by: sraddha adhikari st107931 tc/set thesis examination committee: dr. teerapat sanguankotchakorn...

By: Sraddha AdhikariSt107931

TC/SETThesis Examination Committee:Dr. Teerapat Sanguankotchakorn (Chairperson)Assoc. Prof. Tapio J. ErkeDr. Poompat SaengudomlertProf. Noel Crespi (External Expert)Dr. Mehdi Mani (External Expert)

Asian Institute of TechnologyMay 17, 2010

Why P2P?Bandwidth Bottleneck has shifted from Users

Side (e.g. dial up connection) to Central ServerDevelopment of popular sites like YouTube

hindered by client/server architecture [4]

src: [11]2

P2P versus C/S

3

Peer-to-Peer NetworksPeers or nodes are the basic building blocksShift of load and responsibility to all entities

in P2P networkPeers incorporate with each other to

accomplish some task/objectivesResources in the network scale with the

number of peers in the systemReliable network: no single point of failureResilient Network: avoid dependence on

central resources

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PROBLEM STATEMENTP2P networks (overlay network) have their own

routing mechanisms that play major role in their performance [9].

Content Discovery is still identified as a major problem in Unstructured P2P networks [1] [2] [6] [11] [12].

Nodes in P2P networks do not have global view of the network which leads to inefficient routing of query.

P2P delivery of short videos demands an efficient content location mechanism [4].

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Content Discovery ProblemThe content discovery problem is simple to

state: Given a data item X stored at some dynamic set of nodes in the system, find it.

A

G

F

E

D

C

B I want X

I HAVE

X

Various Search Mechanisms: FloodingMost typical query method in Decentralized and

Unstructured P2P networks Query Flooding overloads the whole network with

redundant messages Difficult to choose appropriate TTL to terminate

the flood.Many duplicate messages introduced by floodingGnutella, first decentralized P2P application has

performance issues like generation of huge network traffic, slow response and congestion [5] [12]

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Various Search Mechanisms: Expanding Ring Introduced to improve search in Gnutella by

[7].Value of TTL is gradually increased to find

the contentThere is duplication of messages to the same

peersPeers do not learn from past experiences to

bypass previously forwarded peersThis approach still floods the network with

messages8

Various Search Mechanisms: Random Walk

Totally blind search where nodes forward their query to a random node at each hop

If the forwarded node is overloaded with queries, it would take time to process, which adds to delay of random walk mechanism [3].

Sequential search, hence search time increases

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Peer-to-peer & Social NetworksDue to the fact that there is human being

behind every peer there is similarity between social networks and peer-to-peer networks.

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Proposal: Social P2P Network

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We propose to implement human strategies in social networks to improve search mechanism in P2P.

In short, we propose a social P2P network (socP2P).

We believe and will verify that human strategies in social networks are useful in improving content discovery in P2P network.

Objectives of Proposed Search Mechanism

Locate resources in the network efficiently with- high success rate- low overhead- low delay

Detect nodes having similar interest and use them to make search more effective.

Exploit “search mechanism” to gather interest information of nodes in network so that additional overhead is not required to obtain these information.

Develop an efficient and scalable “Resource Discovery Algorithm” in P2P networks using social relationships between peers.

Evaluate the proposed algorithm by simulation and comparisons.

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Limitations

We do not consider any dynamics due to node joins and leaves and content sharing and removing.

We do not consider issues of selfish peers who do not contribute their resources to the network and are commonly known as free-riders.

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Human Characteristics copied in proposed algorithm

Human beings can be grouped into different interest categories.

We find out resources that we are looking for by directly contacting some acquaintances that have knowledge about the resource that we are looking for.

When we interact with people, we try to remember useful information (what they are involved in, save their contact number) so that we can use these information later .

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Detection of Interest Similarity in socP2P

Nodes do not declare their interest.Interest of nodes is learned during the search

process.If ‘B’ replies successfully to the query of ‘A’, it is

learnt that they have interest on the same file.Hence Interest Similarity between then is

declared.A directed Interest Link is created from A to B.Considering the interest similarity between

them, B might be useful to A in future as well.

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Two Principals of Our ApproachPrincipal 1Use search queries to automatically adapt to

make resource related interest relationships.

Principal 2Exploit the query request encounters by

nodes to keep a record of what the requesting node is interested in? - It is overheard knowledge by node- Helps in recommending “right nodes” to the querying node.

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Two Types of Links created Based on Interest Similarity

Directed Interest Links

Network Suggested Forward and thus Created Links

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An Example of Directed Interest Link and Recommendation

B

DC

A

E

Find X

A wants X

Find XD

AB

C

C g

ives

X

to A

Search Restricted to ‘M’ NodesSearch is limited to two hops.Our goal is to restrict number of Queries

submitted to the network for a single content.Query Node sends its query to M/2 nodes

(neighbors or friends or both) in the first hop.If these M/2 Nodes do not have requested

content, each of them forward the query to only one node.

