Abstract-In recent years, BitTorrent has emerged as a very scalable peer-to-peer file distribution mechanism. While early measurement and analytical studies have verified BitTorrent's performance, they have also raised questions about various metrics (upload utilization, fairness, etc.), particularly in settings other than those measured. In this paper, we present a simulationbased study of BitTorrent. Our goal is to deconstruct the system and evaluate the impact of its core mechanisms, both individually and in combination, on overall system performance under a variety of workloads. Our evaluation focuses on several important metrics, including peer link utilization, file download time, and fairness amongst peers in terms of volume of content served. Our results confirm that BitTorrent performs near-optimally in terms of uplink bandwidth utilization, and download time except under certain extreme conditions. We also show that low bandwidth peers can download more than they upload to the network when high bandwidth peers are present. We find that the rate-based tit-for-tat policy is not effective in preventing unfairness. We show how simple changes to the tracker and a stricter, block-based tit-for-tat policy, greatly improves fairness.
Bharambe et al. REF utilized a discrete event simulator to evaluate the impact of BitTorrent's core mechanisms and observed that rate-based tit-for-tat incentives cannot guarantee fairness.
Analyzing and Improving a BitTorrent Networks Performance Mechanisms
Proceedings IEEE INFOCOM 2006. 25TH IEEE International Conference on Computer Communications
Proceedings IEEE INFOCOM 2006. 25TH IEEE International Conference on Computer Communications
Computer Science