采用多层恢复机制的IP over WDM网络生存性研究

IP over WDM网络是下一代网络的核心,生存性则是保证服务质量(QoS)的关键要素.当网络中出现故障时,选择在IP层还是光层进行保护和恢复是非常重要的课题.文章在论述IP层和光层的保护和恢复机制的基础上,提出了多层联合恢复机制的思想,针对多层联合恢复机制中各层之间如何协调进行了仔细的分析,并提出了自己的见解.     

基于GMPLS集成动态多层网络故障恢复技术

基于IP/GMPLS over WDM的网络架构下研究多层网络生存性的协调机制,针对基于GMPLS控制平面的生存性协调方案作了详细的论述.主要从故障检测、故障通知和协调控制等几个方面展开详细的分析研究,该方案能减少恢复故障所需的总时间和,以及可对各层生存性技术进行有效的协调控制.     

IP over WDM网络的多层联合恢复策略

由于WDM网络承载着巨大的业务量,其网络可靠性日趋重要.在光层提供生存能力一向具有重要意义,然而由于光层聚集光路径及其粒度较粗的特征,也产生了许多的问题和挑战.MPLS及其扩展MP S的出现,为发展能够协调IP层和光层的联合保护/恢复策略提供了新的方法.鉴于此,文章首先简单介绍了现有MPLS/MP S的恢复机制,然后针对IP over WDM光网络提出了一种联合的二层恢复策略.在这种策略中,光层首先执行恢复动作,如果光层无法恢复所有受损的业务,则上层的IP层接着发起其自身的恢复机制.基于仿真的分析表明,所提出的二层联合恢复策略优于单层的恢复策略;若IP层恢复时具有更好的粒度优势,光层恢复时则具有更高的速度.     

ASON网络多层生存性技术的研究

首先分析了ASON（自动交换光网络）的多层网络架构的背景。然后从网络扁平化的趋势中．探讨两层网络的生存性技术。对IP／GMPLS层网络和光层恢复技术的优劣作出比较，得出需要多层协调恢复的原因。从多层顺序恢复策略来探讨了包括延迟时间法、恢复率法和恢复令牌法的各种协调机制的优点和不足，提出一种改进的基于延迟时间的协调机制。     

智能光网络的多层生存性技术

文章对多层网络生存性问题、独立的网络生存性配置方案和多层网络生存性配置方案进行了概括和分析,对基于IP,GMPLS/Optical智能光网络多层结构的调整策略进行了研究,并讨论了基于智能光网络的统一控制平面、利用层间信令协调机制的集成多层网络生存性方案。     

多层网络中的生存性

未来传输网络中,不同的网络技术(如IP、SDH和WDM技术)的融合需要不同网络层次之间进行有效地配合,特别是网络生存性领域更是如此。首先对多层网络生存性机制的框架以及在多层网络环境下实现网络生存性的技术进行了概述,同时以IP over WDM为例,说明了这些方法的应用方式。     

ASON网络多层生存性技术的研究

首先分析了ASON(自动交换光网络)的多层网络架构的背景。然后从网络扁平化的趋势中,探讨两层网络的生存性技术。 对IP/GMPLS层网络和光层恢复技术的优劣作出比较,得出需要多层协调恢复的原因。从多层顺序恢复策略来探讨了包括 延迟时间法、恢复率法和恢复令牌法的各种协调机制的优点和不足,提出一种改进的基于延迟时间的协调机制。     

IP over OTN的联合优化组网方案探讨

分析了我国运营商在骨干网普遍采用的IPoverWDM网络现状和存在问题,重点从中转业务优化处理和两层保护协调机制出发,探讨了近期和未来IPoverOTN的联合组网方案以及在传送平面、控制平面和管理平面的关键技术。     

基于GMPLS的多层网络故障恢复框架设计

针对GMPLS控制平面的生存性提出了一种故障恢复机制,以实现多层网络生存性机制之间的迅速协调,通过对方案的分析能减少故障恢复时间的总和,优化网络效率.     

