Hopfield神经网络在B—ISDN路由选择中的应用

宽带综合业务数字网（Ｂ－ＩＳＤＮ）采用异步转移模式（ＡＴＭ）作为其传输技术,引入了虎通道（ＶＰ）和虚通路（ＶＣ）概念。本文针对Ｂ－ＩＳＤＮ中的ＶＰ路由问题,提出了一种基于Ｈｏｐｆｉｅｌｄ神经网络的ＶＰ路由选择算法,给出了神经网络能量函数的表示方法及神经元的状态方程。计算机模拟结果表明,本算法能根据网络的物理结构和业务需求情况,快速、有效地实现ＶＰ路由选择,提高网络的生存性。     

向宽带综合业务发展的世界通信技术

本文简介了宽带通信业务在美国等发达国家的发展情况以及目前提供宽带通信业务的手段。综述了支持宽带通信业务的新技术。对支持宽带通信的网络进行了前景预测和标准化情况介绍。另外，还介绍了窄带综合业务数字网（Ｎ－ＩＳＤＮ）向宽带综合业务数字网（Ｂ－ＩＳＤＮ）的发展、虚通道（ＶＰ）的应用以及异步转移模式（ＡＴＭ）为基础建立全国性Ｂ－ＩＳＤＮ等开发应用实例。     

多媒体通信技术（三）：多媒体通信的信息处理技术

０引言 多媒体通信网为多媒体提供一个传输环境,网络的带宽、信息交换方式以及高层协议直接决定着传输及服务的质量。目前绝大部分的多媒体业务都是在现行的各种网络上运行的,并且按照多媒体通信的要求对现有的网络进行改造和重组。目前的通信网络可大体上分为３类：１类为电信网络,如公用电话网（ＰＳＴＮ）、分组交换网（ＰＳＰＤＮ）、数字数据网（ＤＤＮ）、窄带和宽带综合业务数字网（Ｎ－ＩＳＤＮ和 Ｂ－ＩＳＤＮ）等;２类为计算机网络,如局域网（ＬＡＮ）、广域网（ＷＡＮ）等;３类为电视传播网络,如有线电视网（ＣＡＴＶ）、…     

IN/B-ISDN综合实现视频点播的方案

本文提出了在ＩＮ／Ｂ－ＩＳＤＮ综合的平台上实现视频点播业务的新方案,即用智能网的方法将Ｂ－ＩＳＤＮ宽带网络中的各种ＯＶＤ服务器统一控制和管理起来,既方便用户接入ＶＯＤ业务,又可使ＶＯＤ资源得到充分的利用。     

向B－ISDN方向发展

介绍了宽带综合业务数字网（Ｂ—ＩＳＤＮ）国内外的发展状况；Ｂ－ＩＳＤＮ所提供的业务及用户；实现Ｂ－ＩＳＤＮ的技术标准和发展我国Ｂ—ＩＳＤＮ的建议。     

可视型通信业务B—ISDN

可视型通信业务Ｂ－ＩＳＤＮ吴腾奇可视型（Ｖｉｓｕａｌ）通信不但传送声音，而且传送图像，甚至可以同时传送长篇文章。提供这种可视型通信服务的工具称为宽带综合业务数据网（Ｂ—ＩＳＤＮ）。实现Ｂ—ＩＳＤＮ的关键性技术则是异步传送模式（ＡＴＭ）。一、可视型通信...     

智能网与其他基础网络的结合

通信事业迅猛发展,各种通信新技术的崛起和应用,不断更新和改造着现有的通信网络和设备,它要求网络中引进更多更强的智能,以提高网络对业务的应变能力。智能网（ＩＮ）在这方面提供了最好的支持,是目前电信业务发展的方向。智能网是一种以快速、方便地提供新业务为目的的新型网络,也可以说是一种面向业务的通用网络结构。智能网的目标是服务于所有的基础网络,包括公用电话交换网（ＰＳＴＮ）,综合业务数字网（Ｎ－ＩＳＤＮ）,移动通信网（Ｍｏｂｉｌｅ）,公用分组交换数据网（ＰＳＰＤＮ）,以及宽带网（Ｂ—ＩＳＤＮ）。根据这个…     

窄带综合业务数字网(N-ISDN)端到端测试方法

７０年代以前,电信业务仅局限于电话和电报业务。近２０年来,出现了很多新型的电信业务,如声音、图象、文字、数据等。由于各业务特性的不同,各自不同的信息传递和网络处理给电信的运行、维护与管理带来诸多不便。而综合业务数字网（Ｉｎｔｅｇｒａｔｅｄ Ｓｅｒｖｉｃｅｓ Ｄｉｇｉｔａｌ Ｎｅｔｗｏｒｋ）不仅可以提供目前各种通信网络中现有的业务,而且将通信和数据处理结合,开创了不少新业务,弥补了传统电信网的很多缺陷。窄带综合业务数字网（Ｎ－ＩＳＤＮ）正是电信业务发展的重要方向之一,在Ｎ－ＩＳＤＮ应用到电信网之前,对它的各项技术指标的测试也是非常必要的。 窄带综合业务数字网端到端测试包括端到端的信令配合测试、业务验证和性能测试。原邮电部通过引用ＹＤＮ ０３８－１９９７（国内ＮＯ．７信令方式技术规范──综合业务数字网用户部分）和ＹＤＮ ０３４－１９９７（ＩＳＤＮ用户──网络接口技术规范）两个标准制订了《窄带综合业务数字网（Ｎ－ＩＳＤＮ）端到端测试规范》。下面就Ｎ－ＩＳＤＮ端到端测试的方法作一介绍。一、准备测试仪表和话机 １．ＴＵＰ／ＩＳＵＰ信令测试仪表。ＴＵＰ／ＩＳＵＰ信令测试仪连接在被测信令所在的２Ｍ系统上,一般两个交换局之间...     

