面向IPTV业务的IP承载网优化改造研究精选.docVIP

摘要 IPTV是承载于 IP 网络的一种电信级业务，按各功能操作特点，可以分成流媒体类、通信类、游戏类和信息服务类等四类。其中流媒体类包括音视频点播和音视频直播。通信类业务包括视频通信和短信。流媒体类业务对带宽需求较高，通信类业务对实时性要求很高。因此，IPTV业务与通常的 Internet数据业务有很大不同。在带宽、QoS、可靠性、安全性等方面对承载网有很高的技术要求。 本文主要研究现有IP承载网如何支撑IPTV业务的问题。通过对IPTV业务对承载网络需求的分析，指出目前网络的瓶颈主要在于现网无法提供端到端的QS保证和无法提供全网组播业务支持。针对上述问题，结合IP城域网建设思路，对现有电信网络优化改造进行研究，对如何提升网络的业务承载能力，尤其是QoS、组播方面，提出解决方案。对于QoS的部署，首先分析比较了QoS的三种服务模型，通过对三种模型的技术分析，并结合现有电信网络规模和设备特点，提出选择Diff-Serv模型进行QoS的部署，并详细论述了QoS在现网各个层面部署的策略和实现方式。对于组播的部署，首先对组播的两种业务模型进行了分析和技术比较，从成熟性和扩展性考虑选用了ASM方式进行现网部署，然后阐述了组播从承载网骨干层、汇聚层到接入层各个层面的实现方式，重点对接入层面向用户的组播复制点和控制点的选择提出了根据业务发展阶段采取不同实现方式的方案。接下来阐述了IPTV直播和点播业务的技术实现方案，重点内容围绕如何综合运用QoS和组播技术支撑IPTV业务规模开放进行论述。最后介绍了现网改造和QoS组播策略部署测试验证情况。 关键词：IPTV 承载网 QoS 组播 ABSTRACT IPTV is a kind of telecom service running on IP network, which includes video stream service, communication service, game service and information service. And Video stream service consists of Video on Demand (VoD) and Video broadcasting, which has high bandwidth and real-time requirement. So, IPTV service is quite differently from traditional Internet service, such like http mail ftp and so on. Now, Chinatelecoms IP network faces great challenge on bandwidth QoS reliability and safety for IPTV service. This article covers how todays IP network would support IPTV service. The article analyzes detailed requirement of IPTV service, and points out the main issue is that todays IP network cant provide QoS service and multicast function. This article discusses total solution of optimizing and reconstructing current IP network. First, three service models of QoS are compared and it is concluded that we should choose Diff-Serv model to deploy according to the network topology and devices used in current IP network. Then the policy and method of QoS to be deployed on each layer of network are discussed in detail. Second, two models of multicast are compared and ASM model is chosen to deploy .Then the policy and method of multicast to be deployed on each layer of network are discu