[tor-bugs] #25723 [Circumvention/Snowflake]: Multiplex - one client splits traffic across multiple proxies

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#25723: Multiplex - one client splits traffic across multiple proxies
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 Reporter:  dcf                             |          Owner:  dcf
     Type:  defect                          |         Status:  assigned
 Priority:  Low                             |      Milestone:
Component:  Circumvention/Snowflake         |        Version:
 Severity:  Normal                          |     Resolution:
 Keywords:  anti-censorship-roadmap-2020Q1  |  Actual Points:
Parent ID:                                  |         Points:
 Reviewer:                                  |        Sponsor:
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Comment (by dcf):

 Replying to [comment:2 uiouio27]:
 > Does that mean that the required feature is covered? As far as I
 understand, that would switch the connection when a proxy leaves but not
 when it is very slow. Would it be still convenient to utilize several
 proxies but coordinately and congestion-based sending traffic to them?

 Good question. The multiplexing described in that document is simpler than
 what this ticket is about. You are correct that the failover only helps
 when a proxy dies, not when it is slow. But also, there's no way for a
 client to use, say, two 50 KB/s proxies as a single 100 KB/s channel—you
 can only use one at a time. The problem is that the bridge would be
 getting two streams of data and would not know how they should be
 interleaved.

 But beyond that, while it's true a client manages a pool of proxies with
 the goal of switching between them, currently it doesn't work. After the
 first proxy dies, there's no way for the client to switch over to another
 proxy and resume the session. See #29206 and
 https://lists.torproject.org/pipermail/anti-censorship-
 team/2020-February/000059.html for how we are adding a meta-protocol to
 make it possible to recover a session after a proxy dies, and make use of
 multiple proxies at once.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/25723#comment:4>
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