N ETWORKed M EDIA L AB. D EPT. OF I NFO. & C OMM., K-JIST Structured P2P Network for Loop Avoidance Chanmo Park August 27, 2003

N ETWORKed M EDIA L AB. D EPT. OF I NFO. & C OMM., K-JIST 2/26 Contents What is P2P? Essentials of P2P Sharing Approaches toward P2P Sharing (gnutella, Kazza, Morpheus 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

N ETWORKed M EDIA L AB. D EPT. OF I NFO. & C OMM., K-JIST 3/26 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

N ETWORKed M EDIA L AB. D EPT. OF I NFO. & C OMM., K-JIST 4/26 Essentials of P2P Sharing Construction of P2P Network oSelf-Organization Decentralized Resource Administration oSharing resources Content Discovery Stability oRecovery from the failure

N ETWORKed M EDIA L AB. D EPT. OF I NFO. & C OMM., K-JIST 5/26 Approaches toward P2P Sharing Unstructured network and pure decentralized oGnutella Unstructured network and partially decentralized oKazza, Morpheus Structured network and pure decentralized oCAN

N ETWORKed M EDIA L AB. D EPT. OF I NFO. & C OMM., K-JIST 6/26 Gnutella Protocol for P2P File Sharing(1) Characteristics oGnutella is a distributed system for file sharing provide means for network discovery provide means for file searching and sharing oDefines a network at the application level oEmploys the concept of peer-to-peer all hosts are equal (symmetry) there is no central point oanonymous search, but reveal the IP addresses when downloading

N ETWORKed M EDIA L AB. D EPT. OF I NFO. & C OMM., K-JIST 7/26 Gnutella Protocol for P2P File Sharing(2) Network Discovery oA discovers its horizon (e.g., TTL = 2) send ping to its neighbors (broadcast) ping msg is forwarded if TTL>0 oReceiving ping, B,C and E, respond pong pong contains network info about its sender B forwards pong msgs from E and C, to A

N ETWORKed M EDIA L AB. D EPT. OF I NFO. & C OMM., K-JIST 8/26 Gnutella Protocol for P2P File Sharing(2) Network querying oA searches the network (e.g., TTL = 2) send query to its neighbors (broadcast) the query is forwarded if TTL > 0 oB,C and E, respond with query_hit query_hit contains network info about where to download the file from B forwards query_hit msgs from E and C, to

N ETWORKed M EDIA L AB. D EPT. OF I NFO. & C OMM., K-JIST 9/26 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

N ETWORKed M EDIA L AB. D EPT. OF I NFO. & C OMM., K-JIST 10/26 Kazza and Morpheus Kazza, Morpheus ounstructured network opartially centralized systems which use the concept of SuperNodes oPeers are automatically elected to become SuperNodes if they have sufficient bandwidth and processing power oIn Morpheus, a central server provides new peers with a list of one or more SuperNodes with which they can connect. SuperNodes index the files shared by peers connected to them and proxy search requests on behalf of these peers. Queries are therefore sent to superNodes

N ETWORKed M EDIA L AB. D EPT. OF I NFO. & C OMM., K-JIST 11/26 CAN (Content Addressable Network) oa distributed, internet-scale hash table that maps file names to their location in the network Purely decentralized Scalable

N ETWORKed M EDIA L AB. D EPT. OF I NFO. & C OMM., K-JIST 12/26 Challenges Duplicated Messages oFrom loop and flooding Missing some contents oFrom loop and TTL Oriented to File Why? oUnstructured Network oToo Specific

N ETWORKed M EDIA L AB. D EPT. OF I NFO. & C OMM., K-JIST 13/26 Approach to Structured P2P Network Contribute to a way oto construct structured and general P2P network without loops and TTL oto know knowledge about constructed P2P network 2-D Space oMapping each nodes network identifier into 2-D space oZone Each node occupies allocated area Aggregate nodes with same network identifier into a zone Maintain a binary tree oCore Represent each zone Manage its zone Gateway between neighbor zones and its member oMember Belonged to a zone Each message should be sent to its zone and members in its zone

N ETWORKed M EDIA L AB. D EPT. OF I NFO. & C OMM., K-JIST 14/ Overview of Structured P2P Network zone Core node Member node Member Tree Tx within a zone Tx between zones

