波分复用系统加密技术研究

波分复用系统是将多个独立的光波耦合复用到一根光纤中传输,从而更有效地提供带宽,让IP、ATM、SDH等数据通过统一的光纤层传输的系统。波分复用系统在改善网络性能的同时,也给网络的安全带来了一定的隐患。文中针对波分复用（WDM）自身特点及所面临的安全威胁,提出基于WDM的加密技术研究思路,为实现对WDM／OTN／ASON网络综合数据业务的安全保密奠定了基础。     

波分复用光网络的自愈方法分析

WDM (WavelengthDivisionMultiplexing ,波分复用 )系统的应用使得大容量的业务日益集中于同一系统内 ,这同时提高了对网络自愈性能的要求 ,从而导致各种自愈技术的发展。因为光器件具有高速交换的优点 ,因而从光层对业务恢复具有极大的优越性。文中主要分析了几种典型的光层的自愈方法     

波分复用光网络

本文介绍光网络的组成以及和电网络的联系，重点介绍了波分复用光纤网络的特点，通过选择光波长实现光交换的原理、ＷＤＭ星形和环形光网络的构成等。     

波分复用无源光网络

介绍波分复用无源光网络（ＷＤＭＰＯＮ）的结构相对传统的ＰＯＮ结构的优越性,同时分析了两种最新ＷＤＭＰＯＮ结构中采用的两项技术：光源共享和频谱分割的原理和技术细节,最后指出ＷＤＭＰＰＯＮ是宽带接入网的最佳选择,文中ＷＤＭＰＯＮ优缺点的讨论,对电信运营者考虑 入网应采取何种结构,具有重要的参考价值。     

粗波分复用(CWDM)系统及其测试

对粗波分复用技术的产生、发展和应用进行描述，并与密集波分复用技术进行比较，最后介绍了粗波分复用系统的测试及其注意事项。     

第一章 光波分复用系统的基本原理

介绍光波分复用系统的基本原理。分别介绍光波分复用器、掺饵光纤放大器;光波分复用技术的主要优点、协调要点;光通路的波长分配、目标传输距离和光缆传输衰减、波长转换器、光监控通路及每信道最小发送功率等光波分复用系统五大主要参数的选择考虑。     

波分复用系统实际富余度及光通道代价的测量试及讨论

随着波分复用技术在传输网络上的进一步应用，波分复用系统的测试技术变得十分重要，探讨波分复用系统实际富余度及光通道代价的测试方法及相应问题。     

波分复用全光通信网

信息社会的发展需要采用高性能低价格的大容量,高速率传输网络,基于波分复用的全光网能充分利用光纤带宽,是光纤通信系统向大容量,高速率发展的有效途径。本文介绍了ＷＤＭ全光网的网络结构,相关设备和技术,并对几个典型的全光联网实例进行了描述,最后展望了ＷＤＭ全光网络的发展趋势。     

波分复用光开关及最新进展

光开关是当今密集波分复用光通信网络中的关键器件，目前已成为研制开发的热点。文中介绍了几种主要的热门光开关结构及其最新进展情况。     

WDM光网络中基于链路的动态组播共享保护算法

针对WDM光网络中单链路失效的情况,提出了一种基于链路的保护动态组播业务的优化共享保护算法(Link-based optimized shared-protection algorithm for multicast sessions,LB-OSPM).该算法在对工作树任意光纤链路失效情况寻找保护路径时,允许组播内不同保护路径共享预留波长资源,同时通过引入预留波长使用情况矩阵和波长预留矩阵记录预留波长资源的使用情况,实现了不发生冲突的不同组播的保护链路间共享预留波长资源.研究采用欧洲光网络(European Optical Network,EON)的拓扑对不同波长资源配置和网络负载情况下LB-OSPM算法的网络连接阻塞率做了仿真.结果表明,通过引入共享机制,LB-OSPM算法在对单链路失效保证100％恢复率的同时可以获得更低的连接阻塞率,提高了波长资源利用效率.     

WDM网络动态组播业务共享保护算法

该文研究了WDM网络中动态组播业务的保护.为提高网络资源的利用率,降低连接请求阻塞率,和单播业务的共享保护方案类似,组播连接之间也可以共享保护波长.本文提出了一种动态组播业务共享保护算法,并对算法的性能进行了仿真,同时和组播业务专有保护算法进行了比较.仿真结果表明,共享保护算法比专有保护算法使用了更少的波长资源,具有更低的连接阻塞率.     

网状WDM网中多播业务的共享保护设计

研究网状波分复用(WDM)光网络中动态多播业务的保护方案,提出一种共享保护和重配置(SPR)算法.该算法根据网络状态动态调整链路代价,为每个多播业务请求建立最小代价工作树,并为光树上互不重叠的工作段提供链路分离的保护段.当网络中发生链路失效时,进行业务段保护切换和局部资源重配置.仿真表明,该算法可以合理共享波长资源、平衡网络负载,有效保护WDM网中任意单链路失效,并在多链路失效情况下大大提高业务恢复能力.     

