[metrics-bugs] #26171 [Metrics/Statistics]: Explain which cells are counted for onion service traffic graphs

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#26171: Explain which cells are counted for onion service traffic graphs
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 Reporter:  teor                |          Owner:  metrics-team
     Type:  defect              |         Status:  new
 Priority:  Medium              |      Milestone:
Component:  Metrics/Statistics  |        Version:
 Severity:  Normal              |     Resolution:
 Keywords:                      |  Actual Points:
Parent ID:                      |         Points:
 Reviewer:                      |        Sponsor:
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Comment (by teor):

 Replying to [ticket:26171 teor]:
 > I can't work out what is being measured on the onion service traffic
 graph:
 > https://metrics.torproject.org/hidserv-rend-relayed-cells.html
 >
 > Does it include:
 > * cells sent from rendezvous points to clients?
 > * cells sent from rendezvous points to services?
 > * cells sent to rendezvous points from clients?
 > * cells sent to rendezvous points from services?

 I can answer this question from the tor code:

 Tor reports the number of relay cells relayed by the rendezvous point.
 (It doesn't report the circuit-level extend and destroy cells).

 https://github.com/torproject/tor/blob/bd153e46408fa4f9432a5de1b1f5f106f00e34cf/src/or/command.c#L565

 Using the same wording as the question:
 * cells sent from clients to services via rendezvous points and
 * cells sent from services to clients via rendezvous points

 > Also, the related blog post says:
 > "A related statistic here is "How much of the Tor network is actually
 hidden service usage?". There are two different ways to answer this
 question…"
 > https://blog.torproject.org/some-statistics-about-onions
 >
 > Does the graph try to answer this question?

 I don't think it does, but I'd need to look at the metrics code to
 confirm.

 > Or is it just measuring rendezvous point traffic without counting the
 traffic on the relays on rest of the circuit?

 I'm going to assume that metrics makes no attempt to multiply the traffic
 by the number of relays in the circuit.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/26171#comment:3>
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