Contracts: Practical Contribution Incentives for P2P Live Streaming - - PowerPoint PPT Presentation

▶
contracts practical contribution incentives for p2p live
SMART_READER_LITE
LIVE PREVIEW

Contracts: Practical Contribution Incentives for P2P Live Streaming - - PowerPoint PPT Presentation

Apr 19, 2023 45 likes •558 views

Contracts: Practical Contribution Incentives for P2P Live Streaming Michael Piatek, Arvind Krishnamurthy, Arun Venkataramani, Richard Yang, David Zhang, Alexander Jaffe U. of Washington, U. of Massachusetts, Yale, PPLive Live streaming

slide-1
SLIDE 1

Contracts: Practical Contribution Incentives for P2P Live Streaming

Michael Piatek, Arvind Krishnamurthy, Arun Venkataramani, Richard Yang, David Zhang, Alexander Jaffe

  • U. of

Washington, U. of Massachusetts, Yale, PPLive

slide-2
SLIDE 2

Michael Piatek NSDI’10

Live streaming with PPLive

  • P2P distribution
  • Over 20 million active

users worldwide

  • Current design offers

no reward for capacity contributions

How to provide contribution incentives?

2

slide-3
SLIDE 3

Michael Piatek NSDI’10

Overview

  • 1. Challenges for live streaming incentives
  • 2. Contracts design
  • 3. Evaluating PPLive with Contracts

3

slide-4
SLIDE 4

S

1

PPLive design

1

slide-5
SLIDE 5

S

1

PPLive design

1 2

slide-6
SLIDE 6

S

1

PPLive design

1 2 3

slide-7
SLIDE 7

S

1

PPLive design

1 2 3

slide-8
SLIDE 8

S

1

PPLive design

1 2 3 1

slide-9
SLIDE 9

S

1

PPLive design

1 2 3 4 1

slide-10
SLIDE 10

S

1

PPLive design

1 2 3 4 1

slide-11
SLIDE 11

S

PPLive design

1 2 3 4 1

slide-12
SLIDE 12

S

PPLive design

1 2 3 4 1 5

slide-13
SLIDE 13

S

PPLive design

1 2 3 4 1 5 1 2 3

slide-14
SLIDE 14

S

PPLive design

1 2 3 4 1 5 1 2 3

slide-15
SLIDE 15

S

PPLive design

1 3 4 1 5 1 2 3

slide-16
SLIDE 16

S

PPLive design

1 3 4 1 5 1 2 3 6

slide-17
SLIDE 17

S

PPLive design

1 3 4 1 5 1 2 3 6 2 3 3 2 4 5

slide-18
SLIDE 18

S

PPLive design

1 3 4 1 5 1 2 3 6 2 3 3 2 4 5

slide-19
SLIDE 19

S

PPLive design

1 3 4 1 5 1 2 3 6 2 3 3 2 4 5

Wire-level protocol very similar to BitTorrent

slide-20
SLIDE 20

Michael Piatek NSDI’10

Can we apply tit-for-tat?

  • Bilateral reciprocation:

Contribute to peers that contributed to you

  • Challenges for live streaming:
  • Capacity heterogeneity
  • Limited trading opportunities
  • No compelling reward

14

slide-21
SLIDE 21

Michael Piatek NSDI’10

Capacity heterogeneity

  • Top 10% of users contribute 58% of total capacity

15

slide-22
SLIDE 22

Michael Piatek NSDI’10

Capacity heterogeneity

  • Top 10% of users contribute 58% of total capacity

Supported users Capacity utilization

All users watching at max possible quality

15

slide-23
SLIDE 23

Michael Piatek NSDI’10

Capacity heterogeneity

  • Top 10% of users contribute 58% of total capacity
  • With balanced exchange:

Supported users Capacity utilization

Supporting 95% of clients wastes 85% of capacity Maximizing quality excludes 86% of users

16

slide-24
SLIDE 24

Michael Piatek NSDI’10

Imbalanced exchange?

  • Is relaxing balance sufficient?
  • Reciprocation depends on trading opportunities
  • But, live streams swarm over few blocks
  • Clients near the source: block monopoly
  • Distant clients: perpetual trade imbalance
  • Outcome: few trading opportunities

17

slide-25
SLIDE 25

Michael Piatek NSDI’10

Transfer opportunities

Data availability from a snapshot of client buffer states

18

slide-26
SLIDE 26

Michael Piatek NSDI’10

Transfer opportunities

Data availability from a snapshot of client buffer states

Reciprocation most common with similar distance to the source

19

slide-27
SLIDE 27

Michael Piatek NSDI’10

Transfer opportunities

Data availability from a snapshot of client buffer states

Most transfers are between peers with a large imbalance of blocks to send

20

slide-28
SLIDE 28

Michael Piatek NSDI’10

Rewarding contribution

  • For bulk data:

Increase contribution rate → increase download rate

  • Live streaming: inelastic

All users download at the stream rate

How to create a compelling reward?

