[Nanog] Lies, Damned Lies, and Statistics [Was: Re: ATT VP: Internet to hit capacity by 2010]
Petri Helenius
petri at helenius.fi
Tue Apr 22 12:12:30 UTC 2008
michael.dillon at bt.com wrote:
> But there is another way. That is for software developers to build a
> modified client that depends on a topology guru for information on the
> network topology. This topology guru would be some software that is run
>
While the current bittorrent implementation is suboptimal for large
swarms (where number of adjacent peers is significantly less than the
number of total participants) I fail to figure out the necessary
mathematics where topology information would bring superior results
compared to the usual greedy algorithms where data is requested from the
peers where it seems to be flowing at the best rates. If local peers
with sufficient upstream bandwidth exist, majority of the data blocks
are already retrieved from them.
In many locales ISP's tend to limit the available upstream on their
consumer connections, usually causing more distant bits to be delivered
instead.
I think the most important metric to study is the number of times the
same piece of data is transmitted in a defined time period and try to
figure out how to optimize for that. For a new episode of BSG, there are
a few hundred thousand copies in the first hour and a million or so in
the first few days. With the headers and overhead, we might already be
hitting a petabyte per episode. RSS feeds seem to shorten the
distribution ramp-up from release.
The p2p world needs more high-upstream "proxies" to make it more
effective. I think locality with current torrent implementations would
happen automatically. However there are quite a few parties who are
happy to have it as bad as they can make it :-)
Is there a problem that needs to be solved that is not solved by
Akamai's of the world already?
Pete
More information about the NANOG
mailing list