Abstract: Finding partners for a peer in P2P VoD systems is still a critical issue，especially when VCR functions are supported.Peers’ cache are usually limited，and peers’ play occasion may jump to any point of the stream at any time.So，it is very expensive to track buffer contents，which change constantly.This paper presents a search table topology structure based on dynamic time coordinate system for large-scale P2P VoD system.In this coordinate system，any peer’s coordinate maintains constant unless the peer’s play occasion jumps to another point of the stream.Thus a chord-like search table topology is designed.Simulations show that our design achieves good performance.

Key words: Peer-to-Peer, VoD, resource locating

摘要： 在P2P点播系统中，如何快速发现合作节点这一资源定位问题是一个挑战。特别在用户进行VCR操作时，这一问题更显突出。播放点的随节点播放而连续前移和用户VCR操作造成的节点跳转使得系统追踪节点缓存信息代价很高。提出了一种基于动态时间坐标系的复杂度为O（logM）（M为节目的分段数）搜索表拓扑组织方法，以解决P2P VoD系统资源定位困难的问题。仿真结果标明，该方法具有很好地可扩展性和较高地查找效率。

关键词: Peer-to-Peer, VoD, 资源定位