【作者】 窦军；

【导师】 曾华燊；

【作者基本信息】 西南交通大学 ， 通信与信息系统， 2011， 博士

【摘要】 Internet是在线路传输速率低、误码率高的通信条件下,以文本数据传输为主的应用背景下诞生的网络,同时现有的Internet在体系结构上存在着用户数据交换平台层次结构复杂、传输效率低下和服务质量(Quality Of Service, QoS)难以保证的缺点。随着高速率低误码率的密集波分复用(DWDM)光骨干通信技术的发展,为了克服这些缺点,四川省网络通信技术重点实验室(SC-Netcom Lab)提出了“单层用户数据交换平台体系结构”(Single-layer User-data Switching Platform Architecture, SUPA)作为一种新的基于DWDM的骨干网体系结构。SUPA采用带外信令控制思想将用户数据交换平台(User-data switching Platform, U-Platform)与信控管理平台(Signaling&Management Platform, S&M-platform)分离,从而将U-Platform简化为单物理层结构,为实现骨干网节点的高速高效交换奠定了基础。同时,面向目前最流行的以太网,四川省网络通信技术重点实验室提出的“面向以太网的物理帧时槽交换”(Ethernet-oriented Physical Frame Timeslot Switching, EPFTS)技术将DWDM物理信道／波长的复用与交换节点的交换机制相结合以提高传输效率,使服务质量保障机制直接嵌入物理层,为用户提供有服务质量保证的、面向虚线路连接(Virtual Line Connection)的传输服务。由于SUPA的最大优点就是通过带外信令技术,结合基于DWDM的EPFTS技术,将服务质量保证延伸到端用户,真正为用户提供端到端的QoS保证的服务,因此,SUPA网络(SUPA Network, SUPANET)能够在同一网络中同时开展语音、视频和数据业务,满足下一代Internet (Next Generation Internet, NGI)或下一代网络(Next Generation Network,NGN)“三网合一”的需求。作者首先分析了现行Internet面临的高速交换、服务质量保障、网络安全和接入多样性等挑战,综合分析了国内外NGI/NGN研究的现状,提出了在NGI研究中从“体系结构”方面应对挑战的基本思路。针对OSI/RM和现有Internet网络体系结构存在的不足,作者分析了NGI需求和NGI总体目标,在利用带外信令思想重新审视Internet体系结构的基础上,指出进一步的简化将可以在两类不同的平台(U-Platform和S&M-platform)分别进行。通过扩展OSI/RM以适应未来网络应用虚拟化和面向服务的需求,作者提出了一种新的NGI体系结构——‘开放式网络应用服务参考模型’’(Open Network Application Service/Reference Model, ONAS/RM)。该新模型被定义成包含应用支撑层、传输层和交换基层的三层体系结构以实现上述NGI总体目标。在分析“渐进演进”和“革新重建”两种NGI研究观念的特点基础上,针对未来的骨干网络将基于高速率和低误码率的DWDM,而接入网络将基于可能高误码率的多种通信技术的通信现状,作者所在的实验室提出了解决NGI中问题的“骨干通信交换平台优先,外延次之”的BSF-OES(Backbone Substrate First, Outwards Expansion Second)策略。该策略强调引入带外信令,将U-Platform与S&M-platform分离,在骨干网(特别是基于DWDM光通信骨干网)中最大限度地简化U-platform,并在兼容现行Internet和平滑过渡的基础上,强调率先在NGI的骨干网中构建一个内嵌QoS机制和安全措施的薄的交换基层以应对高速交换问题,当骨干网技术成熟并广泛应用后再向边缘推广应用。本文将SUPA作为一种NGI骨干网络的框架,论证了应用该策略如何应对技术挑战、保护现有投资和平滑过渡到NGI的可行性。按照BSF-OES策略,作者也强调SUPA的体系结构采用阶段性研发策略,分三个阶段进行基于EPFTS的SUPA框架研究。第一阶段SUPA在S&M-platform保持现有的Internet协议栈并进行必要的增强的基础上,重点进行了基于EPFTS的U-platform的SUPA初步研究。作者在概述第一阶段SUPA体系结构、论述相关核心技术成果并论证SUPA研发思路可行性的基础上,分析了第一阶段SUPA研究存在的问题,指出进行第二阶段SUPA研究的必要性。为此,作者提出在第二阶段SUPA研究中重点进行U-platform和S&M-platform都是基于EPFTS交换基层的SUPA框架的优化研究,而将按ONAS/RM模型构建未来网络模型的第三阶段SUPA框架留待以后进一步详细研究。由于第一阶段SUPA仅在U-Platform由EPFTS支持,作者提出第二阶段SUPA的S&M-platform也由EPFTS支持,进一步简化S&M-platform为4层结构。同时,作者采用带外信令与带内信令相结合的可重组体系结构思想进行SUPA体系结构的优化。这种思想的特点就是,出于效率的考虑,按带外信令将SUPA系统在总体构建上划分成两类平台(U-platform和S&M-platform),尽量简化U-platform以提高交换效率；而这两类平台内还可以进一步按带内信令思想进行各自平台内的“带内”OAM (Operation Administration and Maintenance,操作管理与维护)等功能的增强,减少两类平台(U-platform和S&M-platform)之间的信息交互,以提高相同平台之间简短“带内”信控管理信息的交换效率。作为本文的研究重点,作者全面研究了第二阶段SUPA的体系结构,提出了第二阶段SUPA的系统框架,重点研究了第二阶段SUPA基于EPFTS的S&M-platform框架与OAM。作者详细研究了SUPA系统的S&M-platform及其接口,研究了SUPA信控管理协议的信令流程和信令消息转换过程,同时,研究了U-platform中的基于EPF子层的“带内”OAM子层。作者在第一阶段SUPA有关服务质量保障体系的基础上进一步研究了第二阶段SUPA服务质量保障体系,定义了相关的SUPA服务、协议和接口。作者探讨了SUPA可靠性、可用性和OAM等问题,并重点研究了SUPA中U-Platform的OAM功能和机制,对所提出的SUPANET中基于重路由的保护机制和基于“带内”OAM的保护交换机制的有效性进行了仿真验证。最后,作者总结了本文的主要研究工作及其创新点,指出这些研究所涉及的相关研究成果为SUPA框架的后续研究奠定了基础。更多还原

