Re: [quicwg/base-drafts] Move Generating Acknowledgements to Transport (#2916)

Jana Iyengar <notifications@github.com> Wed, 11 September 2019 01:18 UTC

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Subject: Re: [quicwg/base-drafts] Move Generating Acknowledgements to Transport (#2916)
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janaiyengar commented on this pull request.



> +An endpoint measures the delays intentionally introduced between when an
+ACK-eliciting packet is received and the corresponding acknowledgment is sent.
+The endpoint encodes this delay for the largest acknowledged packet in the
+Ack Delay field of an ACK frame (see Section 19.3). This allows the receiver
+of the ACK to adjust for any intentional delays, which is important for
+delayed acknowledgements, when estimating the path RTT. A packet might be
+held in the OS kernel or elsewhere on the host before being processed.
+An endpoint SHOULD NOT include these unintentional delays when populating
+the Ack Delay field in an ACK frame.
+
+An endpoint MUST NOT excessively delay acknowledgements of ack-eliciting
+packets.  The maximum ack delay is communicated in the max_ack_delay transport
+parameter; see Section 18.1.  max_ack_delay implies an explicit contract:
+an endpoint promises to never delay acknowledgments of an ack-eliciting packet
+by more than the indicated value. If it does, any excess accrues to the RTT
+estimate and could result in spurious retransmissions from the peer.

I think this should have been "delayed retransmissions".

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