The document discusses peer-to-peer (P2P) networking, highlighting its advantages over traditional client/server architecture, such as scalability, reliability, and efficiency. It primarily focuses on the BitTorrent protocol, which facilitates fast and efficient file sharing and explains key terminology including seeders, leechers, and trackers. Additionally, it addresses legal concerns related to torrenting, emphasizing that the protocol itself is not illegal but the content shared may be.

1. BitTorrent – A revolution
in P2P networking
Mihir Jyoti Chakrabarti, Arijit Roy, Anirban
Sen
27 11 06
Swami Vivekananda Institute of Science and
Technology

2. Introduction
WHAT IS P2P NETWORKING?
2

3. Client/Server Architecture
 What is it?
 Client sends request, server provides the client with
data.
 Server is the only data source.
3

4. Client/Server Architecture
4
 Problems
 Scalability: how many users can a server support?
 What happens when user traffic overload servers?
 Limited resources (bandwidth, CPU, storage)
 Reliability: if number of servers is small, what happens
when they break, fail, get disconnected, are
mismanaged by humans?
 Efficiency: if your users are spread across the entire
globe, how do you make sure you answer their
requests quickly?

5. The Alternative: Peer-to-Peer
 A simple idea
 Provides as well as consumes network services.
 A cooperative model: clients = peers = servers
5
A
B E
DC

6. Peer to Peer
6
 The benefits
 Scalability: Number of “servers” grows with users
 BYOR: bring your own resources (storage, CPU, B/W)
 Reliability: load spread across many peers
 Probability of them all failing is very low…
 Efficiency: peers are distributed
 Peers can try and get service from nearby peers

7. Types of P2P programs
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 Centralized
 In a centralized system a server maintains directories
of what is stored in each peer computer. The central
server directs the connections between peers.
 Example Napster , Maze etc

8. Types of P2P programs
8
 De-Centralized
 With a decentralized program each peer connect
directly to other peers without being directed by a
server. This connection is repeated making the
resulting network large.
 Example: Gnutella

9. What is BitTorrent
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 Programmer Bram Cohen designed the protocol in
April 2001 and released its first implementation of
the BitTorrent client on 2 July 2001.
 Protocol for the practice of peer-to-peer file sharing
 Designed for fast, efficient content distribution
 Ideal for large files, e.g. movies, DVDs, ISOs, etc.
 Not a full fledged P2P system
 Does not support searching for files

10. Important Terminology
10
 .torrent – Metadata file containing information(size,
about) about file to be shared via BitTorrent.
 Share Ratio – The ratio of the amount of data you've
uploaded to the amount of data you've downloaded.
 Peer – One instance of a BitTorrent client running on a
computer connected to the Internet to which other clients
connect and transfer data.
 Seeder – A peer who has a complete copy of the torrent
and offers it for upload.

11. Important Terminology
11
 Leech – Usually a peer who has a negative effect on
the swarm by having a very poor share ratio - in other
words, downloading much more than they upload.
 Swarm – Together, all peers (including seeders) sharing
a torrent. For example, six ordinary peers and
two seeders make a swarm of eight.
 Tracker – A tracker is a server that keeps track of which
seeds and peers are in the swarm. The tracker is not
directly involved in the data transfer and does not have a
copy of the file.
 Piece – This refers to the torrent files being divided up
into equal specific sized pieces (i.e. 512Kb, 1Mb).

12. Sharing Pieces
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Initial Seeder
1 2 3 4 5 6 7 8
Peer
1 2 3
Peer
54 76 8 1 2 3 54 76 8
Seeder Seeder

13. Working of BitTorrent
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Tracker
Swarm
Leechers
Seeder

14. The Beauty of BitTorrent
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 More seeders = more availability of the full file
 Great for content distribution
 More peers = more replicas of pieces
 More replicas = faster downloads
 Multiple sources for each piece

15. Screenshot of a BitTorrent Client
15

16. History of BitTorrent
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 Bram Cohen (born October 12, 1975) created the
first file sharing program to use the protocol, also
known as BitTorrent.
 Prior to version 6.0, BitTorrent was written in Python,
and was free software. Very early versions released
prior to December 30, 2001 were released into
the public domain without a license. Versions up to and
including 3.4.2 were distributed under the MIT license.
 Since version 6.0, the BitTorrent client has been a
rebranded version of µTorrent. As a result, it is no
longer open source.

17. BitTorrent Revolution
17

18. BitTorrent Revolution
18

19. 19
WHAT IS LEGAL AND
ILLEGAL?

20. Illegal Events
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 Finland: Finreactor
 Hong Kong: Individual actions
 Singapore: Odex actions against users
 Slovenia: Suprnova
 Sweden: Pirate Bay
 TorrentSpy

21. Conclusion
21
 One thing for sure, torrent is not equal to piracy.
 The torrent protocol is just a transmission mean
for users to download files more easily.
 It is the content (not the protocol) that makes the
act illegal. When it comes to downloading through
the torrent protocol, there’s no real way to stay
completely safe.
 However, it remains one of the most effective peer-
to-peer protocols in the world. If you’re worried that
you may be downloading something that’s against
the laws in your country, follow your moralistic
instinct.

22. Reference
22
 http://en.wikipedia.org
 http://www.google.co.in
 http://www.krazytech.com
 http://www.slideshare.net
 http://blog.seattlepi.com/timothymccormack/2013/0
7
 http://historycomputer.com/Internet/Conquering/Bit
Torrent.html
 http://www.youtube.com
 http://www.bittorrent.com

23. Clear Your Doubts
23