【Abstract】 Internet was developed for text-oriented network applications when line transmission rate was very low while error rate was very high. Moreover, U-platform (User-data switching platform) in Internet architecture has congenital defects of complex three-layer structure, low user-data transfer efficiency and bad QoS (Quality of Service) provisioning. With the development of DWDM optical fiber transmission techniques in very high-speed transmission rate and low error rate, a novel DWDM-based backbone network architecture called "SUPA"(Single-layer User-data switching Platform Architecture) is developed at SC-Netcom Lab (Sichuan Network Communication Key Laboratory) to prevent these defects.By re-clarifying out-of-band signaling concept in the context of networking, SUPA separates U-platform from S&M-platform (Signaling&Management Platform), and simplify U-platform into a single physical layer to make it as a basis of backbone nodes for high-speed and high-efficient switching. Meanwhile, oriented to the most popular Ethernet, EPFTS (Ethernet-oriented Physical Frame Timeslot Switching) technology is also promoted at SC-Netcom Lab to combine multiplexing of DWDM physical channel (wavelength) with switching fabrics of switch nodes for greatly improving transfer efficiency, to support Virtual Line connection service for end-users with embedded QoS mechanism in physical layer. The most advantage of SUPA is the integration of the out-of-band signaling and EPFTS over DWDM to support end-to-end QoS service for end-users. Therefore, SUPANET (Single-layer User-data switching Platform Architecture Network) can support audio, video and data services in a single network in order to meet the merged network requirements of NGI (Next Generation Internet) or NGN (Next Generation Network).The author firstly analyzes the challenges of high-speed switching, QoS provisioning, security and access diversity in current Internet, and comprehensively analyzes the domestic and overseas reserach status of NGI/NGN, proposes a basic development approach to cope with the technical challenges in NGI architecture. With the rethinking of inadequacy of orthodox OSI/RM model and current Internet architecture, the author analyzes requirements and general objectives of NGI, provides a new representation of Internet architecture with out-of-band signaling concept, points out that the simplification should be carried out in both platforms (U-Platform and S&M-platform), and proposes a refined model ONAS/RM (Open Network Application Service/Reference Model) to extend OSI/RM architecture to meet the requirements of application virtualization and oriented-service in future networks. To realize the above-mentioned NGI general objectives, ONAS/RM is defined as a new three-layer architecture including Application Supporting Layer, Transport Layer and Substrate Layer.Moreover, in contrast to "evolutionary" or "revolutionary" strategy, SC-Netcom Lab proposes a "BSF-OES"(Backbone Substrate First, Outwards Expansion Second) development strategy to solve the problems in NGI. This strategy is based on the vision of communication world where future backbone networks will be based on low error-rate DWDM with very high bit rates; while access networks will be based on diverse communications techniques possibly with high error-rates. Introduction of the out-of-band signaling enables separation of U-platform from S&M-platform and consequently reduces the U-platform to minimal, especially over optical fiber communications in backbone. Based on consideration of interoperability with Internet and