Re: [tor-bugs] #20403 [Metrics]: Make it easier for relay operators to find their observed bandwidth

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#20403: Make it easier for relay operators to find their observed bandwidth
-------------------------+---------------------
 Reporter:  teor         |          Owner:
     Type:  enhancement  |         Status:  new
 Priority:  Medium       |      Milestone:
Component:  Metrics      |        Version:
 Severity:  Normal       |     Resolution:
 Keywords:               |  Actual Points:
Parent ID:               |         Points:
 Reviewer:               |        Sponsor:
-------------------------+---------------------

Comment (by tom):

 Replying to [comment:2 teor]:
 > Replying to [comment:1 tom]:
 > > So depictor (consensus-health) uses stem to get its info, so it's
 really easy for me to include any information here:
 https://stem.torproject.org/api/descriptor/router_status_entry.html   It's
 really difficult to get anything else - downloading descriptors for the
 network would take a _lot_ of time, just downloading the votes and
 consesnsuses takes 10+ minutes.
 >
 > I think I might be asking for the "bandwidth (int) -- bandwidth claimed
 by the relay (in kb/s)", but I am not sure how it is sourced.

 So I'm pretty sure stem's documentation is wrong.

 On my relay (rittervg)'s
 consensus.routers['C0EDB08D7540D1DD3CA69809ED17D979F51B66E3']
 https://atlas.torproject.org/#details/C0EDB08D7540D1DD3CA69809ED17D979F51B66E3
 RouterStatusEntry:

  - .is_unmeasured is false
  - .measured is empty
  - .bandwidth is the value from the consensus w line (the agreed upon
 value by the bwauths)

 If I manually pull all the server descriptors (which I'm trying to avoid
 but I guess I could) I get the following new values:

  - .observed_bandwidth - 1434333
  - .average_bandwidth - This is the value Atlas displays under 'Advertised
 Bandwidth'
  - .burst_bandwidth - 1536000

 My relay's torrc says

  - RelayBandwidthRate 1250 KBytes
  - RelayBandwidthBurst 1500 KBytes

 > > I'm a little confused by the terms you're using.  When you say
 "observed bandwidth" do you mean the relay's 'advertised bandwidth' a
 relay operator puts in the config, the unit-less values the bwauths
 calculate and vote on, or a third thing I'm not recalling? (And if it is
 the third thing, where does that get exposed: Consensus, MicroConsensus,
 Descriptor, Microdescriptor, or ExtraInfo?)
 >
 > By "observed bandwdith" I mean the "bandwdith-observed" figure from the
 descriptor "bandwdith" line:
 > https://gitweb.torproject.org/torspec.git/tree/dir-spec.txt#n418
 >
 > I'd like it more easily available because it's one of the two figures
 that an operator doesn't set themselves - the other is the measured
 bandwidth.
 >
 > And used in conjunction with the advertised bandwidth to calculate the
 bandwidth in the consensus "w" line:
 > https://gitweb.torproject.org/torspec.git/tree/dir-spec.txt#n2268
 >
 > (That figure is useful, but more confusing, because it's sometimes the
 advertised bandwidth, and sometimes the observed bandwidth.)

 And .observed_bandwidth from the descriptor also

 > >  And then the same question for "consensus weight".
 >
 > Whatever Atlas uses for consensus weight in the relay details page.
 > I assume it's measured bandwidth from the consensus w line, but I'm not
 sure.
 >
 > If it is, it's already there in the consensus column of the relay flags
 table.
 >
 > https://gitweb.torproject.org/torspec.git/tree/dir-spec.txt#n2274



 Yes, I'm 95% sure this is working correctly currently.



 > > Looking closer at the stem documentation, I might have done things
 wrong in #20372 actually. Adding Damian to confirm the below is correct:
 > >
 > > - On a vote .measured is the bwauth's vote for the relay's (unitless)
 bandwidth value
 > > - On a consensus .measured is the average* of the bwauths votes for
 the relay's (unitless) bandwidth value
 > > - On a vote or consensus .bandwidth is the _relay's_ advertised
 bandwidth (and is what teor wants available)
 >
 > Not quite, I think it's the minimum of advertised and observed, which
 confuses a lot of operators, because sometimes it's controlled by the
 torrc, and other times by their relay's self-reported performance:
 > https://gitweb.torproject.org/torspec.git/tree/dir-spec.txt#n418
 >
 > > *not really average but let's pretend it is for simplicity
 >
 > (low-median)

 Ah interesting, so it just takes the median value (and if there's an even
 number, the lower of the two in the middle?  Didn't realize that.


 > > (Currently, the value on each Authority is the .measured but the value
 on the consensus is .bandwidth - which would be wrong as the consensus
 would be reporting the self-reported advertised bandwidth...)
 >
 > That's strange, because all the figures in the table appear to be a low-
 median (consensus .measured) to me.

 Yup, turns out the stem documentation seems to be wrong.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/20403#comment:3>
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