ATM网络VP层的控制技术研究

文中介绍了ATM网络VP层控制技术的研究意义和现状;给出了ATM网络的分层控制体系,指出分层控制为ATM网络管理控制带来了极大的方便;并对VPC层逻辑网络规划、控制的相关问题及其内容进行了分析、分类与总结。     

An adaptive multipath routing scheme for connectionless traffic in an ATM network

This paper addresses the problem of routing connectionless traffic through an ATM network. A solution is proposed based on a per-packet adaptive multipath routing scheme which is added to the routing algorithm implemented at the Inter-Working Units. A scheme is presented that distributes packets among multiple Virtual Paths (VPs) according to the utilization of the links on these VPs. The utilization of the VPs is determined by a periodic feedback mechanism. Simulation studies show the effectiveness of the proposed adaptive multipath routing scheme.The work by J. Sole-Pareta was supported in part by a CIRIT (Generalitat de Catalunya) grant (expedient number EE92/2-338), and in part by the National Science Foundation under Grant No. INT-94033646. The work by I. Akyildiz was supported in part by the National Science Foundation under Grant No. INT-94033646.     

基于PBIL进化算法的ATM虚通道路由规划

合理规划ATM(异步传输模式)网络的虚通道路由能有效提高网络业务服务质量和网络资源利用率，针对其NP完全特性，提出了一种基于PBIL(Population-Based Incremental Learning)进化算法的ATM虚通道路由规划算法，有效结合了遗传算法和竞争学习算法的特点，仿真表明，相对于文中提到的其它三种算法，该算法解的质量最高，能有效地收敛到问题的次优解，甚至最优解．     

ATM网络基于ABR服务的流量控制算法及其研究

讨论了在ATM网络中ABR业务拥塞控制机制及其改进方法,即在增强比例速率控制算法（EPRCA）中通过检测缓存队列长度来控制网络拥塞,大大降低了拥塞产生的可能性,防止了网络拥塞的崩溃,并提高了缓存的利用率.     

无线自组网中一种高效的路由协议

无线自组网与传统的有线网不同,它由一些可移动的结点组成,这些结点的带宽、计算能力和能量都受到一定限制。针对这种网络,研究者们提出了按需路由协议,这些协议非常适合无线自组网这种拓扑结构,但是由于缺乏对全局拓扑和结点移动性的了解,可能达不到最优。因此提出了一种高效的路由协议ERNC,该协议基于已提出的SHORT路由协议[13],并对以前所提出的NAOR协议[14]进行了扩展,即利用网络编码技术来进一步提高路由协议的性能。最后,使用NS-2模拟器来评估ERNC的性能,结果显示ERNC在分组投递率和平均端到端时延等方面获得了比已有协议更好的性能。     

The torus routing chip

The torus routing chip (TRC) is a selftimed chip that performs deadlock-freecut-through routing ink-aryn-cube multiprocessor interconnection networks using a new method of deadlock avoidance calledvirtual channels. A prototype TRC with byte wide self-timed communication channels achieved on first silicon a throughput of 64 Mbits/s in each dimension, about an order of magnitude better performance than the communication networks used by machines such as the Caltech Cosmic Cube or Intel iPSC. The latency of the cut-through routing of only 150 ns per routing step largely eliminates message locality considerations in the concurrent programs for such machines. The design and testing of the TRC as a self-timed chip was no more difficult than it would have been for a synchronous chip. Bill Dally received his B. S. degree in Electrical Engineering from the Virginia Polytechnic Institute in 1980 and his M.S. degree in Electrical Engineering from Stanford University in 1981. From 1980 to 1982 he worked at Bell Telephone Laboratories, where he contributed to the design of the BELLMAC-32 microprocessor. From 1982 to 1983 he worked as a consultant in the area of digital systems design. Since 1983 he has been a graduate student in Computer Science at Caltech, and is expected to complete his Ph.D. studies in the spring 1986. His current research interests include computer architecture, computer aided design, VLSI, design, and concurrent systems. Chuck Seitz earned B.S., M.S., and Ph.D. degrees from M.I.T. Before joining the Computer Science faculty at Caltech in 1977, he worked as a member of the technical staff of the Evans & Sutherland Computer Corporation from 1969 to 1971, as an Assistant Professor of Computer Science at the University of Utah from 1970 to 1972, and as a consultant to Burroughs Corporation from 1971 to 1978. He is currently a Professor of Computer Science at Caltech, where his research and teaching activities are in the areas of VLSI architecture and design, concurrent computation, and self-timed systems.The research described in this paper was sponsored in part by the Defense Advanced Research Projects Agency, ARPA Order number 3771, and monitored by the Office, of Naval Research under contract number N 00014-79-C-0597, in part by Intel Corporation, and in part by an AT & T Ph.D. fellowship     

