WDM智能光网络与IP业务

详细分析了 ＷＤＭ光网络的结构以及联网技术的演进过程，对如何压扁网络层次，实现ＩＰ直接ｏｖｅｒ ＷＤＭ，发挥 ＷＤＭ光传送网的巨大带宽优势进行了研究，提出 ＭＰＬＳ是当前解决 ＩＰ层与光层的融合以及跨层管理问题的关键技术。     

Energy Consumption in Optical IP Networks

As community concerns about global energy consumption grow, the power consumption of the Internet is becoming an issue of increasing importance. In this paper, we present a network-based model of power consumption in optical IP networks and use this model to estimate the energy consumption of the Internet. The model includes the core, metro and edge, access and video distribution networks, and takes into account energy consumption in switching and transmission equipment. We include a number of access technologies, including digital subscriber line with ADSL2+, fiber to the home using passive optical networks, fiber to the node combined with very high-speed digital subscriber line and point-to-point optical systems. In addition to estimating the power consumption of today's Internet, we make predictions of power consumption in a future higher capacity Internet using estimates of improvements in efficiency in coming generations of network equipment. We estimate that the Internet currently consumes about 0.4% of electricity consumption in broadband-enabled countries. While the energy efficiency of network equipment will improve, and savings can be made by employing optical bypass and multicast, the power consumption of the Internet could approach 1% of electricity consumption as access rates increase. The energy consumption per bit of data on the Internet is around 75 ${bm mu}$J at low access rates and decreases to around 2–4 ${bm mu}$J at an access rate of 100 Mb/s.      

A Bandwidth Guaranteed Integrated Routing Algorithm in IP over WDM Optical Networks

In this paper, we have developed an integrated online algorithm for dynamic routing of bandwidth guaranteed label switched paths (LSPs) in IP-over-WDM optical networks. Traditionally, routing at an upper layer (e.g., IP layer) is independent of wavelength routing at the optical layer. Wavelength routing at the optical layer sets up a quasi-static logical topology which is then used at the IP layer for IP routing. The coarse-grain wavelength channels and the pre-determined virtual topologies with respect to some a priori assumed traffic distribution are barriers to efficient resource use and inflexible to changing traffic. We take into account the combined knowledge of resource and topology information at both IP and optical layers. With this added knowledge, an integrated routing approach may extract better network efficiencies, be more robust to changing traffic patterns at the IP layer than schemes that either use dynamic routing information at the IP layer or use a static wavelength topology only. LSP set-up requests are represented in terms of a pair of ingress and egress routers as well as its bandwidth requirement, and arrive one-by-one. There is no a priori knowledge regarding the arrivals and characteristics of future LSP set-up requests. Our proposed algorithm considers not only the importance of critical links, but also their relative importance to routing potential future LSP set-up requests by characterizing their normalized bandwidth contribution to routing future LSP requests with bandwidth requirements. Moreover, link residual bandwidth information that captures the link's capability of routing future LSPs is also incorporated into route calculation. Extensive simulation was conducted to study the performance of our proposed algorithm and to compare it with some existing ones, such as the integrated minimum hop routing algorithm and the maximum open capacity routing algorithm. Simulation results show that our proposed algorithm performs better than both routing algorithms in terms of the number of LSP set-up requests rejected and the total available bandwidth between router pairs.     

WDM光网络上宽带IP的传送方式

综述了基于波分复用 ( WDM)技术的光网络发展以及因特网技术和 IP业务的特点 ,在此基础上介绍并分析比较了光网络上传送 IP的多种方式 ,包括 WDM光网络上ATM、SDH以及千兆比以太网与 IP网络相结合形成网络的协议和结构。最后探讨了未来宽带 IP传送网络的发展方向。     

一种数据封装新格式--GFP

介绍了一种新的用于宽带传输的流量适配协议-通用成帧过程(GFP),它提供了有效的和QoS友好的机制,将各种不同物理层或逻辑链路层信号映射到字节同步通道上,也支持基于用户管理目的的基本客户控制功能.介绍了GFP的技术特点,并与当前应用最为普遍的一些适配协议进行了比较.     

