[tor-relays] relay lost most of its consensus weight

Wed Sep 14 01:38:45 UTC 2016

> On 14 Sep 2016, at 11:34, jensm1 <jensm1 at bbjh.de> wrote:
> 
> Addendum: Did a bit of research (or rather checked some random relays on Atlas).
> 
> It seems like it's not only my relay that experienced a significant drop at the same time. I can't find anything obvious these relays have in common. new/old, large/small, guard/exit/middle, different countries and ASes.
> So it might be BWAuth related after all.

I don't think you need to worry about this in the short term - it is entirely normal for a relay's consensus weight to fluctuate.

But here's my analysis, based on recent authority votes.
8 authorities vote on your relay
8 have the relay's observed bandwidth as 1112 (kilobytes per second)
4 measure your bandwidth, as:
377
394
1680
2820
https://collector.torproject.org/recent/relay-descriptors/votes/

The consensus has your weight as the low-median of these values: 394.
https://collector.torproject.org/recent/relay-descriptors/consensuses/2016-09-14-00-00-00-consensus

When your relay is measured again in another week, it might be that a figure closer to ~1500 becomes the low-median. If so, your observed bandwidth might end up being used as your consensus weight.

The long-term fix for bandwidth measurement this is for the Tor network to geographically distribute more bandwidth authorities, or use a distributed bandwidth measurement system (this is an unsolved problem for untrusted distributed networks).

It is possible that connections between your relay and other relays are blocked or slowed by some kind of firewall. This seems unlikely, because you're on the default ports. Do you block any outgoing ports from your tor instance? Has your provider imposed a bandwidth cap?

Tim

> 
> Am 14.09.2016 um 02:49 schrieb jensm1:
>> That's exactly what baffles me. I didn't make any changes to the relay configuration since updating to 0.2.8.7. I've always had some fluctuations in the Advertised Bandwidth as reported by Atlas, but I assume these are from the BWAuth measurements?
>> 
>> The only thing on my end, that I could imagine, is that the VPS provider changed something in his configuration. But since I don't see any interruption of the servers uptime (neither in Tor, nor in Debian, nor in the VPS control panel), I assume this couldn't be anything drastic like moving the VM to a different host machine.
>> 
>> 
>> 
>> Am 14.09.2016 um 02:10 schrieb teor:
>>>> On 13 Sep 2016, at 23:30, jensm1 <jensm1 at bbjh.de>
>>>>  wrote:
>>>> 
>>>> I last restarted the relay five days ago (update to 0.2.8.7). Can a restart really cause the consensus weight to drop several days later? If it drops within a few hours, I'd get that, but what would delay that response that much?
>>>> (Not complaining, just genuinely curious.)
>>>> 
>>> I'm really not sure - any flag changes should have an impact within an hour.
>>> Several days later is more likely to be bandwidth authority measurement - is your relay up and capable of transmitting as much traffic as it was before it was restarted?
>>> Are its ports open to all other relays?
>>> Can it open connections to other relays, regardless of their ports?
>>> Did you make any other config changes at the same time?
>>> 
>>> Tim
>>> 
>>> 
>>>> Am 13.09.2016 um 10:37 schrieb teor:
>>>> 
>>>>>> On 13 Sep 2016, at 18:05, jensm1 <jensm1 at bbjh.de>
>>>>>> 
>>>>>>  wrote:
>>>>>> 
>>>>>> Hi,
>>>>>> 
>>>>>> I just realised that my relay 'itwasntme' lost most of its consensus
>>>>>> weight yesterday morning. The relay is only three weeks old, but it was
>>>>>> finally picking up some traffic, which now is gone again.
>>>>>> What could be the cause for this? Is there a problem with my relay or
>>>>>> configuration?
>>>>>> 
>>>>>> 
>>>>> It looks like you just recently gained some consensus weight, then temporarily lost it after you restarted your relay.
>>>>> We're working on improving the stability algorithm so these temporary downtimes don't affect relays as much.
>>>>> But in any case, wait a week or two, and it will be back.
>>>>> (If not, please let us know.)
>>>>> 
>>>>> Tim
>>>>> 
>>>>> 
>>>>> 
>>>>>> Thanks for your help!
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> https://atlas.torproject.org/#details/F46C312E279185364F46EA06C58F7925280911E2
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> 
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>>>>>> 
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>>>>> Tim Wilson-Brown (teor)
>>>>> 
>>>>> teor2345 at gmail dot com
>>>>> PGP C855 6CED 5D90 A0C5 29F6 4D43 450C BA7F 968F 094B
>>>>> ricochet:ekmygaiu4rzgsk6n
>>>>> xmpp: teor at torproject dot org
>>>>> 
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>>>>> 
>>>>> 
>>>>> 
>>>>> 
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>>>>> 
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>>> Tim Wilson-Brown (teor)
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>>> ricochet:ekmygaiu4rzgsk6n
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Tim Wilson-Brown (teor)

teor2345 at gmail dot com
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