Re: [quicwg/base-drafts] MUST ACK each ack-eliciting packet once (#3092)

MikkelFJ <notifications@github.com> Tue, 22 October 2019 13:24 UTC

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Date: Tue, 22 Oct 2019 06:24:09 -0700
From: MikkelFJ <notifications@github.com>
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Subject: Re: [quicwg/base-drafts] MUST ACK each ack-eliciting packet once (#3092)
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mikkelfj commented on this pull request.



> @@ -3007,9 +3007,6 @@ guidance offered below seeks to strike this balance.
 
 ### Sending ACK Frames {#sending-acknowledgements}
 
-An ACK frame SHOULD be generated for at least every second ack-eliciting packet.
-This recommendation is in keeping with standard practice for TCP {{?RFC5681}}.
-
 An endpoint MUST NOT excessively delay acknowledgements of ack-eliciting

I don't want to make this a hard argument, I'm just slightly concerned. Maybe it is a non-issue, or maybe potential issues are shadowed by other concerns such as PTO. Some devices might not want to fire up a transmitter radio more often than necessary. But generally I'm just concerned with a MUST that cannot be enforced or fully controlled - you can easily claim it works under usual conditions but it might not under abnormal conditions. A SHOULD would make it possible to drop packets under those a conditions. A MUST would either have to make assumptions that are hard to prove correct, or have complex code to handle edge case where ACK's queue op, or violate the MUST. I suspect most implementations would go for the latter and hope they don't violate by sending ACK's often enough.

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