A Brief History of P2P Networks

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A Brief History of P2P Networks
Laird Popkin, CTO, Pando Networks
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Goal of this Presentation

• The goal of this presentation is to present a
  quick overview of p2p technology so that were
  all talking the same language.
  
• Please jump in with questions, corrections, etc.

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The Internet is Peer to Peer

• The fundamental technology of the Internet is
  TCP/IP. At this level, the internet composed
  entirely of peers connected by a mesh network.
  Everyone had an internet IP address, and could be
  both a client and a server. This allows the
  internet to scale infinitely.
• But client/server applications (FTP, HTTP) are
  much easier to implement. This creates many
  independent islands, each with a scaling
  problem if theyre popular. Witness the Slashdot
  Effect.
• With P2P, the more popular something is, the
  more powerful it becomes, matching the
  fundamental scalability of the Internet. This
  requires more cleverness than client/server, but
  that just makes it more fun.

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P2P Generations

• P2P used to mean file sharing. For example
• First Generation Napster
• Second Generation Kazaa, Gnutella, eDonkey
• Third Generation BitTorrent
• Now P2P means many different things

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First Generation Napster

• The first popular p2p application was Napster.
  Launched in 1999, it collected an index of all of
  the music files on users computers and provided
  a centralized searchable database, then retrieved
  the music from one users computer.
• Worked great. Sued immediately, shut down in
  2001.

Diagram from HowStuffWorks.com
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Second Generation - Decentralization Kazaa

• Decentralized architecture, computers form a
  mesh that performs searching and file
  delivery.
  
• Added supernodes to coordinate communication.
• Bundled in adware, spyware, etc., to monetize
  installs.
  
• Trained people to avoid p2p apps.
• Lead to hacks such as KaZaa Lite
• Weak security
• Lead to interference in the network
• Upgrade server was single point of control (used
  to shut off Morpheus).
  
• Was extremely popular, until lawsuit.

Diagram from http//cis.poly.edu/ross/papers/Unde
rstandingKaZaA.pdf Understanding KaZaa from Brook
lyn Polytechnic
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Second Generation - Open Gnutella

• Decentralized architecture, computers form a
  mesh that performs searching and file
  delivery.
  
• No central database (so cant be shut down by a
  lawsuit)
  
• Open protocol (many clients)
• Completely decentralized is very hard to make
  work.
  
• bootstrap problem how do new clients join a
  decentralized network?
  
• Cascade problem searches can crush network.
• Morpheus adopted, but Gnutella didnt scale
  well, so growth was limited.
  
• Gnutella community of developers has continued
  to evolve and grow. Added ultrapeers, Bitzi
  lookups, etc.

Diagram from Limewire.com
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Second Generation - Swarm eDonkey

• eDonkey introduced
• Magnet links, allowed creation of web sites
• Swarm delivery extremely fast
• Protocol was reverse engineered, allowing
  creation of eMule, etc.
  
• Attempted to migrate to fully distributed Overnet

• Was extremely popular, until shut down.
• Architecture wasnt fully distributed, so
  shutting down servers shut down network.

Diagram from http//www.ed2k-serverboard.de/diesel
/edonkey/Serverbeschreibung.html
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Third Generation - Secure, Swarming BitTorrent

• Secure, Swarm Delivery has many advantages.
• Resilient to communication errors and
  interference.
  
• Can be extremely fast for popular content.
• Tit-for-tat penalizes cheaters
• Tracker makes each torrent independent, allows
  for overall network to scale,
  
• No search avoids legal risks

Diagram from Brams 2002 white paper
Incentives Build Robustness in BitTorrent

• Also
• Open protocol, many implementations
• Widely adopted, probably over 50 of internet by
  data volume
  
• Web links lead to tracker web sites. Are web
  sites in Norway safe?
  
• DHTs remove dependence on Trackers

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Now P2P is growing in many directions

• P2P is exploding in range. Some examples
• AllPeers integrated BitTorrent into FireFox for
  social file sharing
  
• BitTorrent pursuing eCommerce, technology
  licensing
  
• CacheLogic is providing a P2P CDN, with variable
  QoS/pricing.
  
• Distributed Computing Industry Association
  facilitates policies, education, etc.
  
• Democracy Player subscribes to RSSBitTorrent
• Joost and Babelgum use P2P to provide a TV
  Experience over the internet
  
• Pando made sending easy, integrated into user
  applications, video platform.
  
• PeerApp and Oversi provide caching servers to
  ISPs
  
• PPLive, PPStream, etc., focusing on live video
  streaming
  
• Shareaza, Xfactor, etc., provide a common GUI
  over multiple protocols.
  
• Solid State and One Click Media are browser
  plug-ins that play stream on demand video
  
• Vuze, was Azureus, now focused on video
  download/playback
  
• Who did I forget?

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