环形IP骨干网

环形网具有很高的生存能力及良好的业务疏导和自愈能力,因此,环形拓扑在传送网中得到了广泛的应用。目前,大多数已建成的SONET传送网或WDM传送网都采用了物理上的环形网结构。尽管本质上环形网由节点间的点到点传输线路组成,但传送网基础设施（包括终端复用器、ADM、DXC等）及光缆线路组成的传输系统平台在电路的调配上却具有相当的灵活性。通过SONET强大的OAM功能,环上节点可在各种子速率下配置成具有不同业务功能的逻辑拓扑结构,如星形、环形、格形等。SONET这种基于同步复接技术的电路调配方式在最初的IP网络规划中也…     

SUCCESS-DWA: a highly scalable and cost-effective optical access network

Passive optical networks have been identified as promising access solutions that can open the first-mile bottleneck, bringing gigabits-per-second data rates to end users. Current TDM PONs enjoy low cost by sharing resources in time, but suffer from limited capacity. In the future, WDM technology may be employed to achieve high performance. In this article we introduce a novel PON employing dynamic wavelength allocation to provide bandwidth sharing across multiple physical PONs. Tunable lasers, arrayed waveguide gratings, and coarse/fine filtering combine to create a flexible new optical access solution. The network's excellent scalability can bridge the gap between conventional TDM PONs and WDM PONs. The powerful architecture is a promising candidate for next-generation optical access networks.     

IP switching for scalable IP services

Internet protocol (IP) switching is emerging as a critical technology for improving the speed and scalability of the Internet. This paper discusses IP Navigator, a form of IP switching developed specifically for use in core network backbones, such as Internet service provider networks and major corporate backbones. IP Navigator combines the high speed and quality of service capabilities of asynchronous transfer mode (ATM) with the scalability and flexibility of IP. This paper presents an overview of the techniques that have been developed for operating IP over ATM. We outline the IP Navigator design and compare IP Navigator with other IP switching approaches     

Designing scalable on-demand policy-based resource allocation in IP networks

Today, the policy-based management approach is recognized as an efficient solution to simplify the complex task of managing and controlling networks. To this end, the IETF has introduced a reference framework to build PBM systems. However, this framework only addresses the provisioning of relatively long validity period services based on pre-defined service level agreements. Furthermore, very little work addresses the scalability properties of the instantiation of this framework in a real network. This work aims to extend the IETF PBM framework in order to support dynamic provisioning of short term services (end system signaling) as well as an instantiation scheme that is scalable (distributed provisioning of edge routers). This instantiation scheme is based on the distribution of the provisioning process while keeping centralized only the parts that involve critical resources, that is, the bandwidth brokerage. The performance properties of the proposed scheme are then demonstrated throughout both extensive experimentation and a short analytical study. The results of this work are intended to be used as a guideline to help network operators to design scalable PBM system in order to offer to their customers services with QoS assurance in an on-demand basis.     

Analysis and design of backbone architecture alternatives for IP optical networking

The unprecedented growth of IP traffic is leading Internet service providers and network operators worldwide to investigate architectural alternatives for cost effective, reliable, scalable, and flexible multiterabit IP backbones. In this paper, several overlay, service, and transport layer networking architectures, which employ IP, MPLS, SONET/SDH, and DWDM technologies, are proposed and analyzed. Multiple parameters, such as network capacity, cost, restoration strategy, reconfigurability, and accommodation of preemptable traffic, are considered for the architectural comparison. Detailed network design and economic analysis are provided for the different alternatives considering a typical nationwide U.S. backbone with projected IP traffic in approximately three years. Several sensitivity analysis results are also shown, to evaluate the effect of cost changes in some of the critical technological factors in these architectures, such as 10 Gb/s optics cost or IP router cost. The results show the value of transport layer networking architectures for multiterabit IP backbones, and how, when compared to service layer architectures, they provide additional desirable features such as wavelength reconfigurability and restoration scalability.     