Thus query is forwarded to maximum (1 x (M/2) + (M/2) x 1) = M

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Search Mechanism in socP2P

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Recommended Nodes Based Search

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Friend Based Search

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SIMULATION & RESULTS MATLAB CODEEach result is simulated 20 times except for

Network Size 1000 (12-15 times).Simulation Methodology - Network Generation

- Content Generation & Distribution- Query Generation

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Average Success Rate

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In the above formula, NBS = Neighbors Based SearchFBS = Friends Based SearchRBS = Recommended Nodes Based

Search

Average Success Rate (ASR)

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Percentage of nodes a query is forwarded to


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27



28



29


ASR in relation to Number of Queries

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Comparison between socP2P, socP2P without Node Overhearing & Random Walk

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32Percentage of nodes a query is forwarded to


33Percentage of nodes a query is forwarded to

Average Success Rate versus Popularity of Files

34Popularity of resource


35

Popularity of resource


36



37


Shortest Path to Content

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Shortest Path to Content (Comparison socP2P & Random Walk)

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Shortest Path to Content (Comparison with Gnutella, Gnutella with Shortcuts and socP2P)

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Network Size and Network value

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Network Size and Network Value

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Code Validation

Parameters Value

Total Request 884

Documents 609

Total Number of Peers 735

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Table: Simulation Parameters Used By Reference Paper

Observation Parameter: Average Success Rate

Performance similarity

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Simulation Length (minutes)

ConclusionFriend lists of nodes, overheard knowledge

by nodes and recommendation by nodes on the basis of overheard knowledge help to improve search in P2P network.

socP2P has achieved high success rate compared to random walk and Gnutella with shortcuts.

High success rate is achieved with less delay and low overhead in the network.

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Future WorkDistribution of content taking care of bandwidth

efficiency, delay and load distribution in the network.

Possible works directed towards enhancing socP2P:

Mutual Interest LinksIdentifying rare files to increase their success

rateIncluding Overhearing Part in the Forwarded

Node46

References [1] Balakrishnan, H., Kaashoek, M.F., Karger, D., Morris, R. & Stoica, I.

(2003). Looking Up Data in P2P Syatems. Communications of the ACM, 46(2), 43-48.

[2] Bisnik, N. & Abouzeid, A. (2005). Modelling and Analysis of Random Walk Search Algorithms in P2P Networks. Hot-p2p, Second International Workshop on Hot Topics in Peer-to-Peer Systems, pp.95-103.

[3] Chawathe, Y., Ratnasamy, S., Breslau, L., Lanham, N. & Shenker, S. (2003). Making Gnutella-like P2P Systems Scalable. Making Gnutella-like P2P Systems Scalable. Proceedings of ACM SIGCOMM, Kasruhe, Germany, 2003.

[4] Cheng, X. & Liu, J. (2009). NetTube: Exploring Social Networks for Peer-to-Peer Short Video Sharing. IEEE INFOCUM 2009 Proceedings, 2009, 1152-1160.

[5] Hui, K.Y.K., Lui, J.C.S., & Yau, D.K.Y. (2006). Small World Overlay P2P Networks. Computer Networks, vol. 50, no. 15, pp.2727-2746, 2006.

[6] Liu, L., Antonopoulos, N., & Mackin, S. (2007). Social Peer-to-Peer for Resource Discovery. 15th EUROMICRO International Conference on Parallel, Distributed and Network-Based Processing (PDP’07), Page(s): 459-466.

[7] Lv, Q., Cao, P., Cohen, E., Li, K., & Shenker, S. (2002). Search and replication in unstructured peer-to-peer networks. Proceedings of the 16th international conference on Supercomputing, New York, USA, 84-95.

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References [8] McGarthwaite, L. (2005). Client-Server versus Peer-to-Peer

Architecture: Comparisons for Streaming Video. Proceedings of the 5th Winona Computer Science, Undergraduate Research Seminar, April 20-21, 2005, Winona, MN, US.

[9] Ripeanu, M. (2001). Peer-to-Peer Architecture Case Study: Gnutella Network. Proceedings of IEEE 1st International Conference on Peer-to-peer Computing, Linkoping Sweden.

[10] Sripanidkulchai, K., Maggs, B., & Zhang, H. (2003). Efficient Content Location Using Interest-Based Locality in Peer-to-Peer Systems. INFOCOM 2003. Twenty-Second Annual Joint Conference of the IEEE Computer and Communications. IEEE Societies, Volume: 3, Page(s): 2166-2176 vol.3.

[11] Tang, J., Zhang, W., Xiao, W., Tang, D., & Song, J. (2006). Self-Organizing Service-Oriented Peer Communities.

[12] Upadrashta, Y. , Vassileva, J. & Grassmann, W. (2005). Social Networks in Peer-to-Peer Systems.

[13] url: http://www.cs.virginia.edu/~mngroup/hypercast/general.html

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Thank you !

Questions and Suggestions are welcome !!

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by: sraddha adhikari st107931 tc/set thesis examination committee: dr. teerapat sanguankotchakorn...

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