WDM网络中的光层组播技术

组播应用主要是一些带宽密集型的业务,而光网络又能够提供巨大的带宽。随着光通信技术的发展,如何在光层实现组播已经成为光网络研究的热点之一。主要介绍了组播的应用以及在光层实现组播的关键技术;分析了实现光层组播的节点结构、光树的概念以及针对组播的波长路由算法。     

Dynamic Routing and Wavelength Assignment Using Cost Based Heuristics in WDM Optical Networks

Dynamic routing and wavelength assignment problem in optical networks is a two-step problem that is influenced by the choice of a successful optimal path selection and wavelength assignment. Proper selection techniques reduce the number of wavelengths required in the network and thereby improves traffic grooming. Heuristic algorithms and integer linear programming models help in selection of route and wavelength separately. Hence, the computation time is large which makes the system slow. A cost function is computed which uses independent parameters in the network for the selection of route and wavelength for a call. The heuristic reduces computation time by combining the search of route and wavelength to be assigned. In addition, the network performance is analyzed with and without alternate routing along with proposed heuristics. The selection of proper route and wavelength finding technique is very essential since it improves the grooming factor of the network thereby allowing more traffic support by the network. Our objective is to investigate and propose a cost based heuristics for dynamic traffic routing and wavelength Assignment in WDM optical networks. For this we plan to develop cost functions and heuristics to compute the route and wavelength assignment strategy. Here, our objective is to reduce the computation time for selection of route and wavelength assignment strategy by weighted cost function. The function has to include network parameters for its processing. Our work provides an overview about DRWA by applying cost based heuristics in WDM networks. This paper explains the proposed cost function and its applications in line with selection of independent parameters. The details of other functions like cost function formulation, hop-based route assignment, available wavelength based route assignment, mathematical analysis of proposed cost function are also explained. Results and discussions based on the findings are presented.

     

WDM光网络的多优先级业务疏导机制

IP over WDM网络中,业务疏导能有效提高波长带宽利用率.然而,单一化的业务疏导机制难以满足不同业务的QoS要求,也很难做到经济合理地使用光路.提出了一种支持多优先级业务的疏导机制,该机制根据光路传输的时延和丢包特性来选择恰当的疏导路径,同时,该机制结合了抢占和流量分割技术,能有效地实现流量分割和多路抢占,降低了业务的阻塞概率.仿真结果显示,该疏导机制在保证业务QoS的同时,降低了高优先级业务的阻塞概率;在业务负载低时,能有效减少抢占.     

WDM光网络的研究进展

波分复用技术（WDM）在主干传送网应用越来越普遍,WDM网络技术的研究也获得了迅速发展,综述了当前主干WDM网络的最新研究进展和发展趋势。     

Topics in Optical Communications - Service Differentiation and Traffic Engineering in IP over WDM Networks

The emergence of WDM-based optical transport has brought about unprecedented potential for ultra-high-speed IP core networks. It also holds great challenges, not least of which is to determine the optimal way of merging the optical domain with the IP domain. Beyond this issue, still a subject of research, the path to an efficient and resilient optical transmission IP core network is beset by numerous difficulties caused by shortcomings inherent to IP. Simply merging WDM and IP will not automatically produce a core network capable of serving the needs and adapting to the nature of diverse IP traffic. This article demonstrates the complexities of and proposes a possible solution for optimizing the next-generation core network, evolving the management plane IP/WDM integration model proposed in the 1ST WINMAN project. We concentrate on making the core network efficient for transporting differentiated service traffic, adaptive to changes in traffic patterns and resilient against possible failures, which would disrupt its operation. To these ends we introduce MPLS TE and DiffServ QoS functionality in our network model, thus ensuring maximum utilization of resources and automated guarantees of optimal quality for different types of transported traffic.     

