Performance Analysis of BitTorrent Systems with Sharing Ratio Enforcement
Date Issued
2012
Date
2012
Author(s)
Chang, Evan
Abstract
BitTorrent is the most widely used Peer-to-Peer file sharing protocol on the internet. It had been the largest consumer of internet traffic for years, until surpassed by Netflix in recent years. The unique mechanisms and the built-in incentives that distinguish BitTorrent from other P2P file sharing protocols result in excellent utilization and scalability, making it the top choice for file sharing communities. One of the problems of the built-in incentives is that it lacks the incentive to encourage peers to stay seeding after they finished downloading. So a lot of the communities have incorporated a mechanism called Sharing Ratio Enforcement to compensate it.
In this paper we study the impact of the SRE mechanism on the system performance of the BitTorrent systems. We derive a mathematical model that is capable of predicting the time that all peers finish downloading under a flash crowd scenario and heterogeneous network with an arbitrary number of classes of peers. Furthermore, we incorporate our model with a model from a previous work by Liao et al. to make it capable of modeling a system that the system throughput is capped on the downlink instead of the uplink. Finally we propose that the leechers can strategically select from which peers to download when there are too many seeders in the system that the uploading throughput is larger than the downloading throughput of the system. We study how this modification influences the system performance by using our model.
Subjects
Sharing Ratio Enforcement
Performance analysis
Type
thesis
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