دانلود رایگان مقاله ارزیابی اطلاعات و مشکل اضافه پرداخت همراه در سیستم همتا به همتا

Abstract

Most incentive schemes for peer-to-peer (P2P) file-sharing are rate-based, only giving consideration to upload rate when measuring contributions. Besides giving room for strategic peers to benefit from concealing high value chunks, rate-based metrics also aggravate overpayment. Overpayment is a phenomenon that one pays a higher than necessary price for goods. In a P2P system, overpayment exists because in most cases, the incentive schemes have design flaws. Specifically, in rate-based systems, bandwidth allocation policies ignore different values of different chunks, and it directly induces overpayment. In this work, taking the chunk value in the reciprocity process into consideration, the overpayment problem in a BitTorrent network is investigated, and four side effects of overpayment are identified. A novel strategy called value-based BitTorrent (VBT) is proposed, which is found to be able to alleviate the degree of overpayment and consequently relieve the side effects of overpayment.

10. Conclusions

P2P systems have achieved outstanding success and much efforts has been put into investigating incentive mechanisms for strategic P2P networks. In this work, observing that different chunks have different values to both the system and individual peers, a valuebased metric is devised to measure contributions instead of using rate-based metrics. A variation of BitTorrent is also proposed, called value-based BitTorrent (VBT). VBT is found to effectively punish the strategic behaviors of an under-reporting chunk map, and there is a positive correlation between investment and return for cooperative peers in VBT networks. Moreover, VBT always outperforms BitTorrent in terms of system performance. Taking the chunk value in the reciprocity process into consideration, the overpayment problem in a BitTorrent network is investigated, and four side effects of overpayment are identified. A new scheme is proposed to visualize overpayment and a series of metrics is proposed based on this method to quantify overpayment. The proposed VBT is found to be able to alleviate the degree of overpayment and consequently relieve the side effects of overpayment.