[tor-bugs] #30420 [Core Tor/Tor]: Should we recommend that relay operators turn on tcp bbr?

[Tor Bug Tracker & Wiki]

#30420: Should we recommend that relay operators turn on tcp bbr?
------------------------------+-----------------------------------------
     Reporter:  arma          |      Owner:  (none)
         Type:  task          |     Status:  new
     Priority:  Medium        |  Milestone:
    Component:  Core Tor/Tor  |    Version:
     Severity:  Normal        |   Keywords:  network-health, performance
Actual Points:                |  Parent ID:
       Points:                |   Reviewer:
      Sponsor:                |
------------------------------+-----------------------------------------
 The internet seems to have a growing number of howto's for switching your
 kernel to use the "bbr" congestion control mode of tcp:
 https://github.com/google/bbr
 https://en.wikipedia.org/wiki/TCP_congestion_control#TCP_BBR

 Thought 1: doing an experiment where various fractions of Tor relays
 switch to this congestion control mode would be neat. Maybe it's the sort
 of thing that Shadow could help with, since switching the real Tor network
 is both cumbersome and dangerous.

 (Though, since Shadow builds its own tcp implementation, it would need to
 have an implementation of the bbr variation in order to do a test with it.
 And it would need to have realistic *non* Tor background flows to test the
 comparison. What a great use case for driving forward Shadow innovation to
 be able to capture this test. Cc'ing Rob.)

 Thought 2: If God wanted us to be using tcp bbr, we'd be using it by
 default already. And we're not, so we should learn why that is. For
 example, the wikipedia page indicates that it's not good at fairness in
 some situations -- and since Tor relays are often guests on their network,
 we might not want to give people more reasons to get angry at them.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/30420>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online