光接入网：第五讲 光接入网的演进

本讲首次简要讲述光接入网升级的一般考虑，然后着重介绍无源光网络（ＰＯＮ）传送图像业务的主要方案，接下来进述ＰＯＮ为基础ＳＤＶ业务和应用以及ＳＤＨ在接入网中的应用，最后讲述以ＡＴＭ为基础的宽带ＰＯＮ（ＡＰＯＮ）。     

基于ATM的无源光网络媒质接入控制协议的设计

针对基于ＡＴＭ的无源光网络（ＡＴＭ－ＰＯＮ）设计了一种媒质接入控制（ＭＡＣ）协议。该协议的设计遵照ＩＴＵ－Ｔ有关ＡＴＭ－ＰＯＮ的建议Ｇ．９８３．１（１９９８年１０月）中所定义的帧结构。该协议能够支持ＣＢＲ／ＶＢＲ、ＡＢＲ和ＵＢＲ等多种业务,并能够保证用户公平地接入和充分地利用网络的资源。其中ＣＢＲ／ＶＢＲ业务的优先级最高,同时也确保ＡＢＲ业务至少能以最小信元通信。系统的剩余带宽资源被分配给ＵＢＲ业     

理想的光纤接入方案——APON技术

介绍了一种基于ＡＴＭ无源光网络（ＡＰＯＮ）技术的光纤接入方案,给出了ＡＰＯＮ系统的结构、工作方式。对照ｘＤＳＬ技术讨论了 ＡＰＯＮ的优良特性。文中还综合各种因素,分析了ＡＰＯＮ系统的可实现性及发展前景。     

厂商动态

上海邮通实业与东莞电信合作构建 ＡＴＭ—ＰＯＮ试验网 ＦＳＡＮ（Ｆｕｌｌ Ｓｅｒｖｉｃｅ Ａｃｃｅｓｓ Ｎｅｔｗｏｒｋ）是一种 ＡＴＭ－ＰＯＮ高速率接入光分配系统,在国际上属先进技术。采用ＦＳＡＮ技术组网可利用已有的一些接入网技术实现全业务接入,即在接入网中不仅可以支持宽带、窄带以及交互式宽带业务,而且还支持一些目前尚未定义的新业务。最近,上海邮通实业发展有限公司率先引进法国ＣＳＴ公司的ＤＯＲＩＳ ＦＳＡＮ系统,与广东省东莞市电信局合作,在该市长安镇构建国内首个ＦＳＡＮ试验网。 东莞市的接入网发展较快,…     

FTTH—0512系统在CATV中的应用

目前光纤接入网发展很快,形式多种多样。ＦＴ－ＴＨ－０５１２系统是在光纤用户环路（ＦＴＴＬ）技术的基础上开发而成的,它可提供电话业务、数据业务、ＣＡＴＶ业务及其他宽带业务。该系统主要由中央局接口单元（ＣＯＩＵ）、光网络单元（ＯＮＵ）、无源光网络（ＰＯＮ）及ＯＡＭ系统等４个主要部分组成,ＦＴＴＨ－０５１２系统结构如图１和图２所示。 其中ＣＯＩＵ是ＦＴ－ＴＨ－０５１２系统与交换机的接口设备;ＯＮＵ是ＦＴＴＨ－０５１２系统与用户的接口设备;ＰＯＮ是ＣＯＩＵ和ＯＮＵ之间的光分配网络;ＯＡＭ系统负责日常维护…     

ATM与B－ISDN

论述了ＡＴＭ宽带交换在目前阶段是实现Ｂ－ＩＳＤＮ的关键和核心。ＡＴＭ具有较强的网路业务流量控制、管理和维护功能。采用ＡＴＭ技术是Ｂ－ＩＳＤＮ的业务所提出的技术要求。目前一些发达国家正积极开展Ｂ－ＩＳＤＮ技术转向实用化的工作     

