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Submitted To:-   Mr. Nayyar Khan   Miss Suhani AgarwalSubmitted By:-   Ankit Malvi CSE-16   Ankit Chauhan CSE-14   Himanil...
Contents…    Simple Solution: One BIG Server (but a problem too…)    How server Works…?    Solution Of the problem    ...
Simple Solution: One Big Server Make the file available on a central server Each client downloads file from this server...
How SERVER works?
Problem Being Solved Here? Sharing a fairly large file Involves making a replica Problem is somewhat similar to, but no...
Entering Bit Torrent Released in the summer of 2001 Uses basic ideas from game theory to largely eliminate  the free-rid...
Something About Creator…..        Bram Cohen – the creator of Bit Torrent:
What is BitTorrent?   Efficient content distribution system using   file swarming. Usually does not perform   all the func...
Basic Components  Seed    Peer that has the entire file  Leeches    Peer that has an incomplete copy of the file  A T...
Basic Idea Initial seeder chops file into many pieces. Leecher first locates the .torrent file that directs it to a  tra...
BitTorrent Lingo Seeder = a peer that provides the complete file. Initial seeder = a peer that provides the initial copy. ...
Pieces & Sub-Pieces A piece is broken into sub-pieces ... typically 16KB in  size Policy: Until a piece is assembled, on...
File sharing Large files are broken into pieces of size between 64 KB and 1 MB      1      2        3      4       5      ...
Simple example                         {1,2,3,4,5,6,7,8,9,10}               Seeder:   A                                   ...
How delay is avoided between pieces..?? When transferring data over TCP, it is critical to  always have several requests ...
BT: internal mechanism Built-in incentive mechanism (where all the magic happens):   Choking Algorithm   Optimistic Unc...
Choking Choking is a temporary refusal to upload. It is one of BitTorrent’s most powerful idea to deal with free riders (...
Choking Algorithm Goal is to have several bidirectional connections  running continuously Upload to peers who have uploa...
Choking Specifics number of its peers  A peer always unchokes a fixed   (default of 4)  Decision to choke/unchoke done b...
Optimistic unchoking A BitTorrent peer has a single “optimistic unchoke” to which it uploads regardless of the current do...
Endgame Mode Policy: When all the sub-pieces that a peer doesn’t  have are actively being requested, these are  requested...
Bit Torrent p2p file-sharingsystem Aspects important for the acceptance of a p2p system : 1. High availability; 2. Users a...
Upload-Only mode Once download is complete, a peer has no  download rates to use for comparison nor has any  need to use ...
conclusion
Open any torrent client say BitTorrent ,BitLord..
That’s all …..You are done……You got your torrent file……….
Next What ??? Now you need to share it! You can upload it to a forum,  or a BitTorrent site, like www.MiniNova.com etc……...
Conclusion BitTorrent was conceived as a way of distributing large files more quickly, efficiently, and reliably. Thanks ...
References Google Search… www.en.wikipedia.com.com www.howstuffsworks.com www.what-is-torrent.com Torrent s/w officia...
Thank You….. Questions…??
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Bit torrent

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BitTorrent was conceived as a way of distributing large files more quickly, efficiently, and reliably. Thanks to BitTorrent though, the download of large files has become more feasible, and people have become accustomed to acquiring video through the net. At this point it is virtually impossible for anyone to bring an end to illegal downloads. whether or not BitTorrent will continue to play a role in this is yet to be seen

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Transcript of "Bit torrent"