VPDN技术简介

ＶＰＤＮ是拨号业务的ＶＰＮ,指利用公共网络的拨号及接入网实现的虚拟专用网,可为企业、小型ＩＳＰ、移动办公人员提供接入服务。ＶＰＤＮ能够充分利用现有的网络资源,提供经济、灵活的联网方式,为客户节省设备、人员和管理所需要的投资,降低用户的费用,所以必将得到广泛的应用。下面就ＶＰＤＮ作一介绍。 一、VPDN基本原理 ＶＰＤＮ主要由网络接入服务器（ＮＡＳ）、用户端设备（ＣＰＥ）和管理工具组成。ＶＰＤＮ的构成如图１所示。 其中ＮＡＳ由大型ＩＳＰ或电信部门提供,其作用是作为ＶＰＤＮ的接入服务器,提供广域网接口,…     

TU-T关于B-ISDN信令研究的新进展(上)

ＴＵ－Ｔ关于Ｂ－ＩＳＤＮ信令研究的新进展（上）●段强编者按：国际电信界已普遍认为宽带综合业务数字网（Ｂ－ＩＳＤＮ）是通信网络的发展方向，对其研究也相当活跃。其中，国际电信联盟标准化组织（ＩＴＵ－Ｔ）针对Ｂ－ＩＳＤＮ所制订的一系列规范，对其发展起着重要...     

MULTICAST ROUTING SCHEMES IN ATM

In this study, we investigate the problem of accommodating multicast traffic in ATM networks, with emphasis on the virtual path (VP) environment. We propose a network structure called “virtual copy network” that is suitable for multicast communication and connection setup scheme, taking into account the VP environment. With our technique, we can expect statistical multiplexing gain in accommodating multiple multicast traffic streams over a VP. Also, we propose two multicast routing algorithms (the CNR-LH algorithm and the improved CNR-LH algorithm) for an ATM network environment. In these algorithms, in addition to determining an adequate route, the exact corresponding VPs on the route are also obtained. We examine the efficiency of the algorithms by demonstrating their basic characteristics using computer simulations.     

Virtual path control for ATM networks with call level quality ofservice guarantees

The configuration of virtual path (VP) connection services is expected to play an important role in the operation of large-scale asynchronous transfer mode (ATM) networks. A major research challenge is to understand the fundamental tradeoff between the network call throughput and the processing load on the signaling system and to provide an algorithm for VP capacity allocation that achieves an optimal network operating point while guaranteeing quality of service (QoS) at the call level and satisfies a priori bounds on the processing load of the call processors. We present a taxonomy of previous approaches to the problem and identify their strengths and weaknesses. Based on these observations, we provide an algorithm for the VP capacity allocation problem that satisfies nodal constraints on the call processing load and blocking constraints for each source-destination (SD) pair. The algorithm maximizes the network revenue under the above set of constraints and is parameterized by the number of traffic classes in the network, the method of presentation of networking resources, the admission control policy used in every link and VP, and the network routing scheme. Finally, we apply the algorithm to three sample networks and study several of its performance characteristics. In one case, we applied the calculated VP distribution to the Xunet ATM testbed and verified experimentally the predicted performance     

差分式电流模式CMOS OTA-C双二阶滤波器

应用信号流图法，提出了一种新颖的差分式连续时间电流模式ＣＭＯＳ跨导—电容双二阶滤波器，该滤波器仅使用最少量的差分式ＯＴＡ和电容并且能有效地消除偶次谐波失真、具有较低的特征参数灵敏度等优点；面向实际电路完成了ＭＯＳ管级的计算机仿真，仿真结果表明所提出的电路方案正确有效，适于全集成。     

Simulation of the Tree Algorthm in ATM Networks

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A novel robust routing algorithm for multi-granularity connection requests in wavelength division multiplexing mesh networks

In this paper, we propose a novel robust routing algorithm based on Valiant load-balancing under the model of polyhedral uncertainty (i.e., hose uncertainty model) for WDM (wavelength division multiplexing) mesh networks. Valiant load-balanced robust routing algorithm constructs the stable virtual topology on which any traffic patterns under the hose uncertainty model can be efficiently routed. Considering there are multi-granularity connection requests in WDM mesh networks, we propose the method called hose-model separation to solve the problem for the proposed algorithm. Our goal is to minimize total network cost when constructing the stable virtual topology that assures robust routing for the hose model in WDM mesh networks. A mathematical formulation (integer linear programming, ILP) about Valiant load-balanced robust routing algorithm is presented. Two fast heuristic approaches are also proposed and evaluated. We compare the network throughput of the virtual topology constructed by the proposed algorithm with that of the traditional traffic grooming algorithm under the same total network cost by computer simulation.     

