ELEC 2402 Computer Communications

Mini-Project Briefing

Ma LingjunOct. 10, 2007

Mini-Project Briefing

• Topic: Peer-to-Peer Networking and Its Applications.

• Write a report based on your own study of the topic, about 10 pages in length.

• Deadline: 6pm, Nov. 30th, 2007.– Please print out your report and submit it to

me at CYC 807 prior to the deadline.

Mini-Project Briefing

• Overview– A brief introduction of Peer-to-Peer

Networking– Instructions on Report Structure– A Sample Report– Score Policy– Recommended Reading– Q&A

2

Defintion of P2P

1) Significant autonomy from central servers

2) Exploits resources at the edges of the Internet

storage and content

CPU cycles

human presence

3) Resources at edge have intermittent connectivity, being added & removed

3

It’s a broad definition:

P2P file sharingNapster, Gnutella, KaZaA, eDonkey, etc

P2P communicationInstant messagingVoice-over-IP: Skype

P2P computation seti@home

DHTs & their appsChord, CAN, Pastry, Tapestry

P2P apps built over emerging overlays

PlanetLab

Wireless ad-hoc networking not covered here

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P2P file sharing

Alice runs P2P client application on her notebook computerIntermittently connects to Internet; gets new IP address for each connectionRegisters her content in P2P system

Asks for “Hey Jude”Application displays other peers that have copy of Hey Jude.Alice chooses one of the peers, Bob.File is copied from Bob’s PC to Alice’s notebook: P2PWhile Alice downloads, other users uploading from Alice.

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Millions of content servers

Hey Jude

Magic Flute

StarWars

ERNPR

Blue

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Killer deployments

Napsterdisruptive; proof of concept

Gnutellaopen source

KaZaA/FastTrackToday more KaZaA traffic then Web traffic!

eDonkey / OvernetBecoming popular in EuropeAppears to use a DHT

Is success due to massive number of servers, or simply because content is free?

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P2P file sharing software

Allows Alice to open up a directory in her file system

Anyone can retrieve a file from directoryLike a Web server

Allows Alice to copy files from other users’ open directories:

Like a Web client

Allows users to search nodes for content based on keyword matches:

Like Google

Seems harmless to me !

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Instant Messaging

Alice runs IM client on her PCIntermittently connects to Internet; gets new IP address for each connectionRegisters herself with “system”Learns from “system” that Bob in her buddy list is active

Alice initiates direct TCP connection with Bob: P2PAlice and Bob chat.

Can also be voice, video and text.

We’ll see that Skypeis a VoIP P2P system

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P2P Distributed Computing

seti@homeSearch for ET intelligenceCentral site collects radio telescope dataData is divided into work chunks of 300 KbytesUser obtains client, which runs in backgrd

Peer sets up TCP connection to central computer, downloads chunkPeer does FFT on chunk, uploads results, gets new chunk

Not peer to peer, but exploitsresources at network edge

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BitTorrent url tracker

1. GET file.torrent

file.torrent info:• length• name• hash• url of tracker

2. GET 3. list of peers

4.

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BitTorrent: Pieces

File is broken into piecesTypically piece is 256 KBytesUpload pieces while downloading pieces

Piece selectionSelect rarest pieceExcept at beginning, select random pieces

Tit-for-tatBit-torrent uploads to at most four peersAmong the uploaders, upload to the four that are downloading to you at the highest ratesA little randomness too, for probing

Instructions on Report Structure

• An introduction– What is P2P networking? – What are the advantages of P2P networking?– How can P2P networking be classified?

• Typical Applications of P2P networking• A case study – BitTorrent• Future work

Sample Report

• Please refer to the sample report attached to the Mini-project Guideline.

Score Policy

• Introduction 15%• Typical Applications 25%• Case Study 30%• Future Work 15%• Others 15%

Recommended Reading

• Surveys– A survey of peer-to-peer content distribution

technologies– A Survey and Comparison of Peer-to-Peer

Overlay Network Schemes– A Survey of Peer-to-Peer File Sharing

Technologies– Peer-to-Peer Computing

• Tutorials

Recommended Reading

• Go to http://cis.poly.edu/~ross/p2pTheory/P2Preading.htm for a comprehensive reading list.

• Other sources– Enter key words P2P, Peer-to-Peer, P2P

Tutorial, P2P Survey at Google– IEEE/ACM electronic libraries (via lib.hku.hk)– Books available at library

Other things you need to know…

• You MUST follow the format of the sample report, including font and line spacing. Otherwise, your score suffers!

• Pay special attention to the texts in the marked in red.

• PAPER version before Nov. 30th, 2007.• No plagiarism!

Q&A