A survey of BitTorrent study Jian Liang EL933 Prof. Yong Liu
Dec 19, 2015
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]
TrackerWeb Server
.torr
ent
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
pieces
Web Server
Overview – system components
Web page with link to .torrent
A
B
C
Peer
[Leech]
Downloader
“US”
Peer
[Seed]
Peer
[Leech]
Tracker
piecespieces
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
piecespieces
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 worksPaper Method Data set Research
DifferentiationYV_INFOCOM04 Model + Trace Trace log of 150-
200 torrents trackers
Service capacity, scalability of flash crowd
QS_SIGCOMM04 Model + simulation + little trace
3 days trace from one torrent tracker
User evolution, peer game
PG_IPTPS05 Trace 8 months trace from website, peer traffic and tracker
Torrent website availability, content integrity
GCXTDZ_IMC05 Trace + model 48 days tracker trace and 10 days ISP traffic (50 tracker sites and 3k peers)
Performance across multi-torrents, BT limitation found from traces.
BHP_INFOCOM06 Comprehensive simulation
None Fairness, 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 30-300 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)