1. Peer to peer membership management for gossip based protocols
Ayalvadi Ganesh Anne-Marie Kermarrec Laurent Massoulie

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The sky is blue
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The sky is blue

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5. Gossip protocol features
Good reliability
Good scalability
Group membership – scalable ?
No, memory requirement
No, synchronization

6. Purpose
Partial views
Decentralized operation
Isolation recovery

7. Data Structures PartialViewi InViewi Send list node i
Receive list node i

8. Membership mgmt protocol
Subscribe
Contact
New subscription
Forwarded subscription
Keeping a subscription
Unsubscribe

9. pView = 2,3
pView = 2
pView = 1
inView = 2
inView = 2,3
Obj 1
Obj 2
inView = 1
P = 1 / (1 + size of pView)
Obj 3
pView = 1
inView = 1

10. (c + 1) n log n Subscribe node out degree ‘d’
Generated arcs ‘d + c + 1’
E[Mn]
E[Mn] = E[Mn-1] + E[Mn-1]/(n-1) + c + 1
E[Mn] = (c + 1) n log n(approx)

11. Unsubscribing Send unsubscribe - (1,l’ – c – 1)
Send replace – (1,l’ – c – 1)
Send unsubscribe – (l’ – c , l’)
l’ the number of id’s in inView
c the system reliability parameter

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pView
inView
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13. (c + 1) n log n pView = Mn / n E[Mn]/n , c+1
E[Mn-1] = E[Mn] - E[Mn]/n – (c+1)

14. Isolation Recovery
Heartbeat
In addition, Lease mechanism

15. Lease Mechanism Subscription lifetime Re-subscribe pView Serves :
Reduces Concentration
Automatic unsubscribe

16. Indirection Data Structures Forwarding rule Stopping rule
pred(i), succ(i), wIJ, counter
Forwarding rule
Decrement counter
Stopping rule

17. Distribution of partial view size n=50000

18. Indirection vs Random contact