A survey of BitTorrent study Jian Liang EL933 Prof. Yong Liu

Surveyed paper Service Capacity of Peer to Peer Networks (INFOCOM 2004) X. Yang, G. Veciana Modeling and Performance Analysis of Bit Torrent-Like Peer- to-Peer Networks (SIGCOMM 04) D. Qiu, R. Srikant The Bittorrent P2P File-sharing System: Measurements and Analysis (IPTPS 2005) J. Pouwelse, P.Garbacki, D. Epema, H. Sips Measurements, Analysis, and Modeling of BitTorrent-like Systems (IMC 2005) L. Guo, S. Chen, Z. Xiao, E. Tan, X. Ding, and X. Zhang Analyzing and Improving BitTorrent Performance (INFOCOM 2006) A. Bharambe, C. Herley and V Padmanabhan

Outline Overview of BitTorrent Research interests covered Methodology on BT study Compare of these 5 papers Interesting facts reflected in these works Argument Current development of BitTorrent

Overview – system components Web page with link to.torrent A B C Peer [Leech] Downloader “US” Peer [Seed] Peer [Leech] Tracker Web Server.torrent

Overview – system components Web page with link to.torrent A B C Peer [Leech] Downloader “US” Peer [Seed] Peer [Leech] Tracker Get-announce Web Server

Overview – system components Web page with link to.torrent A B C Peer [Leech] Downloader “US” Peer [Seed] Peer [Leech] Tracker Response-peer list Web Server

Overview – system components Web page with link to.torrent A B C Peer [Leech] Downloader “US” Peer [Seed] Peer [Leech] Tracker Shake-hand Web Server Shake-hand

Overview – system components Web page with link to.torrent A B C Peer [Leech] Downloader “US” Peer [Seed] Peer [Leech] Tracker pieces Web Server

Overview – system components Web page with link to.torrent A B C Peer [Leech] Downloader “US” Peer [Seed] Peer [Leech] Tracker pieces Web Server

Overview – system components Web page with link to.torrent A B C Peer [Leech] Downloader “US” Peer [Seed] Peer [Leech] Tracker Get-announce Response-peer list pieces Web Server

Overview – BT features Temporal one torrent community (no across torrents communication). File/pieces/blocks. Content trade is piece based, while transfer is block based. Partial pieces can not be uploaded.

Overview – BT features Peer selection- Fit-for-Tat (download speed based) “Interest”/”chock”/”unchock” Piece selection - Local Rarest First (not global rarest)

Outline Overview of BitTorrent Research interests covered Methodology on BT study Compare of these 5 papers Interesting facts reflected in these works Argument Current development of BitTorrent

Research focus Generic network performance –Traffic volume, download/upload throughput, uplink utilization, peer behavior, service capacity, Incentives –Fairness, peer game Robustness –Website availability, peer workload, content integrity. Limitation and improvement

Outline Overview of BitTorrent Research interests covered Methodology on BT study Compare of these 5 papers Interesting facts reflected in these works Argument of their works Current development of BitTorrent

Methodology Passive ways –(tracker log, torrent website monitor, traffic capture) Active ways –Join the BT network to monitor peer performance Simulation Modeling

Outline Overview of BitTorrent Research interests covered Methodology on BT study Compare of these 5 papers Interesting facts reflected in these works Argument of their works Current development of BitTorrent

Compare of these five works PaperMethodData setResearch Differentiation YV_INFOCOM04Model + TraceTrace log of torrents trackers Service capacity, scalability of flash crowd QS_SIGCOMM04Model + simulation + little trace 3 days trace from one torrent tracker User evolution, peer game PG_IPTPS05Trace8 months trace from website, peer traffic and tracker Torrent website availability, content integrity GCXTDZ_IMC05Trace + model48 days tracker trace and 10 days ISP traffic (50 tracker sites and 3k peers) Performance across multi-torrents, BT limitation found from traces. BHP_INFOCOM06Comprehensive simulation NoneFairness, uplink utilization, improvement

Outline Overview of BitTorrent Research interests covered Methodology on BT study Compare of these 5 papers Interesting facts reflected in these works Argument Current development of BitTorrent

Interesting results YV_INFOCOM04 –Exponential growth of service capacity in initial flash crowd –For less popular torrent (<50 peers), the performance is quite unpredictable

Interesting results QS_SIGCOMM04 –Purpose a good BT fluid model and matches their simulation result well. –No surprising results yet.

Interesting results PG_IPTPS05 –The arrival processes of peers are not Poisson assumed by SIGCOMM04 paper. –Power law relationship btw peer speed and # peers

Interesting results PG_IPTPS05 –The availability of centralized supporting system is bad –# of seeds after 10 days is not accurate predictor for content life time, one single seed can be up for long period of time.

Interesting results PGES_IPTPS05 –Centralized moderation seems very effective in removing fake and corrupted files. 5k of 8k torrent uploaded by 20 moderators daily. –Donated resource for meta-data entail integrity and privacy risks without control.

Interesting results GCXTDZ_IMC05 –Exponentially decreasing peer arrival rate, lack of seeds make service availability poor quickly after flash crowd. –The leecher download speed at different time stages is highly diverse.

Interesting results GCXTDZ_IMC05 –BT can provide unfair services. Peer contribution ratio decrease with its downloading speed increase. –The probability for a peer to abort downloading voluntarily is independent of its speed and downloading progress.

Interesting results GCXTDZ_IMC05 –The life spans of torrent is btw hours with average 8.5 days; average population of a torrent is only about 102 peers. –Seeding time is average as 8.42 hours

Interesting results BHP_INFOCOM06 –The uplink utilization close to 100% –Workload of seeds increase slowly during flash crowd

Interesting results BHP_INFOCOM06 –Single seed utilization outperforms that of multi- seeds –The more concurrent upload, the less uplink utilization

Interesting results BHP_INFOCOM06 –For low bandwidth peers with small neighbors, random block exchange outperform LRF –But LRF outperform random block exchange in term of # interesting connections

Interesting results BHP_INFOCOM06 –Block-level TFT outperform download speed based TFT in term of fairness –Quick BW estimation help archive optimal utilization

Interesting results BHP_INFOCOM06 –Bandwidth-matching tracker policy further improve both utilization and fairness

Outline Overview of BitTorrent Research interests covered Methodology on BT study Compare of these 5 papers Interesting facts reflected in these works Argument Current development of BitTorrent

Argument INFOCOM06 : –the simulation does not consider user control of their uplink/downlink (BitComet enable uplink speed limits) –Tradeoff of the improvement ideas –Bandwidth measure overhead is ignored –Bandwidth clustering helps but is that violation of Internet ethics by separating different capable users?

Outline Overview of BitTorrent Research interests covered Methodology on BT study Compare of these 5 papers Interesting facts reflected in these works Argument Current development of BitTorrent

Current BT development DHT enabled peer search (BitComet, Bitsprite) Decentralized torrent search (eXeem) BT like Content delivery system (VOD, IPTV)