Abstract: Bittorrent is the P2P system which works on central index server. The peer must get an expansion named torrent index file from the central index server before downloading. The index server becomes the bottleneck of the system. A torrent file optimization strategy based on Merkle tree is proposed, which makes the torrent file size smaller than before and lightens the overhead of the index server, improves the scalability of BT.

Key words: Merkle tree, torrent file, central index server, optimization strategy

摘要： BitTorrent(BT)是中心索引式的P2P系统。节点要进行下载必须从中心索引服务器获取一个扩展名为torrent的索引文件，中心索引服务器成为系统的瓶颈。文章提出一种基于Merkle树的torrent文件优化策略，使torrent文件大幅减小，减轻中心索引服务器的负担，改善BT的可扩展性。

关键词: Merkle树, torrent文件, 中心索引服务器, 优化策略

CLC Number: 

• TP393