Consolidation algorithm for point-to-multipoint ABR service

The authors present a novel feedback consolidation algorithm for point-to-multipoint available bit rate service in asynchronous transfer mode networks, which aims to achieve a fast transient response while exhibiting low consolidation noise. Simulation shows that the proposed algorithm gives satisfactory results when contrasted with other schemes     

ATM traffic engineering for ABR service provisioning

The Available Bit Rate (ABR) service is being designed as a low-cost transport service over ATM, which will be using the bandwidth left available after servicing connections of another, high-priority class. The implementation of the ABR service requires large buffers at each multiplexing/switching stage to keep cell-loss rates down to a minimum, and a feedback mechanism from the network to the terminals in order for the latter to adjust their traffic profiles according to the prevailing congestion conditions. Thus, an enhanced set of traffic control functions is necessary to support this new service. In this paper the main traffic analysis and control problems related with the ABR service are addressed, modelled and answered on the basis of effective rates defined for the multiplexed connections. Emphasis is given to a simple CAC scheme which consists in allocating peak rates to the high-priority class and effective rates to the ABR class. An adaptive shaping mechanism is then required to enforce the contracted effective rates for the ABR streams. Producing ON/OFF streams facilitates the control functions by allowing the use of approximate closedform calculations.This work has been carried out partly in the framework of the RACE EXPLOIT project.     

效用max—min公平准则及其在ABR业务中的应用

本文提出一种新的基于效用函数的max-min(UMM）公平准则,它实现的是用户效用之间的公平分配。在ABR业务下,本文提出UMM公平性的另外两个等价定义,考察了用户的最小需求和最大需求。为了求解UMM公平分配,文中给出集中式的UMM公平分配算法及其数学证明。文章从保证分配效率的角度出发赋予峰值信元位率PCR以新的含义。UMM公平性不仅是对以往ABR业务中max-min公平性的概括,还具有很好的推广前景,特别适用于多应用类型的网络资源分配。     

Improving fairness using dynamic weights in ATM ABR service

A new scheme termed active fairness is proposed that substantially improves fairness in allocating bandwidth among the available bit rate (ABR) connections in ATM networks. In contrast to the one set of weights used in the generalised fairness scheme, active fairness maintains two sets of weights at each link. Simulation results prove the efficacy of the proposed scheme     

Efficient consolidation algorithm for multicast ABR service in ATMnetworks

A new efficient consolidation algorithm at a branch-point switch for multicast available bit rate (ABR) service is proposed. The scheme can achieve a faster response to congestion status and has a lower consolidation noise compared with existing algorithms. Particularly network environments with a large number of branch points     

ATM网中ABR业务的缓存性能

ＡＢＲ（ＡｖａｉｌａｂｌｅＢｉｔＲａｔｅ）业务是ＡＴＭ网为了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质量的关键问题。本文通过对一个简单ＡＢＲ流量控制模型的分析得出：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。     

On max-min fair congestion control for multicast ABR service in ATM

In the ATM Forum activities, considerable efforts have focused on the congestion control of point-to-point available bit rate (ABR) service. We present a novel approach that extends existing point-to-point (unicast) congestion control protocols to a point-to-multipoint (multicast) environment. In particular, we establish a unified framework to derive a multicast congestion control protocol for an ABR service from a given rate-based unicast protocol. We generalize a known necessary and sufficient condition on the max-min fairness of unicast rate allocation for a multicast service. Using this condition, we show that the resulting multicast protocol derived using our framework preserves the fairness characteristics of the underlying unicast protocol. The practical significance of our approach is illustrated by extending a standard congestion control mechanism for an ABR service to a multicast environment. The performance of the resulting multicast protocol is examined using benchmark network configurations suggested by the traffic management subworking group at the ATM Forum, and simulation results are presented to substantiate our claims     

Performance analysis of congestion avoidance algorithms with non‐zero MCR guarantee for ABR service in ATM networks

This paper proposes a novel explicit rate allocation algorithm called Fast Rate Allocation Congestion Avoidance (FRACA) algorithm supporting non‐zero minimum cell rate (MCR). The non‐zero MCR guarantee strategy for ABR service in ATM networks focused in this paper is MCR plus equal share (The ATM Forum Traffic Management Specification, version 4.0. April 1996). The main goals for designing the algorithm are the fast convergence according to the max–min fairness criteria, fairness among all sessions, maximum network utilization while the switch queue length is properly controlled. At the same time, it should work well under a wide range of network conditions without the need for adjusting the algorithm parameters. The performance of the proposed algorithm is evaluated and compared with the Generic Weighted Fairness (GWF) ERICA + (J Comput Comm 2000; 149). Simulation results show that the proposed algorithm achieves the design goals in the evaluated scenarios. Copyright © 2004 John Wiley & Sons, Ltd.     

