[tor-relays] New Test for Measuring the Accuracy of Tor Relays' Advertised Bandwidths

[Georg Koppen]

Scott Bennett:
> Georg Koppen <gk at torproject.org> wrote:
> 
>> Some of you might remember the speed test Rob had been running during
>> August 2019 to investigate the accuracy of the advertised bandwidth a
>> relay is reporting in its server descriptor.[1] Back then this involved,
>> for each relay, downloading several large data streams for a period of
>> about 20 seconds to get a better estimation of the relay's true capacity
>> (See: [1] and follow-up emails for the exact details of the experiment).
>>
>> We plan to do this speed test again in about 1 week and relay operators
>> can opt-out of it (again) if they want to. We still believe that the
>> overhead of this speed test is in line with regular usage, but if anyone
>> doesn't want to participate that's fine. Let us know if so (by replying
>> to this thread or off-list, if preferred) and we remove your relay(s)
>> from the list to scan.
>>
>> Thanks,
>> Georg
>>
>> [1]
>> https://lists.torproject.org/pipermail/tor-relays/2019-July/017535.htmlff.
>>
>      Okay, I read that, but I do not see where you offer any method to
> account for other traffic that the relay being tested may be dealing with
> at the time you are testing it.  IOW, your testing procedure would be fine
> if only the tor network, or at least each relay while it were being tested,
> were entirely idle w.r.t. the traffic of other users.  This is the same
> defect that the authorities' testing procedures suffer from.
>      Do you have a solution to offer?

I guess it depends on what your goal is as to whether calling it a
defect or not. For the test at hand, sure, we can't test as if no user
activity would be ongoing but that's not too important if we want to
test whether the advertised bandwidth significantly underestimates the
true capacity of Tor relays.

Georg

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