Regional differences in P2P

Petri Helenius pete at he.iki.fi
Sun Jul 18 06:44:53 UTC 2004


Alexei Roudnev wrote:

>
>Interesting. Are there any p2P systems which optimize traffic by localizyng
>it, when possible?
>
>
>  
>
Most p2p applications keep the connections which provide data at better 
speed and drop the ones which don´t. The effectiveness of this criteria 
varies from application to application. As far as I´m aware there are no 
applications that look at the locality of the data. There are many 
different approaches to increase the locality by modifying the traffic 
in various ways,  from simple ones like ours which allows you to mark 
packets or announce prefixes over BGP4 for your network to police the 
p2p heavy remote-and-expensive prefixes to more extensive ones where the 
actual packet contents are modified to steer the payload traffic.

Depending on the aggressiveness of the applications, this works 
differently. DirectConnect and Bittorrent are very aggressive on 
adapting their network configuration while eDonkey or FastTrack seem to 
be more relaxed. Obviously content availability also plays a big factor 
here since it´s hard to download from somewhere which does not yet have 
the bits.

As far as I know no p2p networks do larger scale topology calculations 
but all base their activity on local selfish host behavior. Which is 
probably right on the mark 90% of the time anyway.

Pete





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