光交换、路由器与P比特级IP网

为了适应广域网（ＷＡＮ）对带宽需求的高速增长，必须以格形全光广域核心网取代现有的同步光环网（ＳＯＮＥＴ）。人们对在核心网络中采用波长交换技术给予了极大的关注，却忽略了光交换技术在核心网边缘的光分组路由器的重大作用。 当今路由器的端口数一般是每束光纤中光纤数目的数倍，这在目前是绰绰有余的，因为可以把每一束光纤当作一个目的地来处理。但是为了有效地利用波长交换，必须把每一个收到的分组搭在适当的波长上以便直接送到距最终目的地最近的节点，从而尽量减少中间路由。当每个路由节点的端口数与它所服务的波长数相当时…     

Deflection routing in IP optical networks

This paper deals with optical packet switching in a full-IP transport network scenario. Given the technological limits of accomplishing packet buffering in the optical domain, deflection routing is here explored as an alternative technique for resolving packet contentions without buffering packets. Two different network topologies have been considered here, that is a regular six-node network with different connectivity factors and the classical NSF network. A limited amount of optical buffering is considered in the switching nodes that performs both input queuing and shared queuing of packets to be switched. The performance improvements that can be obtained by deflection routing have been evaluated considering different methods for choosing the alternative paths where to deflect packets that cannot be transmitted onto the shortest path to the addressed destination.     

Evolution of optical core networks

Optical networks have developed rapidly over the last ten years and show every sign of continuing to grow and adapt to the newchallenges of supporting more traffic, more reliably and flexibly, at lower cost. We briefly review the developments of the last tenyears and then discuss current thinking on how core optical networks will develop into the future, exploring the similarities anddifferences with the previous generation of technologies. We have attempted to provide a low-jargon paper with links to moredetailed studies where appropriate.     

Evolution of optical core networks

Optical networks have developed rapidly over the last ten years and show every sign of continuing to grow and adapt to the new challenges of supporting more traffic, more reliably and flexibly, at lower cost. We briefly review the developments of the last ten years and then discuss current thinking on how core optical networks will develop into the future, exploring the similarities and differences with the previous generation of technologies. We have attempted to provide a ‘low-jargon’ paper with links to more detailed studies where appropriate.     

IP over optical networks: architectural aspects

The Internet transport infrastructure is moving toward a model of high-speed routers interconnected by intelligent optical core networks. A consensus is emerging in the industry on utilizing an IP-centric control plane within optical networks to support dynamic provisioning and restoration of lightpaths. At the same time, there are divergent views on how IP routers must interact with optical core networks to achieve end-to-end connectivity. This article describes the architectural alternatives for interconnecting IP routers over optical networks, considering the routing and signaling issues. Also, the application of IP-based protocols for dynamic provisioning and restoration of lightpaths, as well as the interworking of multivendor optical networks is described     

IP over DWDM宽带IP主干网

随着Internet(因特网)主机数的增长以及宽带业务带来的主机业务流量的增加，互联网上业务量以指数形式增加。作为一种最有前途的解决用户需求不断增加的方案。IP overDWDM(基于密集波分复用的互联网协议)受到业界的广泛关注。为此主要讨论了IPoverDWDM技术，包括其原理、关键器件、路由选择以及发展趋势。     

Waveband grooming and IP aggregation in optical networks

An automatically switched optical network (ASON) can be used as the transport layer of generalized multiprotocol label switching (GMPLS) networks. The design of an ASON involves determining the number of optical cross-connects (OXC) in the network, the required number of ports per OXC, and the interconnection topology of the OXCs. Given the number of ports per OXC, we present a linear algorithm to find the number of OXCs and to identify a cost-effective topology. We then develop a scheme that can be used to perform waveband grooming for several different topologies of an ASON that uses single-layer multigranular OXCs. We identify the bottlenecks and investigate the effect of traffic grooming schemes in the design of an ASON as a function of the peak access rate per customer. We evaluate the topologies and architectures for a national trunk network.     

Multipath routing with topology aggregation for scalable inter-domain service provisioning in optical networks

In this paper, we propose to use static virtual topology for a scalable inter-domain optical service provisioning, while addressing the resource efficiency issue by using multipath routing. To this end, we discuss methods for virtual topology aggregation with consideration of inter-domain routing, and propose two heuristic algorithms for two representative applications, referred to as real-time streaming and bulk data transfer. We consider specific requirements of each application, including transmission deadline and jitter, and evaluate the impact of differential delay issue of multipath routing on the performance of proposed algorithms. Numerical results show that the proposed multipath routing algorithms yield a low blocking ratio of inter-domain connections even on the static virtual topology, which is known for poor blocking performance otherwise. The resulting differential delay is sufficiently small for the studied applications, and can be compensated with relatively small buffers. We show that a scalable inter-domain service provisioning in optical networks can be achieved by using a combination of static virtual topology and multipath routing.     