一种MPOA边缘设备的研制

ＡＴＭ Ｆｏｒｕｍ提出的局域网仿真（ＬＡＮＥ）技术是一种将传统局域网接入到ＡＴＭ网络的重要方法,以ＬＡＮＥ为基础的ＭＰＯＡ将使ＡＴＭ真正进入企业网,本文提出一种ＭＰＯＡ边缘设备的方案,已经实现了局域网仿真网桥的功能,并且达到了很高的性能。     

ATM—PON宽带接入网研究

从接入网的定界角度出发,综合分析了接入网（ＡＮ）、用户驻地网（ＣＰＮ）,终端设备（ＴＥ）以及网间接口,并结合Ｂ－ＩＳＤＮ来考虑全网的互通性,通过对ＡＮ,ＣＰＮ,业务节点等的分析,给出一种基于ＡＴＭ－ＰＯＮ（异步转移模式－无源光网络）的宽带接入网解决方案。     

ATM PON中MAC算法的研究

ＡＴＭ ＰＯＮ网络属于分布式媒质共享拓扑结构，所承载业务的 ＱｏＳ要求各异，如何在保证系统传输效率的同时满足用户对服务质量的需求，是ＡＰＯＮ ＭＡＣ算法的关键。分析了 ＡＰＯＮ系统的特点，提出了分布式分层调度的方案。     

面向21世纪的宽带接入技术--以ATM为基础的无源光网络

本文结合以ＡＴＭ为基础的光源光网络的最新进展，系统介绍ＡＰＯＮ的通用结构，主要业务，光网要求以及传输性能要求同时，也探讨了存在的某些可能的解决方法。     

ATM业务量管理及其对ATM交换机设计的影响

ＡＴＭ网络允诺为各种通信业务在同一个通信网络中提供满足各自服务质量的要求的服务。为此，ＡＴＭ网络体系应能提供业务量管理（ｕｔａｆｆｉｃ ｍａｎａｇｅｍｅｎｔ）功能以支持网络业务千差万别的服务质量要求。本文首先阐述了ＡＴＭ论坛（ＡＴＭ Ｆｏｒｍ）中所定义的ＡＴＭ业务种类，它们各自的服务质量要求，以及为保证服务质量所应采用的管理策略。ＡＴＭ交换机是网络中的关键部件，其不同的设计思想对网络中不同业务服务     

ATM网络业务恢复机制研究

提出了基于网管控制下的层次化ATM网络业务恢复管理机制，指出了在网络维护管理过程中采用多种恢复机制并进行层次化技术处理的重要性。ATM网络的正常可靠运行需要从网络各个层次，运用各种恢复管理机制对业务进行管理维护。在网络实际运行过程当中，联合应用网络各层次上的恢复管理机制是非常重要的。描述了该技术具体应用以及基于网管控制的业务恢复策略。     

Frame relay and ATM interworking

Frame relay has proven to be a very successful wide area networking service, and ATM is gaining momentum in the industry to become the preferred common backbone technology for supporting a wide variety of network services, including native ATM cell relay service and frame relay service. In the years ahead, ATM is poised to become the dominant networking technology. Since frame relay and cell relay services will coexist for a long time to come, it is imperative that the network and service interworking specifications be defined and implemented. This article focuses on the topic of frame relay and ATM cell relay service and network interworking. The authors provide the rationale, the standards-based methodology, the major open issues, and a likely evolution scenario for the interworking of frame relay and ATM cell relay networks and services     

ATM与帧中继互连技术

ＡＴＭ技术是ＩＴＵ－Ｔ推荐的Ｂ－ＩＳＤＮ交换技术，而帧中继在提供广域网业务方面很成功。因此，在ＡＴＭ发展的初期不可避免地会与帧中继技术并存。本文阐述了ＡＴＭ与帧中继网络互加和业务互连的相关技术及其存在的问题。     

