TCP over ATM的拥塞控制研究进展

指出了TCP／IP在ATM网络中运行遇到的困难，综述了TCP拥塞控制方案与ATM层拥塞控制策略的进展，概述了TCPoverATM研究的现状，指出了将来的工作方向。

Congestion control scheme in ATM networks based on fast tracing-queue

One of the more challenging and unresolved issues in ATM networks is the congestion control of available bit rate （ABR）. The dynamic controller is designed based on the control theory and the feedback mechanism of explicit rates With the given method of a chosen parameter, it can guarantee the stability of the controller and closed loop system with propagation delay and bandwidth oscillation. It needs less parameters（only one） to be designed. The queue length can converge to the given value in the least steps. The fairness of different connections is considered further. The simulations show better performance and good quality of service（QoS） is achieved.

Congestion Control Algorithms for the Internet-A Secondary Publication

In the last five years,there has been a V-shaped recovery in the number of papers on congestion control algorithms on the Internet.In this paper,congestion problems on the Internet are discussed,such as congestion collapse and bufferbloat from the perspective of the necessity of congestion control algorithms.The typical congestion control algorithms are introduced,and the research areas and methods of congestion control algorithms are described.Recent research trends and future prospects of congestion control algorithms are also presented.

Congestion control for ATM multiplexers using neural networks：multiple sources／single buffer scenario

A new neural network based method for solving the problem of congestion control arising at the user network interface (UNI) of ATM networks is proposed in this paper. Unlike the previous methods where the coding rate for all traffic sources as controller output signals is tuned in a body, the proposed method adjusts the coding rate for only a part of the traffic sources while the remainder sources send the cells in the previous coding rate in case of occurrence of congestion. The controller output signals include the source coding rate and the percentage of the sources that send cells at the corresponding coding rate. The control methods not only minimize the cell loss rate but also guarantee the quality of information (such as voice sources) fed into the multiplexer buffer. Simulations with 150 ADPCM voice sources fed into the multiplexer buffer showed that the proposed methods have advantage over the previous methods in the aspect of the performance indices such as cell loss rate (CLR) and voice quality.

TCPW BR: A Wireless Congestion Control Scheme Base on RTT

The wireless network is limited by the transmission medium,and the transmission process is subject to large interference and jitter.This jitter can cause sporadic loss and is mistaken for congestion by the congestion control mechanism.The TCP Westwood protocol(referred to as TCPW)is such that it cannot distinguish between congestion loss and wireless jitter loss,which makes the congestion mechanism too sensitive and reduces bandwidth utilization.Based on this,the TCPW protocol is modified based on the estimate of the Round-Trip Time(referred to as RTT)value-called TCPW BR.The algorithm uses the measured smooth RTT value and divides the congestion level according to the weighted average idea to determine congestion loss and wireless jitter loss.The simulation results show that the TCPW BR algorithm enhances the wireless network’s ability to judge congestion and random errors.

Design of ATM Networks Congestion Controller Based on the Virtual Queue

The single bottleneck node of ATM networks is considered. The virtual queue mechanism and the method of proportion-integral-differential(PID) control are adopted in the congestion control. The sufficient condition of the considered system’s stability is given. The method of determining the PID parameters is given further. To quicken the speed of startup and remove the congestion rapidly, the factors of increase and decrease are set according to the length of queue. The result of simulation shows that the system, given an appropriate group of parameters, can acquire good robustness and dynamic performance, and guarantees the quality of service at the same time.

TCP Window Based Congestion Control -Slow-Start Approach

Transmission control protocol (TCP) has undergone several transformations. Several proposals have been put forward to change the mechanisms of TCP congestion control to improve its performance. A line of research tends to reduce speed in the face of congestion thereby penalizing itself. In this group are the window based congestion control algorithms that use the size of congestion window to determine transmission speed. The two main algorithm of window based congestion control are the congestion avoidance and the slow start. The aim of this study is to survey the various modifications of window based congestion control. Much work has been done on congestion avoidance hence specific attention is placed on the slow start in order to motivate a new direction of research in network utility maximization. Mathematical modeling of the internet is discussed and proposals to improve TCP startup were reviewed. There are three lines of research on the improvement of slow start. A group uses the estimation of certain parameters to determine initial speed. The second group uses bandwidth estimation while the last group uses explicit request for network assistance to determine initial startup speed. The problems of each proposal are analyzed and a multiple startup for TCP is proposed. Multiple startups for TCP specify that startup speed is selectable from an n-arry set of algorithms. We then introduced the e-speed start which uses the prevailing network condition to determine a suitable starting speed.

