NETWORKed MEDIA LAB.

DEPT. OF INFO. & COMM., K-JIST

Structured P2P Network for Loop Structured P2P Network for Loop AvoidanceAvoidance

Chanmo ParkAugust 27, 2003

cmpark@netmedia.kjist.ac.kr

NETWORKed MEDIA LAB.

DEPT. OF INFO. & COMM., K-JIST 2/26

ContentsContents What is P2P? Essentials of P2P Sharing Approaches toward P2P Sharing (gnutella, Kazza, Mor

pheus and CAN) Challenges Approach to Structured P2P Network Overview of Structured P2P Network Elements of Structured P2P Network Details of Structured P2P Network Conclusion References

NETWORKed MEDIA LAB.

DEPT. OF INFO. & COMM., K-JIST 3/26

What is P2P?What is P2P? Direct access between peer computers, rather than

through a centralized server Applications that take advantage of resources (storage,

cycles, content, human presence) available at the edges of the internet

Offers a way of decentralizing administration on the resources

Sharing of computer resources by direct exchange Self-organizing capacity

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DEPT. OF INFO. & COMM., K-JIST 4/26

Essentials of P2P SharingEssentials of P2P Sharing Construction of P2P Network

o Self-Organization

Decentralized Resource Administrationo Sharing resources

Content Discovery Stability

o Recovery from the failure

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DEPT. OF INFO. & COMM., K-JIST 5/26

Approaches toward P2P SharingApproaches toward P2P Sharing Unstructured network and pure decentralized

o Gnutella

Unstructured network and partially decentralized o Kazza, Morpheus

Structured network and pure decentralizedo CAN

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DEPT. OF INFO. & COMM., K-JIST 6/26

Gnutella Protocol for P2P File Sharing(1)Gnutella Protocol for P2P File Sharing(1) Characteristics

o Gnutella is a distributed system for file sharing provide means for network discovery provide means for file searching and sharing

o Defines a network at the application levelo Employs the concept of peer-to-peer

all hosts are equal (symmetry) there is no central point

o anonymous search, but reveal the IP addresses when downloading

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DEPT. OF INFO. & COMM., K-JIST 7/26

Gnutella Protocol for P2P File Sharing(2)Gnutella Protocol for P2P File Sharing(2) Network Discovery

o A discovers its horizon (e.g., TTL = 2) send ping to its neighbors (broadcast) ping msg is forwarded if TTL>0

o Receiving ping, B,C and E, respond pong pong contains network info about its sender B forwards pong msgs from E and C, to A

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DEPT. OF INFO. & COMM., K-JIST 8/26

Gnutella Protocol for P2P File Sharing(2)Gnutella Protocol for P2P File Sharing(2) Network querying

o A searches the network (e.g., TTL = 2) send query to its neighbors (broadcast) the query is forwarded if TTL > 0

o B,C and E, respond with query_hit query_hit contains network info about where to downloa

d the file from B forwards query_hit msgs from E and C, to

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DEPT. OF INFO. & COMM., K-JIST 9/26

Gnutella Protocol for P2P File Sharing(3)Gnutella Protocol for P2P File Sharing(3) There is nothing that stops a servant flooding its network region with messages.

Cost of maintaining Network Cost of searching file

From “A Quantitative Analysis of the Gnutella Network Traffic”

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DEPT. OF INFO. & COMM., K-JIST 10/26

Kazza and MorpheusKazza and Morpheus Kazza, Morpheus

o unstructured network

o partially centralized systems which use the concept of “SuperNodes”

o Peers are automatically elected to become SuperNodes if they have sufficient bandwidth and processing power

o In Morpheus, a central server provides new peers with a list of one or more SuperNo

des with which they can connect. SuperNodes index the files shared by peers connected to them and pro

xy search requests on behalf of these peers. Queries are therefore sent to superNodes

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DEPT. OF INFO. & COMM., K-JIST 11/26

CAN (Content Addressable Network)CAN (Content Addressable Network) CAN (Content Addressable Network)

o a distributed, internet-scale hash table that maps file names to their location in the network

Purely decentralized Scalable

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DEPT. OF INFO. & COMM., K-JIST 12/26

ChallengesChallenges Duplicated Messages

o From loop and flooding

Missing some contentso From loop and TTL

Oriented to File Why?

o Unstructured Networko Too Specific

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DEPT. OF INFO. & COMM., K-JIST 13/26

Approach to Structured P2P NetworkApproach to Structured P2P Network Contribute to a way

o to construct structured and general P2P network without loops and TTL

o to know knowledge about constructed P2P network

2-D Spaceo Mapping each nodes’ network identifier into 2-D spaceo Zone

Each node occupies allocated area Aggregate nodes with same network identifier into a zone Maintain a binary tree

o Core Represent each zone Manage it’s zone Gateway between neighbor zones and it’s member

o Member Belonged to a zone Each message should be sent to its zone and members in its zone