N ETWORKed M EDIA L AB. D EPT. OF I NFO. & C OMM., K-JIST 15/26 Elements of Structured P2P Network Core/Member Nodes oNeighboring zone information core info, zone info, direction oMember information member node information, routing table Strategies oRouting Messages oConstructing Structured P2P Network oManaging Zone oConstructing Member Tree oDiscovering Contents

N ETWORKed M EDIA L AB. D EPT. OF I NFO. & C OMM., K-JIST 16/26 Core/Member nodes 7 neighboring zone information oCore node (IP, Port#) oZone Range (x1,y1)~(x2,y2) Numbering zone o4 bits o00 : less than o01 : belong to o10 : greater than Member information oIP, Port# Member Tree oUplink node info (only 1) oDownlink node info (limited by 2)

N ETWORKed M EDIA L AB. D EPT. OF I NFO. & C OMM., K-JIST 17/26 Routing Messages Within a zone oDepends on the Member Tree (Binary Tree) Between zones oIf not a core, just send its core oThen core route this message along X coordinate until reaching destination x oAfter that, route the message along Y coordinate Every Message should have originators IP and Port

N ETWORKed M EDIA L AB. D EPT. OF I NFO. & C OMM., K-JIST 18/26 Constructing Structured P2P Network(JOIN) RP NodeCore Bootstrapping JOIN/(JOIN_FWD) Join As Core/Join As Member Inform Neighboring Zones Zone Management Routing Message Inform Neighboring Zones Inform Members

N ETWORKed M EDIA L AB. D EPT. OF I NFO. & C OMM., K-JIST 19/26 Managing Zone(1) same network identifier? Yes No Accept as a Member Split Zone & Rearrange Neighbors Msg AsMember Msg AsCore Reply Inform Neighbors Msg Type? AsMember AsCore Inform Members Set itself & Inform Neighbors Join Completed

N ETWORKed M EDIA L AB. D EPT. OF I NFO. & C OMM., K-JIST 20/26 Managing Zone(2) Splitting Zone oNetwork ID of New node is within its zone range, but Network ID is different Direction of Split oX or Y direction oDepends on Difference of X and Y between two network IDs Rearrange neighboring zones Two nodes inform neighbors of this change X Y

N ETWORKed M EDIA L AB. D EPT. OF I NFO. & C OMM., K-JIST 21/26 Constructing Member Tree Each node oMaintain information of all members oCreates a binary tree Using sorted IP address oRule one link between core and a member Uplink is only one Downlink is limited by Core

N ETWORKed M EDIA L AB. D EPT. OF I NFO. & C OMM., K-JIST 22/26 Discovering Content Content Discovery oSend the Msg to its Member and its core oCore On receiving it, Send it neighbor zones along X coordinate Also send it Neighboring Y zones with flooding DiscoveryHit X Y

N ETWORKed M EDIA L AB. D EPT. OF I NFO. & C OMM., K-JIST 23/26 Current Status Still Experimenting Environment oGT-ITM Creating Network Topology About 100,000 nodes Your advice Your advice oSimulator Myns oOS Linux oDev. Lang. Gcc/g++ version 2.96

N ETWORKed M EDIA L AB. D EPT. OF I NFO. & C OMM., K-JIST 24/26 Conclusion By introducing 2-D space oConstruct structured P2P network oReduce duplicated msgs (from zone and aggregation of same LAN nodes) oGuarantee visiting the whole node Future Work oimplementing simulator oAdd Recovery Mechanism oAdd native IP multicasting on Local Area Network oReflect real network topology on simulator

N ETWORKed M EDIA L AB. D EPT. OF I NFO. & C OMM., K-JIST 25/26 Thank You!

N ETWORKed M EDIA L AB. D EPT. OF I NFO. & C OMM., K-JIST 26/26 References K. Calvert, M. Doar, and E. Zegura. Modeling Internet Topology. IEEE Transactions on Communications, pages , December GT_ITM, Geogia Tech. myns Simulator, Univ. of Maryland, Suman Banerjeehttp:// S. Ratnasamy, P. Francis, M. Handley, R. Karp, S. Shenker, "A Scalable Content-Addressable Network", ACM Sigcomm 2001A Scalable Content-Addressable Network Peer-to-Peer Architecture Case Study: Gnutella. M. Ripeanu International Conference on Peer-to-Peer Computing (P2P2001), Linkoping, Sweeden, August 2001 Peer-to-Peer Architecture Case Study: Gnutella. Kazza, Morpheus,