A framework of scalable optical metropolitan networks for improvingsurvivability and class of service

The issues of scalability and class of service have been among the most important research focuses in design of the control plane for wavelength-routed WDM networks. We introduce a framework for achieving a scalable design in metropolitan area networks with WDM as the core technology (called optical metropolitan networks). The framework is summarized with the topics of survivability, scalability and class of service. A novel design concept, called interarrival planning, which aims to achieve scalable control and management in optical metropolitan networks, is addressed     

IP骨干网流量的自动化预测

高效、可靠的网络流量预测是网络规划、扩容建设的基础。互联网流量目前缺乏完备的理论模型,行业内大多根据工程实践特点,设计简化可操作的预测模型以满足IP网络规划需求。首先根据中国电信自身IP骨干网流量预测工作的需求及特点,使用时间序列分析的多因子回归模型和函数自适应模型对IP骨干网流量进行分析和预测,基于大量现网实际数据的仿真运算,对比两种模型的特点、优劣和适用场景,提出了一种预测模型选择和参数优化的原则和方法。在此基础上,构建了可以满足百千量级时间序列要求的自动化流量预测系统,极大简化并提升了流量预测工作的效率。最后,展望了未来IP流量预测工作的延展方向和关注重点。     

Low-loss wavelength routers for WDM optical networks and high-capacity IP routers

The author proposes, for future wavelength-division-multiplexing (WDM) optical networks, new wavelength routers with reduced losses and improved wavelength response. This paper focuses on the most general type of wavelength router, the N/spl times/N router. This device is particularly attractive in a metropolitan network, where a star arrangement based on the N/spl times/N router allows the network configuration (the wavelength path of each signal) to be varied and managed in a simple fashion. The N/spl times/N router has been shown to be suitable for both packet and circuit switching. In particular, ultrahigh-capacity IP routers have been demonstrated by using fast tunable lasers and burst mode receivers.     

Architectures and performance of optical packet switching nodes for IP networks

As new bandwidth-hungry Internet protocol (IP) services are demanding more and more capacity, transport networks are evolving to provide a reconfigurable optical layer in order to allow fast dynamic allocation of wavelength-division-multiplexing (WDM) channels. To achieve this goal, optical packet-switched systems seem to be strong candidates as they allow a high degree of statistical resource sharing, which leads to an efficient bandwidth utilization. In this paper, we propose an architecture for optical packet-switched transport networks, together with an innovative switching node structure based on the concept of per-packet wavelength routing. The traffic performance of such node when loaded by a typical IP traffic is evaluated through computer simulation; packet loss probability and average delay performance are shown for various load conditions.     

Architectures and performance of AWG-based optical switching nodes for IP networks

In order to support the continuous growth of transmission capacity demand, optical packet switching technology is emerging as a strong candidate, promising to allow fast dynamic allocation of wavelength-division multiplexing (channels, combined with a high degree of statistical resource sharing). This work addresses the design of optical switch architectures, based on previous proposals available in the technical literature that use an arrayed waveguide grating (AWG) device to route packets. Since the port number of currently available AWGs is a limiting factor, we propose two new modified structures which better exploit the switching capability of this component in the wavelength domain. Since a limited hardware complexity is a key requirement for all-optical switches, due to the high cost of optical components, these different node configurations are compared in terms of complexity. Traffic performance of these new structures in a full optical packet switching scenario is also examined.     

Resilience for IP-over-DWDM backbone networks

Given the extensive growth in Internet traffic and increasing emphasis on service quality, one of the most crucial elements of IP backbone network design is to provide resilience to serious failures such as fibre-optic cable breaks. In previous years, the unit of bandwidth granularity for many IP backbone networks has grown from STM-1 (155 Mbit/s) through to STM-16 (2.4 Gbit/s), with STM-64 (10 Gbit/s) backbone circuits becoming prevalent. The increased concentration of traffic makes the IP backbone extremely vulnerable to failure, meaning a key challenge is to engineer embedded resilience into the network. This paper considers such issues and discusses various trade-offs associated with different levels of protection in an IP backbone network