Re: [quicwg/base-drafts] Attempt to define slow start/congestion avoidance (#4005)

Jana Iyengar <> Tue, 25 August 2020 01:34 UTC

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Date: Mon, 24 Aug 2020 18:34:34 -0700
From: Jana Iyengar <>
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Subject: Re: [quicwg/base-drafts] Attempt to define slow start/congestion avoidance (#4005)
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@janaiyengar commented on this pull request.

> -acknowledged.  When a loss or ECN-CE marking is detected, NewReno halves
-the congestion window, sets the slow start threshold to the new
-congestion window, and then enters the recovery period.
+The congestion controller is in congestion avoidance any time the congestion
+window is at or above the slow start threshold.
+Congestion avoidance uses an Additive Increase Multiplicative Decrease (AIMD)
+approach that increases the congestion window by one maximum datagram size per
+congestion window acknowledged. A congestion controller MUST NOT increase the
+congestion window by more than this amount.
+When first entering congestion avoidance, when a packet is declared lost, or
+when the ECN-CE count is increased, the congestion controller described in this
+document halves the congestion window, reduces the slow start threshold to the
+resulting size, and enters the recovery period. A congestion controller MUST
+reduce the congestion window when a loss or ECN-CE marking is detected.
 ## Recovery Period

## Recovery Period {#recovery}

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