基于mesh的新一代光传送网生存性研究

随着mesh拓扑在新一代光传送网中的应用,基于mesh的光传送网生存性将成为一个值得研究的课题。本文从光层生存入手,首先分析了mesh生存性的主要特征;接着对mesh网的保护与恢复进行了总结与归纳,并介绍了不同保护机制的应用特点;最后对mesh网中多层联合保护策略进行了较为深入的探讨。     

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。     

下一代网格状光传送网的生存性探讨

随着网格状网拓扑在新一代光传送网中的应用，基于网格状网的光传送网生存性成为一个值得研究的课题。从光层保护入手，首先分析了网格状网生存性的主要特征；接着对网格状网的保护与恢复进行了总结与归纳，并介绍了不同保护机制的应用特点；最后对网格状网中多层联合保护策略进行了较为深入的探讨。     

多波长光传送网的保护

介绍了多波长光传送网的一些基本优点,并和ＳＤＨ网络作了简单的对比,详细介绍了多波长光传送网的保护和故障恢复,特别是光环形网的保护倒换和故障恢复功能,最后对系统性能检测和保护判据的确定作了简单的论述。     

WDM光传送网生存性以及多层网络恢复策略

网络的生存性一直是传送网研究的重点。对于 WDM光传送网 ,可以在光层进行业务恢复 ,提高了网络抗故障能力。分析了光层恢复的特点和所存在的问题 ,以及多层网络恢复方案相互协调的策略     

下一代网络生存性的总体考虑

网络的生存性民为网络、特别是下一代网络设计中需要关注的重要内容,随着网络规模和容量的日益扩大,网络的生存性显得越来越重苛。本文介绍网络生存性的概念与意义,讲述网络保护和恢复的总体考虑,并以ＳＤＨ传送网为例简要介绍电层的保护、恢复方法和设计考虑。最后讨论网络的多层生存性问题。     

多业务传送平台的保护与恢复机制

介绍了同步数字体系（SDH）多业务传送平台（MPTP）中所采用的多种保护和恢复机制.包括SDH自动倒换与恢复、虚级联技术的保护、以太网二层交换的恢复、弹性分组环（RPR）的自动保护以及多协议标签交换（MPLS）的保护和恢复功能等,并对它们的保护和恢复机制的优缺点进行了分析比较。     

宽带光纤传送网的分层恢复技术与层间综合自愈策略

宽带光纤传送网中各层的恢复技术都得到了研究和发展 ,各层的恢复技术具有各自的特点 ,为了有效地提高全网的生存性 ,必须以一种综合的方式将各层的恢复技术纳入到一个统一的自愈策略中去。文中在宽带光纤传送网分层模型的基础上 ,分别分析了 SDH层、ATM层和光层恢复技术的特点 ,并提出了一种将串行启动和并行启动有效结合的层间综合自愈策略。     

接入层OTN建设的必要性分析

首先分析了本地传送网接入层的业务特点,LTE基站回传、OLT上联带宽、大客户专线以及智慧城市等业务将使接入层业务呈现多样性和大带宽化.然后简要介绍了接入层OTN系统具有的大带宽透明传输能力、多业务接入能力、可靠的保护及良好的运维能力等技术特点.并以南方某城市中心区域建设接入层OTN系统为例,分析了接入层OTN系统的多业务承载情况.最后从本地传送网接入层面临的容量需求挑战、管线基础资源限制以及建设接入层OTN系统的优缺点等方面,详细阐述了建设接入层OTN系统的必要性,分析显示建设接入层OTN系统是本地传送网接入层多业务承载的一种理想选择.     

WDM光网络的保护和恢复技术

文章概述了IP、SDH和WDM层网络的生存性技术,重点介绍了光传送网的光层生存性技术与光网络恢复技术,还对故障定位、多层生存性机制的协调等问题进行了简单介绍,最后给出了一个业务配置RWA算法与恢复RWA算法的实际方案。     

ATM网络业务恢复机制研究

提出了基于网管控制下的层次化ATM网络业务恢复管理机制，指出了在网络维护管理过程中采用多种恢复机制并进行层次化技术处理的重要性。ATM网络的正常可靠运行需要从网络各个层次，运用各种恢复管理机制对业务进行管理维护。在网络实际运行过程当中，联合应用网络各层次上的恢复管理机制是非常重要的。描述了该技术具体应用以及基于网管控制的业务恢复策略。     

光传送网的一体化网管研究

光传送网技术可望成为下一代的主导传送网技术。详细讨论了光传送网（ＯＴＮ）和光传送网的管理技术。结合ＴＭＮ、ＳＮＭＰ和ＣＯＲＢＡ，着重研究了ＯＴＮ的一体化网管。一种Ｑ－Ａｄａｐｔｅｒ被提出来用于集成ＴＭＮ和ＳＮＭＰ，一种直接的ＣＯＲＢＡ／ＳＮＭＰ接口被用来实现ＣＯＲＢＡ和ＳＮＭＰ的集成。最后简要分析了几个和ＯＴＮ一体化网管相关的问题：ＩＰ层和光层的联合路由，多层保护以及ＯＴＮ的ＯＡＭ技术。     

Convergence of Protection and Restoration in Telecommunication Networks

This paper argues for the need for convergence of protection and restoration schemes in today's telecommunication networks. Such networks are presented both in a layered context and from an end-to-end perspective. Such convergence is both necessary to ensure inter-working amongst a multitude of technologies deployed and desirable to ensure simplified operations. This paper further identifies the issues and inter-working items that need resolution in today's telecommunication and data networks in order to achieve inter working amongst various existing and emerging restoration and protection schemes in a layered and end-to-end context. End-to-end context covers the access, metro, and long haul dimensions of the network. It also encompasses both the services and the transport layers of the network in the context of multi-domain, multi service provider networks. Layering issues arise from the mix of technologies at several layers for example: optical transmission and CWDM/DWDM at physical layer, SONET/SDH framing and management at layer-1, ATM, MPLS, Ethernet, and resilient packet rings at layer-2, and finally IP and routing protocols at layer-3. Given that some degree of routing and signaling intelligence is migrating down to the optical layer equipment, this whole layering concept is currently in transition. This paper shows the need for convergence in the form of a two level protection and restoration scheme. A service independent layer and a mesh restoration capability at the routing layer.     