宽带综合业务数字网的ATM技术

目前宽带综合业务数字网(B—ISDN)已成为各国研究与开发的重要内容。本文简述了信息传输技术的发展趋势,着重介绍了ATM技术的概念、ATM信元结构和传输帧结构、ATM交换技术和ATM系统参考模型。     

Technology interworking for SMDS: from the DXI/SNI to the ATM UNI

As service providers introduce asynchronous transfer mode (ATM) into their networks, they are faced with the issue of technology interworking: for a given service, can a customer who has an ATM user-network interface (UNI) communicate with a customer who does not have an ATM UNI? For switched multimegabit data service (SMDS), technology interworking is well defined. In fact, SMDS is supported by several technology platforms that can interwork with each other. The three major platforms which support SMDS are: a frame-based platform based on the SMDS data exchange interface (DXI), a cell-based platform based on the IEEE 802.6-1990 standard, and a cell-based platform based on ATM. This article examines how SMDS is supported by each of these platforms and how these platforms interwork. Furthermore, this article presents how the major interworking functions required for these platforms appear to be straightforward for suppliers to implement,     

Buffer management and scheduling schemes for TCP/IP over ATM‐GFR

Today ATM technology is facing challenges from integrated service IP, IP switching, gigabit IP router and gigabit ethernet. Although ATM is approved by ITU‐T as the standard technology in B‐ISDN, its survivability is still in question. Since ATM‐UBR (unspecified bit rate) provides no service guarantee and ATM‐ABR (available bit rate) is still unattainable for most users, many existing users have little or no incentives to migrate to ATM technology. The guaranteed frame rate (GFR) service is introduced to deal with this dilemma. The GFR can guarantee the minimum cell rate (MCR) with fair access to excess bandwidth. This paper studies various schemes to support the GFR. We have studied different discarding and scheduling schemes, and compared their throughput and fairness when TCP/IP traffic is carried. Through simulations, it is shown that only per‐VC queueing with weighted round robin (WRR) can guarantee minimum cell rate. Among all the schemes that have been explored, we recommend dynamic threshold–early packet discard (DT–EPD) integrated with MCR+ (a WRR variant) to support the GFR service. Copyright © 2001 John Wiley & Sons, Ltd.     

ATM网络抗毁和自恢复技术研究

基于ATM/MPLS技术的通信网络是承载宽带多媒体业务的综合平台。为了对承载业务进行抗毁保护,对ATM的最基本的1+1、1∶1、m∶n抗毁保护结构进行了研究和总结。同时结合网络传输层,如:PDH、SDH、WDM、MPLS的保护和应用层业务,如:IP、电路交换、以太网和帧中继的抗毁迂回策略,提出了ATM的多层次抗毁自恢复组网结构,为ATM的应用研究提供了借鉴。     

Wireless ATM—an overview

This paper sketches the requirements and possibilities of wireless ATM in local area networks. Because of the wide range of services supported by ATM networks, ATM technology is expected to become the dominant networking technology in the medium term for both public infrastructure networks and for local area networks. ATM infrastructure can support all types of services, from time-sensitive voice communications and desk-top multi-media conferencing, to bursty transaction processing and LAN traffic. Extending the ATM infrastructure with a wireless access mechanism meets the needs of those users and customers that want a unified, end-to-end networking infrastructure with high-performance, consistent service characteristics. The paper introduces ATM concepts, discusses the requirements for wireless ATM, in particular for data link control and radio functions. It closes with some notes on development of wireless ATM research systems standardization and spectrum allocations.     

ATM局域网仿真技术

ＡＴＭ局域网仿真技术是由ＡＴＭ论坛提出的一种利用ＡＴＭ网络支持数据通信业务的方法。本文首先简介了引入此项技术的背景，继而分析了ＡＴＭ局域网仿真的基本思想以及仿真局域网的协议体系，网络配置，功能单元与连接种类等基本概念，并详细分析了ＡＴＭ局域网仿真中各项协议规程的工作机制。