An efficient feedback consolidation algorithm forpoint-to-multipoint ABR service in ATM network

In this letter, we propose an efficient feedback consolidation algorithm for a point-to-multipoint available bit rate (ABR) service in asynchronous transfer mode (ATM) networks. The proposed scheme can achieve fast transient response to the congestion status on a branch as well as effectively eliminate the consolidation noise     

A rate-based congestion control scheme for ABR service in ATM networks

In this article we describe an improved rate-based congestion control scheme for Available Bit Rate (ABR) service in ATM networks. The analytical results are presented and the characteristics of the designed scheme are illustrated by using simulation results. © 1998 John Wiley & Sons, Ltd.     

Characteristics of ABR explicit rate control algorithms in WAN environments and an ABR control algorithm suitable for public networks

This paper investigates the characteristics of available bit rate (ABR) explicit rate control algorithms in wide area network (WAN) environments. An ABR service is expected to make more effective bandwidth utilization possible through closed loop congestion control, and several control algorithms have been proposed. However, in WAN environments a long propagation control delay will affect the effectiveness of the control algorithms. Additionally, if a network supports a large number of connections, some of the algorithms may not work well. Thus we have categorized the control algorithms according to their purpose and mechanism and have evaluated their characteristics by simulation in WAN environments from the viewpoint of throughput, robustness, quickness, stability and fairness. Based on this analysis, we have developed an ABR control algorithm suitable for public networks. © 1998 John Wiley & Sons, Ltd.     

GII public policy issues

National information infrastructure (NII) public policy issues apply to the development of the global information infrastructure (GII) as well. Individual privacy rights; prevention of malicious behavior by irresponsible individuals; protecting the interests of computer system owners, operators, users, and the general public from computer crime; excluding unauthorized access; and preventing destruction of national computer systems (e.g.. interbank transaction systems) are issues that can be endemic to GII operations. More recent issues, such as the need for high-definition television standards, expand the global challenges. Hence, the body of work performed by the Committee on Communications and Information Policy (CCIP) for the IEEE-USA. Which focused on public policy issues of the NII, can serve as a set of lessons learned that should be considered by the GII community. The article identifies the NII issues and concerns to the CCIP, outlines the recommendations already made, and indicates how they relate to the GII     

ABR和UBR业务模型的TCP接入分析

ＡＢＲ和ＵＢＲ业务是ＡＴＭ中新定义的业务类型，主要面向数据传输服务。ＴＣＰ是目前最为流行的数据输协议，采用基于窗口的拥塞控制机制。本文主要讨论了ＴＣＰ接入ＡＢＲ和ＵＢＲ业务时所呈观的一些特点及ＡＴＭ交换机缓存的大小对ＴＣＰ性能的影响。     

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。     

TCP over ATM ABR&UBR性能及问题研究

全面介绍了TCPoverABR、UBR中主要问题的研究现状,并对TCP在这2种传输方式下的性能作了比较.     

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。     

ABR业务在卫星CFDAMA-PB MAC协议上传输的性能分析

CFDAMA作为新型的卫星ATMMAC协议,在保障各类业务QOS的同时实现了较好的时延/吞吐量性能。本文基于GEO卫星网络,通过计算机仿真对ABR业务及Internet业务在CF-DAMA-PBMAC协议上传输的性能进行了比较,并在两种时隙分配算法下,比较了ABR业务的传输性能,得出了相关的重要结论。     

Performance Evaluation of ABR Flow-Control Protocols in a Wireless ATM Network

Using an object-oriented simulation model of a basic client–server scenario in a wireless ATM network, we study the impact of handover and error-control protocols on the performance of high-speed data communication by the ABR service class. We present performance results of the ABR flow-control protocols ERICA and ERICA+ and discuss some implications for the protocol design.     

Performance issues in WWW servers

This paper evaluates techniques for improving operating system and network protocol software support for high-performance World Wide Web servers. We study approaches in three categories: i.e., new socket functions, per-byte optimizations, and per-connection optimizations. We examine two proposed socket functions, i.e., acceptex( ) and send-file( ), comparing send-file( )'s effectiveness with a combination of mmap( ) and writev( ). We show how send-file( ) provides the necessary semantic support to eliminate copies and checksums in the kernel, and quantify the benefit of the function's header and close options. We also present mechanisms to reduce the number of packets exchanged in an HTTP transaction, both increasing server performance and reducing network utilization, without compromising interoperability. Results using WebStone show that our combination of mechanisms can improve server throughput by up to 64%, and can eliminate up to 33% of the packets in an HTTP exchange. Results with SURGE show an aggregate increase in server throughput of 25%     

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.