Implementation of self-healing function in ATM networks

This paper proposes an implementation scheme for the self-healing function in ATM (Asynchronous Transfer Mode) networks and assesses its performance in a developed experimental system. First, our proposed ATM self-healing scheme is described. This scheme realizes more rapid restoration of failed Virtual Paths than other self-healing algorithms, supports the node failure case, and minimizes the spare resources required. Next, an implementation scheme is proposed. We propose that the self-healing function can be implemented as a software process, and that OAM (Operation, Administration, and Maintenance) cells be utilized for fast message transmission. Next, results of a prototype system that we implemented on an ATM cross-connect system are discussed. The fundamental characteristics of restoration performance are measured using the experimental system. Based on these results, restoration characteristics of real world scale networks are estimated by computer simulations. The simulation results indicate that any-one link failure is completely restored within 2 seconds.     

传输链容量的可变性与通信网虚通路带宽优化分配

该文提出了可变传输链容量的思想,并研究了传输链容量可变性对带宽优化分配结果的影响。计算实例表明,在总和不变前提下的各传输链容量的有限可变性,对提高网络为突发性业务的服务质量有重要贡献。     

Parallel communications for ATM network control and management

This paper describes an end-to-end parallel communications scheme based on a vector routing algorithm (VRA) for ATM network control and management. An information string is partitioned into m parts, which are then coded into k > m parts and sent out on k separate subchannels to the receiver. When m of the k parts are received correctly, the original information can be reconstructed. Two desirable effects are achieved in the context of ATM traffic control: (1) the burstiness of the source traffic can be smoothed out by the partition process; (2) the quality of service in terms of error, loss and delay can be controlled using the number of redundant routes k — m as a control parameter. Our results show that VRA is especially suitable for services with highly bursty traffic. We argue that several network management issues, including reliability, evolution and integration, security, and administration and billing can be addressed in a simple manner using the VRA framework.     

Non-derivative algorithm design for efficient routing over unreliable stochastic networks

We study the question of routing for minimum average drop rate over unreliable servers that are susceptible to random buffer failures, which arises in unreliable data or manufacturing networks. Interestingly, we first reveal that the traditional Join-the-Shortest-Queue (JSQ) or optimal Randomized Splitting (RS) strategies are consistently outperformed by the Constant Splitting Rule (CSR) where the incoming traffic is split with a constant fraction towards the available servers.This finding motivates us to obtain the optimal splitting fraction under CSR. However, the objective function to be minimized depends on the mean queue length of the servers, whose closed-form expression is not available and often intractable for general arrival and service processes. Thus, we use non-derivative methods to solve this optimization problem by approximately evaluating the objective value at each iteration. To that end, we explicitly characterize the approximation error by utilizing the regenerating nature of unreliable buffers. By adaptively controlling the precision of this approximation, we show that our proposed algorithm converges to an optimal splitting decision in the almost sure sense. Yet, previous works on non-derivative methods assume continuous differentiability of the objective function, which is not the case in our setup. We relax this strong assumption to the case when the objective function is locally Lipschitz continuous, which is another contribution of this paper.     

ATM网络带宽动态优化的广义粒子模型和算法

提出一种新的广义粒子模型和算法,将ATM网络优化问题转变为对偶力场中粒子的运动学和动力学问题,从而分布并行地动态优化ATM网络的资源和带宽分配以及ATM网络的QoS通信合约.讨论了ATM网络动态优化的广义粒子模型的适应性、收敛性和稳定性等性质.ATM网络带宽分配优化问题是NP一完全问题.根据服务类型、通信流量特性和QoS参数,优化ATM网络的资源和带宽分配,对于提高网络吞吐能力、保证网络QoS性能有重要意义.理论分析和仿真实验表明,广义粒子模型和算法具有高度分布并行性,能体现资源需求的价格机制,能适应复杂的动态环境,易于硬件和软件实现.     

