Large modular expandable optical switching matrices

Large optical switching matrices can be assembled incrementally from identical modules by means of a rearrangement of the Clos architecture that we have labeled SKOL. The design retains the strict-sense nonblocking properties of the Clos design, identical units provide economies of manufacture, and there are also cost advantages associated with the incremental expandability. SKOL modules can be constructed in ways that do not map back to the Clos original. In this form, SKOL is a new multistage switching architecture that is well adapted for construction with integrated optical technologies. We anticipate that the SKOL design can provide the very large, expandable optical switching matrices now demanded for optical networks     

Expanding the switching capabilities of optical crossconnects

Optical-switching technologies exhibit many characteristics that the electronic-switching technologies do not have. One such characteristic lies in switching states. An electronic crosspoint, having open and close as its two switching states, only allows one traversing signal. But an optical-switching crosspoint, such as a directional coupler or a microelectromechanical systems mirror, usually allows two traversing signals. This paper studies how to exploit the characteristic to expand the switching capabilities of an optical switch, and shows new ways of building more crosspoint-efficient rearrangeable nonblocking switches. We show that an optical 2n/spl times/2n rearrangeable nonblocking switch can be created by cascading only two n/spl times/n optical crossbars.     

Optical switching technology comparison: optical MEMS vs. other technologies

Optical switching technologies are very crucial to future mobile broadband all-optical IP networks. Many different optical switching technologies are currently available or under development. The main purpose of the article is to conduct performance comparisons on optical switching technologies in terms of basic performance, network requirements, and system requirements based on a literature survey. The technologies include switching based on optical microelectromechanical systems (MEMS), thermal optical switching, electro-optic switching, and acousto-optic switching technologies. Each optical switching technology has unique performance characteristics specific to the utilized optical phenomena. It might be crucial to integrate some technologies together to achieve a better solution for optical switching. Optical switching is a very hot topic attracting much research effort. Optical MEMS-based switching technology might be one of the most promising approaches at present. Many new optical switching technologies might be created in the near future. Through the impact of nanotechnology, some innovative approaches to optical switching might emerge.     

基于GMPLS的光突发交换网络的研究

文章基于通用多协议标签交换(GMPLS)的光突发交换(OBS)网络的体系结构,研究了如何将GMPLS引入OBS,并使两者能够高效协调地工作.重点讨论了GMPLS与OBS技术相结合的网络(GMPLS-based OBS)的各种关键技术和解决机制.特别在处理突发数据包(BDP)冲突竞争机制上提出了新的方法.最后,指出了GMPLS-based OBS进一步研究的方向.     

核心通信网的光分组交换

文章首先简单说明了新一代通信网需要使用分级交换的由来。接着详细叙述了光分组交换在未来光通信网的应用，包括节点结构、分组格式、输入、输出接口和一些特别重要的技术，如再生、同步、信头处理、缓冲、空间交换和波长转换等。     

基于GMPLS的光突发交换体系及其关键技术

文章给出了基于通用多协议标签交换(GMPLS)的光突发交换(OBS)对等体系(GLOBS)的功能结构和分层视图.在此范畴内,针对标签空间减小和流量工程两方面,结合国内外最新的研究动态,比较了各种已有技术的优缺点,并提出了适合于GLOBS体系的可能的解决方案以及今后工作的重要技术问题.     

Labeled optical burst switching for IP-over-WDM integration

The rapid pace of development in both Internet applications and emerging optical technologies is bringing about fundamental changes in networking philosophies. Key trends are the emergence of dynamic wavelength provisioning and a corresponding reduction in wavelength provisioning timescales. As this transition continues, the current use of the wavelength-routing paradigm for carrying bursty Internet traffic will likely suffer from various shortcomings associated with circuit-switched networks. Meanwhile, optical packet switching technology is still facing significant cost and technological hurdles. Optical burst switching, or OBS, which represents a balance between circuit and packet switching, has opened up some exciting new dimensions in optical networking. This article describes the OBS paradigm, and also proposes the use of labeled OBS, or LOBS, as a natural control and provisioning solution under the ubiquitous IP multiprotocol label switching framework     

