支持OTDM的多粒度光交换结构研究

多粒度光交换能减小光交叉连接矩阵的规模,降低光节点的成本,然而现有多粒度光交换结构的最小交换粒度常为波长,该交换粒度太大,会导致核心节点的链路利用率低。在多层MG-OXC基础上,提出了一种新型多粒度交换结构,实现了波带交换和OTDM的结合。该新型MG-OXC结构端口较少,并且可以提高传输速率,同时也因此降低了同等信息量下波长的使用数量,为网络提供了更大的传输容量,能够很好地适应光网络发展的需要。     

智能多粒度光交叉连接节点的设计与实现

提出了一种新型多粒度光交叉连接(MG-OXC)的体系结构,它可以完成光纤、波带、波长的交换,以及不同粒度业务的上下话路.同时介绍了由三个真实多粒度光交叉连接节点与若干虚拟光节点所组成的智能多粒度光网络试验平台的设计与实现.实验平台支持动态的可配置的网络拓扑、自动的邻居发现、受限的波长、波带路由,以及光层快速的保护与恢复.     

知识窗

波带交换波带交换(WBS)是将多个波长组合在一起作为整体进行交换,由于在光交叉连接(OXC)中只使用一个端口,可减少端口数,降低成本。在波长路由网络中,OXC通常是单一粒度,仅在波长级进行交换,每个波长需要一个端口。波带交换网络则使用多粒度OXC(MG-OXC),可对波长、波带以至光纤进行交换和分插。MG-OXC包含波长交叉连接(WXC)、波带交叉连接(BXC)和光纤交叉连接(FXC)。按照交换结构的不同,可有多层结构的MG-OXC和单层结构的MG-OXC,前者的光交换结构包含独立的WXC、BXC和FXC3个部分,后者则具有一个公共的光交换结构。单层…     

支持突发粒度的多粒度光交换研究

现有的多粒度光交换一般只支持光纤、波带和波长这三种粒度的光交换,其最小粒度通常为波长粒度.针对这种缺陷,提出了一种支持突发粒度的多粒度光交换方案,包括支持突发粒度的多粒度光交换的节点结构、路由策略、波带分配算法.这种方案利用了光突发交换的交换粒度小、统计复用特性等优点来提高链路利用率,同时利用多粒度先交换减少光交叉连接(OXC)的端口数和降低OXC的成本.仿真结果表明,所提出的支持突发粒度的多粒度光交换能有效降低包丢失率和端对端时延.     

动态业务条件多颗粒度交换光网络性能研究

本文研究了动态业务条件下基于波带、波长两级交换的多颗粒度光交叉连接节点(MG-OXC)的优化设计,并提出了一种适用于多颗粒度交换光网络(MG-ON)的动态路由、波长分配和业务分组(Traffic Grouping)算法.利用实际网络拓扑对上述MG-ON方案进行了数值仿真实验,比较研究了MG-ON与传统OXC节点构成的波长路由光网络(WRON)的动态业务阻塞率性能,结果表明MG-ON的网络性能可以满足动态业务的要求.     

波带交换中一种新型的多颗粒光交叉连接结构

随着波分复用(WDM)技术的迅速发展和广泛应用,光网络中交叉连接的规模不断增大,网络结构也越来越复杂.为了降低WDM网络中光域传输和交换的成本,人们提出了波带交换(WBS)技术,并对此进行了大量的研究.文章介绍了部分WBS和多颗粒光交叉连接(MG-OXC)的基本概念,并提出了一种新型的MG-OXC结构.     

