P2P - Principle Architecture and Challenges

Prof. Kang Xi By Anand Lotia Srijish Sridharan (0356187) (0332873)

INTRODUCTION

INTRODUCTION
What does a Peer mean in P2P?
Hosts on Internet having equal rights
Fundamental architecture in today’s world
Server-Client and P2P architecture

HISTORY OF P2P

HISTORY OF P2P
Is the P2P concept new or did it already exist?
USENET and DNS – similar concept to P2P networks
Peer-to-Peer communication model:
Each peer can act as Server and Client
Each peer can initiate the communication session
Peers are directly connected to each other for file transfer

HISTORY OF P2P
USENET
Based on UUCP (Unix-to-Unix Protocol)
Used to exchange files, system patches, etc
Now uses NNTP (Network News Transport Protocol)

HISTORY OF P2P
DNS (Domain Name System)
DNS information is spread over different servers
Can act as Server or Client

HISTORY OF P2P
Launch of the first Peer-to-Peer application
Napster – Shawn Fanning (1999)
Created to share music in the Northeastern University

HISTORY OF P2P
Following the pioneer
Morpheus
Kazaa
BearShare
iMesh

Peer-to-Peer Architecture

Peer-to-Peer Architecture Architecture Based on File Listing Based on Node Connections Centralized Decentralized Unstructured Structured

Depending upon the listing of files:
Centralized (Hybrid)
Decentralized
Depending upon how the nodes are connected:
Unstructured
Structured

Centralized (Hybrid)
File listing exists on central server
All peers connect to this central server
Examples: Napster, ICQ

Decentralized
No Central Server
Each node connected to many other nodes
May be pure Peer-to-Peer or with Super Peers
Examples: Gnutella, BitTorrent

Unstructured
Nodes created arbitrarily
Each node copies link information from other connected nodes
Simple, however not efficient
Examples: FastTrack, Gnutella

Structured
Implements algorithms to ensure connection between nodes.
Efficient, however complex algorithms involved
Examples: DHT and HyperCuP

Types of P2P Networks

Napster
Gnutella
FastTrack
eDonkey
BitTorrent

Napster
Peers connect to the Central Server
File request sent to the server
Server responds with the ID of the sharing peer
Peers are directly connected for file transfers
Control messages used to ignoring spam users, sending private messages, creating favorites list, etc

Napster Clients
Napster
Napigator

Gnutella
Peers connected to each other in flat ad-hoc topology
Each peers – acts as client and server
Dynamic network – Peers can connect and disconnect as they wish without affecting the network

Connection procedure in Gnutella network

File Query and Response in Gnutella

Gnutella Clients
BearShare
LimeWire
Cabos
Shareaza

Gnutella – Analysis and Improvement
Flexibility
Performance & Stability
Reliability
Anonymity

FastTrack
Based on Hybrid architecture
Two tiers of control
First Tier – nodes connected to Super Peers
Second Tier – Super Peers connected to each other
Download same file from multiple users

FastTrack Clients
Kazaa
iMesh
Grokster
Morpheus

eDonkey
Based on hybrid architecture
Two tier architecture
First Tier – central servers for maintaining list of files
Second Tier – for file transfers
Two types of server software used – MetaMachine and eServer

eDonkey Protocol Features
Ability to search files based on meta-data (music, artist, bit-rate, extension, number of sources, file size)
Ability to download same file from multiple peers
Ability to share partial files
Ability to detect corrupt files

eDonkey Connection Procedure
Client initiates TCP connection to connect to the Server
File query messages is sent using UDP
Requesting peer connects to the sharing peer by TCP
Files are divided in 9.5 MB blocks
MD4 (128 bit) checksum is calculated for every block

eDonkey Clients
eDonkey2000 (developed by MetaMachine)
eMule
MLDonkey
aMule

BitTorrent
Based on decentralized network
Files are divided into pieces or blocks
Pieces can be of size from 64 kB to 4 MB
Pieces can be further fragmented into blocks of 16 kB

BitTorrent
Trackers – tracks seeders, leechers and file pieces from different users
Seeders – Hold complete files and shares with other peers
Leechers – Download files from other peers

BitTorrent
Users download .torrent files which includes meta-data information
Torrent files can have one or multiple trackers
Files are downloaded in pieces or blocks
Implements file sharing fairness

BitTorrent surpassed eDonkey traffic (2006)

BitTorrent Clients
Azureus
BitComet
µTorrent
BitTorrent

Challenges in P2P

Challenges in P2P
Challenges faced in P2P networks
Distribution of copyrighted files
Security Issues
Bandwidth Consumption

Challenges in P2P
Distribution of Copyrighted Files
Several P2P networks sued by music companies and private organizations (RIAA, MPAA, ARIA)
Users are also targeted
Copyright laws limited to few countries

Challenges in P2P
Security Issues
Spread of virus, malware, spyware, adware, etc
Use of Steganography
Spread of null files by RIAA, MPAA
Peers can be assigned reputation values
Pseudospoofing & Shilling attacks

Challenges in P2P
Bandwidth Consumption
Bandwidth for existing Internet traffic (2007)

Windows P2P Networking

Windows P2P Networking Model
Works with IPv6
Uses UPnP messages to communicate
Peers discovered by Simple Service Discovery Protocol

Microsoft Windows P2P Architecture

CONCLUSION

CONCLUSION
Potential of P2P networks are vast and still being discovered and developed
Can be used, not only for file transfer, but also real time media streaming, VOIP, distributed computing, etc

THANK YOU

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P2P - Principle Architecture and Challenges

by Srijish Sridharan

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