Re: [quicwg/base-drafts] Rework section on persistent congestion (#3961)

Marten Seemann <notifications@github.com> Wed, 29 July 2020 14:12 UTC

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Date: Wed, 29 Jul 2020 07:12:35 -0700
From: Marten Seemann <notifications@github.com>
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Subject: Re: [quicwg/base-drafts] Rework section on persistent congestion (#3961)
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@marten-seemann commented on this pull request.



> +
+This design does not use consecutive PTO events to establish persistent
+congestion, since a PTO expiration is controlled by application patterns in
+addition to network activity. For example, a sender that sends small amounts of
+data with silence periods between them restarts the PTO timer every time it
+sends, potentially preventing the PTO timer from expiring for a long period of
+time, even when no acknowledgments are being received. The use of a duration
+enables a sender to establish persistent congestion without depending on the
+occurrence of PTOs.
+
+### Establishing Persistent Congestion
+
+A sender establishes persistent congestion on receiving an acknowledgement, if
+the following conditions are true:
+
+* a prior RTT sample exists;

#3889 says exactly that:
> The persistent congestion period SHOULD NOT start until there is at least one RTT sample.

... which means that you need to have had a RTT sample when you sent the first packet, right?

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