P比特光交换节点研究

光网络中引入全光交换技术可以无需进行光电光转换和电信号处理,使网络具备透明性,大大降低节点的复杂性和节点成本。多粒度交换节点减小了交换矩阵的规模,降低了交换矩阵的复杂性,是波分复用（WDM）网络节点发展的一个方向。随着正交频分复用（OFDM）技术的引入,带宽可变的节点技术得到了越来越广泛的关注。文章介绍了传统的基于波长的光交叉连接器（OXC）交换结构、多粒度交换结构,以及基于正交频分复用/单载波频分复用（OFDM/SCFDM）的节点交换结构,并通过实验对基于带宽可变的可重构的光分插复用器（ROADM）、OXC节点技术进行了验证。在实验中提出的基于子波带的交换结构中,节点容量达到了P比特量级。     

多粒度光网络波带组合策略的研究

为了有效地传输不同波长粒度的业务,对多粒度光网络波带组合进行了研究。首先介绍了多粒度光网络的模型和光交叉节点,并在此基础上分析了多粒度交叉连接结构的两种结构,单层和多层多粒度交换结构。结合多粒度的交换结构,给出了几种波带组合策略,并对这些策略进行了分析和比较。     

多粒度交换光网络路由和波长分配算法研究

多粒度交换能减少交换节点中的交换矩阵规模及复用器和解复用器的数目，从而降低其成本，但是使得RWA问题变得较多纤光网更加复杂．本文提出了一种称为多维空间图(MDS-G)的模型，该模型能够全面准确地描述多粒度光网络中的资源状态，基于该模型的算法能够将多粒度交换光网络的路由和波长分配两个通常分开解决的子问题一步解决，从而得到较现有的方法更好的性能，仿真也证实了这一点．     

多粒度光交换技术在ASON中的应用

提出了适应这一增长趋势的多粒度光交换技术,对多粒度光交换系统节点在网络中做了相应部署,分析了多粒度交换网络环境下的流量梳理,最后进行多粒度故障检测,利用GMPLS协议针对多粒度LSP实现故障通知,完成相应的保护/恢复过程.     

一种改进的多粒度光交叉连接结构

多粒度光交叉连接能够提供光纤、波带和波长三种粒度的光交换,这一机制能有效提高交换性能,同时通过交换端口数的减少来降低光交换的成本。在这种交换结构中,需要在下层进行交换的信号需要首先经过上层的交换,或者所有信号都需要被不加区分地解复用出来进行交换,这造成了信号的过大损耗和失真,以及交换端口的浪费。我们在介绍了现有的研究以后,提出一种改进后的多粒度光交叉连接结构。通过仿真分析,可以看出这一新结构能够比其他结构更灵活地配置交换端口,同时能够避免不必要的信号损耗和失真,降低交换成本。     

Performance analysis and dimensioning of multi-granular optical networks

Recent years have demonstrated the limited scalability of electronic switching to realize transport networks. In response, all-optical switching has been identified as a candidate solution to enable high-capacity networking in the future. One of the fundamental challenges is to efficiently support a wide range of traffic patterns, and thus emerges the need for equipment that is both practical and economical to construct and deploy. We have previously proposed the use of multi-granular optical cross-connects (MG-OXC), which support switching on both the wavelength and sub-wavelength level. To this end, the MG-OXCs are equipped with cheap, highly scalable slow switching fabrics, as well as a small number of expensive fast switching ports. The goal of this work is two-fold: first to demonstrate that a small number of fast switching ports suffices to support a wide range of traffic requirements, and second that multi-granular optical switching can offer cost-benefits on a network-wide scale. The first objective is studied through simulation analysis of a single switching node, and results indicate that a limited number of fast switching ports can significantly improve burst blocking performance over slow only switches. Furthermore, under certain circumstances, the MG-OXC can even approach the performance of a fast only switch design. Secondly, we introduce an Integer Linear Programming model for the total network installation cost, and our evaluation indicates that multi-granular optical switching can be a cost-effective solution on the network level, in comparison to slow only or fast only approaches. Furthermore, we can achieve reduced costs of individual OXC nodes, which allows us to minimize scalability problems corresponding to emerging fast switching fabrics.     

