高生存性光接入网结构分析

从网络结构方面对光接入网生存性进行了研究,在对各种网络接入结构生存性初期分析的基础上,利用共享链路组(SRLG)的概念定量分析了各种接入拓扑结构的网络生存性,表明了星型环接入网结构在网络生存性方面较现行各种网络结构的优越性;提出了改进的网络生存率计算算法,利用分层计算和等价归并结合的方式,减少了计算量,提高了计算效率,尤其在总故障数目多的情况下可以大大减少计算时间,快速计算网络生存率.     

光接入网的拓扑结构描述研究

当前光接入网的连接对象和覆盖场景不断拓展,光接入网的拓扑结构需要满足网络发展的新需求。本文研究探讨了光接入网的拓扑结构描述方式,提出了从光纤层面和光缆层面两个角度对光接入网的拓扑结构描述。在光纤层面,对现行国际标准规定的光接入网拓扑结构进行了调整;在光缆层面,对光接入网的主要拓扑单元进行了梳理归纳。两者相结合,可衔接光接入网承载的光系统和物理设施部署,更有效地对光接入网拓扑结构进行描述。     

光接入网与光器件

阐述了接入网在电信网中的重要地位、光接入网的拓扑结构和无源光网络的关键技术，对光接入网所使用的光器件也作了全面的介绍。     

EPON在应急通信中的网络拓扑结构研究

基于EPON技术的应急通信光接入是适应各种突发事件的一种新型宽带接入方式,文章通过探讨网络连通性,对接入网的可靠性进行了分析;基于传统拓扑结构,分别提出了混合型和改进混合型应急通信接入网的网络结构.     

无线光CDMA在接入网中的优势和挑战

介绍了无线光CDMA接入网的基本原理,分析了适合无线光CDMA接入网的拓扑结构,详细阐述了将无线光CDMA技术应用到接入网中所具有的优势和面临的挑战,最后展望了无线光CDMA技术接入网中的应用前景。     

波长动态调度TWDM光接入网中的生存性保证

摘要：如何在波长动态调度的时分波分复用光接入网中正确定位故障并进行保护倒换,以保证强生存性是需要解决的关键技术问题。为解决上述问题,提出了一种具有成本效益的利用控制信道定位故障的和基于动态波长调度的生存性保证方案,并对方案进行了生存性和成本的综合定量分析。分析计算表明,所提方案最优时只需付出1%的生存性保证成本,就能带来54%的生存性提高,并且保护倒换能控制在50 ms内完成。     

用户光接入网建设实施浅探

阐述了用户光接入网的拓扑结构、光缆的配线方式、终端设备的设置原则等建设问题,以及用户光接入网对未来应用技术、业务开发和网络规划的影响。     

光无线混合宽带接入网的现状和发展

简要介绍了光无线混合宽带接入网(HOWBAN)的网络结构和主要优点,综述了其网络部署、路由机制和生存性问题的研究进展,并指出该领域存在的问题和今后的发展趋势.     

一种基于OCDMA技术的环型光接入方案

分析了时分多址无源光网络(TDMA-PON)技术缺陷,提出了采用光码分多址(OCDMA)技术构建新型无源光接入系统的方案.通过选择网络节点结构构建环型光码分多址无源光网络(OCDMA-PON),并且结合仿真结果分析了网络传输性能.分析表明:将光码分多址技术的固有安全性和环型网络的拓扑安全性有机结合能有效解决传统光接入网存在的可靠性问题.     

弹性分组环垂直拓扑结构高生存性的定量分析

提出了弹性分组环环网垂直拓扑结构,使该结构具有较高的网络生存性.对该网络拓扑结构的高生存性进行了一定的数学定量分析,运用软件进行建模仿真,仿真结果验证了该垂直拓扑结构具有较高的生存性,减小了网络链路发生灾难性失效的概率.     

A Study of Path Protection in Large-Scale Optical Networks

We consider the problem of designing a network of optical cross-connects (OXCs) which provides end-to-end lightpath services to large numbers of client nodes, under the requirement that the network will survive any single-link failure. Our main objective is to quantify the additional resource requirements of implementing path protection schemes over a network with no survivability properties. To this end, we present heuristic routing and wavelength assignment algorithms for dedicated path protection and two variants of shared path protection, and integrate them into the physical and logical topology design framework we developed in an earlier study. We apply our heuristics to networks with up to 1000 client nodes, with a number of lightpaths that is an order of magnitude greater than the number of clients, and for a wide range of values for system parameters such as the number of wavelengths per fiber, the number of optical transceivers per client node, and the number of ports per OXC. Our results provide insight into the relative resource requirements of dedicated and shared path protection schemes. We also find that, using shared path protection schemes, it is possible to build cost-effective survivable networks that provide rich connectivity among client nodes with only a modest additional amount of resources over a network with no survivability properties.     

