[tor-bugs] #24388 [Metrics/Atlas]: Add unreachable or addresses to details view and a synthetic flag

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#24388: Add unreachable or addresses to details view and a synthetic flag
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 Reporter:  irl            |          Owner:  irl
     Type:  enhancement    |         Status:  accepted
 Priority:  Medium         |      Milestone:
Component:  Metrics/Atlas  |        Version:
 Severity:  Normal         |     Resolution:
 Keywords:                 |  Actual Points:
Parent ID:                 |         Points:
 Reviewer:                 |        Sponsor:
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Comment (by teor):

 This flag only applies to IPv6.
 And it will not be shown, as long there are a majority of ReachableIPv6
 authorities voting for each and every consensus.

 Here's why:
 * relays with unreachable IPv4 ORPorts are always marked as not Running,
 and excluded from the consensus. Their addresses never appear in onionoo's
 unreachable_orports field, because they are never included in the
 consensus
 * if a majority of voting authorities have IPv6, IPv6 ORPorts are treated
 the same as IPv4 ORPorts.
 * if a minority of voting authorities have IPv6, some IPv6 addresses may
 appear in unreachable_orports, but the numbers will be small (see
 Karsten's graphs on #23761)

 Reference:
 https://metrics.torproject.org/onionoo.html#details_relay_unreachable_or_addresses

 So if one of the 5 IPv6 authorities stops IPv6 or goes down, this feature
 will be very useful.
 Otherwise, it won't get used at all.
 (We didn't know this until after #23761, and more authorities adding IPv6,
 and the consensus-health ReachableIPv6 feature.)

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/24388#comment:2>
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