ATM网络中ABR业务的开环控制机制

ＡＴＭ网络中ＡＢＲ业务的流量控制是ＡＴＭ论坛的流量管理规范（ＴＭ４．０）中没有完全解决的问题,ＡＢＲ基于速率的闭环控制方案在最大－最小准则下获得了一定进展。但在拥塞发生在信源外或对突发性业务进行控制的情况下,添加开环控制的ＡＢＲ拥塞控制可以获得比闭环控制更佳的作用。研究了ＡＢＲ的开环控制方案,早期的ＵＩＬＩ机制本身存在在一定的问题,在交换机处采用基于计数的ＵＩＬＩ机制能够取得较好的效果。     

ATM网络中基于ABR业务的闭环拥塞控制

论文讨论了ＡＴＭ网络中ＡＢＲ业务的特性及基地ＡＢＲ业务的拥塞控制机制，了拥塞控制技术的最新发展情况，并比较了各种控制机制的优缺点。     

基于速率自适应预测的ATM网络ABR业务流量控制

本文深度将自适应预测方法引入ＡＢＲ流控算法中。ＡＴＭ网络的国带宽模型是一非平稳随机过程。高速网络中可用带宽的反馈信息由于线路的传播时延造成了流理控制的滞后。西方节ＡＢ国的这两特点，对ＡＴＭ Ｆｏｒｕｍ的ＴＭ４．０规定进行了一定的修改，采用离散化的ＡＴＭ网传输模型，提出了一种基于速率自适应预测的ＡＢＲ业务流控方法，较好地补偿了时延带来的控制的滞后效应，且具有参数易于选择的优点。通过仿真，论证了该方法     

ATM网络中ABR业务的监控方案

基于离散事件动态系统理论,提出了一种崭新的用于控制ＡＴＭ网络中ＡＢＲ业务流量的监控方案,这种方案具有简单易于实现的特点,仿真结果与理论预测值的一致证明了该方案的正确性。     

ATM网络中ABR业务的流量控制

本文讨论了ＡＴＭ网络中ＡＢＲ业务的特性及基于ＡＢＲ业务的拥塞控制机制，了拥塞控制技术的最新发展情况，并比较了各种控制机制的优缺点。     

ATM网络中ABR业务的公平速率分配

简单介绍了ＡＴＭ网络中ＡＢＲ业务的阻塞控制问题,总结了和分析了ＡＢＲ业务的２大类公平速率分配算法,并对介绍的７种算法进行了比较。     

ATM网中ABR业务及其反馈流量控制

ABR（AvailableBitRate）业务是近年来为了充分利用ATM网络的剩余带宽而提出的一种新型业务类型，自从1993年被ATM论坛正式提出以来得到了很快的发展。文章对该业务的特点和发展过程作了较全面的介绍，对该类型业务的流量控制方法作了比较深入的分析和研究，对流量控制中关键因素的改进提出了自己的见解。     

串行网络中ABR业务的流量控制和缓存设计

本文提出一种ABR业务速率在优化率和请求率之间的切换控制方法。在上述控制算法基础上,研究了保证信元在交换节点处无丢弃,同时输出带宽得到充分利用的交换节点的缓存和阈值设计问题。新的流量控制机制实现了源节点发送率和交换节点缓存的小抖动控制。     

ATM网中的ABR业务的缓存性能

ＡＢＲ业务是ＡＴＭ网为充分利用网络的剩余带宽而提供的一种新型数据业务。ＡＢＲ业务采用反馈式流量控制，因而交换结点的缓存成了关系业务服务的关键问题。本文通过对一个简单ＡＢＲ流量控制模型分析得出；适当地设置交换结点的缓存大小和门限值，可以保证该结点处无信元丢失，同时保证输出线路容量得到充分利用。对一个复杂模型的模拟结果表明，本文提出的缓存大小和门限值的设置方法是行之有效的。     

ATM网络中ABR业务的带宽分配算法研究

在ＡＴＭ网络（异步传输模式）中，ＡＢＲ（可用比特速率）业务主要面向数据通信服务，ＡＢＲ带宽利用率的高你七所采用的带宽分配算法有密切的关系。文中介绍了ＡＢＲ业务中带宽分配的一般性原则，并讨论了一种新的事宽分配算法。     

