Floodgate: A Micropayment Incentivized P2P CDN


Floodgate is a research peer-to-peer architecture that aims at providing a scalable Content Delivery Network-like system by incentivising the peers to share their resources for monetary benefits.

How is it different

P2P protocols like BitTorrent use the tit-for-tat mechanism to 'force' peers to upload content while they are downloading. This approach however has several problems. Attacks aimed at downloading more than the fair share of content have been proposed and implemented in real-world. Furthermore, there is no real incentive to seed the content (i.e. keep uploading after the download has been completed). This impairs the use P2P technologies as a mean of providing a viable CDN.

Floodgate is a micropayment supported P2P protocol with the aim of incetivizing the peers to upload the content fairly as well as to seed the content.

How does it work?

The figure below sums up the basic steps in the protocol.

The network is managed by a central entity T. Each customer (peer) wishing to join the network registers and creates an account with T, the account being tied to a real-world monetary account like credit card or bank account. The content provider T controls the tracker as well as the web server that serves the torrent file.

Once a peer c1 registers itself with T and creates an account, when it wishes to download a content, it searches for the associated torrent file in a known public repository operated by T and downloads it. c1 then contacts the tracker specified in the torrent file. The tracker replies with the list of peers in the network who are in various stages of downloading or seeding the content. In addition, it also sends to c1 micropayment tokens that can be used by the peer to pay for content pieces it successfully downloads from various peers in the network.

Just as in BitTorrent, the peer then contacts other peers in the list given by the tracker to start downloading pieces of the content. After each successful download of a piece, c1 sends the appropriate micropayment token to the peer from which it downloaded the piece. Each received token is redeemable at T in the form of future download credit or other payment options like cash, as the case may be. The exact business model adopted by T is independent of the working of Floodgate, making Floodgate more flexible.

Status of Floodgate?

A prototype has been developed. An academic paper describing the working on Floodgate will be published in the refereed 17th International Conference on Computer Communications and Networks, USA.

Source Code

Version 1.0 of the Floodgate sourc code, based on the BitTorrent 5.0.7 reference implementation is available for download here, under the same license as the BitTorrent itself - 'BitTorrent Open Source License'. This code was released on 30th July, 2008.

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