【作者】 胡曦明；

【导师】 汪斌强；

【作者基本信息】 解放军信息工程大学 ， 通信与信息系统， 2007， 博士

【摘要】 网络电视打破了传统广播电视的信息分配模式,给人们获取、传播与利用信息的方式和效率带来革命性进步,给信息通信技术产业的发展带来全新机遇。从满足终端用户需求和产业发展要求的角度,网络电视业务是互联网发展的主流业务,充分体现了应用牵引的网络发展模式。由于现有边缘网的承载服务能力无法满足网络电视业务可控制、可管理和可运营的综合要求,国家863计划高性能宽带信息网(3Tnet)启动了重大子项课题—“大规模接入汇聚路由器(ACR)系统性能和关键技术研究”。ACR要实现对网络电视业务的支持,需要可有效支持网络电视业务的交换结构,而网络电视的应用将产生大规模的组播通信,这使得ACR的交换结构不能采用目前常用的为组播业务处理预留冗余资源的交换结构设计方法。由于ACR的交换结构对网络电视数据的处理,直接关系到ACR的工作性能,所以如何设计一种有效支持网络电视业务的交换结构,成为ACR研发过程中需要解决的关键课题。针对ACR的研发需求,本文以有效支持网络电视业务的交换结构为研究课题,依托ACR项目开展了研究工作。交换结构对网络电视数据的处理不是一种简单的组播数据处理,需要满足网络电视体验质量保障的要求,这使得现有复制组播、扇出组播和受限复制组播的组播交换结构模型,不能为如何设计有效支持网络电视业务的交换结构提供明确可行的解决方案。为此,本文首先通过深入分析网络电视数据的传输过程,发现了到达交换结构的网络电视数据所具有的特征;在此基础上,本文基于具有理想工作性能的输出排队交换结构的工作原理,提出了一种有效支持网络电视业务的交换结构模型——扇出无关交换结构,其核心思想是;交换结构输入端口的缓存中如果没有数据在排队,那么表明所有到达交换结构的数据均能立即被交换结构进行相应的数据处理并传输至输出目的端口中进行排队;并且,当输入数据在一定范围内变化时,无论端口规模如何变化,交换结构保持输入端口中无数据缓存状态所需的加速比或者传输链路扩展倍数保持一定;然后,由输出端口采用适当的输出排队策略来输出网络电视数据,从而为网络电视业务提供满足其传输带宽要求的输出链路带宽,由此可以满足网络电视体验质量保障的要求。随后,本文依照扇出无关交换结构模型,采用空分的数据处理思想,设计了一种空分扩展型扇出无关交换结构,其工作原理是;在调度机的统一调度下,Crossbar与组播模块并行工作,输入端口中的单播数据由Crossbar交换到输出目的端口,而输入端口中的网络电视数据和视频会议、远程教育、远程医疗等非网络电视业务的组播数据则由组播模块进行组播复制并输出到扇出包含的输出端口中。本文对空分扩展型扇出无关交换结构的整体结构、工作过程、子模块设计以及调度模型与调度算法进行了详细讨论;在此基础上,本文采用流体模型理论的数学方法对空分扩展型扇出无关交换结构的工作性能实现了量化分析,并且通过仿真实验实际验证了空分扩展型扇出无关交换结构的工作性能可以满足网络电视体验质量保障的要求,从而论证了扇出无关交换结构是一种有效支持网络电视业务的交换结构模型。为了能给工程实现提供更多的可选方案,本文在空分扩展型扇出无关交换结构之后,依照扇出无关交换结构模型,分别采用时分以及空分和时分联合的数据处理思想,设计了时分复用型以及空分时分联合型扇出无关交换结构,并对两者的整体结构、工作过程、调度模型与调度算法以及工作性能进行了深入分析。前者的工作原理是,不设置组播模块,由Crossbar在不同的时间段里,单独处理单播数据或者单独处理网络电视数据和非网络电视业务的组播数据;后者的工作原理是,设置组播模块并且组播模块在所有时间段里只处理网络电视数据和非网络电视业务的组播数据,而Crossbar在一些时间段里处理单播数据,在另一些时段里则处理网络电视数据和非网络电视业务的组播数据。本文依照扇出无关交换结构模型而设计的空分扩展型、时分复用型和空分时分联合型等三种不同类型的扇出无关交换结构都可以有效支持网络电视业务,从而为在工程上实现ACR的交换结构提供了多种切实可行的解决方案。针对ACR的研发需求,本文将扇出无关交换结构实际应用于ACR交换结构模块的设计和实现中,通过讨论ACR交换结构模块的总体设计、器件选型和硬件电路实现,详细说明了采用扇出无关交换结构来设计和实现ACR交换结构模块的具体方法。更多还原

