Deep Diving into BitTorrent Locality

TL;DR

This paper investigates the potential and limits of localizing BitTorrent traffic across multiple ISPs by analyzing a large dataset of torrents and peers, providing scalable insights into transit cost reductions and ISP-user benefits.

Contribution

It introduces scalable methodologies to analyze ISP-wide BitTorrent locality, extending understanding from small case studies to large-scale, multi-ISP datasets involving millions of peers.

Findings

Transit traffic reduction varies widely across ISPs.

Maximum localization achievable without fine-grained control.

Impact of broadband speed upgrades on transit traffic.

Abstract

A substantial amount of work has recently gone into localizing BitTorrent traffic within an ISP in order to avoid excessive and often times unnecessary transit costs. Several architectures and systems have been proposed and the initial results from specific ISPs and a few torrents have been encouraging. In this work we attempt to deepen and scale our understanding of locality and its potential. Looking at specific ISPs, we consider tens of thousands of concurrent torrents, and thus capture ISP-wide implications that cannot be appreciated by looking at only a handful of torrents. Secondly, we go beyond individual case studies and present results for the top 100 ISPs in terms of number of users represented in our dataset of up to 40K torrents involving more than 3.9M concurrent peers and more than 20M in the course of a day spread in 11K ASes. We develop scalable methodologies that permit us to process this huge dataset and answer questions such as: "\emph{what is the minimum and the maximum transit traffic reduction across hundreds of ISPs?}", "\emph{what are the win-win boundaries for ISPs and their users?}", "\emph{what is the maximum amount of transit traffic that can be localized without requiring fine-grained control of inter-AS overlay connections?}", "\emph{what is the impact to transit traffic from upgrades of residential broadband speeds?}".