21

slide-29
SLIDE 29

Michael Piatek NSDI’10

Overview

  • 1. Challenges for live streaming incentives
  • 2. Contracts design
  • 3. Evaluating PPLive with Contracts

22

slide-30
SLIDE 30

Michael Piatek NSDI’10

Contracts design overview

  • Recognizes globally effective contributions

Global evaluation contract rather than bilateral reciprocation Reward contributions with robustness by

  • ptimizing the overlay topology
  • If the system becomes capacity constrained,

contributors fail last

23

slide-31
SLIDE 31

Michael Piatek NSDI’10

Evaluating contributions

  • Goals:
  • 1. Contribute capacity

– As in any P2P system, contributions required

  • 2. Choose effective peers

– Live streaming has playback deadlines – Prioritize peers that replicate data quickly

24

slide-32
SLIDE 32

Michael Piatek NSDI’10

Tracking contributions

  • Cryptographic receipts attest to

the contributions of peers

  • Presented to other peers to

demonstrate contributions 1 Data Receipts 2

25

slide-33
SLIDE 33

Michael Piatek NSDI’10

Tracking contributions

  • Cryptographic receipts attest to

the contributions of peers

  • Presented to other peers to

demonstrate contributions 1 Data Receipts 2 E (From to , for example) 1 E

25

slide-34
SLIDE 34

Michael Piatek NSDI’10

Tracking effectiveness

  • Gossip receipts in a one hop

neighborhood

  • Allows to compute:
  • Effectiveness of peers ( )
  • Contributions of peers of

peers ( ) 1 Receipts 3 2 4 2→1 3→2 4→2 E E 1 2 Data

  • Clients prioritize effective peers

26

slide-35
SLIDE 35

Michael Piatek NSDI’10

Evolving the topology

  • Compute contributions of distant peers using

forwarded receipts

  • Preferentially connect to highest capacity peers

Prune unproductive peers

  • High capacity peers: percolate towards the source
  • Low capacity peers: pushed to mesh periphery

27

slide-36
SLIDE 36

Michael Piatek NSDI’10

Evolving the topology

  • Compute contributions of distant peers using

forwarded receipts

  • Preferentially connect to highest capacity peers

Prune unproductive peers

  • High capacity peers: percolate towards the source
  • Low capacity peers: pushed to mesh periphery

Because failures cascade, proximity to the source improves quality of service

28

slide-37
SLIDE 37

Michael Piatek NSDI’10

Collusion defenses

  • Limit identity creation at PPLive coordinator
  • Weight contributions by

diversity of network addresses

  • Flow integrity check –

Incoming data rate cannot exceed stream rate Outgoing data rate cannot exceed capacity

29

slide-38
SLIDE 38

Michael Piatek NSDI’10

Overview

  • 1. Challenges for live streaming incentives
  • 2. Contracts design
  • 3. Evaluating PPLive with Contracts

30

slide-39
SLIDE 39

Michael Piatek NSDI’10

Evaluation overview

This talk

  • Contracts improves performance
  • Contracts strengthens contribution incentives

Paper

  • Computational and network overhead
  • Comparison with FlightPath [OSDI’08]
  • Topology convergence
  • Over-provisioning and loss-rate

31

slide-40
SLIDE 40

Michael Piatek NSDI’10

Experimental setup

  • Modified PPLive to support Contracts and

rate-based tit-for-tat

  • Synthetic broadcast on 100 Emulab machines
  • Churn from clients joining at 10 second intervals,

remaining for 20 minutes, repeating for 2 hours

  • Capacities from measured distribution of over

90,000 PPLive users

32

slide-41
SLIDE 41

Michael Piatek NSDI’10

PPLive performance

Stream rate chosen to induce capacity constraints

33

slide-42
SLIDE 42

Michael Piatek NSDI’10

PPLive performance

Stream rate chosen to induce capacity constraints

28% of peers receive 90%

  • f blocks by the deadline

33

slide-43
SLIDE 43

Michael Piatek NSDI’10

PPLive performance

Stream rate chosen to induce capacity constraints

Only 13% of users with loss-free playback

33

slide-44
SLIDE 44

Michael Piatek NSDI’10

PPLive + tit-for-tat

Tit-for-tat reduces performance for live streaming

34

slide-45
SLIDE 45

Michael Piatek NSDI’10

PPLive + tit-for-tat

Tit-for-tat reduces performance for live streaming

High capacity users close to the source Distant peers cannot obtain enough data to trade, regardless of capacity

34

slide-46
SLIDE 46

Michael Piatek NSDI’10

PPLive + Contracts

Contracts substantially improves performance

35

slide-47
SLIDE 47

Michael Piatek NSDI’10

PPLive + Contracts

Contracts substantially improves performance

Loss-free playback 4× unmodified PPLive

35

slide-48
SLIDE 48

Michael Piatek NSDI’10

Incentives

Contracts strengthens contribution incentives

36

slide-49
SLIDE 49

Michael Piatek NSDI’10

Incentives

Tit-for-tat reward increases slowly, varies widely

37

slide-50
SLIDE 50

Michael Piatek NSDI’10

Incentives

Contracts strengthens contribution incentives

38

slide-51
SLIDE 51

Michael Piatek NSDI’10

Conclusions

  • Live streaming exhibits new challenges for

fostering P2P contribution incentives

  • Contracts improves performance and incentives
  • Evaluation contract rather than bilateral

exchange

  • Restructure topology to reward contributions

with quality of service

39