波长路由网络在城域网设计中的研究

波长路由网络(Wavelength Routing Network,WRN)是在WDM系统中,以光波长路由为基础,引入光波长交叉器和光分插复用器而建立的具有高度灵活性和生存性的光网络,是未来通信网络的主要发展方向之一,同时城域网是WRN网络的一个非常重要的应用.从用户的现有和未来的需求出发,提出了在城域网设计时必须注意的一些新的问题,指出WRN是城域网设计的一种合理的选择,通过对网络物理和逻辑拓扑结构的仔细研究,提出此次设计的最佳网络拓扑,同时选用一种新的路由选择和波长分配(WRA)技术,设计一个符合实际并对未来具有一定指导意义的城域网络.     

基于强化学习的资源最优化逻辑拓扑映射算法

光传送网(OTN)中光节点波长复用/解复用器以及光开关矩阵可实现任意结构的逻辑拓扑在物理拓扑上的映射,不合理的映射方案将消耗额外端口资源。提出一种基于强化学习(RL)的逻辑拓扑最优化映射算法,将预处理后的拓扑状态和逻辑通道数据用于训练RL模型,以对逻辑通道进行全局波长资源分配,最终达到资源最优化目的。仿真结果表明:所提算法有效减小逻辑拓扑映射过程中的资源消耗,从而最小化网络部署成本。     

与网络同步发展的光分插复用器

光分插复用器(OADM)的出现直接与密集波分复用器(DWDM)的使用和快速进展有关。早些时候,沿光纤传输主干线各区间使用了少量的光分插器件,而且这些器件只用在单波长传输光纤上,不涉及光学多路传输,因此也没有为此生产专门产品。光分插复用     

光交叉连接/光分插复用器的应用前景

文章通过比较波分复用、光时分复用和光码分多址复用技术,得出波分复用是当前光网络发展主流的结论。重点分析了在波分复用系统中,交叉连接/光分插复用器在骨干网、城域网和自动交换光网络中的应用,指出在下一代网络中,光交叉连接/光分插复用器将会有很好的发展前景。     

大容量全光交换及其市场预测

对 DWDM光网络中的大容量全光交换机进行了分析 ,对未来五年内相关市场进行了预测。对目前已开始进入商业化使用的全光交换机之一——光分插复用器 (OADM)的应用予以了举例分析     

基于OXC构建灵活可靠的全光城域网研究

【目的】光交叉连接(OXC)技术解决了光传送网(OTN)系统电交叉能力不足的部分问题以及固定光分插复用器(FOADM)/可重构光分插复用器(ROADM)板卡间复杂的手工连纤和调度不灵活问题。文章研究了如何在OTN城域网(MAN)中引入OXC技术提升网络的灵活性,并解决了OXC过于集中带来的一些网络安全问题。【方法】文章介绍了OXC技术的优势,综述了现网OTN系统的架构以及承载业务的安全配置模式。通过建立各种OXC应用模型,比较分析了各类模型的灵活性和安全性等。【结果】在现网中进行测试,并总结各类模型评价指标,找出了最优的应用方案。【结论】文章创新地提出了一种基于OXC的全光MAN建设模型以促进OXC技术的应用发展,加强算力间的调度能力,形成算网一体化新型基础设施,为用户提供了低时延、高可靠、端到端的算力连接。     

新结构光波分复用器性能分析

分析了光波分复用器的工作原理 ,光学特性 ,提出了一种新结构光波分复用器 ,用温度循环的方法测试了新结构光波分复用器的温度特性 ,讨论了新结构光波分复用器的工艺改进方法 ,实验表明 :新结构光波分复用器比传统结构稳定 ,性能可靠     

双路上／下载光分插复用器

提出一种新颖的双路上/下载光分插复用器结构设计方案,可实现高速的密集波分复用(DWDM)全光通信网中两路不同波长信号同时上/下话路功能.该上/下载光分插复用器由偏振分束组合棱镜、λ/4波片、直角棱镜、全反镜和偏振光调制器组成.当光信号进入上/下载光分插复用器后,各信号光首先被分解为P-偏振光分量和S-偏振光分量,通过控制偏振光调制器的状态,改变输入到上/下载光分插复用器中各信号光P-偏振光分量和S-偏振光分量的转换状态,并在主光路输出端口和下载光路输出端口将各信号光的P-、S-偏振光分量重新合并后,实现与偏振无关的光信号输出.该上/下载光分插复用器结构可上/下载任意一路波长信号或同时上/下载两路波长信号,灵活性强,具有光学元件少、结构紧凑、易于光学装配和调试等特点.(PD4)     

