[bittorrent] New P2P protocols

Joseph Ashwood ashwood at msn.com
Thu Mar 31 18:22:51 EST 2005

[written later: complete chaos on my internet connection with regards to
sending email, sorry about the delay]

----- Original Message ----- 
From: "Nick Johnson" <arachnid at notdot.net>
Subject: Re: [bittorrent] New P2P protocols

> -Multicast. Online codes applied to encoding a single chunk into 1k
> encoded blocks provide an ideal multicast platform: A server can multicast
> encoded packets to multiple listeners, and they need only recieve a
> sufficient quantity to reconstruct the chunk. Our working idea for this is
> to have multiple multicast channels at different bitrates, each
> transmitting encoded chunks of the most wanted block by that channel's
> listeners. Since each channel has a different rate, listeners can
> subscribe to whatever set of channels makes best use of its available
> bandwidth.

A quick suggestion on this. Set all the channels to the same rate, broadcast
non-overlapping subsets of the data over the different channels. This will
put the root bandwidth usage at approximately the same level as with a
single high bandwidth multicast, but the multicast clients can meter
themselves. The ability to reconstruct files after a random download will
take care of the rest. The biggest upside to this is that the cost of
joining these has been lowered. In a multiple speed environment the client
(since there is a central broadcast point I will simply use the
client-server terminology) has to account for which streams are at what
speeds, and guess from there. In a single speed environment the clients can
simply add streams until they've reached maximum speed, and they are free to
add themselves randomly to the streams resulting in a higher probability of
equal distribution of file subsections.

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