  1. 1. Submitted To:- Mr. Nayyar Khan Miss Suhani AgarwalSubmitted By:- Ankit Malvi CSE-16 Ankit Chauhan CSE-14 Himanil Gupta CSE-39
  2. 2. Contents…  Simple Solution: One BIG Server (but a problem too…)  How server Works…?  Solution Of the problem  Entering “BIT TORRENT”.. -Something about creator…… -Definition -Basic Component -Basic Idea
  3. 3. Simple Solution: One Big Server Make the file available on a central server Each client downloads file from this server Problems  Solution does not scale very well  With a large number of clients, the server’s resources get overwhelmed
  4. 4. How SERVER works?
  5. 5. Problem Being Solved Here? Sharing a fairly large file Involves making a replica Problem is somewhat similar to, but not the same as, replication in a distributed file system, a Content Delivery Network or a Distributed Hash Table overlay network
  6. 6. Entering Bit Torrent Released in the summer of 2001 Uses basic ideas from game theory to largely eliminate the free-rider problem  All previous systems could not deal with this problem well Makes no strong guarantees unlike DHTs It is working extremely well in practice, unlike DHTs 
  7. 7. Something About Creator….. Bram Cohen – the creator of Bit Torrent:
  8. 8. What is BitTorrent? Efficient content distribution system using file swarming. Usually does not perform all the functions of a typical p2p system, like searching.
  9. 9. Basic Components  Seed  Peer that has the entire file  Leeches  Peer that has an incomplete copy of the file  A Torrent file  Passive component  Files are typically fragmented into 256KB pieces  The torrent file lists SHA1 hashes of all the pieces to allow peers to verify integrity  Typically hosted on a web server  A Tracker  Active component  Allows peers to find each other  Returns a random list of peers
  10. 10. Basic Idea Initial seeder chops file into many pieces. Leecher first locates the .torrent file that directs it to a tracker, which tells which other peers are downloading that file. As a leecher downloads pieces of the file, replicas of the pieces are created. More downloads mean more replicas available As soon as a leecher has a complete piece, it can potentially share it with other downloaders. Eventually each leecher becomes a seeder by obtaining all the pieces, and assembles the file. Verifies the checksum.
  11. 11. BitTorrent Lingo Seeder = a peer that provides the complete file. Initial seeder = a peer that provides the initial copy. Leecher Initial seeder One who is downloading (not a derogatory term) Leecher Seeder
  12. 12. Pieces & Sub-Pieces A piece is broken into sub-pieces ... typically 16KB in size Policy: Until a piece is assembled, only download sub- pieces for that piece This policy lets complete pieces assemble quickly
  13. 13. File sharing Large files are broken into pieces of size between 64 KB and 1 MB 1 2 3 4 5 6 7 8
  14. 14. Simple example {1,2,3,4,5,6,7,8,9,10} Seeder: A {1,2,3} {1,2,3,4,5} Downloader CDownloader B
  15. 15. How delay is avoided between pieces..?? When transferring data over TCP, it is critical to always have several requests pending at once, to avoid a delay between pieces being sent Bit Torrent breaks pieces into sub-pieces At any point in time, some number, typically 5, are requested simultaneously Every time a sub-piece arrives, a new request is sent This scheme has been found to saturate most connections in practice
  16. 16. BT: internal mechanism Built-in incentive mechanism (where all the magic happens):  Choking Algorithm  Optimistic Unchoking
  17. 17. Choking Choking is a temporary refusal to upload. It is one of BitTorrent’s most powerful idea to deal with free riders (those who only download but never upload). Tit-for-tat strategy is based on game-theoretic concepts.
  18. 18. Choking Algorithm Goal is to have several bidirectional connections running continuously Upload to peers who have uploaded to you recently Unutilized connections are uploaded to on a trial basis to see if better transfer rates could be found using them
  19. 19. Choking Specifics number of its peers  A peer always unchokes a fixed (default of 4)  Decision to choke/unchoke done based on current download rates, which is evaluated on a rolling 20- second average  Evaluation on who to choke/unchoke is performed every 10 seconds  This prevents wastage of resources by rapidly choking/unchoking peers  Supposedly enough for TCP to ramp up transfers to their full capacity  Which peer is the optimistic unchoke is rotated every 30 seconds
  20. 20. Optimistic unchoking A BitTorrent peer has a single “optimistic unchoke” to which it uploads regardless of the current download rate from it. This peer rotates every 30s Reasons:  To discover currently unused connections are better than the ones being used  To provide minimal service to new peers
  21. 21. Endgame Mode Policy: When all the sub-pieces that a peer doesn’t have are actively being requested, these are requested from EVERY peer When the sub-piece arrives, the replicated requests are cancelled This ensures that a download doesn’t get prevented from completion due to a single peer with a slow transfer rate Some bandwidth is wasted, but in practice, this is not too much
  22. 22. Bit Torrent p2p file-sharingsystem Aspects important for the acceptance of a p2p system : 1. High availability; 2. Users always receive a good version of the content they are requesting; 3. Ability to deal with flashcrowds; 4. High download speed.
  23. 23. Upload-Only mode Once download is complete, a peer has no download rates to use for comparison nor has any need to use them The question is, which nodes to upload to? Policy: Upload to those with the best upload rate. This ensures that pieces get replicated faster Also, peers that have good upload rates are probably not being served by others
  24. 24. conclusion
  25. 25. Open any torrent client say BitTorrent ,BitLord..
  26. 26. That’s all …..You are done……You got your torrent file……….
  27. 27. Next What ??? Now you need to share it! You can upload it to a forum, or a BitTorrent site, like www.MiniNova.com etc…… Make sure your client is ready to seed to those who want the file before you upload, though, or else no one will get it.
  28. 28. Conclusion BitTorrent was conceived as a way of distributing large files more quickly, efficiently, and reliably. Thanks to BitTorrent though, the download of large files has become more feasible, and people have become accustomed to acquiring video through the net. At this point it is virtually impossible for anyone to bring an end to illegal downloads. whether or not BitTorrent will continue to play a role in this is yet to be seen.
  29. 29. References Google Search… www.en.wikipedia.com.com www.howstuffsworks.com www.what-is-torrent.com Torrent s/w official websites
  30. 30. Thank You….. Questions…??
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