[72580] in North American Network Operators' Group
Re: Regional differences in P2P
daemon@ATHENA.MIT.EDU (Petri Helenius)
Sun Jul 18 02:46:30 2004
Date: Sun, 18 Jul 2004 09:44:53 +0300
From: Petri Helenius <pete@he.iki.fi>
To: Alexei Roudnev <alex@relcom.net>
Cc: k claffy <kc@caida.org>, swmike@swm.pp.se, nanog@merit.edu
In-Reply-To: <09f901c46c8f$b6c1bdd0$6401a8c0@alexh>
Errors-To: owner-nanog-outgoing@merit.edu
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 donīt. The effectiveness of this criteria
varies from application to application. As far as Iīm 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 itīs 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