Statistical multiplexing and mix-dependent alternative routing inmultiservice VP networks

We consider problems in traffic integration and routing for virtual path (VP)-based multiservice networks. The objective is to exploit statistical multiplexing among various traffic types in order to improve system utilization. Difficulties arise due to statistical multiplexing since a connection's bandwidth requirement depends on the characteristics of the interfering traffic. We first consider whether segregating heterogeneous traffic with different quality of service (QoS) requirements on separate VPs is desirable. Next we consider routing heterogeneous permanent connections given a predefined traffic type mix onto multiple VPs between a source destination pair. We show that it is not necessarily advantageous to have each VP carry every traffic type. In fact, perhaps surprisingly, an optimum solution to this problem suggests that only a small number of traffic types, or even homogeneous traffic, need be present on each VP. Based on this observation, we propose a simple alternative routing algorithm with routing sequences depending on the traffic mix     

基于约束路由的绿色虚拟拓扑设计算法

摘 要：针对Internet核心网日益严重的能耗问题,建立了绿色虚拟拓扑设计(GVTD)问题的形式化模型,通过业务汇聚、按需配置网络资源、动态虚拟拓扑设计和多粒度睡眠机制降低网络能耗。提出了一种基于约束路由的启发式算法——CBR-GVTD算法,利用单跳路由和多跳路由相结合的方法构建网络虚拟拓扑,并通过基于约束的路由实现网络功耗与路由性能的折衷。模拟结果表明,CBR-GVTD算法可在接口平均利用率为80%~90%和最大路由跳数不超过5的条件下,最多可降低62%~90%的网络功耗     

A simple adaptive routing scheme for congestion control inShuffleNet multihop lightwave networks

The authors describe a simple adaptive routing scheme for datagram (connectionless) and virtual circuit (connection-oriented) transmission that relieves congestion resulting from nonuniform traffic patterns and network failures. The authors describe a fixed-routing algorithm for dedicated channel ShuffleNets. Based on the fixed routing algorithm, an adaptive routing scheme for datagram transmission is presented followed by performance results for uniform and nonuniform traffic patterns and fault tolerance. The adaptive routing of datagrams uses only the local queue size information available at the network interface units (NIUs) and redistributes the load as congestion develops. Since datagrams are individually routed through the network, they may not arrive at their destination in the order they were generated and may need to be resequenced. The authors compute an upper estimate on the resequencing buffer size for stream traffic. A virtual circuit version of the adaptive routing algorithm eliminates the need for resequencing buffers     

The layout of virtual paths in ATM networks

We study the problem of designing a layout of virtual paths (VPs) on a given ATM network. We first define a mathematical model that captures the characteristics of virtual paths. In this model, we define the general VP layout problem, and a more restricted case; while the general case layout should cater connections between any pair of nodes in the network, the restricted case layout should only cater connections between a specific node to the other nodes. For the latter case, we present an algorithm that finds a layout by decomposing the network into subnetworks and operating on each subnetwork, recursively; we prove an upper bound on the optimality of the resulting layout and a matching lower bound for the problem, that are tight under certain realistic assumptions. Finally, we show how the solution for the restricted case is used as a building block in various solutions to more general cases (trees, meshes, K-separable networks, and general topology networks) and prove a lower bound for some of our results. The results exhibit a tradeoff between the efficiency of the call setup and both the utilization of the VP routing tables and the overhead during recovery from link disconnections     

Architecture for restorable call allocation and fast VP restorationin mesh ATM networks

This paper presents an architecture for restorable call allocation and fast virtual path (VP) restoration in mesh ATM networks. In this architecture, virtual working and spare capacities needed for call allocation and restoration are reserved and released dynamically on a call-by-call basis at the time of call admission and termination. This obviates the need for advance assignment of spare and working capacities. To shorten the call processing delay, this is done in a parallel-distributed fashion. To provide restorable call allocation, parallel-distributed call processing algorithms of sender-chooser type are suggested. The algorithms integrate, on the call level, virtual bandwidth allocation, virtual spare-capacity assignment, and fixed, alternate, or state-dependent routing. Each routing scheme leads to a particular tradeoff between call processing complexity, call setup delay, and bandwidth efficiency. For each pair of nodes, two sets of VPs are provisioned. The first, working VP (WVP) set, is used for call allocation during the normal operation. The second, spare VP (SVP) set, is used for WVP restoration in the event of failures of network elements. Each SVP protects a preassigned subset of the node pair's WVPs. Each SVP is selected to be link/node disjoint from the WVPs that it is assigned to protect. This assures a protection of the WVP set by a small number of SVPs. Since SVPs are preset and appropriate virtual spare capacities are reserved in advance, the architecture guarantees full restorability and provides very fast restoration. The restoration is done on the VP level in a self-healing manner. The suggested architecture requires only local information to be maintained at each node