Approaches to optical Internet packet switching

Wavelength-division multiplexing is currently being deployed in telecommunications networks in order to satisfy the increased demand for capacity brought about by the explosion in Internet use. The most widely accepted network evolution prediction is via an extension of these initial predominantly point-to-point deployments, with limited system functionalities, into highly interconnected networks supporting circuit-switched paths. While current applications of WDM focus on relatively static usage of individual wavelength channels, optical switching technologies enable fast dynamic allocation of WDM channels. The challenge involves combining the advantages of these relatively coarse-grained WDM techniques with emerging optical switching capabilities to yield a high-throughput optical platform directly underpinning next-generation networks. One alternative longer-term strategy for network evolution employs optical packet switching, providing greater flexibility, functionality, and granularity. This article reviews progress on the definition of optical packet switching and routing networks capable of providing end-to-end optical paths and/or connectionless transport. To date the approaches proposed predominantly use fixed-duration optical packets with lower-bit-rate headers to facilitate processing at the network-node interfaces. Thus, the major advances toward the goal of developing an extensive optical packet-switched layer employing fixed-length packets are summarized, but initial concepts on the support of variable-length IP-like optical packets are also introduced. Particular strategies implementing the crucial optical buffering function at the switching nodes are described, motivated by the network functionalities required within the optical packet layer     

Advanced optical interconnection technology in switching equipment

Demands for increased interconnection density and higher bandwidth, coupled with stringent cost constraints of advanced wide bandwidth telecommunication switching equipment, are exhausting conventional electrical interconnection capabilities. The requirement for greater interconnection capabilities, spawned in part by the advances in integrated circuit technologies and the need for enhanced digital services, dictate that technology advancement must occur in traditional electronic packaging and/or interconnection techniques. The resolution of these technological needs is paramount for the successful competitive introduction of these systems. Presently, a “bottle-neck” occurs at the board-to-board level of the interconnection hierarchy. Therefore, an opportunity exists for the development of new optical interconnection techniques which can be incorporated into system designs beginning at this interconnection level and beyond. The strategic insertion of optical interconnection technology into these electronic processing systems not only meets projected performance requirements, but potentially offers them at a competitive cost. This paper describes some of the new optical strategies switching equipment designers are incorporating into today's products. These strategies range from optical data links to an implementation of a flexible optical backplane called OptiFlex     

光突发交换网络中冲突性能分析

光突发交换(OBS)被认为是下一代光纤通信网络的典型代表.文章研究了在OBS核心节点中突发数据包由于竞争相同的输出数据信道而发生的冲突问题,对冲突时的网络性能进行了分析,得出了在不同网络负荷情况下的包丢失率情况,研究结果对OBS网络的实际建设有一定的理论指导意义.     

Optical signal processing for optical packet switching networks

Optical packet switching promises to bring the flexibility and efficiency of the Internet to transparent optical networking with bit rates extending beyond that currently available with electronic router technologies. New optical signal processing techniques have been demonstrated that enable routing at bit rates from 10 Gb/s to beyond 40 Gb/s. We review these signal processing techniques and how all-optical-wavelength converter technology can be used to implement packet switching functions. Specific approaches that utilize-ultra-fast all-optical nonlinear fiber wavelength converters and monolithically integrated optical wavelength converters are discussed and research results presented.     

光突发交换网络中新型减小竞争冲突方案

光突发交换是下一代光网络中的有效核心交换技术之一,在光突发交换网络中数据突发的调度是影响交换性能的重要因素,如何有效地对数据突发进行合理调度,以减小丢包率正是关键问题所在.采用在波长域业务整形与边缘节点延迟调度相结合的方法对数据突发进行调度,与LAUC-VF算法进行仿真对比分析,该方法能有效地降低突发包丢失率.     

The perspective of optical packet switching in IP dominant backboneand metropolitan networks

This article analyses the rationale and technical solutions for the use of optical packet switching techniques for both backbone and metropolitan applications. It also provides information on state-of-the-art technologies available for medium-term product development     

光突发交换中的突发包组装技术研究

光突发交换是近几年出现的一种很有前途的光交换技术，比电路交换灵活，带宽利用率高，又比光分组交换易于实现，突发包的组装是光突发交换的关键技术，在很大程度上影响到光突发交换网络的性能。文中介绍了光突发包的格式，描述了交换网络中突发包组装所需的层次结构和功能结构，并给出了一种典型的生成算法。最后，对选择突发包组装时间应考虑的各种因素进行了系统的分析。     