smooth migration from Internet, this strategy implies first to focus on building a thin substrate to cope with high-speed switching problem with embedded QoS mechanism and security measures, and outwards expansion will be done only when backbone technologies are fledged and wherever applicable. In this thesis, SUPA is used as a framework of NGI backbone network architecture to demonstrate feasibility of such strategy and how to cope with technical challenges, to protect investments, and to make smooth migration to NGI. According to BSF-OES strategy, the author also emphasizes three phases of the research and development strategy to EPFTS-based frameworks of SUPA.SUPA phase1is about preliminary study on SUPA focusing on EPFTS in U-platform and remaining existing Internet protocol stacks in S&M-platform with necessary enhancement. The author summarizes the architecture developed in SUPA phase1, discusses the related kernel technique results to demonstrate feasibility of SUPA development strategy, and analyzes the defects in phase1and the necessity of phase2researches and experiments. As a result, the author proposes SUPA phase2as EPFTS based substrate researches and experiments for both U-platform and S&M-platform with further refinement of SUPA. However, SUPA phase3is for further study aiming for a future network model as desribed in ONAS/RM model.As only U-platform is supported by EPFTS in SUPA phase1, the author proposes that S&M-platform in SUPA phase2should be also supported by EPFTS to further simplfy the S&M-platform into a4-layer end-system model. Meanwhile, the author adopts a reconfigurable architecture design of combining out-of-band signaling with in-band signaling to make further refinement of SUPA. For efficiency, it is the inherent design in SUPA that there is separation between S&M-platform and U-platform generically to simplify U-platform with out-of-band signaling, while there is enhancement of functions such as OAM (Operation Administration and Maintenance) in both platforms separately to transfer short "in-band" Signaling&Management informations with in-band signaling.Taking SUPA phase2as the research emphases in this thesis, the author carried out overall study of the architecture developed in phase2. The author puts forward and develops a systematic framework of phase2, with emphasis on EPFTS-based S&M-platform framework and OAM. The author lays stress on discussing S&M-platform and its interfaces, signaling procedures and signaling massage transformation processes, as well as in-band OAM sublayer over EPF (Ethernet-oriented Physical Frame) sublayer in U-platform. Based on finished research on QoS ensurement system of SUPA phase1, the author continues to carry out research on QoS ensurement system in SUPA phase2, defines related SUPA services, protocols and interfaces. The author discusses problems of reliability, availability and OAM, emphasizes on research of U-platform OAM functions and mechanisms in SUPANET, several mechanisms proposed for re-routed protection switch and inband OAM-based protection switch are proved feasible in simulation experiments. Finally, the author sums up the main works and innovations, which results lay a foundation for further research on SUPA frameworks.更多还原