On Approaches to Congestion Control over Wireless Networks

Congestion control in wireless networks has been extensively investigated over the years and several schemes and techniques have been developed, all with the aim of improving performance in wireless net-work. With the rapid expansion and implementation of wireless technology it is essential that the congestion control problem be solved. This paper presents a survey of five congestion control schemes which are dif-ferent in slow start threshold calculation, bandwidth estimation, and congestion window manipulation. A comprehensive comparison of these approaches is given in relation to assumptions, bandwidth estimation, congestion window size manipulation, performance evaluation, fairness and friendliness and improved throughput.

A Dynamic Adaptive Layered Multicast Congestion Control Mechanism

To solve the problem that most of existing layered multicast protocols cannot adapt todynamic network conditions because their layers are coarsely granulated and static,a new congestioncontrol mechanism for dynamic adaptive layered multicast(DALM) is presented.In this mechanism,anovel feedback aggregating algorithm is put forward,which can dynamically determine the number oflayers and the rate of each layer,and can efficiently improve network bandwidth utilization ratio.Additionally,because all layers is transmitted in only one group,the intricate and time-consuminginternet group management protocol(IGMP) operations,caused by receiver joining a new layer orleaving the topmost subscribed layer,are thoroughly eliminated.And this mechanism also avoids otherproblems resulted from multiple groups.Simulation results show that DALM is adaptive and TCPfriendly.

An Adaptive Congestion Control Optimization Strategy in SDN-Based Data Centers

The traffic within data centers exhibits bursts and unpredictable patterns.This rapid growth in network traffic has two consequences:it surpasses the inherent capacity of the network’s link bandwidth and creates an imbalanced network load.Consequently,persistent overload situations eventually result in network congestion.The Software Defined Network(SDN)technology is employed in data centers as a network architecture to enhance performance.This paper introduces an adaptive congestion control strategy,named DA-DCTCP,for SDN-based Data Centers.It incorporates Explicit Congestion Notification(ECN)and Round-Trip Time(RTT)to establish congestion awareness and an ECN marking model.To mitigate incorrect congestion caused by abrupt flows,an appropriate ECN marking is selected based on the queue length and its growth slope,and the congestion window(CWND)is adjusted by calculating RTT.Simultaneously,the marking threshold for queue length is continuously adapted using the current queue length of the switch as a parameter to accommodate changes in data centers.The evaluation conducted through Mininet simulations demonstrates that DA-DCTCP yields advantages in terms of throughput,flow completion time(FCT),latency,and resistance against packet loss.These benefits contribute to reducing data center congestion,enhancing the stability of data transmission,and improving throughput.

Improving Network Performance by Ameliorating TCP Congestion Control Mechanism

With the rapid growth of rate-based services and wirelessapplications, improving Transmission Control Protocol(TCP)congestioncontrol has been becoming more important in the network researchfield. This paper first Briefly introduces the Additive-IncreaseMultiplicative-Decrease(AIMD)(a,b)algorithm, and then presents an im-Proved TCP congestion control mechanism(D-AIMD)whose principles andsimulation results are discussed in detail. This mechanism can beeasily implemented with lower additional overheads and canefficiently improve network per- Formance.

Nonlinear dynamics in Internet congestion control model with TCP Westwood under RED

This article develops a discrete time dynamic feedback model of a congestion control system for a simple network with TCP Westwood （TCPW） connections and a single bottleneck link with random early detection （RED） gateway. By using this model, the nonlinear dynamics of the TCPW/RED network are analyzed and its parameter sensitivities are studied. It is shown that periodic doubling bifurcation occurs when the RED control parameters or other parameters are varied. By theoretical analysis, the fixed point, the critical value of parameters and the nature of the bifurcation are determined. Moreover, by using bifurcation diagrams and Lyapunov exponent, the result of theoretical analysis is validated and the bifurcation and chaotic phenomena are numerically studied of the congestion control system with TCPW connections and RED gateway.