Waveband Switching for Dynamic Traffic Demands in Multigranular Optical Networks

Waveband switching (WBS) in conjunction with multigranular optical cross-connect (MG-OXC) architectures can reduce the cost and complexity of OXCs. In this paper, we study the performance of different MG-OXC architectures under dynamic traffic. In the case with online incremental traffic, we compare two MG-OXC architectures in terms of the blocking probability of new lightpath requests and study the impact of port counts and traffic loads. We develop an online integer linear programming model (On-ILP), which minimizes the number of used ports and the request blocking probability, given a fixed number of wavelengths and MG-OXC architecture. The On-ILP optimizes the routing of new lightpaths so as to maximize lightpath grouping and reduce the port count given that existing traffic cannot be rearranged. We also propose a new efficient heuristic algorithm, called maximum overlap ratio (MOR) to satisfy incremental traffic and compare it with the On-ILP, first-fit, and random-fit algorithms. Our results and analysis indicate that using WBS with MG-OXCs can reduce the size (and, hence, the cost) of switching fabrics compared to using ordinary OXCs. Based on the results and observations in the incremental traffic case, we further study the performance of a particular MG-OXC architecture under fully dynamic or fluctuating traffic. Our simulations show that the proposed heuristic algorithm waveband assignment with path graph, which groups wavelengths to bands and uses wavelength converters efficiently under fluctuating traffic, significantly outperforms other heuristic algorithms.     

光网络中的波带交换技术

波分复用光网络已成为广域骨干网最可行的体系解决方案.波带交换(WBS)因其能减小光交叉连接器的端口数、控制复杂性和连接费用等,引起了广泛的关注.文章指出了WBS和传统波长路由的不同之处,对WBS的两种多粒度光交叉连接器结构进行了分析.文中还提出了基于WBS的各种方案和光路成组策略,讨论了WBS网络中的波带转换和故障恢复问题.     

An OXC Architecture Suitable for High Density WDM Wavelength Routed Networks

A novel optical crossconnect architecture, capable for tens of terabit throughput and allowing the integration of wavelength and space switching, is presented for both WP and VWP networks. The architecture offers significant advantages in terms of crosstalk performance and node complexity. In the architecture, there are no crossovers and crosspoints. Therefore, the signal-to-crosstalk ratio per wavelength channel can be very high since each channel is processed independently from the others. This will also allow to introduce other all-optical techniques like adding/dropping of OTDM channels as well as optical regeneration. The proposed architecture is wavelength and link modular and particularly suitable for crossconnects with a very large number of wavelength channels. Performance aspects of a single as well as of a cascade of crossconnects have been simulated using a simulation tool.     

A waveband switching architecture and algorithm for dynamic traffic

The proposed multi-granular optical cross-connect (MG-OXC) architecture and heuristic algorithm significantly reduce the number of used ports and hence the cost of an existing network, and also help in reducing the blocking probability of dynamic connection requests.     

一种WDM全光IP路由器的结构设计与分析

为突破“电子瓶颈”的限制，Internet向波分复用(WDM)全光网络演进已是必然的趋势．在光Internet中，光路由器是最为关键的设备之一．文章提出了一种光路由器实现的结构，该结构是以光突发标记交抉为核心，不需经过多次的O／E／O转换，即可实现边缘到边缘的全光域数据传输和处理．文章还对该结构具体实现中的关键问题：光突发数据的格式和装配、报头的提取和识别、路由及光标记交换和拥塞等进行了详细的分析研究，提出了可行的解决办法．最后设计了一个实验系统，并给出了相应的实验结果．     

一种新型光交换技术:光码标签突发包交换

一种新型光交换技术-光码标签突发包交换技术。该技术是光突发包交换与光码标签交换的结合体，具有两者的共同优点，是一种性能优良的光交换技术。本文首先介绍了该技术的原理，然后给出了网络节点功能结构的设计，最后讨论了该技术的性能。