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Re: [quicwg/base-drafts] Update initial congestion window on MTU decrease (#3998)

Gorry Fairhurst <notifications@github.com> Wed, 19 August 2020 08:31 UTC

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Date: Wed, 19 Aug 2020 01:31:31 -0700
From: Gorry Fairhurst <notifications@github.com>
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Subject: Re: [quicwg/base-drafts] Update initial congestion window on MTU decrease (#3998)
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@gorryfair commented on this pull request.



> +If the maximum datagram size is decreased in order to complete the handshake,
+the initial congestion window SHOULD be recalculated with the new smaller size.
+This avoids overly large initial congestion windows.  The initial window is
+not recalculated at any other time.

My comment related to the handshake because I saw that as most important. I agree though with Jana, a change of PMTU can require that the IW is updated, given that IW is also used after the handshake and might be cached for future connections. Could we change the final sentence in the PR to say something like: The initial window SHOULD also be recalculated when a change of the path MTU is detected.

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