对ASON承载IP网的研究(上)

随着业务的发展,IP网逐渐成为统一的多业务分组传送平台,应提供更为严格的可靠性保障机制,其目标不仅是要保障任何情况下的业务连通性,还要保证业务的QoS指标.ASON能快速地提供端到端连接,并能提供多种保护恢复机制,提高网络可靠性.如果采用ASON来承载IP网,则ASON可以为IP网提供保护恢复机制.本文主要探讨ASON承载IP网的需求,研究ASON为IP网提供保护恢复的可行性,从IP网和ASON的保护恢复现状、ASON为IP网提供保护恢复的技术和经济性方面进行详细的分析.     

基于ASON的业务研究与应用

随着ASON技术的发展和应用,传送网正在经历从承载网络向业务网络的演进。ASON作为承载网,可以为IP,3G和软交换等业务网络提供可靠的传送服务;ASON作为业务网,可以直接为客户提供高品质的专线,BoD和OVPN等新业务。本文主要探讨了ASON作为业务网时,提供BoD和OVPN等新业务的方式。     

基于ASON的业务研究与应用

随着ASON技术的发展和应用，传送网正经历从承载网络向业务网络的演进。作为承载网，ASON为IP、3G和软交换等业务网络提供可靠的传送服务：作为业务网，ASON直接为客户提供高品质的专线、BoD和DOVPN等新业务。[编者按]     

电信运营商IP承载网发展策略研究

IP承载网是各大电信运营商最主要的多业务综合承载网络,承载互联网业务、视频业务、政企专线业务、移动业务及IP话音业务等。随着话音业务、移动业务及OTT(Over The Top)业务向IP承载网迁移,如何提供差异化的承载性能和可靠性是IP承载网演进应重点考虑的问题。文章结合业务和技术发展趋势,对IP承载网的发展演进进行分析研究,为电信运营商的IP承载网规划建设提供参考。     

ASON精彩观点

基于SDH的智能光网通(ASON)设备和系统在我国已实现了产业化,正逐步应用于城域网和本地传送网中,而OTN结合了光域和电域处理的优势,能够提供巨大的传送容量、完全透明的端到端波长/子波长连接以及电信级的保护,也逐渐受到业界青睐。智能光网络采用智能控制、多业务传送技术,具有多重快速保护和恢复机制,可以让传送网具有更高的管理能力、安全性和快速反应以满足市场多种业务需求的能力。因此业界认为,ASON技术在城域传送网中的应用更能发挥其优势。本期ASON专题汇集了多位业界专家的技术经验和ASON建网、优化建议,希望能对运营商更好地利用ASON构建支持新一代融合型业务的城域网提供参考。     

中国联通LTE承载规划探讨

1 引言 LTE业务对承载网的挑战主要表现为两个方面:一方面在移动业务宽带化的趋势下要求承载网具备很强的带宽扩展能力;另一方面LTE网络扁平化、深度覆盖以及同步需求的变化,要求承载网在具备IP业务感知能力的同时考虑较完善的承载网端到端保护方案、组大网的能力以及同步解决方案.烽火通信凭借自身雄厚的技术实力和对用户需求的深刻理解,深入研究LTE业务需求,提供适于网络发展,切合网络特点的网络规划方案,作为运营商网络建设的规划参考.     

一种ASON网络中分级服务的实现与仿真

自动交换光网络(ASON)中具有灵活多样的生存性机制,根据业务对故障恢复的可靠性要求,可以为其提供适当的保护恢复机制.文章提出了一种在ASON中实现的分级服务方案,首先以恢复时间为标准定义出不同的生存性等级,然后给出了实现该方案的功能模块及流程图,最后对该方案进行了仿真分析.     

ASON组网中的保护恢复机制

目前在光传送网的建设中开始出现ASON技术的应用.就ASON技术在组网中所涉及的保护恢复机制作了简单介绍,并讨论了ASON网络设计中应用业务生存性机制的考虑因素.     

基于SDH的ASON网络恢复机制分析

简述目前ASON网络体系结构和主要特点,讨论ASON网络目前能够提供的网络保护恢复机制,比较控制层和传送层保护恢复机制的特点,分析ASON网络中路径保护策略,提出与传统OTN融合后的A-SON网络业务恢复策略.     

联通LTE承载规划探讨

LTE业务对承载网的挑战主要表现为两个方面,一方面在移动业务宽带化的趋势下要求承载网具备很强的带宽扩展能力,另一方面LTE网络扁平化、深度覆盖以及同步需求的变化,要求承载网在具备IP业务感知能力的同时考虑较完善的承载网端到端保护方案,组大网的能力以及同步解决方案。烽火通信凭借自身雄厚的技术实力和对用户需求的深刻理解,深入研究LTE业务需求,提供适于网络发展、切合网络特点的网络规划方案,作为运营商网络建设的规划参考。     

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.     

A review of fault management in WDM mesh networks: basic concepts and research challenges

The article first presents a broad overview of the fault management mechanisms involved in deploying a survivable optical mesh network which employs optical crossconnects. We review various protection and restoration schemes, primary and back-up route computation methods, shareability optimization, and dynamic restoration. We then describe different parameters that can measure the quality of service provided by a WDM mesh network to upper protocol layers (e.g., IP network backbones, ATM network backbones, leased lines, virtual private networks), such as service availability, service reliability, restoration time, and service restorability. We review these concepts, the factors that affect them, and how to improve them. In particular, we present a framework for cost-effective availability-aware connection provisioning to provide differentiated services in WDM mesh networks. Through the framework, the more realistic scenario of multiple near-simultaneous failures can be handled. In addition, the emerging problem of protecting low-speed connections of different bandwidth granularities is also reviewed.     

