中文摘要：

本文提出的视频点播系统基于双层P2P架构实现，由城域网与驻地网媒体内容分发构成2级数据分发服务平台，用户终端点播并接受视频服务的同时，还能为其他用户提供数据服务，双层P2P架构有效地扩展了系统带宽，增强了服务能力，降低了系统成本，并提供QoS保证。

英文摘要：

A video on demand system based on two-layer P2P architecture is proposed. The top layer is metropolitan area network based content delivery network, and the bottom one is local domain content delivery network. Customer terminal can provide data for other users when it receives media data. The proposed system can effectively utilize the bandwidth, enhance service capability, reduce cost, and provide QoS assurance.