Re: [quicwg/base-drafts] Clarify PTO packets count towards amplification limit (#3539)

Martin Thomson <> Mon, 23 March 2020 04:42 UTC

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From: Martin Thomson <>
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Subject: Re: [quicwg/base-drafts] Clarify PTO packets count towards amplification limit (#3539)
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martinthomson approved this pull request.

Not sure how to split the difference between the limit applying to the packet that was just sent (causing PTO to be armed) or the packet that arming the PTO timer implies.

Personally, I would have put the test at the point that you send a packet, but that's not how this is structured, and you do have "because packets sent on PTO count against the anti-amplification limit", which captures the important concept neatly.

> @@ -558,6 +545,23 @@ keys are discarded, the PTO and loss detection timers MUST be reset, because
 discarding keys indicates forward progress and the loss detection timer might
 have been set for a now discarded packet number space.
+#### Before Address Validation
+Until the server has validated the client's address on the path, the amount of
+data it can send is limited to three times the amount of data received,
+as specified in Section 8.1 of {{QUIC-TRANSPORT}}. If no data can be sent,

as specified in Section 8.1 of {{QUIC-TRANSPORT}}. If no additional data can be sent,

When you arm the timer, you might be sending a packet that is within the limit, but the next packet might exceed the limit.

I don't know if this should be adjusted somehow, but this might help.

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