Leveraging Social Networks for Increased BitTorrent Robustness Wojciech Galuba, Karl Aberer EPFL,...
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Transcript of Leveraging Social Networks for Increased BitTorrent Robustness Wojciech Galuba, Karl Aberer EPFL,...
![Page 1: Leveraging Social Networks for Increased BitTorrent Robustness Wojciech Galuba, Karl Aberer EPFL, Switzerland Zoran Despotovic, Wolfgang Kellerer Docomo.](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649e115503460f94afd27a/html5/thumbnails/1.jpg)
Leveraging Social Networks for Increased BitTorrent Robustness
Wojciech Galuba, Karl AbererEPFL, Switzerland
Zoran Despotovic, Wolfgang Kellerer Docomo Euro-Labs, Munich, Germany
![Page 2: Leveraging Social Networks for Increased BitTorrent Robustness Wojciech Galuba, Karl Aberer EPFL, Switzerland Zoran Despotovic, Wolfgang Kellerer Docomo.](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649e115503460f94afd27a/html5/thumbnails/2.jpg)
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Motivation 1
BitTorrent relies on cooperative behavior But freeriding possible
15-80% of peers are freeriders
Freerider
![Page 3: Leveraging Social Networks for Increased BitTorrent Robustness Wojciech Galuba, Karl Aberer EPFL, Switzerland Zoran Despotovic, Wolfgang Kellerer Docomo.](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649e115503460f94afd27a/html5/thumbnails/3.jpg)
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Current solution: Tit-for-tat
Tit-for-tat (TFT) strategy:Reward good uploaders by giving them higher
priority TFT defense ineffective:
Large-view exploitSeeders don’t download all peers look
equal to seeders
![Page 4: Leveraging Social Networks for Increased BitTorrent Robustness Wojciech Galuba, Karl Aberer EPFL, Switzerland Zoran Despotovic, Wolfgang Kellerer Docomo.](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649e115503460f94afd27a/html5/thumbnails/4.jpg)
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Friend-to-Friend (F2F) systems
Source of the problem In P2P nets everyone is
a stranger A solution: connect to friends’
computers only Reliable, stable identities
Take advantage of existing social trust Cooperation more likely
Social network
P2P network
![Page 5: Leveraging Social Networks for Increased BitTorrent Robustness Wojciech Galuba, Karl Aberer EPFL, Switzerland Zoran Despotovic, Wolfgang Kellerer Docomo.](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649e115503460f94afd27a/html5/thumbnails/5.jpg)
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Motivation 2
How can we leverage the social network to solve freeriding?
Is the social network a good content distribution medium?
BitTorrent
![Page 6: Leveraging Social Networks for Increased BitTorrent Robustness Wojciech Galuba, Karl Aberer EPFL, Switzerland Zoran Despotovic, Wolfgang Kellerer Docomo.](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649e115503460f94afd27a/html5/thumbnails/6.jpg)
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The social BitTorrent
Approach BitTorrent on top of a social network Friends’ computers added to the peer list Protocol unchanged
Communication only along the social links Mutually authenticated Can be encrypted for privacy
Friend discovery We use a centralized friend server Possible decentralized implementation:
PGP Jabber/XMPP
![Page 7: Leveraging Social Networks for Increased BitTorrent Robustness Wojciech Galuba, Karl Aberer EPFL, Switzerland Zoran Despotovic, Wolfgang Kellerer Docomo.](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649e115503460f94afd27a/html5/thumbnails/7.jpg)
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Freeriding disincentiveUser interface:
AliceUpload/download: 1.2
BobUL/DL: 2.5
CarolUL/DL: 0.9
DanielUL/DL: 1.2
EveUL/DL: 0.02
Users unlikely to freeride on friends
Hmmm... I need to talk to Eve
![Page 8: Leveraging Social Networks for Increased BitTorrent Robustness Wojciech Galuba, Karl Aberer EPFL, Switzerland Zoran Despotovic, Wolfgang Kellerer Docomo.](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649e115503460f94afd27a/html5/thumbnails/8.jpg)
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Evaluated systems
BT – BitTorrent implementation Using trackers to discover peers
SBT – the social BitTorrent Only friend connections
HBT – hybrid implementation Both on peer list:
friend peers peers obtained from the trackers
Friend uploads have absolute priority
![Page 9: Leveraging Social Networks for Increased BitTorrent Robustness Wojciech Galuba, Karl Aberer EPFL, Switzerland Zoran Despotovic, Wolfgang Kellerer Docomo.](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649e115503460f94afd27a/html5/thumbnails/9.jpg)
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Experimental setup Simulated in protopeer.net Tit-for-tat (TFT), downloaders ordered by:
TFT on: how much they upload TFT off: how much they download
1024 peers, 25 MB file, single initial seeder Mixture of peers with 0.5, 1 and 2Mbit/s upload
bandwidth Social net generated based on MSN Messenger data
![Page 10: Leveraging Social Networks for Increased BitTorrent Robustness Wojciech Galuba, Karl Aberer EPFL, Switzerland Zoran Despotovic, Wolfgang Kellerer Docomo.](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649e115503460f94afd27a/html5/thumbnails/10.jpg)
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Social network alone is an efficient content distribution medium Though: long-tail problem
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Swarm density
Def: Fraction of peers in the social network interested in downloading a file
Low swarm density distribution graph becomes disconnected
Source
No access to source
![Page 12: Leveraging Social Networks for Increased BitTorrent Robustness Wojciech Galuba, Karl Aberer EPFL, Switzerland Zoran Despotovic, Wolfgang Kellerer Docomo.](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649e115503460f94afd27a/html5/thumbnails/12.jpg)
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Low swarm density many failed downloads Trackers (in BT and HBT) solve the problem
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Social links give HBT advantage only if swarm density > 2%
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Linear scaling with content size
![Page 15: Leveraging Social Networks for Increased BitTorrent Robustness Wojciech Galuba, Karl Aberer EPFL, Switzerland Zoran Despotovic, Wolfgang Kellerer Docomo.](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649e115503460f94afd27a/html5/thumbnails/15.jpg)
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O(logN) scaling with the number of peers
![Page 16: Leveraging Social Networks for Increased BitTorrent Robustness Wojciech Galuba, Karl Aberer EPFL, Switzerland Zoran Despotovic, Wolfgang Kellerer Docomo.](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649e115503460f94afd27a/html5/thumbnails/16.jpg)
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Open problems
We assumed uniform distribution of interested peers In reality interest clustered in social nets
Even better performance?
Content discoveryCan friends-of-friends be trusted?
Social BT geo locality less inter-AS traffic?
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Conclusions
Social network alone an efficient and scalable content distribution medium
Social BitTorrent Increased robustness to freeridingAs long as swarm density >2%
F2F approach to content distribution:Authenticated connections, trust Increased privacy