Re: [quicwg/base-drafts] Should we allow ACK-only packets to be declared lost? (#3451)

Martin Thomson <> Wed, 12 February 2020 03:46 UTC

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Date: Tue, 11 Feb 2020 19:46:56 -0800
From: Martin Thomson <>
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Subject: Re: [quicwg/base-drafts] Should we allow ACK-only packets to be declared lost? (#3451)
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We should at least recognize that ACK-only packets can be declared lost.  One interpretation of the current text is that ACK-only packets MUST NOT be declared lost.

The reason that you might not want to declare these as lost that is that the requirements for acknowledging ACK-only packets are (necessarily) more loose than ACK-eliciting packets.  But I believe that it is simpler to allow code to declare them lost.  Correct me if I am wrong, but I believe that you have one fewer condition if you ignore whether a packet is in flight or not when doing loss detection.  It is also likely better to mark lost ACKs as lost as it means that you don't ignore a potential congestion signal.

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