Re: [quicwg/base-drafts] Change PTO to be per packet number space (#3066)

ianswett <> Tue, 29 October 2019 21:37 UTC

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Date: Tue, 29 Oct 2019 14:37:14 -0700
From: ianswett <>
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Subject: Re: [quicwg/base-drafts] Change PTO to be per packet number space (#3066)
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ianswett commented on this pull request.

>  When a PTO timer expires, the PTO period MUST be set to twice its current
 value. This exponential reduction in the sender's rate is important because
 the PTOs might be caused by loss of packets or acknowledgements due to severe
-congestion.  The life of a connection that is experiencing consecutive PTOs is
-limited by the endpoint's idle timeout.
-A sender computes its PTO timer every time an ack-eliciting packet is sent. A
-sender might choose to optimize this by setting the timer fewer times if it
-knows that more ack-eliciting packets will be sent within a short period of
+congestion.  Even when there are ack-eliciting packets in-flight in multiple
+packet number spaces, the exponential increase in probe timeout occurs across
+all spaces to prevent excess load on the network. The life of a connection that

Hopefully it's clearer now.

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