Contribution to future metropolitan access network planning considering link failures in photonic switched networks

Photonic switching for traffic optimization in Metropolitan Access Optical Networks using technologies of optical packet/burst switching (OPS/OBS) seems to be a future-proof solution considering high capacity and the highly variable traffic in these networks. Looking for this future, we propose a study based on the analyze of survivability of traffic unconsidering protection mechanism but considering mesh and ring efficient topologies with node architecture to OPS. The results are obtained through computer modeling and simulation. The main parameters analyzed are as follows: capacity, average number of hops, packet loss fraction, and link utilization for each topology. These parameters are adopted to evaluate the performance of each topology considering failures. Minimum electronic buffering is included at node ingress (client side) to avoid packet loss in the access to the optical layer: high throughput and low latency. It is also observed that optical buffering is not necessary for adequate network performance.     

光网络选路和波长分配研究

文章在叙述了光网络中选路和波长分配(RWA)要解决的基本问题后,对有关方面的近年研究作了综述,主要包括:虚拓扑重构、业务量疏导的RWA、多播RWA、抗毁网络的RWA.抗毁问题涉及WDM网络的抗毁选路、区分可靠性、网状网的快速恢复、多故障下的抗毁.     

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     

广义全保护的动态ASON规划研究

传送网络正由传统光网络向智能光网络演进,文章提出了"广义全保护的动态自动交换光网络(ASON)"的概念,该网络可满足无阻塞的动态业务提供和对于任何网络失效的完全可生存性.文章还讨论了满足如上要求的数学算法模型,阐述了该网络的容量规划问题.     

Path diversification for future internet end-to-end resilience and survivability

Path Diversification is a new mechanism that can be used to select multiple paths between a given ingress and egress node pair using a quantified diversity measure to achieve maximum flow reliability. The path diversification mechanism is targeted at the end-to-end layer, but can be applied at any level for which a path discovery service is available. Path diversification also takes into account service requirements for low-latency or maximal reliability in selecting appropriate paths. Using this mechanism will allow future internetworking architectures to exploit naturally rich physical topologies to a far greater extent than is possible with shortest-path routing or equal-cost load balancing. We describe the path diversity metric and its application at various aggregation levels, and apply the path diversification process to 13 real-world network graphs as well as 4 synthetic topologies to asses the gain in flow reliability. Based on the analysis of flow reliability across a range of networks, we then extend our path diversity metric to create a composite compensated total graph diversity metric that is representative of a particular topology’s survivability with respect to distributed simultaneous link and node failures. We tune the accuracy of this metric having simulated the performance of each topology under a range of failure severities, and present the results. The topologies used are from national-scale backbone networks with a variety of characteristics, which we characterize using standard graph-theoretic metrics. The end result is a compensated total graph diversity metric that accurately predicts the survivability of a given network topology.     

下一代光传送网的保护和恢复策略研究

随着网状网(Mesh)拓扑结构在下一代光传送网中的应用,基于Mesh的光传送网的生存性将成为研究热点。文章从光层生存性入手,首先分析Mesh生存性的主要特征,接着对Mesh网的保护与恢复策略进行归纳和总结,并介绍不同保护机制的应用特点,最后对Mesh网中的多层联合保护策略作了较为深入的探讨。     

基于SDH的电力光纤通信网生存性探讨

文章结合当前电力光纤通信网的建设情况以及光纤网络技术的发展,阐述了基于同步数字体系(SDH)的网络主要的保护恢复方法及应用,网络互连时可采用的保护方式,并针对多层网络协同工作的问题,对基于SDH的多层网络生存性协调进行探讨,为网络拓扑的实际应用和网络结构的优化提供参考.     

网络生存性的测度

基于对现有生存性测度方法优缺点的考虑,提出了以网络在整个破坏过程中的网络连通度的估计为基础的一种新的基于网络拓扑结构的生存性测度方法。结合实例,给出了在节点失效、链路失效和节点链路混合失效3种失效模型下网络生存性定量分析方法和优化方法。从实例分析中容易看出,文中所提出的分析、优化方法是评估网络生存性和设计高生存性网络的一种相对简单而有效的方法。     

A novel domain-by-domain survivable mechanism in multi-domain wavelength-division-multiplexing optical networks

In multi-domain wavelength-division-multiplexing (WDM) optical networks, the inter-domain routing is a challenge since each single-domain cannot view the full network topology. At the same time, survivability is also an important issue in optical networks since the failures of fiber links or network nodes may lead to a lot of traffic being blocked. In this paper, we study the survivability in multi-domain WDM optical networks, and propose a new survivable mechanism called load balanced domain-by-domain routing (LBDDR). In LBDDR, in order to obtain the efficient inter-domain survivable routes, we present the domain-by-domain routing (DDR) method which can find the intra-domain sub-working path and sub-backup path in each single-domain to form the inter-domain working path and backup path for each demand. In order to reduce the blocking probability, we present the load balanced routing method which can encourage the traffic to be uniformly distributed on the links with more free wavelengths. Simulation results show that, compared with conventional mechanism, LBDDR can obtain better performances.