TCP/IP over ATM的性能

分析了 Ｉ Ｐ与 Ａ Ｔ Ｍ 结合的两类模型，根据 Ａ Ｔ Ｍ 网络承载 Ｔ Ｃ Ｐ／ Ｉ Ｐ业务的网络协议堆栈模型，在搭建的局域网和模拟仿真基础上分析了 Ｔ Ｃ Ｐ层、 Ａ Ｔ Ｍ 中 Ｕ Ｂ Ｒ和 Ａ Ｂ Ｒ 业务类型的拥塞控制过程对网络端到端性能的影响。

TCP-ATCA: Improved Transmission Control Algorithm in Satellite Network

An adaptive transmission control algorithm based on TCP （TCP-ATCA） is proposed to reduce the effects of long propagation delay and high link error rate of the satellite network on the performances. The flow control and the error recovery are differentiated by combined dynamic random early detection-explicit congestion notification （DRED-ECN） algorithm, and, moreover, the pertaining congestion control methods are used in TCP-ATCA to improve the throughput. By introducing the entire recovery algorithm, the unnecessary congestion window decrease is reduced, and the throughput and fairness are improved. Simulation results show that, compared with TCP-Reno, TCP-ATCA provides a better throughput performance when the link capacity is higher （ ≥600 packet/s）, and roughly the same when it is lower. At the same time, TCP-ATCA also increases fairness and reduces transmission delay.

Congestion Control for ATM Networks Based on Diagonal Recurent Neural Networks

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Fuzzy Neural Network Based Traffic Prediction and Congestion Control in High-Speed Networks

Congestion control is one of the key problems in high-speed networks, such as ATM. In this paper, a kind of traffic prediction and preventive congestion control scheme is proposed using neural network approach. Traditional predictor using BP neural network has suffered from long convergence time and dissatisfying error. Fuzzy neural network developed in this paper can solve these problems satisfactorily. Simulations show the comparison among no-feedback control scheme, reactive control scheme and neural network based control scheme.

卫星TCP/ATM传输中的明确窗口指示拥塞控制策略研究

卫星ATM是近年来卫星通信领域的一个研究热点 ,TCP业务在卫星ATM中的传输是其中一个重要的研究课题 .由于在TCP协议中主要是通过对窗口的控制来实现拥塞控制 ,而卫星信道传输的长延时特性大大降低了TCP层拥塞控制的效率 .本文提出一种基于UBR传输的明确窗口指示拥塞控制策略 ,仿真结果表明在效率、公平性、VBR背景传输下的性能等各方面 ,取得了比目前广泛使用的RenoTCP更好的结果 .并且该算法实现简单 ,交换机实现零信元丢失的缓冲区很小并且与TCP源连接的数目无关 .

Stability condition of FAST TCP in high speed network on the basis of control theory

Considering the instability of data transferred existing in high speed network, a new method is proposed for improving the stability using control theory. Under this method, the mathematical model of such a network is established. Stability condition is derived from the mathematical model. Several simulation experiments are performed. The results show that the method can increase the stability of data transferred in terms of the congestion window, queue size, and sending rate of the source.

A Fuzzy Flow Control Approach for ABR Service in ATM Networks

The explicit rate flow control mechanisms for ABR service are used to sharethe available bandwidth of a bottleneck link fairly and reasonably among many competitive users andto maintain the buffer queue length of a bottleneck switch connected to the link at a desired levelin order to avoid and control congestion in ATM networks. However, designing effective flow controlmechanisms for the service is known to be difficult because of the variety of dynamic parametersinvolved such as available link bandwidth, burst of the traffic, the distances between ABR sourcesand switches. In this paper, we present a fuzzy explicit rate flow control mechanism for ABRservice. The mechanism has a simple structure and is robust in the sense that the mechanism'sstability is not sensitive to the change in the number of active virtual connections (VCs). Manysimulations show that this mechanism can not only effectively avoid network congestion, but alsoensure fair share of the bandwidth for all active VCs regardless of the number of hops theytraverse. Additionally, it has the advantages of fast convergence, low oscillation, and high linkbandwidth utilization.

ATM网上TCP传输的拥塞控制算法分析

本文讨论了ＴＣＰ协议在ＡＴＭ 网上存在的问题，对三种典型的ＡＢＲ 拥塞控制算法：ＥＦＣＩ、ＥＲＩ－ＣＡ 和ＦＭＭＲＡ 在减少信元丢失和传输时延、提高ＴＣＰ吞吐量等方面的性能进行了分析和比较。