Date: Tue, 26 Mar 2019 15:44:06 +0000 (UTC)
From: ianswett <notifications@github.com>
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Message-ID: <quicwg/base-drafts/issues/2556/476710975@github.com>
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Subject: Re: [quicwg/base-drafts] Should kPersistentCongestionThreshold be 1
 or 2? (#2556)
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Last time I talked to Yuchung, I remember him saying they chose 1 somewhat arbitrarily.

I'm going to argue for 2 (3 * PTO) as a good number because it provides enough time for the PTO timer to go off twice now that the PTO has exponential backoff.  This is in some ways more similar to 1 TLP and then 1RTO in terms of network load.  Additionally, I believe making it only 1 would allow a single tail packet to be lost and persistent congestion to be declared if there was some RTT variation?  That certainly seems undesirable.

Maybe the rationale for why this value was chosen should be clarified further?

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<p>Last time I talked to Yuchung, I remember him saying they chose 1 somewh=
at arbitrarily.</p>
<p>I'm going to argue for 2 (3 * PTO) as a good number because it provides =
enough time for the PTO timer to go off twice now that the PTO has exponent=
ial backoff.  This is in some ways more similar to 1 TLP and then 1RTO in t=
erms of network load.  Additionally, I believe making it only 1 would allow=
 a single tail packet to be lost and persistent congestion to be declared i=
f there was some RTT variation?  That certainly seems undesirable.</p>
<p>Maybe the rationale for why this value was chosen should be clarified fu=
rther?</p>

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6: Last time I talked to Yuchung, I remember him saying they chose 1 somewh=
at arbitrarily.\r\n\r\nI'm going to argue for 2 (3 * PTO) as a good number =
because it provides enough time for the PTO timer to go off twice now that =
the PTO has exponential backoff.  This is in some ways more similar to 1 TL=
P and then 1RTO in terms of network load.  Additionally, I believe making i=
t only 1 would allow a single tail packet to be lost and persistent congest=
ion to be declared if there was some RTT variation?  That certainly seems u=
ndesirable.\r\n\r\nMaybe the rationale for why this value was chosen should=
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