High-capacity multiservice optical label switching for the next-generation Internet

This article presents an optical label switching technology geared toward the next-generation Internet, and highlights its promising potential to accommodate packet, burst, and circuit traffic in a unified optical layer. In particular, we provide detailed discussions on an architecture design for a high capacity optical label switching router by considering enabling optical technologies. In pursuit of an effective contention resolution scheme, we investigate an end-to-end solution by incorporating a traffic shaping function at the network edge with wavelength, time, and space dimensions contention resolution in the core network. Experimental results indicate that this scheme is capable of achieving very low packet loss rates. Furthermore, due to its natural compatibility with GMPLS architecture, optical label switching has great potential for a seamless upgrade of today's optical networks toward the next generation Internet.     

OBS网络数据信道调度算法性能比较与分析

光突发交换(0BS)网络中的数据信道调度算法是提高0BS网络性能的关键技术之一.首先介绍和分析了LAUC、LAUC-VF和0DBR基本原理和性能,结合国内外最新研究成果,介绍了四种支持QoS的数据信道调度算法,最后对其应用场合做出总结.     

Dual-fiber optical burst switching network: A novel architecture for metropolitan area networks

Fiber optic rings are widely deployed in metropolitan area networks (MAN). These rings currently employ architectures and protocols that are neither optimized for nor scalable to the network demand. Therefore, emerging technologies are being pushed to replace the traditional architectures. Among these technologies, optical burst switching (OBS) is an effective and promising technology. In this study, a novel architecture, dual-fiber OBS (DOBS), is proposed. This architecture has similar functions to those of fiber delay lines, partial wavelength conversion and deflection routing. A theoretical model is developed to evaluate the performance of DOBS, which is compared with single-fiber and simple two-fiber schemes by introducing them into ring and mesh MAN in simulations. The results reveal that DOBS can exponentially reduce the burst dropping probability. Moreover, since DOBS can be implement using commercially available devices and dark fibers, it is commercially viable in metro networks.     

Edge node buffer usage in optical burst switching networks

Optical Burst Switching (OBS) combines the benefits of Optical Packet Switching and Optical Circuit Switching technologies to provide an efficient, yet cost effective, method for data transmission in an all-optical, bufferless, core network. While most studies on OBS has concentrated on the core OBS network, we contribute new studies for the buffer requirement of an OBS edge node. The buffer usage for OBS systems only arises in the edge nodes since they contain an array of assemblers which combines electronic data with a common destination into an OBS burst stream for transmission in an all-optical bufferless core network. Specifically, we present two analytical results for buffer usage in an OBS edge node: one for Poisson traffic and the other for self-similar traffic input. The results show that the aggregated traffic from many assemblers inherits the characteristics of the source input traffic. This means that the output traffic approaches Poisson if the input traffic is Poisson, and the output traffic remains self-similar if the input is self-similar. These results lead to the following important design issues when dimensioning buffer requirements in an OBS edge node: if the traffic input is Poisson, the M/G/m model is the model to use for obtaining the upper bound on buffer usage in an OBS edge node; and for the case of self-similar traffic, Brichet’s method can be used to provide the upper and lower bound.     

OBSns:一种OBS通用仿真平台的设计

光突发交换(OBS)是当前全光交换网络技术的研究热点之一,而仿真是OBS研究的一种重要手段。为了给研究者提供方便,同时实现各种研究结果的对比,开发了一种通用的OBS网络仿真平台--OBSns。OBSns以网络仿真工具NS-2为基础,对突发数据传输采用虚拟化的方法,实现了OBS网络的关键元素如突发组装、突发控制分组生成和传输、突发调度等等。同时OBSns是开放的,其各个元素都可以替换,从而为新算法和协议的研究提供了便利。     

光突发交换环网中多接收机情况下的性能分析

因特网应用技术和光通信技术的飞速发展使现在网络的现状发生了翻天覆地的变化.最近,光突发交换技术的出现掀开了光通信技术的新篇章,它是光电路交换和光分组交换的折中方案.研究了光突发交换环网的性能,提出了为每个节点配备多个接收机的方法来降低竞争的发生,仿真结果表明,只要为每个节点配备少量的接收机就能达到很好的性能,不必将每个节点的接收机满配,从而可以降低硬件投入.