OBS网络边缘节点实现方案及相关技术研究

【作者】 罗洪斌；

【导师】 胡钢；

【作者基本信息】 电子科技大学 ， 通信与信息系统， 2004， 硕士

【摘要】 随着网络业务量的爆炸性增长以及高性能光网络设备(如光交叉连接器OXC、光分插赋予器OADM)等的出现,波分复用技术成为下一代骨干网络的核心技术。网络业务不但对网络带宽产生越来越高的需求,而且由于IP业务本身的不确定性和不可预见性,要求网络能够为用户提供各种带宽粒度的服务和应用。然而,当前的网络大都是基于波长路由(WRON)的。众所周知,波长路由技术的最小粒度是一个波长,不能提供更小粒度的服务。从而使得网络的带宽利用率非常低。另一方面,光分组交换技术(OPS)也由于光器件的不成熟而陷入了困境。在这一背景下,光突发交换技术(OBS)应运而生。OBS的基本思想有两个方面:突发包的汇聚(也就是将多个较小的IP分组汇聚成一个大的突发包)以及其传输与控制的分离。OBS技术不但具有OPS技术以及WRON技术的优点,同时克服了它们的缺点。通过本文第三章对这三种技术的比较可以看出,光突发交换技术在支持分组业务的性能上高于波长路由方式,而实现难度(尤其是对光器件技术的要求)低于光分组交换。本课题来源于国家“863”高科技项目“光突发交换网络”。本文重点研究光突发交换网络边缘节点的实现方案及其相关技术。本文第一章介绍了光网络的发展概况和交换技术的发展历程。本文第二章从光突发交换网络的特点、光突发交换网络的总体控制方案以及光突发交换网络的核心节点控制方案等几个方面介绍了光突发交换网络的发展现状。本文第三章详细介绍了光突发交换网络边缘节点的实现方案并重点介绍了光突发交换网络边缘节点的结构,各个部分的功能及其实现方式。针对光突发交换网络中非常重要的突发排队,在本文第四章提出了三种突发排队方式[L1],即:集中排队方式、独立排队方式以及混和排队方式,并对它们的性能进行了理论分析和仿真研究。研究结果表明:集中排队方式在几种排队方式是最好的。本文第五章研究了边缘节点处突发队列的配置及其管理方式。本文提出了三种突发队列管理策略[L8],即:静态突发队列管理策略、伪静态突发队列管理策略以及动态突发队列管理策略,并对它们的性能进行了理论分析和仿真研究。特<WP=9>别的,本文从可扩展性方面对这几种突发队列管理策略进行了对比研究。研究结果表明:与其它两种突发队列管理策略相比,动态突发队列管理策略下所需的缓存最少,对可扩展性的支持更好,因而是最好的。由于光突发交换网络不能够有效的支持服务质量,因此,在本论文承担的项目中,采用了一种复合技术,即在一个光网络中既利用一部分波长运行光突发交换又利用一些波长运行SDH。本文第六章对这一混和网络结构的性能进行了研究[ L2]。由于WDM交换机的容量对光网络的性能具有巨大的影响,本文第七章研究了在波长变换的情况下,无阻塞WDM交换机的容量问题[L4]。最后是全文总结。更多还原

【Abstract】 With the explosive increase in network traffic and the emergence of high performance optical network devices, such as optical cross-connect (OXC) and optical add/drop multiplexer (OADM), wavelength division multiplexing (WDM) technology becomes the core technology of next generation networks. Because traffics are uncertain and unpredictable, optical networks are required to rapidly provide high-quality multi-granularity bandwidth services and applications to users. However, the dominant backbone networks are based on wavelength routing technology. As is well known, the minimum granularity used in the wavelength routing technology is a wavelength. And this leads to low utilization efficiency for the titantic bandwidth provided by the WDM technology. At the same time, optical packet switching (OPS) technology is falled into dilima due to lacking of available optical random access memory and to the difficulty in synchronization. To overcome these problems, optical burst switching (OBS) is proposed in the literature. The basic ideas underlying the OBS are two aspecs: the burstification (i.e. assemble multiple IP packets into a larger data burst) and the separation of transimmison and control. The OBS technology not only can combine the advantages of the wavelength routing technology and the optical packet switching technology, but also can overcome their disadvantages. From the comparison made in chapter 3, one can see that the OBS technology outperforms the wavelength routing technology in supporting packet traffic and is easier than the OPS technology in reasilization.The reaserch in this thesis comes from the hi-tech Research and Development Program of China under contract NO.2002AA122021. The focus in this thesis is on the realization of the OBS network edge node and correlant critical technologies such burstification queue manner, burstification queue management. Firstly, This thesis briefly reviews the ongoing project related to the optical technology and the history of switching technology in chapter 1. And chapter 2 briefly reviews the various aspecs of OBS networks, especially on the charater of OBS technology, on the control mechanism of the OBS network and on the critical technologies telated to the core node of OBS networks.Chapter 3 describes the architecture of an OBS edge node and the realization scheme in detail. Some related technologes are also presented in this chapter.Since there is no research on the burstification manner, which refers how to <WP=11>switch the incoming traffic from the line cards equipped at the OBS edge node to the burstification queues, chapter 4 proposes three burstification queue manners: centralized burstification queue manner, individual burstification queue manner and hybrid burstification manner. The performance of the three burstification queue manner is extensively studied by analysis and simulation. Results from analysis and simulations demonstrate that the centralized burstification queue manner is the best among them.Chapter 5 studies the burstification queue management problem, which refers to how many burstification queues we should set at each OBS ingress edge node and how to manage these burstification queues efficiently. This thesis proposes thress burstification queue management policies: static burstification queue management policy, quasi-static burstification queue management policy and dynamic burstification queue management policy. The performance of the three burstification queue management policies is studied in this thesis. Besides the analysis, extensive simulations are also made. Results from analysis and simulations demonstrate that the dynamic burstification queue management policy outperforms the other two burstification queue management policies since it employs less buffer and has better scalability than the other two burstification queue management policies.Since it’s difficult to support Quality-of-Service (QoS) in optical burst switching networks, in our project, we take a hybrid network architecture. That is, we combine the wavelen更多还原