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SocialSwarm: Exploiting Distance in Social Networks for Collaborative Flash File DistributionPresented by: Su YingbinOutlineIntroductionSocialSwam DesignNotations AlgorithmsEvaluationConclusion

Tit-for-tat as incentive to uploadWant to encourage all peers to contributePeer A said to choke peer B if it (A) decides not to upload to BEach peer (say A) unchokes at most 4 interested peers at any timeThe three with the largest upload rates to AWhere the tit-for-tat comes inAnother randomly chosen (Optimistic Unchoke)To periodically look for better choicesTypical BitTorrent incentives create inefficienciesClients typically avoid increasing the number of unchoke slotsBandwidth reserved to peers wont actually be used totally.Social hubs cant receive the highest priority in receiving file

Karame et al. show that combining locally optimal solutions of the smaller social teams would give a globally optimal solution for the entire social network.Just work as a team!SocialSwam Design GoalMaximize collaboration between social peers

Maintain game-based techniques to encourage the cooperation of non-social peersSocialSwarm Interaction OverviewRetrieve social peers and non-social peers from tracker

Identifies Bobs social peers

Coordinates chunk collection with them

Altruistically shares bandwidth with them

Interact with each other as well as standard BitTorrent clients

How ?How to identify social peers and non-social peers ?Social Distance

How to collaborate with each other among a social group as well as non-social peers ?Adaptive Bandwidth AllocationChunk PrioritizationOptimistic Unchoke Candidate SelectionNotations

Altruism Between Direct Social Peers

I(a, b) is the number of reciprocal interactions a has had within a given time window with b I(a, all) is the number of reciprocal interactions a has had with all of its peers duringthe same window of time. A(a, b) represents the proportional willingness that a peer a has to share resources with each of its direct peersApproximating SocialDistance Between Indirect Peers

-------- direct peersPeers beyond this value are considered as non-socialNotations

Overall Rarity for Each Given Chunk

Social Rarity for Each Given Chunk

Non-social Rarity for Each Given Chunk

The gather-and-share TechniqueFrom the social group perspectiveWhen the average social rarity for all chunks is high, allocate more bandwidth for non-social peers.As the average social rarity for all chunks decreasing, allocate more bandwidth for social peers.Average social rarity for all chunks:

Maximum percentage of bandwidth allocated to social peers:

The gather-and-share TechniqueFrom the social individual perspectiveChunk prioritization

Optimistic Unchoke Candidate Selection

combines the social, non-social, and overall rarities to form a combined weighted rarity for each given chunktarget a peer with the largest group of rare chunks at each time interval tiSocialSwarm in a Nutshell

Social Network Data Set500 nodes with their interactions Wall Postings extracted from Facebook

Each pair of reciprocal postings is considered a single interaction.

Interactions are used to determine the direct level of altruism between Facebook users.

Beyond MaxSocialDistance are considered as non-social peers

Baseline Test Parameters

Comparison of Basic Download Time

Client Download Rate Comparison

Chunk Rarity Reduction Comparison

Effect of File Size on Peer Throughput

Effect of Maximum SocialDistance on Peer Throughput

Effect of Additional Seed Capacity

Bandwidth Contribution and Unchoke Slot Allocation

ConclusionTypical incentives create inefficiencies

SocialSwarm exploits SocialDistance to reduce this inefficiencies

The gather-and-share technique achieve better performance