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

Nick Banks <notifications@github.com> Tue, 22 October 2019 14:03 UTC

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Date: Tue, 22 Oct 2019 07:03:54 -0700
From: Nick Banks <notifications@github.com>
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Subject: Re: [quicwg/base-drafts] MUST ACK each ack-eliciting packet once (#3092)
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nibanks commented on this pull request.

Generally looks good, but I don't think we can have an absolute requirement that every ack-eliciting packet is acknowledged.

> +Every packet SHOULD be acknowledged at least once, and ack-eliciting packets
+MUST be acknowledged at least once within the maximum ack delay. An endpoint

I think I agree with @mikkelfj that MUST might not be the right word here. It's obviously unenforceable for one. But also, I think there are valid reasons where a packet won't be acknowledged. For one, we have a memory limit for the data structure we use to keep track of packets that need to be acknowledged. At a high enough rate, with enough (random?) packet loss you could have enough gaps to hit that limit. In that case, we start forgetting older packet numbers, and will never end up acknowledging them.

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