【Abstract】 IPTV not only breaks through the distribution pattern of traditional television but also innovates in the manner and the efficiency of obtaining, spreading and utilizing information and offers a vital opportunity to develop information communication technology industry. In the perspective of both the demand of terminal users and the development requirement of information communication technology industry, IPTV embodies the mode of application leading the development of network, and destines to be one of the primary services in the future internet.At present, since the performance of current border network can not meet the controllable, manageable and operateable requirements of operators about IPTV, "High Performance Broadband Information Networks" (3Tnet) of the National High-Tech Research and Development Program of China (863 Program) launches the project of "System performance and key technologies research on the access and convergence router (ACR)". In order to support IPTV, ACR needs the kind of switch fabric which can support IPTV; however, the switch fabric of ACR can not be developed via reserving redundant resource for multicast processing because IPTV will produce a great deal of multicast communication. The support of IPTV will cast great impact on the performance of ACR, so how to develop the switch fabric which can support IPTV becomes the key problem in ACR. For this reason, this thesis devotes its research effort to the kind of switch fabric which can support IPTV.As for a switch fabric, the support of IPTV is not just the same as the support of multicast but needs to satisfy the requirements of quality of experience guarantees. For this reason, the state-of-the-art multicast switch fabric models, including copy multicast, fanout multicast and bounded copy multicast, can not provide clear solution for the design of switch fabric which can support IPTV. Along with a deep investigation made into the transmission process of IPTV, the characteristic of TV data arriving at a switch fabric is found out. On this basis, a new scheme of switch fabric model, named as fanout-free switch fabric, to support IPTV is proposed, which originates from the working style of the ideal output queued switch fabric. Concretely, the scheme of Fanout-free switch fabric is built on such principle that if there is no data in the queues of any input port of a switch fabric, that means all of the data arriving at the switch fabric has been processed and transmitted into the queues of output ports; moreover, no matter how the number of either input ports or output ports varies, the factor of either speedup or link dilation needed to achieve the state of that there is no data in the queues of any input port holds its own; where after, output ports take the responsibility to drain TV data out of the switch fabric at an appropriate rate so as to satisfy the requirements of quality of experience guarantees of IPTV.Subsequently, this thesis introduces a kind of space division expansion fanout-free switch fabric, in which arriving unicast data is switched and transmitted to output ports by crossbar; and in parallel, arriving TV data together with other multicast data of non-TV services such as video conference, distance education and telemedicine are copied and transmitted to the destined output ports by multicast module. And then, space division expansion fanout-free switch fabric is thoroughly discussed from the aspects of its architecture, operating process, design of each component, scheduling model and scheduling algorithm. Furthermore, quantitative analysis is achieved via the method of the fluid model theory, and the simulation is carried out which demonstrates that the performance of space division expansion fanout-free switch fabric can satisfy the requirements of quality of experience guarantees. Both the result of the quantitative analysis and the simulation prove that fanout-free switch fabric can support IPTV.In order to provide more feasible solutions, other two kinds of fanout-free switch fabric, called as time division multiplexing fanout-free switch fabric and combined space and time division fanout-free switch fabric, are proposed on the principle of time division multiplexing mode and on the principle of combined space and time division mode respectively. Likewise, such aspects as the architecture, operating process, scheduling model, scheduling algorithm and performance of both kinds are thoroughly discussed. Without multicast module, time division multiplexing fanout-free switch fabric relies on the crossbar to process either unicast data or TV data and other multicast data of non-TV services in different time phases. However, as for combined space and time division fanout-free switch fabric, not only the multicast module deals with TV data and other multicast data of non-TV services but also the crossbar processes either unicast data or TV data and other multicast data of non-TV services in different time phases.The proposals of space division expansion fanout-free switch fabric, time division multiplexing fanout-free switch fabric and combined space and time division fanout-free switch fabric provide various practical solutions to design and implement the switch fabric of ACR. According to the demand of ACR, this thesis uses the scheme of fanout-free switch fabric to develop the switch fabric module of ACR. Via a detailed analysis of the switch fabric module of ACR from such aspects as design, the selection of chips and hardware implementation, this thesis gives an explicit explanation about how to design and implement the switch fabric module of ACR based on the scheme of fanout-free switch fabric.更多还原