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BITTORRENTMay22,20131ByK Ravi Teja Varma09131A1272B. Tech, 8th Sem
CONTENTSMay22,20132•Introduction•Types Of Data Sharing•Traditional Client-Server Downloading•Peer-Peer Downloading•Gnutella Network•Why BitTorrent?•What actually a BitTorrent is?•BitTorrent Terminology•How BitTorrent works?•Downloading Files Using BitTorrent•Seeding Torrent•How to create a dot torrent file•Conclusion•References
INTRODUCTIONMay22,20133• Humans tend to share things.• As electronic data plays a vital role these days, they acquirethe “sharing” attribute.• Sharing electronic data(emails, ebooks, multimedia files) is theneed of the hour.• Data sharing must be fast enough as we are now moving to 3Gand 4G technologies, users expect data sharing at high speeds.
TYPES OF DATA SHARING Manual Sharing Using Removable Media: Such as USBdrives, External Hard disks. Centralized Servers of Computer Networks: Network ofcomputers interconnected for sharing resources andinformation via a central server. Distributed Peer-to-Peer networking: Is a Computer networkwhere each system in the network acts as client or serverallowing shared access of resources without the need ofcentral server.May22,20134
TRADITIONAL CLIENT-SERVER DOWNLOADINGMay22,20135•You open a Webpage and click a link to download a file to yourcomputer.•The Web browser software on your computer (the client) tellsthe server (a central computer that holds the Web page and the fileyou want to download) to transfer a copy of the file to your computer.•The transfer is handled by a protocol (a set of rules), such as FTP(File Transfer Protocol) or HTTP (HyperText Transfer Protocol).
CONTD.May22,20136•The transfer speed is affected by a number of variables, including thetype of protocol, the amount of traffic on the server and the number ofother computers that are downloading the file.•If the file is both large and popular, the demands on the server are great,and the download will be slow.
PEER-PEER DOWNLOADINGMay22,20137•In peer-to-peer sharing, a software program is used instead a WebBrowser to locate computers that have the file user want.•These are ordinary computers like the users, they are called PEERS.• The process works like this:• You run peer-to-peer file-sharing software (for example,a Napster program or Gnutella) on your computer and send out arequest for the file you want to download.•To locate the file, the software queries other computers that areconnected to the Internet and running the file-sharing software.
CONTD.May22,20138•When the software finds a computer that has the file you want onits hard drive , the download begins.•Others using the file-sharing software can obtain files they wantfrom your computers hard drive.•The file-transfer load is distributed between the computersexchanging files, but file searches and transfers from yourcomputer to others can cause bottlenecks.
CONTD.May22,20139•Some people download files and immediately disconnect withoutallowing others to obtain files from their system, which iscalled leeching.• This limits the number of computers the software can search for therequested file .
GNUTELLA NETWORKMay22,201310How a Gnutella client finds a songGiven that there is no central server to store the names and locations ofall the available files, how does the Gnutella software on your machinefind a song on someone elses machine?The process goes like this:• Type the name of the song or file we want to find.• Your machine knows of at least one other Gnutella machinesomewhere on the network.
CONTD.May22,201311•Your machine sends the song name you typed in to the Gnutellamachine(s) .•These machines search to see if the requested file is on the local harddisk. If so, they send back the file name (and machine IP address) to therequester.•At the same time, all of these machines send out the same request tothe machines they are connected to, and the process repeats.•A request has a TTL (time to live) limit placed on it.
CONTD.May22,201312 A request might go out six orseven levels deep before itstops propagating. If eachmachine on the Gnutellanetwork knows of just fourothers, that means that yourrequest might reach 8,000 or soother machines on the Gnutellanetwork if it propagates sevenlevels deep.
CONTD.May22,201313•It is an extremely simple and clever way of distributing a query tothousands of machines very quickly.•This approach has one big advantage -- Gnutella works all thetime , as long as you can get to at least one other machine runningGnutella software, you are able to query the network.•No court order is going to shut this system down, because there isno one machine that controls everything.
WHY BITTORRENT?May22,201314•Unlike some other peer-to-peer downloadingmethods, BitTorrent is a protocol that offloads some of the filetracking work to a central server called a Tracker.•Another difference is that it uses a principal called tit-for-tat.•This means that in order to receive files, you have to givethem. This solves the problem of leeching -- one of developerBram Cohens primary goal.
WHAT IS BITTORRENT?May22,201315•BitTorrent is a protocol that enables fast downloading of large filesusing minimum Internet bandwidth.•It costs nothing to use and includes no spyware or pop-upadvertising.•The most popular video, audio or software files can be transferredfaster and cheaper by using BitTorrent.
BITTORRENT TERMINOLOGYMay22,201316Leeches - People who download files but do not share fileson their own computer with others.Seed or seeder - A computer with a complete copy of aBitTorrent file (At least one seed computer is necessary for aBitTorrent download to operate).Swarm - A group of computers simultaneously sending(uploading) or receiving (downloading) the same file..torrent - A pointer file that directs your computer to the fileyou want to download.Tracker - A server that manages the BitTorrent file-transferprocess.
HOW BITTORRENT WORKS?May22,201317•You open a Web page and click on a link for the file you want.•BitTorrent client software communicates with a tracker to findother computers running BitTorrent that have the complete file(seed computers) and those with a portion of the file (peers that areusually in the process of downloading the file).•The tracker identifies the swarm, which are connected computersthat have all or a portion of the file and are in the process of sendingor receiving it.•The tracker helps the client software to trade pieces of the file wewant with other computers in the swarm. Your computer receivesmultiple pieces of the file simultaneously.
CONTD.May22,201318If you continue to run the BitTorrent client software after yourdownload is complete, others can receive .torrent files from yourcomputer; your future download rates improve because you are rankedhigher in the "tit-for-tat" system.
DOWNLOADING FILES USING BITTORRENTMay22,201319•Just like you need a URL: www.google.com to go to that siteand download content.We need a „torrent file‟ that tellsBitTorrent the necessary information to download the content.•Websites like legaltorrents.com offer all kinds of torrents.•Once you have obtained torrent file, you need to import it toBitTorrent:•Click File->Add Torrent or Press CTRL+O.•Double click on Torrent file.
SEEDING TORRENTMay22,201321•Seeding is where you leave your BitTorrent clientafter you finish download to help distribute it.•BitTorrent will continue seeding until you remove it(Right click the torrent and hit Remove) .
CONCLUSION News of increased adoption of this revolutionary protocolcontinues to emerge, and this seems to be a rich area forcontinued research in computer networking, with significantpotential benefits to society. If BitTorrent and similar protocols do find a legal place in theinternet, it will certainly help to pave the way for distributingrich media on the internet, and provide the impetus for newinnovations.May22,201325