基于GMPLS的IP over WDM

GMPLS（通用多协议标记交换）是MPLS技术向光网络发展的产物。它有铲地实现了IP和WDM光网络的无缝结合，是IP over WDM发展的一种趋势。本文主要介绍了GMPLS通用标记的特点及实现形式，LSP（标记交换路径）技术，以及链路管理协议LMP的特点及实现方法。     

中兴通讯长途骨干网波分保护方案

1 引言 为满足GE/2.5 Gbit/s/10 Gbit/s等大颗粒数据业务的传送需求,并降低网络建设成本,IP Over WDM成为近期各运营商关注的焦点技术之一.IP Over WDM又名光因特网,它是由WDM系统和路由交换组成的数据通信网络,其核心是充分利用WDM技术引入的巨大传送带宽和高速路由器交换机的强大交换能力,在IP层与光层之间合理地实现流量工程、保护恢复、QoS和网络管理等优化配置,构筑一种简单高效的网络体系结构.     

中兴通讯长途骨干网波分保护方式分析

引言 近期,为顺应GE/2.5G/10G等大颗粒数据业务的传送需求,并降低网络建设成本,IP Over WDM技术已逐渐成为各运营商关注的新一轮焦点技术.由于IP Over WDM技术的发展导致SDH层边缘化,IP传输将极大地依赖于WDM层面的保护,因此,IP OVER WDM的演进对波分骨干网层面保护技术的灵活性和安全性、保护资源利用率、保护方式的高效率等方面均提出了严峻挑战.     

标签交换光网络

IP对带宽的需求和WDM巨大传输能力的结合要求简化IP与WDM的协议模型。但运营商在传统语音和数据业务的投资使他们不可能在短期内从电路交换网络转移到带宽效率更高的IP/WDM网络上去。WDM技术能够提供多协议支持,彼此独立的不同网络协议可以在网络中共存,现有的、最常用的协议结构是IP/ATM/SDH/WDM（数据业务）和IP/HDLC/PPP/SDH/WDM（电路和专线业务）。目前的数据网络的四个功能层：IP层承载应用程序,ATM层处理流量控制,SDH层管传输,DWDM层提供大量带宽。这种多层叠加网络结构降低了网络效率,增加了网络操作…     

几种集成化光互联网实现方案

新技术的开发和使用使得光网络层具有了许多原来只能在高层实现的网络功能,从而为直接在WDM光网络上承载IP业务创造了条件。概括来讲,较好的集成化方案目前主要有三种：一种是IP路由器与WDM直接相连;另一种是基于多协议波长交换（MPLmS）技术的方案;还有基于标签的光突发交换（LOBS）方案。对这三种新型集成光互联网实现方案进行了研究与探讨。     

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.     

分组传送网环网保护机制的探讨

随着3G移动通信系统IP化和面向IP的全业务时代的到来,城域传送网络正面临着由基于电路交换的SDH网络向基于分组交换的电信级分组传送网（PTN）的逐步演进趋势。保护是PTN满足运营商级需求的重要特性。本文介绍了PTN各种保护机制,重点针对应用在移动回传网络中的PTN环网保护方式进行了探讨,并对各种故障类型触发保护的实现机制进行了分析。     

基于宽带IP组网技术的城域传输网的研究

介绍了宽带城域传输网的概念、特点及发展方向，并分析了城域网宽带IP组网技术，提出了城域网建设的发展方向是城域DWDM，而最具潜力的方案是GE/10 GE over DWDM；给出了GE over DWDM实现的技术分析；最后探讨了IP over WDM的自愈保护方式。     

WDM对终端业务和高层协议的影响

主要从基于 WDM网络的网络层及其高层出发 ,描述了以下问题 :业务准备算法以便最小化电复用的代价 ;波长分配算法 ;光层和电层联合保护和恢复 ;光网络拓扑对高层协议 ,如 IP选路、TCP流量控制和多层交换对光网络拓扑的影响。     

自适应TDM/WDM光网络结构

WDM(波分复用)技术极大地利用了光纤的巨大带宽潜力，为此介绍了一种运用WDM技术的光网络结构，其中心局之间通过光交换设备的控制进行自适应的时分交换，同一中心局内的光交换机之间通过预约的时分复用共享所有可用波长，IP(因特网协议)数据包可以直接在该网络中透明传输。该网络结构具有组网灵活，带宽利用率高，扩容性好以及路由方法简单的优点。     

IP restoration vs. WDM protection: is there an optimal choice?

The exponentially growing number of Internet users armed with emerging multimedia Internet applications is continuously thirsty for more network capacity. Wavelength-division multiplexing networks that directly support IP-the so-called IP over WDM architecture-have the appropriate characteristics to quench this bandwidth thirst. As everyday life increasingly relies on telecommunication services, users become more and more demanding, and connection reliability is currently as critical as high capacity. Both IP and WDM layers can fulfil this need by providing various resilient schemes to protect users' traffic from disruptions due to network faults. This article first reviews the most common restoration and protection schemes available at the IP and WDM layers. These schemes may be present concurrently in the IP over WDM architecture, with the resilient mechanism of each connection specifically chosen as a function of the overall cost, application requirements, and management complexity. The article describes a versatile heuristic based on simulated annealing that may be adopted to optimize the concurrent use of IP restoration and WDM protection schemes in the same (mesh) network. The proposed heuristic allows varying the percentage of traffic protected by the WDM layer and that of traffic relying on IP restoration, taking into account topology constraints and network cost minimization. An additional feature of the proposed heuristic is the potential to trade solution optimality for computational time, thus yielding fast solutions in support of interactive design.     