全光网的关键器件——光交叉连接器与光分插复用器

全光网（AON,all-optical network）以波长路由光交换技术和波分复用传输技术（WDM）为基础,它的网络节点由光分插复用器和光交叉连接器构成,能在光域上实现高速信息流的传输、交换、路由和故障恢复等功能。光交叉连接器（OXC）与光分插复用器（OADM）是全光网中最重要的网络器件,是真正实现全光网关键性功能的必要前提,也是目前国内外光通信器件厂商研究和开发的热点。本文结合全光网的发展,介绍了光交叉连接器（OXC）与光分插复用器（OADM）的基本原理、性能指标,对不同的节点结构进行了比较与讨论,并介绍与比较了目前国内外厂商的主要产品。     

光互联网的关键器件

光互联网是指IP over WDM网，是未来网络的发展方向。本着重介绍了光互联网中的关键器件及其发展现状，包括光放大器、光转发器、光分插复用器、光交叉连接器、光开关、交换路由器。     

自动交换光网络的总体结构与标准框架

本文首先指出自动交换光网络的出现是传送网概念的重大历史性突破，然后阐述了这种新传送体制的总体逻辑结构、控制平面、信令要求、网管能力和要求、网络性能要求和特点等总体问题的考虑，最后简要介绍了ITU－T关于自动变换光网络的标准化框架。     

Physical and logical validation of a network based on all-opticalpacket switching systems

The large growth of telecommunication traffic demand generated by multiple new applications and expected to last at least for the next decade will force telecom operators to consider offering more flexible transport services. All-optical packet switching is a powerful technique to provide this flexibility and to support in a cost-efficient way a wide range of bandwidth consuming applications. After a very brief introduction about the packet-switched network architecture studied in the framework of the ACTS KEOPS project, we describe the structure of the packet-switching node we have defined. We then move into physical and logical analysis of the network including more than 40 network sections based on 160 Gb/s throughput optical packet switching nodes could operate error free. In addition, logical simulations have proved that such networks could provide a quality of service (packet loss rate and packet transfer delay per node) compatible with a large variety of service classes. Both results validate the feasibility of the network concept and pace the way toward a flexible network based on all-optical switching techniques     

Light-Frames-pragmatic framework for optical packet transport: extending ethernet LANs to optical networks

In this paper, a network architecture for the realization of a pragmatic framework for optical packet transport called the light-frame (LF) framework is proposed. The architecture enables the transport of packets over optical media. While doing so, it relaxes the need for address recognition as well as high-speed switching, which are the two key hindering factors that have prevented contemporary optical packet transport solutions from being deployed. Using this framework, a tradeoff was achieved between cost (maturity in deployment) and performance (network efficiency). The idea is to create a logical topology that enables N/sup 2/ connectivity, yielding sublambda granularity, and thereby facilitating packet transport. Methods for topology discovery and conflict resolution are proposed. This paper also discusses stochastic as well as optimization analysis of the framework. The fiber resource requirements of this network solution are compared to a leading access networking solution-passive optical networks (PONs)-and cost benefits are shown. The LF concept due to its finely granular application, despite a present technological bottleneck, presents a good implementation case that allows it to be pushed for next-generation optical packet transport, especially in the access area.     

A passive protected self-healing mesh network architecture andapplications

The self-healing mesh network architecture using digital cross-connect systems (DCSs) is a crucial part of an integrated network restoration system. The conventional DCS self-healing networks using logical channel protection may require a large amount of spare capacity for network components (such as DCSs) and may not restore services fast enough (e.g., within 2 s). The authors propose a passive protected DCS self-healing network (PPDSHN) architecture using a passive protection cross-connect network for network protection. For the PPDSHN architecture, network restoration is performed in the optical domain and is controlled by electronic working DCS systems. Some case studies have suggested that the proposed PPDSHN architecture may restore services within a two-second objective with less equipment cost than the conventional DCS self-healing network architecture in high-demand metropolitan areas for local exchange carrier networks. The proposed PPDSHN architecture may apply to not only the centralized and distributed control DCS network architectures, but also asynchronous, SONET and ATM DCS networks. Transparency of line rates and transmission formats makes the PPDSHN network even more attractive when network evolution is a key concern of network planning     