自动交换光网络的生存性及保护恢复

自动交换光网络(ASON)是当前光传输领域的研究热点，其中保护恢复策略将为增强网络生存性奠定新的基石。本首先介绍了ASON中的保护和恢复机制以及它们各自的特点。并在此基础上讨论它们与传统SDH网络保护恢复机制比较所表现出的几点优势，最后，针对ASON的传送平面和控制平面的保护恢复提出主要的技术要求，这些要求将有助于保证ASON在生存性方面优势的真正实现。     

基于信令控制的网状光网共享恢复策略研究

该文详细研究了基于信令控制的网状光网络共享的分布式恢复策略,并基于现有的各种信令协议及其扩展给出了具体的实现方案和流程。实验证明,基于共享的分布式恢复机制能大大提高网络的资源利用率,有效地缩短恢复时间,满足了IP与光网相互融合的需要,可用于实现自动交换光网络的分布式恢复。     

长途传输网ASON商用实验项目设计

本文通过分析山东分公司骨干传输网络资源现状,完成山东长途传输网ASON商用实验项目的工程设计。本文以WDM作为物理承载网络,根据近几年业务开放情况,配置了业务需求增长比较快的重点客户业务,3G语音数据业务以及IP业务。并考虑到业务的安全性及带宽利用率将3种业务分别配置为钻石级和银级。重点进行了ASON抗故障的多种保护恢复能力方面的测试。同时还进行了配置测试、DCN数据通信网、接口测试、设备硬件等一系列的实验测试。     

Differentiated reliability (DiR) in wavelength division multiplexing rings

Extant (optical) networks normally offer two degrees of service reliability: full protection in the presence of a single fault in the network, and no protection at all. This situation reflects the historical duality that has its roots in the once divided telephone and data environment. The telephone circuit oriented service requires protection, i.e., provisioning of readily available spare resources to replace working resources in case of a fault. The datagram oriented service relies upon restoration, i.e., dynamic search for and reallocation of affected resources via actions such as routing table updates. The current trend in networking, however, is gradually driving the design of networks toward a unified solution that will jointly support traditional voice and data services, as well as a variety of novel multimedia applications. The growing importance of concepts, such as quality of service (QoS) and differentiated services-which provide multiple levels of service performance in the same network-evidences this trend. Consistently with this evolution, the concept of differentiated reliability (DiR) is formally introduced in the paper and applied to provide multiple reliability degrees (or classes) at the same network layer using a common protection mechanism, i.e., path switching. According to the DiR concept, each connection is guaranteed a minimum reliability degree, or equivalently a maximum downtime ratio, that is chosen by the client. The reliability degree chosen for a given connection is thus determined by the application requirements, and not by the actual network topology, design constraints, robustness of the network components, and span of the connection. An efficient algorithm is proposed to sub-optimally design the wavelength division multiplexing (WDM) layer of a ring and illustrate the advantages of the DiR concept.     

ASON标准化进展

全球数据业务的爆炸式增长要求能够提供灵活智能的网络配置和高效快速的网络保护能力．ASON技术的出现迎合了光网络的这一新的发展趋势。ASON是一种具有高灵活性和高可扩展性的基础光网络设施．它能在光层上直接提供服务．从而快速地满足用户的需求，并有效地解决网络的可扩展性、可管理性、快速配置用户带宽和端到端保护等问题。介绍了TTU-T、IETF和OIF等国际组织在ASON标准化方面的最新进展．并对国内有关ASON标准的制定情况进行了总结。     

ASON标准化进展

全球数据业务的爆炸式增长要求能够提供灵活智能的网络配置和高效快速的网络保护能力,ASON技术的出现迎合了光网络的这一新的发展趋势.ASON是一种具有高灵活性和高可扩展性的基础光网络设施,它能在光层上直接提供服务,从而快速地满足用户的需求,并有效地解决网络的可扩展性、可管理性、快速配置用户带宽和端到端保护等问题.本文介绍了ITU-T、IETF和OIF等国际组织在ASON标准化方面的最新进展,并对国内有关ASON标准的制定情况进行了总结.     

Protection approaches for dynamic traffic in IP/MPLS-over-WDM networks

Due to the explosive growth of data-related traffic driven by the Internet, network reliability becomes an important issue. We investigate various protection approaches to handle failures for dynamic traffic demands in IP/MPLS-over-WDM networks. An LSP can be protected at either the IP/MPLS layer or the optical layer. In IP/MPLS layer protection, an LSP is protected by providing a link-disjoint backup LSP between its end nodes. In optical layer protection, an LSP is protected by the backup lightpath of each lightpath traversed by the LSP. We present two integrated routing algorithms: hop-based integrated routing algorithm and bandwidth-based integrated routing algorithm (BIRA) to set up the restorable bandwidth-guaranteed paths efficiently. Then we present a multilayer protection scheme for multiclass traffic in such networks. This scheme takes into account the different QoS and recovery requirements of the traffic to provide protection capability either at the MPLS layer or at the optical layer in a cost-effective manner. We use the connection blocking probability and number of optical-electrical-optical conversions as performance metrics to compare various protection approaches.