基于GMPLS的光网络保护恢复的研究

文中首先比较了GMPLS和SDH／SONET的保护和恢复机制，接下来阐述了GMPLS用于增强网络的保护与恢复能力的信令机制，最后对网络的保护和恢复机制如何使用GMPLS信令来实现进行了详细的分析和讨论．     

IP/MPLS网络与GMPLS网络互联的研究

文章研究了网际协议／多协议标签交换（IP／MPLS）网络升级为通用多协议标签交换（GMPLS）网络的过程中存在的几种演进模型，并重点分析了岛式模型。同时，还分析了MPLS网络和GMPLS网络互联时存在的问题、两种协议问的差异以及解决这些问题所采用的路由、信令和通道计算技术。     

MPLS向GMPLS迁移技术研究

多协议标签交换（MPLS）向通用多协议标签交换（GMPLS）的迁移，实际就是，MPLSTE控制层面向GMPLS控制层面发展的过程。在迁移过程中，MPLS和GMPLS设备或网络同时存在，将出现多种互联情况。标准的互联功能要求，在使用GMPLS技术的同时，保持现有的IP／MPLS网络不受影响。     

GMPLS RSVP-TE中的连接处理过程分析

文章介绍了通用多协议标签交换(GMPLS)资源预留-流量工程( RSVP-TE)协议,它主要用于非IP网络,尤其是在光网络中动态地完成连接的建立、保持和删除.文中介绍了除RSVP-TE协议中的对象以外新引入的一些对象和消息,并通过实例阐述了在光网络中利用GMPLS RSVP-TE进行连接建立、删除以及控制平面重启的过程.最后对GMPLS RSVP-TE中的连接建立过程和RSVP-TE中的连接建立过程进行了比较总结.     

GMPLS的动态路由机制研究

GMPLS由MPLS演进而来,它是MPLS向光层扩展的必然产物,路由技术是GMPLS的一项关键技术。这里简要回顾了MPLS技术,在此基础上对GMPLS中与路由相关的关键技术做了介绍,讨论GMPLS中现有的路由选择策略,论述基于GMPLS支持的对等网络模型对一种联合的网络结构及其控制平面的结构,最后提出基于GMPLS的网络中一种有QoS保证的动态路由机制。     

GMPLS的一种镜像保护恢复机制

对通用多协标记交换(GMPLS)在控制平面的保护恢复技术作了系统的分析和研究;引进了一种对链路信息进行备份恢复的镜像恢复机制,并对此机制进行了分析,提出了改进方案,有效地解决了"多余备份"的现象.     

GMPLS中光层的保护和恢复机制

主要讨论了GMPLS信令对MPLS的扩展,通过对GMPLS新增的LMP协议和通告消息的讨论来解决故障的4个步骤,最后结合GMPLS根据现有光层的保护和恢复机制对保护交换和恢复的特点及实现方法进行了详细的讨论。     

一种基于MPLS VPN的QoS路由机制

文中提出一种基于MPLSVPN的QoS路由机制，通过隧道穿越IP骨干网连接MPLS站点，实现MPLSVPN的QoS路由，查找满足最低代价、最高带宽的链路，在更好地满足VPN中的各种业务对服务质量要求的同时，通过合理调配网络资源，提高了网络资源利用率，实现了可靠高效的QoS路由．     

A concurrent two-layer restoration scheme for GMPLS WDM networks

Next generation backbone networks will likely consist of IP routers as well as optical cross connects (OXCs) and will deploy an optical control plane protocol. Generalized Multi Protocol Label Switching (GMPLS) has been proposed as the candidate of choice for the control plane. Optical fibers may carry large volumes of traffic and therefore adequate mechanisms must exist to enable the network to automatically recover from failures of fiber. In mission critical networks survivability becomes very important. We investigate the problem of autonomous recovery in such networks. The literature contains work in this area that investigates the problem of multilayer recovery. Such recovery had only been sequential in the sense that the published work recovers first in the optical domain, assuming the availability of redundant resources, and then proceeds to recover packet label switched paths. We report a recovery procedure for recovering packet label switch paths (packet LSPs) and lambda label switch paths (λLSP) concurrently. We have conducted an OPNET-based simulation study that compares the performance of the concurrent scheme with the previously published sequential two-layer recovery scheme. The study shows that the concurrent two-layer recovery scheme performs as much as forty-four percent faster than the sequential two-layer recovery scheme.     

组播在MPLS VPN中的一个过渡实现方案

在组播网络中，即使组播用户数量成倍增长，骨干网络中网络带宽也无需增加，在很多多媒体业务中需要网络组播功能。目前由于MPLS VPN网络中很多PE设备尚不支持组播业务，因此在VPN内部署组播业务时遇到了一定的困难。本文讨论一种可以在现有设备条件下，利用DVMRP隧道解决MPLS VPN组播问题的方案。     

通用多协议标签交换GMPLS协议

GMPLS由MPLS演进而来,它是MPLS向光层扩展的必然产物。GMPLS将时隙、波长和光纤端口作为标签用于数据转发,通过采用扩展的信令、路由协议和新增的链路管理机制以适应对智能光网络进行动态控制和传送信令的要求,动态提供网络资源并增加网络的存活性。     

MPLS Recovery Mechanisms for IP-over-WDM Networks

Due to the fast increase of Internet traffic and the enormous bandwidth potential of all-optical transport networks based on wavelength division multiplexing, an IP-over-WDM network scenario is likely to be widespread in future communication networks. At the same time, IP networks are becoming more and more mission-critical. Hence, it is of paramount importance for IP-over-WDM networks to be able to recover quickly from frequently occurring network failures. This paper explains how multi-protocol label switching (both electrical and optical) recovery mechanisms can be important to reach that goal. Moreover, a novel MPLS recovery mechanism called fast topology-driven constrained-based rerouting is presented. Different MPLS recovery mechanisms are compared to each other. Special attention hereby goes to the additional capacity that is required to recover from frequently occurring failures.     

