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Re: [tcpm] More motivating scenarios for tcpm-ack-pull

Jonathan Morton <chromatix99@gmail.com> Sun, 15 March 2020 17:38 UTC

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From: Jonathan Morton <chromatix99@gmail.com>
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Date: Sun, 15 Mar 2020 19:38:13 +0200
Cc: tcpm IETF list <tcpm@ietf.org>, Jon Crowcroft <jon.crowcroft@cl.cam.ac.uk>
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To: Carles Gomez Montenegro <carlesgo@entel.upc.edu>
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Subject: Re: [tcpm] More motivating scenarios for tcpm-ack-pull
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> On 15 Mar, 2020, at 11:38 am, Carles Gomez Montenegro <carlesgo@entel.upc.edu> wrote:
> 
> Thanks a lot for your detailed response, which helped shape our latest
> draft [1] in several ways.
> 
> While we focus on analyzing the problem space and its requirements, it
> will be good to keep an eye on potential solutions as well, including the
> one you describe below. In particular, I found the idea of spacing AKP
> flags (or something similar) in order to control the desired ACK ratio to
> be very interesting!

I'm glad you found my comment useful.

I think one of the big takeaways from draft-gomez-tcpm-delack-suppr-reqs is that the sender has the most information about when, and to what extent, Delayed Acks are helpful, but the receiver is the point at which they must be implemented.  So some means to convey this information from sender to receiver is desirable.  The precise form of that is still open to debate.

And there are well-known circumstances where the receiver already has to interrupt or suspend Delayed Ack processing - when it notices a packet loss, or receives an ECN mark, for example.  I assume these would not change materially on a transport supporting Ack Pull or similar.

 - Jonathan Morton

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