[tor-bugs] #18910 [Metrics/CollecTor]: distributing descriptors accross CollecTor instances

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#18910: distributing descriptors accross CollecTor instances
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 Reporter:  iwakeh             |          Owner:  iwakeh
     Type:  enhancement        |         Status:  needs_information
 Priority:  Medium             |      Milestone:
Component:  Metrics/CollecTor  |        Version:
 Severity:  Normal             |     Resolution:
 Keywords:  ctip               |  Actual Points:
Parent ID:                     |         Points:
 Reviewer:                     |        Sponsor:
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Comment (by iwakeh):

 Replying to [comment:4 karsten]:
 > ...
 > Overall, I think I'd rather want us to keep things simple here for now
 and think about optimizing later.  What do you think?
 Yes , agreed. Let's just go with the simple download solution and first
 focus on the tagging of the descriptors from different sources.

 There are several approaches here:
 1. Only one @source tag from the direct provider.  Implications:
  * a descriptor downloaded from an authority A will be tagged with A's IP.
  * a descriptor downloaded from another CollecTor B, which received it
 from authority A, will be tagged with B's IP.
  * a descriptor downloaded from another CollecTor B, which received it
 from CollecTor C, will be tagged with B's IP.
  * a known descriptor downloaded again from a different source will be
 ignored.
 1. Several @source tags (no duplicates) from various direct providers.
 Implications hereof are the same as above except for the last one: every
 time a descriptor is seen a @source tag is added to the descriptor.
 1. Create a structure of source tags that keeps the initial source. This
 quickly turns into a very complex situation.

 Wanting to keep it simple and considering that at first the
 trustworthiness of all synchronizing CollecTors is established externally
 1. or 2. might be the way to go. The design should allow for a later
 extension and more complex approach of source designation.


 One question about the initial description:
 > It's important that we'd only add those @source annotations to
 > archived descriptors, not to recent descriptors, or we'd serve those
 > descriptors as new every time we're adding a @source.
 How can the sources be determined when archiving?

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/18910#comment:5>
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