关键词: BitTorrent, 激励策略, 着色Petri网（CPN）, 模型模拟

Abstract: Incentive mechanism plays a significant part in BitTorrent protocol. It encourages peers to upload more resources in order to obtain better download rate, and improves the whole system sharing performance. However, the original incentive mechanism in BitTorrent protocol allows such kinds of free-riding nodes, which bring bad incentive effects. This paper proposes a novel incentive mechanism with detailed algorithm for its practical application. In order to make more accurate and sound analysis for this novel incentive mechanism, this paper firstly constructs its colored Petri nets (CPN) based formal model, then validates the accuracy of this model, finally carries out the performance analysis for the BitTorrent protocol with new proposed incentive mechanism using model simulation. The performance analysis results show that the novel incentive mechanism can provide more strict restriction to free-riding node behaviors and archive better incentive effects.

Key words: BitTorrent, incentive mechanism, colored Petri nets (CPN), model simulation