[Bloat] ONTs and ITU - T G.988

[Aaron Wood]

Can't switches send pause frames back over ethernet?

/me googles, and finds:

https://en.wikipedia.org/wiki/Ethernet_flow_control

On Wed, Jan 12, 2022 at 4:57 PM Dave Taht <dave.taht at gmail.com> wrote:

> What appeared to be the case was that a ONT had a 50ms buffer at
> 100Mbit and was reconfigured to drive a gig and thus only had 5ms.
>
> At least, that's what the data looked like. This was on a fairly
> recent reddit thread a month or two back, that I cannot find right
> now. I'm pretty sure it was in the context of eero's
> rolling out a working htb+fq_codel implementation finally for the eero
> 6, (or maybe it was the comcast AQM?0 and us discovering it didn't do
> any good, that the ont was seemingly brutally underbuffered, which
> took days of scratching my head.... multiple flent tests... wish I
> could find that thread...
>
> This is kind of ironic, but the structure of the speedtest (8+ flows
> with short RTTs) actually could lead naturally to buffers that short
> and few would notice.
>
> Anyway, that sparked me finally going and reading up a bit more about
> how ONTs work...
>
>
> On Wed, Jan 12, 2022 at 4:40 PM Marco Belmonte
> <marco at heavenlysanctuary.com> wrote:
> >
> > Dave,
> >
> > Can you describe to me what under buffered would look like? Let's say
> > I'm playing Rocket League on a Frontier FIOS connection... When a
> > situation arises where the connection is under buffered you might see
> > __<Insert DT's Big Brain words here>___.
> >
> > A lot of interrupts being generated? connections timing out? lag?
> >
> > I'm guessing that many of the same symptoms that accompanying buffer
> > bloat also manifest themselves with buffer bleed?
> >
> > Marco
> >
> >
> > On 1/12/2022 3:42 PM, Dave Taht wrote:
> > > Up until this point I haven't cared all that much about fiber, as most
> > > of my observations were that it had "reasonable" buffering and all I
> > > could hold in my head was the 802.11 standards. Since cablemodems are
> > > well on their way to being fixed, wifi is looking good, and I recently
> > > came across an ONT that was actually underbuffered, my holiday reading
> > > consisted of pounding through a ton of fiber specs like this one:
> > >
> > >
> https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-G.988-201711-I!!PDF-E&type=items
> > >
> > > There's a lot of promising info in this spec starting from page 104.
> > >
> > > My 1st question is - are there any ONTs that actually do do pause
> > > frames? Or providers that configure for them?
> > >
> > > My second is - what is a cheap way to setup a lab to emulate a good,
> > > common, version of gpon e2e?
> > >
> > > Third - what OS do these things run? Who makes a "good" one?
> > >
> > _______________________________________________
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>
>
>
> --
> I tried to build a better future, a few times:
> https://wayforward.archive.org/?site=https%3A%2F%2Fwww.icei.org
>
> Dave Täht CEO, TekLibre, LLC
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