must adhere to. A new channel scheduling method called the Virtual Clock mechanism is developed to regulate packet flows in the Flow Network. The VirtualClock mechanism monitors the average transmission rate of each statistical data flow and provides firewalls among flows, as in a TDM system, but with the statistical multiplexing advantages of packet switching. Simulation is used as a design aid and a verification tool throughout this research. Theses. (RRH)
179 citations
"Random early detection gateways for..." refers background or methods in this paper
...These proposed gateways are a precursor to the Early Random Drop gateways that have been studied by several authors [11] [36]....
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...For the version of Early Random Drop gateways used in the simulations in [36], if the queue is more than half full then the gateway drops each arriving packet with probability 0....
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...Zhang [36] shows that this version of Early Random Drop gateways was not successful in controlling misbehaving users....
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...The survey cites the results in which the Early Random Drop gateway is unsuccessful in controlling misbehaving users [36]....
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03 Jun 1990
TL;DR: A leaky-bucket-type scheme operating on a session basis that limits the session's average rate and the burstiness is proposed, combined with an optimistic bandwidth usage scheme which works by marking packets into two different colors, green and red.
Abstract: The authors suggest and investigate a general input congestion control scheme that takes into account a broad spectrum of network issues. As a preventive congestion control strategy, a leaky-bucket-type scheme operating on a session basis that limits the session's average rate and the burstiness is proposed. This restrictive control is combined with an optimistic bandwidth usage scheme which works by marking packets into two different colors, green and red. The packets are marked so that the average green packet rate entering the network is at the reserved average rate. The average red packet rate represents traffic in excess of this guaranteed average rate and is sent to further utilize unused bandwidth in the network. Both types of packets are further filtered by a spacer which limits the peak rate at which the packets enter the network. The marked packets are then sent into the network, where they are treated according to their color, using at each intermediate node a simple threshold policy. >
171 citations
01 Dec 1988
TL;DR: This report describes REAL, a computer network simulator, and presents results of some simulations to illustrate its analytical power, and details of implementation and a performance evaluation are presented.
Abstract: Performance analysis of computer networks is rapidly gaining as networks increase in size and geographical extent. A simulation approach is often useful. This report describes REAL, a computer network simulator, and presents results of some simulations to illustrate its analytical power. Details of implementation and a performance evaluation are also presented.
164 citations
"Random early detection gateways for..." refers methods in this paper
...Our simulator is a version of the REAL simulator [19] built on Columbia’s Nest simulation package [1], with extensive modifications and bug fixes made by Steven McCanne at LBL....
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