Re: [tcpm] 793bis: delayed ACKs

Yuchung Cheng <ycheng@google.com> Fri, 03 January 2020 21:31 UTC

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From: Yuchung Cheng <ycheng@google.com>
Date: Fri, 3 Jan 2020 13:30:43 -0800
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To: Wesley Eddy <wes@mti-systems.com>
Cc: "tcpm@ietf.org Extensions" <tcpm@ietf.org>
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Subject: Re: [tcpm] 793bis: delayed ACKs
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On Thu, Dec 19, 2019 at 2:06 PM Wesley Eddy <wes@mti-systems.com> wrote:
>
> Regarding Gorry's comment below, I have an alternative suggestion.  I
> think the details are discussed well in 5681
> https://tools.ietf.org/html/rfc5681#section-4.2 and that we can simply
> point to that for expansion.
Beside that, perhaps it is worth some additional text on real
practices. With GRO, ACK decimation/compression in the network and in
the host, ACKs are greatly stretched (tens of full-size segments) for
performance reasons. It would only be more common w/ ever faster
networks.

>
>
> On 8/28/2019 11:39 AM, Gorry Fairhurst wrote:
> > Section 3.8.6.3 Delayed ACK.
> > OLD:
> >    and in a stream of full-sized segments there
> >    SHOULD be an ACK for at least every second segment (SHLD-19).
> > - Delayed ACK is specified in RFC1122 as: "...and in a stream of
> > full-sized segments there SHOULD be an ACK for at least every second
> > segment." Although correct, this does not specify a behaviour when
> > segments are not "full-sized". When asked by people, I have think this
> > should be something like:
> > NEW:
> > "the receiver SHOULD send an ACK when the data
> > needing acknowledgment corresponds to no more than two full-sized
> > (MSS) segments."
>
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