[quicwg/base-drafts] Starting persistent congestion on a ack-eliciting packet (#3941)

Martin Thomson <notifications@github.com> Wed, 22 July 2020 12:13 UTC

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Date: Wed, 22 Jul 2020 05:13:38 -0700
From: Martin Thomson <notifications@github.com>
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Subject: [quicwg/base-drafts] Starting persistent congestion on a ack-eliciting packet (#3941)
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Persistent congestion has to start with an ack-eliciting packet.  The section on persistent congestion isn't very clear about this point.

This is because a non-ack-eliciting packet won't be followed up with any probes.  It is therefore possible to send one packet and then not send anything else for an extended period.  After this, the loss of just the next packet will cause persistent congestion.

Note that persistent congestion can be caused by the loss of just two packets after multiple PTOs have occurred, but the common case is that you have at least three packet, or four if you send two packets on PTO.

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