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     

基于管理技术的ATM网络抗毁性研究

提出了基于管理技术的ATM网络抗毁性组织结构概念,指出了在网络规划设计与维护管理阶段进行层次化技术处理的重要性。ATM网络抗毁性组织结构要求在网络规划设计阶段、运用各种规划算法和仿真技术进行抗毁性设计与验证;在网络管理维护阶段,从网络各个层次,运用各种管理算法或机制维护网络抗毁性。在网络实际运行过程当中,该组织结构强调联合应用网络各层次上的抗毁性管理技术,充分发挥各个层次上的抗毁性,以提高整个网络抗毁性能。     

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。     

WDM光网及多层网络生存性的研究

为了适应多层次网络发展的需要，在讨论WDM光层生存性机制的基础上，针对多层网络联合的生存性机制进行了仔细的分析，提出了一种多层协调的实现办法，并讨论了多层空闲资源设计中的共享问题。     

IP over DWDM网络的生存性研究

探讨了IP over DWDM生存性的机制，研究了各个网络层的恢复特点以及不同层间相互作用对生存性的影响，明确了多层网络生存性的优点，从而得出光层能够提供最快的保护，较高的层能够提供智能恢复。最后提出了一种在光层的自动保护倒换的结构，这种保护能够优先考虑来自较高层的告警信息，使IP over DWDM网络做到智能化的快速恢复，为IP over DWDM网络的研究和建设提供了一定基础。     

End-to-end survivable broadband networks

Within the EC-sponsored RACE program, the IMMUNE project was established to analyze and specify appropriate strategies for introducing end-to-end survivability into corporate and public broadband networks to support these strategies by proper techniques and evaluation tools, and to demonstrate distributed restoration on PSN (public switched networks) and CPN (customer premises networks) laboratory models. The first objective was to define a set of survivability requirements and metrics to be used in the rest of the project. This has led to the identification of a range of survivability strategy options ann how they can be mapped onto user, service provider and operator requirements. The next step on the road to integral survivability is designing and planning survivable networks, and the evaluation of the restoration and protection mechanisms that will be applied in these networks. An overview is given of this part of the project. Most protection and restoration mechanisms operate within a single network layer and network part, autonomous from network management. The interaction of mechanisms in different network layers or in different network parts, and the role of network management, are discussed. For the demonstration lab models, two techniques have been selected for implementation: a distributed restoration mechanism for a meshed ATM PSN, and a CPN ATM ring protection switching mechanism. These techniques are described and an overview is given of the ongoing activities within the IMMUNE project, with a summary of the status of the demo models     

宽带光纤传送网的层间综合自愈策略

为了有效地提高宽带光纤传送网的生存性，必须以一种综合的方式将各层的恢复技术的纳入到一个统一的自愈策略中去。本文在宽带光纤传送网分层模型的基础上，提出了一种综合应用串行启动和并行启动的层间综合自愈策略。     

Optimized design of survivable MPLS over optical transport networks

In this paper we study different options for the survivability implementation in MPLS over Optical Transport Networks (OTNs) in terms of network resource usage and configuration cost. We investigate two approaches to the survivability deployment: single-layer survivability, where some recovery mechanism (e.g. protection or restoration) is implemented in a single network layer and multilayer survivability, where recovery is implemented in multiple network layers. The survivable MPLS over OTN design is implemented as a static network optimization problem and incorporates various methods for spare capacity allocation (SCA) to reroute disrupted traffic.The comparative analysis between the single layer and the multilayer survivability shows the influence of the traffic granularity 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. For the multilayer survivability 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, this is at the increase in the optimization problem complexity. These results are based on a cost model with current technology pricing and were obtained for networks targeted to a nationwide coverage.     

On joint protection/restoration in IP-centric DWDM based opticaltransport networks

Previous advances in WDM technology are now beginning to shift the focus more toward optical networking and network-level issues. Providing survivability at the optical layer is inherently attractive, but whether it makes practical sense, given similar mechanisms that are already available at the higher layers, poses serious challenges and raises many questions. Today's core network architecture model has functional overlap among its layers, contains outdated functionality, and is too slow to scale. If IP can be mapped directly onto the WDM layer, some of the unnecessary network layers can be eliminated, opening up new possibilities for developing a simple and integrated-protection/restoration scheme that can be coordinated at both the IP and WDM layers. This article presents an overview of existing optical protection/restoration schemes. Then we present a novel mesh-based hybrid optical protection scheme that utilizes multifiber physical links along with a hierarchical OXC structure. An overview of the envisioned IP-centric DWDM-based optical data network architecture is then presented. The basis of how to implement a more direct IP standard-based approach for closer and efficient IP-WDM integration is also discussed. Finally, we articulate a view of how to provide a joint protection/restoration scheme that is coordinated at both the IP and WDM layers     

光网逻辑层的生存性技术(本期优秀论文)

提出了生存性技术的基本分类原则和光网络生存性的分层视图,在此范畴内,分析比较了包括纯链路、纯路径、Meta-Mesh、p-cycles、SBPP、SLSP在内的逻辑层生存性技术,最后总结出逻辑层生存性技术所具有的灵活性和容量利用高效率的特征.