Simulation tools for multilayer fault restoration - [Modeling and simulation: a practical guide for network designers and developers]

The complexity of networks today makes it difficult to handle fault restoration by means of human intervention. Future network architectures are expected to be self-protecting and, more generally, self-organizing. In this article we describe the modeling methods and simulation tools we have used for the analysis of a new integrated restoration scheme operating at multiple layers/networks. The networks over which we have performed the analysis are ATM and SDH, but the methodology could be applied to other multilayer architectures too. A network model has been created that consists of both ATM and SDH layers. Using this network model, we have seen how the new scheme explores the free bandwidth over both layers. The multilayer bandwidth exploration was modeled using Microsoft Visual C++. Using OPNET Modeler, a node model was created to analyze the restoration message processing within it and the interaction with other nodes for the purpose of simulating the restoration delay. The article emphasizes the simulation methodology rather than the results of the simulation. Among others, we describe which additional functionalities a simulation tool is necessary to have in order to simulate multilayer networks. A comparison of OPNET and Microsoft Visual C++ is made, describing their advantages and the reasons we found it necessary to use both.     

Tutorial: Key Elements for WDM Transport Networks

This paper reports a brief review of the key elements for WDM transport networks. In particular, the transmission aspects, the basic elements of WDM networking, and the issues relating to failure restoration and network management are taken into account.     

Virtual network resource management for next-generation networks

The multilayer structure of transport networks presents a key challenge in network resource management. In this article we present a virtual network approach to the management of transport network resources. We describe the approach as developed for the management of large-scale ATM networks and discuss the application to the next generation of multilayer transport networks.     

Dynamic Survivability in WDM Mesh Networks Under Dynamic Traffic

Network survivability is a crucial requirement in WDM mesh networks. In this paper, we systematically consider the problem of dynamic survivability with dynamic single link failure in WDM networks under dynamic traffic demands. Specifically, we investigate various protection schemes, such as dedicated path protection (DPP), shared path protection (SPP), dedicated link protection (DLP), shared link protection (SLP), and two restoration schemes, path restoration (PR) and link restoration (LR). Moreover, two new shared protection methods are proposed, i.e., SRLG-based shared link protection (SRLG-SLP) and SRLG-based shared path protection (SRLG-SPP). The SRLG (shared risk link group) constraint defines the availability of protection resources to a working path, which requires that any two working paths sharing the same risk of failure (or in the same SRLG) cannot share the same protection resources. Furthermore, in our study, we consider a more practical dynamic single-link failure model, in which the link-failure-interarrival time and link-failure-holding time are considered as two independent parameters. Based on this link-failure model, extensive simulations are done to analyze and compare the dynamic survivable performance of various protection and restoration schemes. Resource utilization, protection efficiency, restoration efficiency, and service disruption ratio are employed as survivable performance metrics versus traffic load, link-failure frequency, and link-failure reparation time to evaluate the survivable performance. Many meaningful results are given. In addition, we show that the developed SRLG-SLP and SRLG-SPP protection schemes perform very well in terms of protection efficiency and service disruption ratio, while sacrificing some performance in terms of resource utilization.     

ATM中话音源的统计模型分析

本文根据ＡＴＭ网的传输特点,从统计的角度分析话音源的特点,建立统计模型并对其统计特性进行分析。     

Integrated Survivability Strategies of IP/GMPLS/Optical Multi-layer Network

In last decade,due to that the popularity of the internet, data-central traffic kept growing,some emerging networking requirements have been posed on the todays telecommunication networks,especially in the area of network survivability.Obviously,as a key networking problem,network reliability will be more and more important.The integration of different technologies such as ATM,SDH,and WDM in multilayer transport networks raises many questions regarding the coordination of the individual network layers.This problem is referred as multilayer network survivability.The integrated multilayer network survivability is investingated as well as the representation of an interworking strategy between different single layer survivability schemes in IP via generalized multi-protocol label switching over optical network.     

Survivable MPLS Over Optical Transport Networks: Cost and Resource Usage Analysis

In this paper we study different options for the survivability implementation in MPLS over optical transport networks (OTN) in terms of network resource usage and configuration cost. We investigate two approaches to the survivability deployment: single layer and multilayer survivability and present various methods for spare capacity allocation (SCA) to reroute disrupted traffic. The comparative analysis shows the influence of the offered traffic granularity and the physical network structure on the survivability cost: for high bandwidth LSPs, close to the optical channel capacity, the multilayer survivability outperforms the single layer one, whereas for low bandwidth LSPs the single layer survivability is more cost-efficient. On the other hand, sparse networks of low connectivity parameter use more wavelengths for optical path routing and increase the configuration cost, as compared with dense networks. We demonstrate that by mapping efficiently the spare capacity of the MPLS layer onto the resources of the optical layer one can achieve up to 22% savings in the total configuration cost and up to 37% in the optical layer cost. Further savings (up to 9 %) in the wavelength use can be obtained with the integrated approach to network configuration over the sequential one, however, at the increase in the optimization problem complexity. These results are based on a cost model with different cost variations, and were obtained for networks targeted to a nationwide coverage