[tor-relays] Consensus weight dropped

[Network Operations Center]

Very thorough explanation, thanks. I assume that there is nothing I can 
do except wait until
a.) a new BWauth script is being introduced
or b.) hope that a third node rediscovers me and once I have 3 votes in 
the bag I'm back on track.

What still confuses me is why several nodes were being dropped by the 
BWauths all on Dec 28. Then on Jan 6th all of the affected nodes have 
been rediscovered for a day. I tracerouted all of the BWauths and I 
don't have trouble sending ICMP packets to said hosts, so it doesn't 
seem routing related.

On 20.01.2015 10:58 PM, Roger Dingledine wrote:
> On Tue, Jan 20, 2015 at 11:44:46AM +0100, Network Operations Center 
> wrote:
>> Thank you!
>> 
>> https://atlas.torproject.org/#details/3D7E274A87D9A89AF064C13D1EE4CA1F184F2600
> 
> The votes from the directory authorities for the last consensus period
> are here:
> http://freehaven.net/~arma/moria1-v3-status-votes
> 
> In this case it looks like schokomilch has these votes for the w line:
> 
> w Bandwidth=2525 Measured=1600  [moria1]
> w Bandwidth=2525                [dizum]
> w Bandwidth=2525                [Faravahar]
> w Bandwidth=2525                [gabelmoo]
> w Bandwidth=2525                [dannenberg]
> w Bandwidth=2525                [urras]
> w Bandwidth=2525                [longclaw]
> w Bandwidth=2525 Measured=674   [tor26]
> w Bandwidth=2525                [maatuska]
> 
> So since only two directory authorities vote a Measured value for it,
> and the design calls for three opinions, it ends up unmeasured, and 
> thus
> with a consensus weight of 20.
> 
> You can read about the reasoning for requiring Measured votes here:
> https://trac.torproject.org/projects/tor/ticket/2286
> 
> In theory gabelmoo and longclaw are supposed to have opinions about
> your relay too:
> https://consensus-health.torproject.org/consensus-health.html#bwauthstatus
> 
> But they don't, so here we are.
> 
> The problem is likely that the bwauth (bandwidth
> authority) scripts are old and buggy and unmaintained. See
> https://trac.torproject.org/projects/tor/query?status=!closed&component=Torflow
> especially the tickets towards the bottom.
> 
> We've already known about this in the context of "the bandwidth
> authority scripts are very poorly tuned for the changes that have
> happened in the Tor network since the scripts were written, so they
> vote wildly varying numbers for relays". But I don't think that
> we'd realized the "some relays don't get three votes at all, so they
> basically get zeroed out" issue. Hm.
> 
> (Ultimately I am hoping for the bwauth scripts to get phased out, in
> favor of one of the secure bandwidth measurement schemes that various
> research groups have been working on lately. Those other designs also
> will have the advantage that it's harder to game the system by lying
> about your bandwidth. But it will be some months at least until we have
> one of those designs to evaluate.)
> 
> --Roger
> 
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