[Bloat] [Ecn-sane] [iccrg] Fwd: [tcpPrague] Implementation and experimentation of TCP Prague/L4S hackaton at IETF104

Luca Muscariello luca.muscariello at gmail.com
Sun Mar 17 16:50:26 EDT 2019

To me there is substantial difference from something like fq_codel or
fq_pie where service differentiation is largely implicit
and approches largely based on explicit marking.

Approaches based on marking face technical and non technical challenges
that have been largely mentioned in these lists.

Fq_codel has a ton of litterature behind both theoretical and experimental
and it is something very close to optimality, in terms of completion time
and latency.

Fq_codel also incentivizes the development of better congestion control as
the reward is immediate. It also makes  Internet performance

Once we know that, the logical approach would be to try to approximate that
thing when the full mechanism is not possible because of a variety of

This is the case in some DC switches that implement AFD+priority fair
queueing at 40Gbps.

Fq_codel has an outstanding footprint in terms of deployment.
Iliad deployed SFQ in 2005 nation wide and Fq_codel as soon as it was
available in France and is the second largest ISP.
Iliad/Free  controls the development of both the home GW and the DSLAM.
They have recently started to commercialize 10Gbps to the home using
switched Ethernet.
I’m very tempted to test it.

Kudos to them for being able to prove it is possible as long as you control
the development of your equipment.

A logical next step  to me seems to push chipcos to build fq_codel in
It is totally feasible.

If on the other hand we say that we can achieve all fq_codel provides with
current chipsets we’ll never create the incentives to make progress.


On Sun 17 Mar 2019 at 15:06, Mikael Abrahamsson <swmike at swm.pp.se> wrote:

> On Sat, 16 Mar 2019, Holland, Jake wrote:
> > Granted, it still remains to be seen whether SCE in practice can match
> > the results of L4S, and L4S was here first.  But it seems to me L4S comes
> > with some problems that have not yet been examined, and that are nicely
> > dodged by a SCE-based approach.
> I'm actually not that interested in an academic competition about what
> solution gives the ultimate "best" outcome in simulation or in a lab.
> I am interested in good enough solutions that are actually deployable and
> will get deployed, and doesn't have any pathological behaviour when it
> comes to legacy traffic.
> Right now the Internet is full of deep FIFOs and they're not going away,
> and they're not getting FQ_CODEL or CAKE.
> CAKE/FQ_CODEL is nice, but it's not being deployed at the typical
> congestion points we have in real life. These devices would have a much
> easier time getting PIE or even RED, if it was just implemented.
> --
> Mikael Abrahamsson    email: swmike at swm.pp.se
> _______________________________________________
> Bloat mailing list
> Bloat at lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/bloat
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