Architectural issues for robust optical access

Optical access networks are beginning to be deployed at the edge of the optical backbone network to support access by the high-end users that drive increased bandwidth demands. This development in the applications of optical networking poses new challenges in the areas of medium access, topology design, and network management. In particular, since optical access networks carry high volumes of critical traffic, the level of reliability and robustness traditionally reserved for core applications must be implemented in access networks. We survey access network architectures and outline the issues associated with providing reliability for these architectures. In the area of architecture design, two main approaches emerge. The first considers dedicated optical access networks, such as stars or folded buses, to implement optical access LANs and MANs. The second is overlay architectures, which use existing network infrastructure. Overlay architectures seek to replicate, on a smaller scale, logical topologies akin to those of backbone networks, or may instead create architectures specifically designed for access purposes     

面向多网络体制并存的开放式可重构路由器体系结构设计与实践

针对现有网络设备在支持可重构和多网络体制并存方面存在的不足,提出了一种面向多网络体制并存的开放式可重构路由器体系结构。通过在控制、转发和交换体系结构设计上,采用虚拟化和硬件分区配置技术,能够对控制、转发和交换进行资源划分与隔离,将路由器中同一个硬件资源虚拟化为多个功能上独立、资源上隔绝的逻辑路由器实例,提高了核心路由器设备的开放性和安全性。     

Signaling and Control Procedures Using Generalized MPLS Protocol for IP over an Optical Network

This paper reviews the existing research activities on signaling and control procedures for IP over optical networks. We focus on the IP‐centric signaling and control architecture based on the generalized multi‐protocol label switching (GMPLS) protocol and analyze various scenarios and technical issues for deploying the IP over an optical network. We analyze the signaling and operations and administration and maintenance requirements for integrating an IP network and an optical network in order to cope with the high bandwidth and poor resource granularity of the optical network, including the optical cross‐connect system. On the basis of network architecture and a reference configuration model, we investigate the GMPLS‐based control architecture and interconnection model appropriate for controlling IP bandwidth and optical lambda resources. The signaling and control procedure based on GMPLS on optical user‐network interface and network‐network interface are comparatively investigated to provide the optical lightpath. We also study protection and restoration procedures to protect link failure when it applies to GMPLS signaling.     

支持协作多点技术的网络架构的研究

协作多点(coordinated multi-point,CoMP)技术因能有效改善小区边缘用户性能,提高系统吞吐量,引起了业界的广泛关注和研究。CoMP的研究要基于一定的网络架构,目前已有的中心式和分布式网络架构存在回程容量大、CoMP时延高、复杂度高等问题。本文提出了改进型分布式网络架构,在传统分布式网络架构的基础上增加了集中控制的逻辑实体,能有效简化CoMP流程,减少CoMP时延以及实现复杂度。     

Improved linear crosstalk tolerance in an un-amplified ring PON

There is increased interest in ring-based passive optical network (PON) architectures due to their local area network (LAN) capability among end users and inherent protection and restoration schemes. The ring architecture includes optical filters and switches with non-ideal channel isolation, leading to the generation of linear crosstalk, which can significantly degrade the system performance if it is not sufficiently suppressed. We use simulation to analyze the effects of linear crosstalk in an un-amplified TDM optical ring and show how we can improve the tolerance of the crosstalk in our architecture that employs optimized tap split ratios as a means of increasing the number of ONUs served. Our approach is based on simulation of the entire network using a combination of wavelength-domain and time-domain techniques. Typically, PON networks use two or three wavelengths that are separated by more than 50 nm to maintain the cost of components low and as such, it is logical that any crosstalk will be negligible. However, the subpar performance of such components motivated our study into the impact of crosstalk. We show that the tap ratio optimization which increases the number ONUs that can be served in the ring can also exacerbate the effects of linear interchannel crosstalk at the ONU’s downstream signal receivers. We also show that surplus power at the last ONU can be utilized to counter this degraded crosstalk performance by careful tap ratio selection, thereby improving the overall tolerance to linear crosstalk in the system.