Re: [quicwg/base-drafts] Why min CWND of 2 instead of 1 (#3586)

Gorry Fairhurst <> Sat, 25 April 2020 06:46 UTC

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Date: Fri, 24 Apr 2020 23:46:01 -0700
From: Gorry Fairhurst <>
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Subject: Re: [quicwg/base-drafts] Why min CWND of 2 instead of 1 (#3586)
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@gorryfair commented on this pull request.

> @@ -245,6 +245,13 @@ QUIC specifies a time-based definition to ensure one or more packets are sent
 prior to a dramatic decrease in congestion window; see
+### Increase the min congestion window to 2 packets
+QUIC recommends a minimum congestion window of 2 packets instead of TCP's 1.
+2 packets avoid waiting for a delayed acknowledgement and allow the PTO to
+send 2 packets instead of 1, which can be particularly important during the

Do we agree on what is intended by congestion-collapse, i.e. persistent long-lasting high level of congestion, as oppose to just "congestion"? (e.g. when there is a very low probability of a successful ACK). ... In will find something on reducing the MSS below once/RTT.

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