Tor bandwidth testing

[Roger Dingledine]

On Fri, Jul 13, 2007 at 03:29:24PM -0700, Michael_google gmail_Gersten wrote:
> I just realized that tor seems to be testing bandwidth at startup with
> received data, not with sent data.
> 
> Is this in fact what's happening? If so, I think this test is backwards.

Tor builds four circuits from itself to itself, and then sends out 500K
worth of cells spread across the four testing circuits.

So it bootstraps its "sent" bandwidth when sending out these padding
cells, and bootstraps its "received" bandwidth when receiving them.

See section 2.1.3 of
https://tor.eff.org/svn/trunk/doc/spec/path-spec.txt for details.

As for how the advertised bandwidth is computed in general, see the
"bandwidth" line in section 2.1 of
https://tor.eff.org/svn/trunk/doc/spec/dir-spec-v2.txt

Hope that helps,
--Roger