P2P Streaming Protocol Pro-incentive Parameters
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P2P Streaming Protocol Pro-incentive Parameters draft-zeng-ppsp-protocol-pro-incentive-para-01 IETF79 Meeting Wenjun (Kevin) Zeng & Yingjie Gu Huawei Technologies. Introduction. Lack of cooperation is one of the key problems that confront today's P2P systems. Free riding Starvation

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Introduction 2192024

P2P Streaming Protocol Pro-incentive Parametersdraft-zeng-ppsp-protocol-pro-incentive-para-01 IETF79 Meeting Wenjun (Kevin) Zeng & Yingjie GuHuawei Technologies


Introduction

Introduction

  • Lack of cooperation is one of the key problems that confront today's P2P systems.

    • Free riding

    • Starvation

  • This proposal intends to

    • analyze various incentive mechanisms/dishonest manipulation

    • extract the common pro-incentive parameters, and

    • propose to incorporate these pro-incentive parameters in information exchanges in the P2P streaming protocols.

  • NOT intend to specify a particular incentive mechanism in the P2P streaming protocol.


Reward based on peer contribution

Reward based on Peer Contribution

  • A typical metric for peer contribution:

    • The amount of upload a peer has contributed.

    • E.g., BitTorrent uses a bilateral mechanism: tit-for-tat.

  • Contribution-based approach is vulnerable to strategic manipulation by peers.

    • E.g., the Discount Parameter (DP) attack is an incentive threat that exploits the tit-for-tat based unchoking.

    • DP: Determines the degree to which the payoff of each move is discounted relative to the previous move

    • If the DP is small, players might defect and not worry about future consequences

    • In p2p systems, Piece Rarity is a DP


Introduction 2192024

Discount Parameter Exploitation

Alice

Bob

Connects to Bob, Request for download piece X

Determines whether Alice is a good uploader ??

ALICE

UNCHOKED

Ok send X.. Request for rarest piece Alice has: Y

Alice : “Y is a rare piece. None of the pieces Bob has is rare enough compared to X”

BOB

CHOKED

Bob loses a round of download

Alice starts looking for other peers


Starvation

Starvation

  • All peers have all pieces, except a few.

  • Origins:

    • Choices made by peers in piece and peer selection

    • Positive Discrimination

      • Use of rarest first approach

  • Can positive discrimination guarantee safe state?

    • Peers benefit from under-reporting, increasing demand for pieces they have and faster completion.

  • Why do we have Under Reporting Peers (URPs):

    • The orthogonal treatment of Piece Rarity and Peer Selection


Dp starvation remedy

DP/Starvation Remedy

  • Peer selection not only depends on the uploading bandwidth of the candidate peers, but also how valuable the pieces they have uploaded are.

  • Piece Rarity parameter

    • local availability (in the target swarm) of a piece:

      • a rarer downloaded piece has more value to the swarm

    • # of upload slots a candidate peer has:

      • long term benefit can be expected from peer with more uploading potential

    • completion factor (i.e., ratio of # of pieces that a peer has to total #of pieces of that file) of the candidate peer:

      • peer with high completion factor is a good one to maintain a good upload/download relation with.

    • the contention in the swarm (i.e., the ratio of total # of peers to total # of seeds):

      • high contention implies more strategic value of a piece.


Pro incentive protocol parameters

Pro-incentive Protocol Parameters

  • Important for peers to collect pro-incentive parameters to support incentive mechanisms and propose to include the parameters in Tracker and Peer Protocols.

    • no_upload_slots: a peer's upload bandwidth (i.e., number of upload slots a peer has).

    • bytes_uploaded: total amount of data that a peer has uploaded

    • bytes_downloaded: total amount of data that has been downloaded from a peer

    • chunk_nos: total # of chunks of a file that a peer has.

    • seed_nos: total # of seeds.

    • peer_nos: total # of peers.

    • chunk_copies_swarm: chunk availability, i.e., total # of copies of a chunk available in the swarm.


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