[Bloat] benefits of ack filtering

[Luca Muscariello]

If I understand the patch well, the ack filter is actually fixing the
problem of ACK compression only.
Because it is enforced on packets in the queue only. It is stateless.

ACK compression would happen even w/o highly asymmetric access links by
just
having concurrent data streams with ack streams.

So, IMO, the patch is harmless per se in all  cases.
ACK compression is harmful though and the patch fixes it.

Background on ACK compression:

Lixia Zhang, Scott Shenker, and Daivd D. Clark.
Observations on the dynamics of a congestion control algorithm: the effects
of two-way traffic.
acm sigcomm 1991.




On Tue, Dec 12, 2017 at 11:03 PM, Jonathan Morton <chromatix99 at gmail.com>
wrote:

> The one "correct" argument against ack-filtering I've seen is that it
> encourages (or rather validates) the use of extreme asymmetry ratios.
>
> However, these extreme ratios are already in widespread use without the
> aid of ack-filtering.  Even ADSL2 Annex A has, as its "ideal" sync rate, a
> 16:1 ratio, which Annex M modifies to under 10:1.  I fear we must conclude
> that technical considerations are not the driving factor here.
>
> A better place to sort out the asymmetry problem (as well as several other
> problems of current interest) would be in a free, competitive market.
> Sadly such a thing is rare in the telecoms sector.
>
> - Jonathan Morton
>
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