高可用应用开发平台的设计与实现

设计并实现了一个高可用应用开发平台，该平台提供了一个灵活的高可用编程环境，不仅包含高可用应用开发框架，还包含了应用开发所必需的检查点服务、分布式锁服务、事件服务、消息服务和成员服务等。采用该平台使得应用程序的开发只需要集中于具体的业务流程上，而不需要过多地考虑其他高可用特性，同时还可提供更强的可移植性。     

高可用应用开发平台的设计与实现

设计并实现了一个高可用应用开发平台，该平台提供了一个灵活的高可用编程环境，不仅包含高可用应用开发框架，还包含了应用开发所必需的检查点服务、分布式锁服务、事件服务、消息服务和成员服务等。采用该平台使得应用程序的开发只需要集中干具体的业务流程上。而不需要过多地考虑其他高可用特性，同时还可提供更强的可移植性。     

Experimental studies on a local rescheduling procedure for dynamic routing of autonomous decentralized AGV systems

This paper addresses a local rescheduling procedure for a distributed routing system of multiple Automated Guided Vehicles in dynamic environments where the requests for transportation are given in real time. The effectiveness of the proposed method is investigated for a transportation system of 143 nodes and 10–30 AGV systems in a semi-conductor fabricating bay. A distributed and parallel routing system (DPRS) is implemented and tested on an experimental five mobile robot system. The results demonstrate that the proposed method can reduce the total computation time by 39% compared with the conventional method without lowering the performance level. It is also experimentally verified that the rescheduling procedure can deal with disturbances in a significantly short computation time.     

Overview of ATM networks: functions and procedures

The purpose of this paper is to present an overview of the ATM technique. The basic principles of the ATM transfer technique, the B-ISDN layered protocol reference model, as well as the architecture and the main functions of the ATM network, are described in this tutorial. In particular, we present the main characteristics of the ATM technique, the structure of the ATM cell, the functions which deal with the protection from errored cells (HEC procedure) and the identification of the boundaries of the ATM cells (cell delineation and scrambling). The VP/VC concept is explained in detail, and the main principles and functions of the three lowest layers (Physical, ATM and Adaptation) of the B-ISDN layered protocol reference model are surveyed. The issue of Quality of Service parameters in ATM networks is reviewed, and the problem of the allocation of the network resources in response to user demands, as well as the problems of congestion control, Usage Parameter Control (UPC) and traffic modelling in ATM networks, are assessed. Finally, we present ‘possible’ sets of traffic characterization parameters, and show how possible B-ISDN sources can be modelled according to the basic on-off ATM traffic source model.     

基于模糊神经网络的ATM网络业务量智能预测

文章尝试将模糊神经网络方法引入ATM网络的业务量预测中。ATM网络业务源一般是随机产生的时变信号,其模型一般很难描述。文章充分考虑了模糊神经网络的学习功能,通过对相关模型的仿真,能够很好地描述ATM网络中的业务流特性,对多媒体的业务量做出了准确的预测。与传统的神经网络方法比较,具有更好的逼近效果。     

Performance improvement of dynamic buffered ATM switch

Performance of ATM networks depends on switch performance and architecture. This paper presents a simulation study of a new dynamic allocation of input buffer space in ATM switching elements. The switching elements are composed of input and output buffers which are used to store received and forwarded cells, respectively. Efficient and fair use of buffer space in an ATM switch is essential to gain high throughput and low cell loss performance from the network. In this paper, input buffer space of each switching element is allocated dynamically as a function of traffic load. A shared buffer pool is provided with threshold-based virtual partition among input ports, which supplies the necessary input buffer space as required by each input port. The system behaviour under varying traffic loads has investigated using a simulation program. Also, a comparison with a static allocation scheme shows that the threshold based dynamic buffer allocation scheme ensures an increased network throughput and a fair share of the buffer space even under bursty loading conditions.     

A roadmap of fuzzy logic in ATM,mobile and active networks: challenges of the new century

 ATM networking technology was conceived 20 years ago, and installations will reach their peak the next 10 years. Active networks will be the technology which will follow the ATM. In this article, we address the most important issues regarding recent advances and future perspectives in ATM, including IP/ATM integration, Active Networks, MobileActive Networks and the impact of fuzzy technology in solving the important problems of the above future networking technologies. In the new century it is imperative that we shift from a technology to an application (needs of consumers) focus, where ubiquitous and invisible (context-aware) computing will be a reality.     

ATM交换机多输入队列模型与PIM算法分析

介绍了ＡＴＭ的交换结构与几种输入了队例模型,提出了在多输入队列的无阻塞的交换结构中采用的ＰＩＭ算法,减少ＦＩＦＯ ＨＯＬ阻塞,并对基于ＰＩＭ时序的交换模型及其性能作了简要分析。     

ATM的前景分析

近年来ATM技术的发展前景受到了很多质疑，本文从ATM的技术前景（包括ATM的技术优势），应用前景和市场前景三个方面，对ATM的发展进行了详细的分析后指出，ATM技术的前途依然光明。