Re: [quicwg/base-drafts] A pacing algorithm (#3630)

Martin Thomson <> Tue, 12 May 2020 22:51 UTC

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Date: Tue, 12 May 2020 15:51:21 -0700
From: Martin Thomson <>
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Subject: Re: [quicwg/base-drafts] A pacing algorithm (#3630)
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@martinthomson commented on this pull request.

> @@ -897,9 +897,29 @@ congestion window, which is recommended to be the minimum of
 max_datagram_size is the current maximum size of a datagram for the connection,
 not including UDP or IP overhead.
-As an example of a well-known and publicly available implementation of a flow
-pacer, implementers are referred to the Fair Queue packet scheduler (fq qdisc)
-in Linux (3.11 onwards).
+Endpoints can implement pacing as they choose, as long as the rate of bytes
+sent over any interval, `t[n] - t[m]`, does not exceed a small multiple, `N`,
+of maximum value of the congestion window, `congestion_window`, averaged over
+the round trip time estimate, `smoothed_rtt`. Allowing for bursts produces the
+following relation for the total number of bytes sent over any interval:
+sent@t[n] - sent@t[m]

number of bytes sent between t[m] and t[n]

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