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DEPT. OF INFO. & COMM., K-JIST 14/26

2160

216

Overview of Structured P2P NetworkOverview of Structured P2P Network

zone

Core node

Member node

Member TreeTx within a zoneTx between zonesTx between zones

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DEPT. OF INFO. & COMM., K-JIST 15/26

Elements of Structured P2P NetworkElements of Structured P2P Network Core/Member Nodes

o Neighboring zone information core info, zone info, direction

o Member information member node information, routing table

Strategieso Routing Messageso Constructing Structured P2P Networko Managing Zoneo Constructing Member Treeo Discovering Contents

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DEPT. OF INFO. & COMM., K-JIST 16/26

Core/Member nodesCore/Member nodes 7 neighboring zone information

o Core node (IP, Port#)

o Zone Range (x1,y1)~(x2,y2)

Numbering zoneo 4 bits

o 00 : less than

o 01 : belong to

o 10 : greater than

Member informationo IP, Port#

Member Treeo Uplink node info (only 1)

o Downlink node info (limited by 2)

0000 0001 0010

1000 1001 1010

0100 0110

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DEPT. OF INFO. & COMM., K-JIST 17/26

Routing MessagesRouting Messages Within a zone

o Depends on the Member Tree (Binary Tree)

Between zoneso If not a core, just send its

core

o Then core route this message along X coordinate until reaching destination x

o After that, route the message along Y coordinate

Every Message should have originator’s IP and Port

0000 0001 0010

1000 1001 1010

0100 0110

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DEPT. OF INFO. & COMM., K-JIST 18/26

Constructing Structured P2P Network(JOIN)Constructing Structured P2P Network(JOIN)

RP

NodeNode CoreCoreBootstrapping

JOIN/(JOIN_FWD)

Join As Core/Join As Member

Inform Neighboring Zones

Zone Management

Routing Message

Inform Neighboring ZonesInform Members

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DEPT. OF INFO. & COMM., K-JIST 19/26

Managing Zone(1)Managing Zone(1)

same network identifier?

Yes No

Accept as a MemberSplit Zone

&Rearrange Neighbors

Msg AsMember Msg AsCore

Reply

Inform Neighbors

Msg Type?

AsMember AsCore

Inform Members Set itself&

Inform Neighbors

Join Completed

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DEPT. OF INFO. & COMM., K-JIST 20/26

Managing Zone(2)Managing Zone(2) Splitting Zone

o Network ID of New node is within its zone range, but Network ID is different

Direction of Splito X or Y directiono Depends on Difference of

X and Y between two network IDs

Rearrange neighboring zones

Two nodes inform neighbors of this change

X

Y

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DEPT. OF INFO. & COMM., K-JIST 21/26

Constructing Member TreeConstructing Member Tree Each node

o Maintain information of all members

o Creates a binary tree Using sorted IP address

o Rule one link between core

and a member Uplink is only one Downlink is limited by 2

6

5

4

2

3

1

7

Core

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DEPT. OF INFO. & COMM., K-JIST 22/26

Discovering Content Discovering Content Content Discovery

o Send the Msg to its Member and it’s core

o Core On receiving it, Send it n

eighbor zones along X coordinate

Also send it Neighboring Y zones with flooding

DiscoveryHit0

216-1

X

Y

216-1

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DEPT. OF INFO. & COMM., K-JIST 23/26

Current StatusCurrent Status Still Experimenting Environment

o GT-ITM Creating Network Topology About 100,000 nodes Your adviceYour advice

o Simulator Myns

o OS Linux

o Dev. Lang. Gcc/g++ version 2.96

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DEPT. OF INFO. & COMM., K-JIST 24/26

ConclusionConclusion By introducing 2-D space

o Construct structured P2P networko Reduce duplicated msgs (from zone and aggregation of sam

e LAN nodes)o Guarantee visiting the whole node

Future Worko implementing simulatoro Add Recovery Mechanismo Add native IP multicasting on Local Area Networko Reflect real network topology on simulator

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DEPT. OF INFO. & COMM., K-JIST 25/26

Thank You!Thank You!

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DEPT. OF INFO. & COMM., K-JIST 26/26

ReferencesReferences K. Calvert, M. Doar, and E. Zegura. Modeling Internet Topology. IE

EE Transactions on Communications, pages 160-163, December 1997.

GT_ITM, Geogia Tech. myns Simulator, http://www.cs.umd.edu/~suman/research/myns/, Uni

v. of Maryland, Suman Banerjee S. Ratnasamy, P. Francis, M. Handley, R. Karp, S. Shenker, "

A Scalable Content-Addressable Network", ACM Sigcomm 2001 Peer-to-Peer Architecture Case Study: Gnutella. M. Ripeanu. 200

1  International Conference on Peer-to-Peer Computing (P2P2001), Linkoping, Sweeden, August 2001

Kazza, http://www.kazaa.com/us/index.htm Morpheus, http://www.openp2p.com/lpt/a/990