Performance and testbed study of topology reconfiguration in IP over optical networks

With the widespread deployment of Internet protocol/wavelength division multiplexing (IP/WDM) networks, it becomes necessary to develop traffic engineering (TE) solutions that can effectively exploit WDM reconfigurability. More importantly, experimental work on reconfiguring lightpath topology over testbed IP/WDM networks is needed urgently to push the technology forward to operational networks. This paper presents a performance and testbed study of topology reconfiguration for IP/WDM networks. IP/WDM TE can be fulfilled in two fashions, overlay vs. integrated, which drives the network control software, e.g., routing and signaling protocols, and selects the corresponding network architecture model, e.g., overlay or peer-to-peer. We present a traffic management framework for IP over reconfigurable WDM networks. Three "one-hop traffic maximization"-oriented heuristic algorithms for lightpath topology design are introduced. A reconfiguration migration algorithm to minimize network impact is presented. To verify the performance of the topology design algorithms, we have conducted extensive simulation study. The simulation results show that the topologies designed by the reconfiguration algorithms outperform the fixed topology with throughput gain as well as average hop-distance reduction. We describe the testbed network and software architecture developed in the Defense Advanced Research Projects Agency (DARPA) Next Generation Internet (NGI) SuperNet Network Control and Management project and report the TE experiments conducted over the testbed.     

A next-generation optical regional access network

We describe an optical regional access network which combines electronic IP routing with intelligent networking functionality of the optical WDM layer. The optical WDM layer provides such networking functions as network logical topology reconfiguration, optical flow switching to offload traffic and bypass IP routers, wavelength routing of signals, protection switching and restoration in the optical domain, and flexible network service provisioning by reconfigurable wavelength connectivity. We discuss key enabling technologies for the WDM layer and describe their limitations. The symbiosis of electronic and optical WDM networking functions also allows support for heterogeneous format traffic and will enable efficient gigabit-per-second user access in next-generation Internet networks     

一种新的WDM光传送网保护设计算法

在WDM网络中,由于光路之间存在的依赖性,物理网络的单链路失效可能会造成虚拓扑不连通而使上层网络(SDH、ATM或IP)无法使用自身的恢复机制来恢复受影响的业务,因此虚拓扑在嵌入物理拓扑时必须避免发生这种情况.已有的分离备用路径(Disjoint Alternate Path,DAP)算法总是假设网络所有波长路由节点都具有全波长转换能力.本文提出的LG_-VTMDP保护设计算法利用分层图同时解决路由和波长分配两个子问题,并考虑了负载均衡和物理链路的容量限制.实验结果表明LG_-VTMDP算法优于DAP算法和已有波长分配算法组合后的性能.本文还在此基础上提出了一种有效的波长转换器放置算法WCP算法.     

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     

考虑链路负载均衡和容量限制的WDM光传送网保护设计

网络的生存性是WDM光传送网设计时必须考虑的问题.在叠加(Overlay)模式的网络构架中,由于光路之间存在的依赖性,物理网络的单链路失效可能会造成虚拓扑不连通而使上层网络(SDH、ATM或IP)无法使用自身的恢复机制来恢复受影响的业务,因此虚拓扑在嵌入物理拓扑时必须避免发生这种情况.本文提出的VTMPD算法就是针对这一问题的保护设计算法.此算法同时考虑了物理链路的负载均衡和容量限制.我们还给出了VTMPD算法和已有的DAP算法的性能对比,测试数据表明VTMPD算法优于已有的DAP算法.     

IP over WDM光网络联合保护策略

随着Internet和网络技术的发展,IP over WDM光网络成为下一代通信网最理想的解决方案。因此,IP over WDM光网络的生存性是下一代通信网成功与否的关键。在传统的保护策略中,IP层和WDM层之间不交换网络的状态信息。探讨了IP层和WDM层保护机制互相协作的必要性,并在通用多协议标签交换GMPLS的基础上,提出了联合保护策略的思想。     

基于传统WDM平台的保护技术

本文重要介绍了基于传统WDM层的保护技术,以广东省IP over WDM测试情况着重阐述光1＋1通信保护技术的性能指标。     

Fault management in IP-over-WDM networks: WDM protection versus IPrestoration

We consider an IP-over-WDM network in which network nodes employ optical crossconnects and IP routers. Nodes are connected by fibers to form a mesh topology. Any two IP routers in this network can be connected together by an all-optical wavelength-division multiplexing (WDM) channel, called a lightpath, and the collection of lightpaths that are set up form a virtual topology. In this paper, we concentrate on single fiber failures, since they are the predominant form of failures in optical networks. Since each lightpath is expected to operate at a rate of few gigabits per second, a fiber failure can cause a significant loss of bandwidth and revenue. Thus, the network designer must provide a fault-management technique that combats fiber failures. We consider two fault-management techniques in an IP-over-WDM network: (1) provide protection at the WDM layer (i.e., set up a backup lightpath for every primary lightpath) or (2) provide restoration at the IP layer (i.e., overprovision the network so that after a fiber failure, the network should still be able to carry all the traffic it was carrying before the fiber failure). We formulate these fault-management problems mathematically, develop heuristics to find efficient solutions in typical networks, and analyze their characteristics (e.g., maximum guaranteed network capacity in the event of a fiber failure and the recovery time) relative to each other