摘 要
随着网络传输速度的飞速发展，网络故障对网络的影响越来越大，因此光网络保护成为越来越引起研究者的注意。根据所保护网元的范围，可将保护方法可以分为链路保护、路径保护和分段保护3类；根据备用路径上资源的使用情况，可以将保护方法分为共享保护和专有保护2类。如何缩短故障倒换时间并降低资源消耗是当前光网络生存性研究所面临的主要问题。分段保护的保护范围适中，保护方式较为灵活，因此得到了广泛关注。现有的分段保护方法通常将整个工作路径划分为多个工作段实施逐段保护，这样的完全保护方式虽然能够实现链路的可靠保护，但需要消耗大量的网络资源；并且，在动态网络环境下，这种完全保护方式属于被动的保护设计方式，即预先考虑到所有可能发生的故障位置并对其全部预留保护资源，无法对直接影响网络可靠性的重负载链路实现重点保护，因此不能适应动态变化的突发性网络环境。网络编码作为最新兴起技术，其思想是一种融合编码和路由的信息交换技术，该思想在传统存储转发的路由方法基础上，通过允许对多个数据包进行编码信息融合，增加单次传输的信息量，从而提高网络整体性能。网络编码的主要优势在于如果己知网络的拓扑结构及链路容量，就可以计算出源点到多个目的节点的最大信息吞吐量，它可以使资源得到充分利用，并且能使网络资源利用达到理论上限，这有赖于网络节点在转发信息前对接收数据进行编码。
光网络中采取共享保护的模式，改进一种新的基于单链路故障的1+N保护机制．此机制在核心节点处进行线性组合，在不通过故障监测和定位的情况下仍然能准确地恢复出由于链路故障丢失的数据。
本文针对现有波分复用（WDM）网络保护机制倒换时间长、资源消耗较大的问题，提出了一种低开销的动态1+N 专有分段保护（DSDP）策略，能够根据当前网络资源耗费情况动态地确定需要保护的网元，采用线性编码方法，利用单个工作路径对多个工作路径进行专有保护。根据文献提出策略能极大地降低用于保护的网络资源消耗，同时能有效地利用光网络资源。 【关键词】：光网络 网络编码 分段保护 1+N保护
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ABSTRACT
With the rapid development of the network transmission speed, the increasing influence of network faults on the network, optical network protection become more and more aroused the attention of researchers. Protected by a range of network elements, protection methods can be divided into link protection, path protection and segmentation to protect three categories; resource usage on the alternate path protection methods can be divided into shared protection and proprietary protection classes. How to shorten the fault switching time and reduce resource consumption is the main problem facing the current optical network survivability Institute. Segmented protection scope of protection is moderate, the protection of a more flexible way, so get wide attention. Segment protection method is usually the working path is divided into multiple working segment in the piecewise protection, full protection mode to achieve the reliable protection of the link, but need to consume large amounts of network resources And dynamic network environment, this fully protect a passive protection design, that is, anticipate all the possible fault locations and all of its reserved for the protection of resources, can not be a direct impact on network reliability, the heavy load chain Road key protection, and therefore can not adapt to the sudden dynamic changes of network environment. Network coding as the latest rise of technology, its thinking is a fusion of coding and routing information exchange technology, the routing method based on the forward thinking in traditional storage, by allowing multiple packets to encode information fusion, single transmission The amount of information, thereby improving overall network performance. The main advantage of network coding is known to the network topology and link capacity, we can calculate the maximum information throughput of the source to multiple destination nodes, which can make the resources are fully utilized and enables utilization of network resources to achieve theoretical limit, which depends on the network node to encode the received data before forwarding
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information.
1+N protection mechanism based on a single link failures is proposed in this paper．which take shared protection mode1．This mechanism performs linear combination in the core nodes．and it can still ac—curately recover lost data due to 1ink failures without fauh monitoring and location．Compared with the traditional protection．simulation experiments show that 1+N protection can reduce the wavelength resource consumption．With l+N protection their resources are still available to conduct short—term recovery．
In order to solve the issues of long switching time and high resource consumption for protection in wavelength division multiplexing(WDM) network, an effective low-cost dynamical segmentel 1+N dedicated protection strategy is introduced. According to resource consumption condition , the strategy can dynamically determine the sements for protection .Based on network coding, a single backup path can be established to provide dedicated 1+N protection for multiple working paths. Simulations show that the strategy can reduce the wavelength consumption. Moreover, the strategy also can use the network resources effectively.
【Key words】 Optical Network network coding segmented protection 1+N protection
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目 录
前 言............................................................................................................................ 1 第一章 光网络............................................................................................................ 2 第一节 光网络的发展 ............................................................................................ 2 第二节 自动交换网络（ASON）......................................................................... 3 第三节 光网络的优点 ........................................................................................... 4 第四节 本章小结 ................................................................................................... 5 第二章 光网络保护与网络编码................................................................................ 6 第一节 光网络中的保护技术 ................................................................................ 6 一、WDM光网络的保护和恢复技术 ................................................................ 6 二、WDM光层保护和恢复技术的优点 ............................................................. 7 第二节 光网络中保护的方式 ................................................................................ 8 一、WDM网状光网络路由方式的保护方式 .................................................... 8 二、当用路径上资源的使用情况不同时的保护方式........................................ 9 第三节 网络编码的提出和发展现状.................................................................. 10 一、网络编码的提出.......................................................................................... 10 二、网络编码的好处.......................................................................................... 11 第四节 网络编码的分段保护机制 ...................................................................... 16 第五节 本章小结 .................................................................................................. 21 第三章 分段保护机制研究...................................................................................... 21 第一节 分段保护 .................................................................................................. 21 一、1+N 节点保护模型 .................................................................................... 21 第二节 保护段的建立方式 .................................................................................. 23 第三节低代价的动态1+N保护策略 .................................................................... 26 第四节 基于单链路故障的新的1+N的保护思想 ............................................. 28 第五节 本章小结 ................................................................................................. 30 结 论.......................................................................................................................... 32
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致 谢.......................................................................................................................... 33 参考文献...................................................................................................................... 34 附 录...................................................................................................................... 37 一、 英文原文...................................................................................................... 37 二、 英文翻译...................................................................................................... 41
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