An Architecture for Differentiated Protection Against Single and Double Faults in GMPLS

In the context of an optical network GMPLS can be used to provide network robustness to faults through end-to-end path protection techniques. In this paper, we present a dynamic distributed model supporting five different classes of protection, including protection against single and double fault, with and without sharing of backup bandwidth. Beyond link and node failures we also consider protection against shared risk link group (SLRG) failure. In this paper, we briefly describe the protection model and the underlying algorithms for route selection and backup bandwidth sharing. After that we face the following issue: Which subset out of the five possible protection classes is convenient for an operator to support on the same network infrastructure? To answer this question it is fundamental to have a clear view of the trade-offs between the costs and the performances associated to each class. To achieve that we carried out an extensive performance analysis by means of simulations. For each protection class, we evaluated two fundamental performance metrics: the recovery probability under multiple faults, and the average per-demand resource usage. On the basis of such results, we are able to identify some basic guidelines driving the choice of the more convenient subset of protection classes to be implemented within a single network.     

用于ION的GMPLS分布式控制体系结构

介绍智能光网络相关概念,研究其分布式控制体系结构,重点研究基于通用多协议标记交换(GMPLS)的智能光网络,将其控制面划分为资源发现、状态信息分发、路由选择和路径控制四个功能模块,该控制面能很好地满足智能光网络的控制需求。     

一种面向IP/GMPLS over WDM网络的优化综合路由算法

为了优化利用IP层和WDM层网络资源,在WDM网络集成辅助图模型的基础上,提出了一种面向IP/GMPLS over WDM网络的基于代价的优化综合路由算法,即CIR(Cost-basedIntegrated Routing).该算法将IP层和WDM层资源可用信息以代价函数形式给出,并将因网络拓扑结构和网络负载分布不均衡等产生的瓶颈链路以及带宽碎片问题也统一纳入考虑,由此将LSP建立问题转化为在集成辅助图上找出一条源、目的节点之间的最短通路问题.仿真结果表明:CIR算法有效地实现了IP和WDM两层资源的联合优化,提高了网络资源利用,降低了网络阻塞率.     

在GMPLS控制光网络中波长转换信息分享

Wavelength converters are used in optical networks to overcome transparent wavelength channel insufficiency. However, current GMPLS control plane does not distribute wavelength converter information to network nodes. To overcome this situation, four wavelength converter information sharing methods for GMPLS-controlled optical networks are proposed. The first two, Conversion Capability during Signaling (CCS) and Conversion Availability during Signaling (CAS), are based on the RSVP-TE signaling protocol, while the others, Conversion Capability Advertisement (CCA) and Conversion Availability Advertisement (CAA), are based on the OSPF-TE routing protocol. Simulations show that CAA obtains the lowest blocking, while CCS the highest. Moreover, CAA only slightly increases the control plane load compared to CAS.     

通用标签交换网络中的故障处理

对GMPLS网络中的故障处理的过程进行了介绍,并对不同业务恢复方法的性能差异进行了分析和对比。     

用于Mesh光网络快速保护恢复的GMPLS信令机制的扩展

分析了Mesh光网络保护机制和恢复机制,并对GMPLS信令机制进行了扩展,给出了扩展后实现保护恢复的协议格式和信令流程,最后依据实验数据给出扩展的GMPLS信令机制的保护、恢复时间的仿真结果.     

MPLS技术发展及应用

随着网络设施的持续发展,网络规模越来越大,需要交换的数据量也与日俱增,因此一个高速传输和交换的网络技术就显得尤为重要.作为下一代网络的关键技术,多协议标签交换(MPLS)技术在改善和提高网络性能方面扮演着越来越重要的角色.因此,网络界很大一部分重点已经转向采用多协议标记交换.这为简化虚拟专用网(VPN)链路,实现服务融合和流量工程提供了极具吸引力的机会,同时最大限度地降低了与早期方法有关的复杂度和开销.重点介绍了多协议标签交换技术的发展方向和一些主要应用.     

Regenerator Placement and Traffic Engineering with Restoration in GMPLS Networks

In this paper, we study regenerator placement and traffic engineering of restorable paths in generalized multiprotocol label switching (GMPLS) networks. Regenerators are necessary in optical networks in order to cope with transmission impairments. We study a network architecture where regenerators are placed only at selected nodes for decreasing cost of regeneration. We propose two heuristic algorithms for optimum placement of these regenerators. Performances of these algorithms in terms of required number of regenerators and computational complexity are evaluated. In this network architecture with sparse regeneration, off-line computation of working and restoration paths is studied for traffic engineering with path rerouting as the restoration scheme. We study two approaches for selecting working and restoration paths from a set of candidate paths and formulate each method as an integer linear programming (ILP) problem. A traffic uncertainty model is developed in order to compare these methods based on their robustness with respect to changing traffic patterns. Traffic engineering methods are compared based on number of additional demands resulting from traffic uncertainties that can be carried over the network. Proposed heuristic regenerator placement algorithms are also evaluated from a traffic engineering point of view.