[tor-relays] weighting algorithm

[Karsten Loesing]

On Sat, Mar 12, 2011 at 04:57:58PM -0500, Flamsmark wrote:
> On 2 March 2011 07:37, Karsten Loesing <karsten.loesing at gmx.net> wrote:
> > We lost 2 of our 4 bandwidth scanners between Saturday at 18:00 UTC and
> > Tuesday at 14:00 UTC.  We need at least 3 scanner results for clients to
> > use the measured bandwidth values instead of the self-reported ones.
> 
> Have you considered adding more bandwidth scanners? Is the quorum of 3/4
> designed to prevent a pair of scanners from being evil, or to ensure that
> representative sample is used?

Mike would be a better person to answer this.

My guess is that we should add more bandwidth scanners.  The main problem
is that the bandwidth scanners are quite resource-intensive in terms of
bandwidth (surprise!), RAM, and personal care by the operator.  Also, the
bandwidth scanner results are tied to a directory authority vote, so the
scanner should be run by the directory authority operators themselves or
by a person trusted by them.

The requirement of having at least 3 bandwidth scanners running has to do
with preventing a single bandwidth scanner from influencing the median.
Even if there were 5 or 6 scanners, we'd require at least 3 scanner
results before falling back to the relays' self-reported bandwidth.

Best,
Karsten