Re: [quicwg/base-drafts] ACK generation recommendation (#3304)

ianswett <> Tue, 17 December 2019 18:03 UTC

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Subject: Re: [quicwg/base-drafts] ACK generation recommendation (#3304)
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There was still a regression with 1/8th RTT and Cubic.  We we using pacing at the time, FYI.  Not pacing or pacing differently may lead to slightly different results.

Given TCP has no formal recommendations on this that I'm aware of, I tend to think we should solve this problem properly or punt it to an extension.  Recommending the heuristic that Chrome arrived at though some(though not exhaustive) experimentation makes me concerned.

Sending fewer ACKs impacts the sender's congestion controller, so ideally the sender would be in control of this, or at least be aware of what the peer's algorithm is.  We could add some transport params to unilaterally communicate that, like we do max_ack_delay, but then do we need to specify how to compensate for that in the recovery draft?

I'm having a really hard time coming up with a good recommendation here without some combination of a new frame and/or transport params.

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