Re: [quicwg/base-drafts] Limit CWND increase in slow start (#3232)

Jana Iyengar <> Thu, 28 November 2019 11:52 UTC

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Date: Thu, 28 Nov 2019 03:52:40 -0800
From: Jana Iyengar <>
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Subject: Re: [quicwg/base-drafts] Limit CWND increase in slow start (#3232)
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janaiyengar commented on this pull request.

> @@ -769,7 +769,10 @@ Implementations MUST either use pacing or limit such bursts to the initial
 congestion window, which is recommended to be the minimum of
 10 * max_datagram_size and max(2* max_datagram_size, 14720)), where
 max_datagram_size is the current maximum size of a datagram for the connection,
-not including UDP or IP overhead.
+not including UDP or IP overhead. An implementation that does not use pacing
+SHOULD limit the congestion window increase during slow start to

We've already said that a sender MUST limit bursts to IW, so there's no reason to repeat that. I would argue this is a SHOULD-level requirement; MAY is strange, since that's really a permission and that's not what we're going after here. I'd suggest dropping the phrase "in order to limit bursts" --- "An implementation that does not use pacing SHOULD limit the congestion window increase during slow start to 2 * max_datagram_size per ACK frame received {{?RFC3465}}. "

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