Enhanced Dynamic Segment Protection in WDM Optical Networks under Reliability Constraints

In this letter, we study the protection problem in wavelength division multiplexing (WDM) optical networks, and propose a novel dynamic heuristic algorithm called differentiated reliable segment protection (DRSP). Differing from previous work, DRSP can effectively avoid the trap problem and is able to find a feasible solution for each connection request. Therefore, DRSP outperforms the previous work. Simulation results have shown to be promising.     

On Finding the Multicast Protection Tree Considering SRLG in WDM Optical Networks

In this letter, a new sharing mechanism, SRLG sharing, is proposed, which allows the links of the same shared risk link group (SRLG) in a primary light tree to share protections in WDM optical networks. In previous studies, how to share spare resources with SRLG constraints has not been studied in multicast optical networks. In this letter, considering SRLG sharing, we propose a novel algorithm –multicast with SRLG sharing (MSS)– to establish a protection light tree. Finally, the algorithm MSS and the algorithm multicast with no SRLG sharing (MNSS) are compared through a simulation to show that our new sharing scheme of SRLG sharing is more efficient than that of no SRLG sharing in terms of spare resource utilization and blocking probability.     

光通道路由保护技术在工程中的应用探讨

结合工程实践经验，对目前WDM系统光层线性保护方式技术作了简单介绍，并针对光通道路由保护方式技术在工程中的应用方式进行了探讨。     

Dynamic Establishment of Segmented Protection Paths in Single and Multi-Fiber WDM Mesh Networks

Wavelength division multiplexed (WDM) networks are matured to provide, scalable data centric infrastructure, capable of delivering flexible, value added, high speed and high bandwidth services directly from the optical (WDM) layer. But, providing fault-tolerance at an acceptable level of overhead in these networks has become a critical problem. This is due to the size of the current and future networks and diverse quality of service (QoS) requirements for multimedia and mission critical applications. Several distributed real-time applications require communication services with fault-tolerance apart from guaranteed timeliness at acceptable levels of overhead. Several methods exist in the literature which attempt to guarantee recovery in a timely and resource efficient manner. These methods are centered around a priori reservation of network resources called spare resources along a protection path. This protection path is usually routed from source to destination along a totally link disjoint path from primary path. This paper considers the problem of routing and wavelength assignment (RWA) in wavelength routed WDM optical networks. In particular, we propose an efficient algorithm to select routes and wavelengths to establish dependable connections (D-connections), called segmented protection paths. Our algorithm does not insist on the existence of totally disjoint paths to provide full protection. We present experimental results which suggest that our scheme is attractive enough in terms of average call acceptance ratio, spare wavelength utilization, and number of requests that can be satisfied for a given number of wavelengths assuming that the requests come one at time, and wavelengths are assigned according to fixed ordering. Furthermore, the results suggest that our scheme is practically applicable for medium and large sized networks, which improves number of requests that can be satisfied and helps in providing better QoS guarantees such as bounded failure recovery time and propagation delays without any compromise on the level of fault-tolerance for a given number of wavelengths and fibers. We conduct extensive simulation experiments to evaluate the effectiveness of the proposed scheme on different networks and compare with existing methods.This work was supported by the Department of Science and Technology, New Delhi, India. An earlier version of this paper was presented at Opticomm 2002 conference, July 29-August 2, Boston, USA.     

城域波分网络中的光环路保护分析

介绍了在城域波分网络中应用的四种环形保护倒换方案及其实现方式，并对各种保护倒换方案的特性进行了分析比较。     

A Novel Shared Segment Protection Algorithm for Multicast Sessions in Mesh WDM Networks

This paper investigates the problem of protecting multicast sessions in mesh wavelength‐division multiplexing (WDM) networks against single link failures, for example, a fiber cut in optical networks. First, we study the two characteristics of multicast sessions in mesh WDM networks with sparse light splitter configuration. Traditionally, a multicast tree does not contain any circles, and the first characteristic is that a multicast tree has better performance if it contains some circles. Note that a multicast tree has several branches. If a path is added between the leave nodes on different branches, the segment between them on the multicast tree is protected. Based the two characteristics, the survivable multicast sessions routing problem is formulated into an Integer Linear Programming (ILP). Then, a heuristic algorithm, named the adaptive shared segment protection (ASSP) algorithm, is proposed for multicast sessions. The ASSP algorithm need not previously identify the segments for a multicast tree. The segments are determined during the algorithm process. Comparisons are made between the ASSP and two other reported schemes, link disjoint trees (LDT) and shared disjoint paths (SDP), in terms of blocking probability and resource cost on CERNET and USNET topologies. Simulations show that the ASSP algorithm has better performance than other existing schemes.     

WDM光纤网故障的光路恢复策略

鉴于近年来波分复用(WDM)系统在长途光纤主干网上得到了愈来愈广泛的应用这一情况,针对如何确保网络的故障恢复(restoration)能力,尽可能缩短故障恢复时间,减少故障恢复代价等问题;概述了一些恢复策略,讨论了它们的性能并对其前景进行展望。