Re: [aqm] [tcpm] TCP ACK Suppression

Joe Touch <touch@isi.edu> Sun, 11 October 2015 21:28 UTC

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To: David Lang <david@lang.hm>
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From: Joe Touch <touch@isi.edu>
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Date: Sun, 11 Oct 2015 14:28:27 -0700
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Cc: "tcpm@ietf.org" <tcpm@ietf.org>, touch@isi.edu, "mallman@icir.org" <mallman@icir.org>, "LAUTENSCHLAEGER, Wolfram \(Wolfram\)" <wolfram.lautenschlaeger@alcatel-lucent.com>, Greg White <g.white@CableLabs.com>, Jonathan Morton <chromatix99@gmail.com>, "aqm@ietf.org" <aqm@ietf.org>
Subject: Re: [aqm] [tcpm] TCP ACK Suppression
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On 10/11/2015 2:18 PM, David Lang wrote:
> But you will notice that in both cases, I am in favor of reducing the
> number of packets on the wire. Packets not send can't interfere with
> other traffic.

The degenerate case of this approach is a circuit. Take a look at
Morris's 1997 ICNP paper to see what happens when you end up with one -
or sometimes less than one - packet per round trip time.

One of the reasons we use packets is to provide more timely,
fine-grained feedback between endpoints. Aggregating them at the source
or in the network (rather than at the receiver) can amplify reaction to
packet loss (when the aggregate ACK is lost) and increases
discretization effects in the TCP algorithms.

Joe