WDM光网络的保护和恢复技术

文章概述了IP、SDH和WDM层网络的生存性技术,重点介绍了光传送网的光层生存性技术与光网络恢复技术,还对故障定位、多层生存性机制的协调等问题进行了简单介绍,最后给出了一个业务配置RWA算法与恢复RWA算法的实际方案。     

具有容错策略的波分复用光传输网络

针对波分复用光传输网络,提出了一种关键光路的容错策略。这种策略为网络中的每个节点预保留信道资源。在网络出现故障后,不同节点之间预保留的信道可以共享,极大地减少了预保留的资源数量。实验模拟显示,在单个错误恢复率略略降低(不到1%)的前提下,预保留的资源只占总资源的不到18%,恢复时间没有延长。结合这种容错策略,也提出了新的分布式容错策略,恢复时只需要非常少的额外资源,而网络能够快速地恢复多个错误。     

IP/WDM网络生存性策略分析

本文在研究网络生存性基本问题的基础上，分析IP层中缩短IP动态路由恢复时间的改进策略和基于MPLS的生存性策略；同时，对不同方案的资源利用率和保护倒换时间进行了比较；最后探讨了多层生存性协调可能遇到的挑战。     

WDM光网络中的业务疏导

目前WDM光网络普通用户大量的一般业务请求数目及波长通道带宽的不断增加极大的增加了网络中电层和光层设备的处理负担,增加了网络成本。对低速电信号复用到高速光通道进行优化,减少网络电层设备的使用,降低网络成本的业务疏导(TrafficGrooming)技术成为目前光网络研究的一个热点。本文主要介绍了WDM光网络中的业务疏导问题的基本概念、技术特点、国内外研究现状进行了总结。     

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。     

IP over WDM网中的综合选路算法

研究了IP over WDM网中,当节点不具备波长变换能力并且配备有限光收发器对时,如何利用综合选路(IR)算法为到达业务请求建立标签交换路径(LSP)。提出一种新颖的辅助图模型(AGM)表示网络的当前状态,基于AGM提出一种动态IR算法-最小光收发器对法(MTA)。MTA总是选择占用光收发器对最少的通路来建立LSP,仿真结果表明：与已有算法相比,MTA可以降低全网的阻塞率,从而提高业务通过率,并且有利于减少业务连接所经光／电变换的次数。     

WDM光突发交换网中的生存性问题

光突发交换拥有光电路交换和光分组交换两种方式的主要特征,是未来光网络的一种有希望的实现形式,本文对wDM光突发交换网络的实现做了简要的介绍,主要从wDM光突发交换网络的生存性出发对相关问题进行了分析研究,并提出了相应的解决方案.     

Cost Effective Shared Path Protection for WDM Optical Mesh Networks with Partial Wavelength Conversion

In this paper, we study routing and wavelength assignment of connection requests in survivable WDM optical mesh networks employing shared path protection with partial wavelength conversion while 100% restorability is guaranteed against any single failures. We formulate the problem as a linear integer program under a static traffic model. The objective is to minimize the total cost of wavelength-links and wavelength converters used by working paths and protection paths of all connections. A weight factor is used which is defined as the cost ratio of a wavelength converter and a wavelength-link. Depending on the relative cost of bandwidth and wavelength conversion, the optimization objective allows a proper tradeoff between the two. The proposed algorithm, the shortest-widest-path-first (SWPF) algorithm, uses a modified Dijkstra's algorithm to find a working path and a protection path for each connection request in the wavelength graph transformed from the original network topology. When there are multiple candidate paths that have the same minimum total cost, the path along which the maximum number of converters used at each node is minimized is chosen by the SWPF algorithm. We have evaluated the effectiveness of the proposed algorithm via extensive simulation. The results indicate that the performance of the proposed algorithm is very close to that of the optimal solutions obtained by solving the ILP formulation and outperforms existing heuristic algorithms in terms of total number of converters used and the maximum number of converters required at each node in the network. The proposed algorithm also achieves slightly better performance in terms of total cost of wavelength-links and converters used by all connections. We also investigated shared path protection employing converter sharing. The results show that the technique can reduce not only the total number of converters used in the network but also the maximum number of converters required at each node, especially when a large number of converters are needed in the network. In this study, although the ILP formulation is based on static traffic, the proposed algorithm is also applicable to routing dynamic connection requests.     

Light-Path Provisioning of the WDM Optical Networks

1IntroductionThere is no doubt that, in the predictable near fu-ture, the circuit switching paradigm will continuously play an active role in the commercial wavelength-divi-sionmultiplexing (WDM) optical networks. In such envi-ronments the end-to-end services are provided by light-paths(LPs) which are established prior to the ses-sion of data transmissions. Like its electronic counter-part, the WDM network is a multi-layer architecture. On the physical layer, the WDM network can be chara…     

A Study of Several Problems Concerning WDM Optical Transmission Networks

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