Peer-to-Peer Networks 15 Self-Organization Christian Schindelhauer - PowerPoint PPT Presentation

Peer-to-Peer Networks 15 Self-Organization Christian Schindelhauer Technical Faculty Computer-Networks and Telematics University of Freiburg

Topology-Management � T-Man: Fast Gossip-based Construction of Large-Scale Overlay Topologies Mark Jelasity Ozalp Babaoglu, 1994 2

Distributed Topology Construction T-Man 3

Finding a Torus 4

Convergence of T-MAN 5

T-Chord � Chord on demand, A Montresor, M Jelasity, O Babaoglu - Peer-to-Peer Computing, 2005 � Apply self-organization to Chord � compare insertion operation Pastry � T-Chord � Apply T-Man � preferring Chord edges � T-Chord-Prox � rank according to RTT 6

Ranking Function T-Chord � 1st rank � nearest sucessor/predecessor on the 
 ring [0 , 2 m − 1] � For each exponent j ∈ [1 , m − 1] � select from view the nodes nearest to [ID + 2 j mod 2 m , ID + 2 j +1 − 1 mod 2 m ] 7

Ranking Function T-Chord-Prox � 1st rank � nearest sucessor/predecessor on the 
 ring [0 , 2 m − 1] � For each exponent j ∈ [1 , m − 1] � select from view the nodes nearest to [ID + 2 j mod 2 m , ID + 2 j +1 − 1 mod 2 m ] � measure latency (RTT) for p random nodes from view in such intervals and choose the closest 8

Adaption for Chord 9

After Exchange of Links 10

T-Chord Performance � Starting with a neighbors on the ring � Loss rate and hop count � experiments on a real-word dataset from 2002 100 8 10 T-Chord (%) 7 T-Chord-Prox (%) T-Chord (n.) T-Chord-Prox (n.) 1 6 Hop Count (n.) Loss Rate (%) 0.1 5 0.01 4 0.001 3 1e-04 2 0 5 10 15 20 Cycles 11

T-Chord Performance � Starting with a neighbors on the ring � Loss rate and hop count 9 8.5 8 7.5 Hop Count 7 6.5 6 5.5 Chord 5 T-Chord T-Chord-Prox 4.5 2 10 2 11 2 12 2 13 2 14 2 15 2 16 2 17 2 18 Size 12

T-Chord Performance � Message Delay 800 700 600 Latency (ms) 500 400 300 Chord T-Chord T-Chord-Prox 200 2 10 2 11 2 12 2 13 2 14 2 15 2 16 2 17 2 18 Size 13

T-Chord Performance 14 Chord (crash) � Robustness T-Chord (crash) 12 T-Chord (churn) T-Chord-Prox (churn) 10 Hop Count 8 6 8 Chord (crash) T-Chord (crash) 4 7 T-Chord (churn) T-Chord-Prox (churn) 2 6 Loss rate (%) 5 0 4 0 10 20 30 40 50 Crashed nodes (%) 3 3500 2 Chord (crash) T-Chord (crash) 1 3000 T-Chord (churn) T-Chord-Prox (churn) 0 Message Delay (ms) 2500 0 10 20 30 40 50 Crashed nodes (%) 2000 1500 1000 500 0 0 10 20 30 40 50 Crashed nodes (%) 14

Peer-to-Peer Networks 15 Self-Organization Christian Schindelhauer Technical Faculty Computer-Networks and Telematics University of Freiburg