Evaluation of congestion control protocols for ABR traffic over ATM networks

Congestion control is very important for effective and stable operation of ATM (Asynchronous Transfer Mode) networks. Owing to the bursty and unpredictable characteristic of data network traffic, its congestion control is particularly a challenge for network researchers and designers. The ATM Forum has recently adopted rate‐based congestion control for ABR (Available Bit‐Rate) traffic which is the service class defined for data network applications. However, there is a number of congestion control schemes prevalent. ATM Forum has decided not to specify switch behaviour for ABR traffic; this has further introduced additional ambiguity. Consequently, an evaluation and comparison of the existing protocols would provide valuable guidance for network designers and engineers; it would also give insight for researchers to explore the essence of different congestion control schemes. In the first part of this paper, we investigate the effectiveness of ABR congestion control in the presence of bursty source traffic and the relationship between the burst time scale and the ABR control time scale. Two ABR congestion control schemes, the ABR Explicit Forward Congestion Indication (EFCI) and ABR Congestion Indication (CI) schemes, are compared with Unspecified Bit Rate (UBR) transport which makes no effort to control congestion. Traffic sources of various burst lengths of 100, 1000, 10000, and an equal mix of 100 and 10000 ATM cells are used in simulations. It is found that ABR congestion control schemes effectively control low frequency, medium to long‐term traffic load transients. This is further supported by the result of integrating TCP over ATM congestion control schemes included in the paper. ABR control schemes do not control high frequency, short‐term load transients well, but ABR control is not necessary in such cases since short‐term transients do not require a large amount of buffering. In the second part of this paper, we evaluate and compare six rate‐based congestion control protocols including Scheme I: EFCI, Scheme II: EFCI with separate RM queues, Scheme III: CI, Scheme IV: CI with separate RM queues, Scheme V: the CAPC2 ER (Explicit Rate), and Scheme VI: the EFCI with utilization‐based congestion indication. Each scheme is simulated and compared in the LAN, WAN, and GFC (General Fairness Configuration) environments specified by the ATM Forum. Effects of varying VC (Virtual Circuits) number and changing endsystem–switch distance has been investigated. Their fairness is also compared using the GFC configuration. We have found that ER control scheme performs significantly better than the other five binary control schemes by its faster response to congestion, smoother regulation of bit‐rates, lower queueing delay, shorter buffer queue length, and fairness. Among the other five schemes, the CI scheme performs better than the EFCI scheme. Providing separate RM queues has significantly improved the EFCI scheme in the WAN environment, but has little effect on the CI scheme. Link utilization‐based congestion detection has suffered from either low utilization or an excess cell loss which is unacceptable in most data applications. Copyright © 2000 John Wiley & Sons, Ltd.     

The DDTCI switch algorithm for ABR traffic control in ATM networks

For the issue of flow control for Available Bit Rate (ABR) traffic in ATM network,a new improved Explicit Rate (ER) algorithm named Dynamic Double Threshold Congestion Indication (DDTCI) algorithm is presented based on the Explicit Forward Congestion Indication (EFCI) Current Cell Rate (CCR) algorithm and Relative Rate (RR) algorithm. Different from the early ER algorithm, both the high-level and the low-level threshold is dynamically changing according to the state of the bottleneck node. We determinate the congestion state with the information of the two dynamic threshold, and control the cell rate of the source by feed back mechanism. Except for the well performance in both link utilization and fairness in distribution of available bandwidth, the improved algorithm can alleviate the fluctuation of sending rate dramatically. The mechanism is modeled by a fluid model, and the useful expressions are derived.Simulation results show up our conclusion.     

ATM网上一种简单通用的业务模型

对于ＡＴＭ网,业务建模是一个很重要的问题。鉴于ＡＴＭ网上的业务特性的多样性,而目前所在的各种业务模型在反映业务统计特性这一方面都有自己的适用范围。为此,本文提出了一种新的简单的业务模型。该模型的输出不但可以满足任意的边缘概率分布,而且其相关性也可长可短,因此,该模型更具有普遍适用性。通过仿真实验,我们对本文所给的业务模型加以了验证。     

ABR业务流量控制的一种智能机制

本文提出了一种ＡＢＲ业务模糊流量控制机制,仿真结果表明它有效地避免了网络阻塞,在网络的吞吐量上要高于强比例速率控制算法（ＥＰＲＣＡ）。该机制与连接业务的特性无关,且不需要改变有关ＡＢＲ闭环反馈的流量控制结构,这为算法的实际应用提供了前提。     

The distributed robust traffic controller for ATM networks

We propose an approach to design a distributed rate‐based traffic controller to flow‐regulate the best‐effort service (e.g. ABR) traffic and guaranteed service traffic through an ATM switch. The controller is distributed among the source nodes and has a very simple structure. Its local controller at each source node is open‐loop stable and only requires the knowledge of the buffer occupancy at the bottleneck switch. We show that this controller is fair and is not sensitive to the change of VCs over time. It does not have oscillation and can achieve a high utilization. Copyright © 2001 John Wiley & Sons, Ltd.     

Congestion control for ABR traffic in an ATM network

This article presents a novel approach to ATM congestion control for ABR (Allowed Bit Rate) service. This approach can achieve a desired fair link utilization using adaptive filters to prevent both network collapse and the ‘beat down’ problem. Copyright © 1999 John Wiley & Sons, Ltd.     

Parameter tuning of rate-based congestion control algorithm for ABR service class in ATM networks

A rate-based congestion control algorithm has been developed and standardized in the ATM forum for ABR service class. In the standard the behaviour of source and destination end systems is specified by several control parameters such as RIF (rate increase factor) and RDF (rate decrease factor). In spite of the fact that the performance of the rate-based congestion control algorithm depends heavily on the selection of these control parameters, no selection method of parameters is shown in the standard. In this paper, by extending our previous work, appropriate settings of rate-control parameters in the various circumstances are investigated. We first analyse the dynamical behaviour of the rate-based congestion control for multiple groups of ABR connections with different propagation delays. Next we evaluate the effect of CBR traffic on ABR connections. Simulation results for a multihop network configuration are also presented to exhibit the trade-off relationship among cell loss probability, link utilization and fairness. Finally, a selection method of control parameters in the multihop network is proposed based on our analytic methods and simulation results © 1998 John Wiley & Sons, Ltd.     

一种新的用于ATM网中ABR点对多点连接的反馈合并算法

本文提出了一种新的用于ＡＴＭ网中的ＡＢＲ点对多点连接的反馈合并算法。新算法不仅能同时解决“合并噪声”和“合并延迟”问题,而且由于提供一种根据反向资源管理信元的ＣＩ域判断支路拥塞程度的机制,因此即使在ＥＲ交换机与二进制交换机并存的网络环境中仍然性能优越,这是现有算法所无法做到的。我们的仿真结果清楚地表明了这一点。