GPS: A General Peer-to-Peer Simulator and its Use for Modeling BitTorrent

Weishuai Yang

Nael Abu-Ghazaleh

{wyang,nael}@cs.binghamton.edu

9/29/2005 GPS: A General Peer-to-Peer Simulator and its Use for Modeling BitTorrent

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Peer-to-Peer

9/29/2005 GPS: A General Peer-to-Peer Simulator and its Use for Modeling BitTorrent

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P2P Simulation Emphases

• Looking up

• Downloading

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54

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6

3

1

54

2

6

3

9/29/2005 GPS: A General Peer-to-Peer Simulator and its Use for Modeling BitTorrent

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BitTorrent (BT) Scenario

HTTP GET

Tracker

Peer 1(Leecher)

Peer 2(Leecher)

Peer 3(Seed)

9/29/2005 GPS: A General Peer-to-Peer Simulator and its Use for Modeling BitTorrent

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BitTorrent (BT) Scenario

Tracker

Peer 1(Leecher)

Peer 2(Leecher)

Peer 3(Seed)

.torrent file

9/29/2005 GPS: A General Peer-to-Peer Simulator and its Use for Modeling BitTorrent

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BitTorrent (BT) Scenario

Tracker

Peer 1(Leecher)

Peer 2(Leecher)

Peer 3(Seed)

Announce Tracker

9/29/2005 GPS: A General Peer-to-Peer Simulator and its Use for Modeling BitTorrent

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BitTorrent (BT) Scenario

Tracker

Peer 1(Leecher)

Peer 2(Leecher)

Peer 3(Seed)

Peer List

9/29/2005 GPS: A General Peer-to-Peer Simulator and its Use for Modeling BitTorrent

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BitTorrent (BT) Scenario

Tracker

Peer 1(Leecher)

Peer 2(Leecher)

Peer 3(Seed)

Hand Shaking

9/29/2005 GPS: A General Peer-to-Peer Simulator and its Use for Modeling BitTorrent

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BT Algorithms

• Piece Selection– Strict Priority– Rarest First– Random First– End Game Mode

• Peer Selection (server side and peer side)• Rechoking, optimistic unchoking, and anti-

snubbing• Pipeline request

9/29/2005 GPS: A General Peer-to-Peer Simulator and its Use for Modeling BitTorrent

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GPS: General P2P Simulator

http://www.cs.binghamton.edu/~wyang/gps

• Modeling downloading process

• Message level simulation

• Graphical

9/29/2005 GPS: A General Peer-to-Peer Simulator and its Use for Modeling BitTorrent

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GPS Architecture

Physical Networks(Nodes, Links ...)

Look-up Protocols(Chord, CAN ...)

P2P Application Agents(BT, Gnutella ...)

P2P User ActionsUser Action Model

ResourceAllocation Model

Network TopologyModel

SimulatorConfiguration

ProtocolConfiguration

General P2P Simulator

9/29/2005 GPS: A General Peer-to-Peer Simulator and its Use for Modeling BitTorrent

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Framework Components

• Core Components– Simulation Engine– Topology– Protocols– Agents (includes Peers & Servers)– Documents– Keywords

• Special Components– GUI– Asynchronous Logging

9/29/2005 GPS: A General Peer-to-Peer Simulator and its Use for Modeling BitTorrent

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BTSim Components

• BTProtocol

• BTTrackers and BTPeers

• BTDocuments

• BTSessions, BTSockets and BTConnections

• BTAlgorithms

9/29/2005 GPS: A General Peer-to-Peer Simulator and its Use for Modeling BitTorrent

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Accounting for Network & Protocol Effect

• Peer Based Bandwidth(PBB) Flow Model– Peer End Allocation

• Dynamic Link-Level Network Bandwidth (DLNB) Flow Model– Bandwidth Allocation Algorithm

• TCP Based Flow (TBF) Model– Macro Formula: BW=MSS*C/(RTT*P^(1/2))

9/29/2005 GPS: A General Peer-to-Peer Simulator and its Use for Modeling BitTorrent

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Macro Model Simulation Validation

MSS=536 bytes RTT=1.7msC=1.22p=0.1%

9/29/2005 GPS: A General Peer-to-Peer Simulator and its Use for Modeling BitTorrent

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Link Based Flow Model Simulation Validation

9/29/2005 GPS: A General Peer-to-Peer Simulator and its Use for Modeling BitTorrent

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Scalability Study

• Peers randomly attached to non-transit nodes• Documents with rankings are randomly stored at Peers• User actions are randomly initiated every 50 seconds

Nodes Peers Docs(500M) Downloads

1 16 8 4 4

2 64 32 16 16

3 252 128 64 64

4 1054 512 256 256

9/29/2005 GPS: A General Peer-to-Peer Simulator and its Use for Modeling BitTorrent

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Scalability Study cont.

(DLNB based)

9/29/2005 GPS: A General Peer-to-Peer Simulator and its Use for Modeling BitTorrent

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Questions?

Thank You!

Weishuai Yangwyang@cs.binghamton.edu