[Bloat] ONTs and ITU - T G.988

[Bloat] ONTs and ITU - T G.988

[Dave Taht]

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?

-- 
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

Re: [Bloat] ONTs and ITU - T G.988

[Marco Belmonte]

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?
>

Re: [Bloat] ONTs and ITU - T G.988

[Dave Taht]

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@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?
> >
> _______________________________________________
> Bloat mailing list
> Bloat@lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/bloat



-- 
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

Re: [Bloat] ONTs and ITU - T G.988

[Aaron Wood]

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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@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@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?
> > >
> > _______________________________________________
> > Bloat mailing list
> > Bloat@lists.bufferbloat.net
> > https://lists.bufferbloat.net/listinfo/bloat
>
>
>
> --
> 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
> _______________________________________________
> Bloat mailing list
> Bloat@lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/bloat
>

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Re: [Bloat] ONTs and ITU - T G.988

[Marco Belmonte]

Well, I for one will be most interesting in watching your progress and 
am available if you need samples (500 Mb Fiber - Frontier FIOS).

Marco

On 1/12/2022 4:57 PM, Dave Taht 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@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?
>>>
>> _______________________________________________
>> Bloat mailing list
>> Bloat@lists.bufferbloat.net
>> https://lists.bufferbloat.net/listinfo/bloat
>
>

Re: [Bloat] ONTs and ITU - T G.988

[Jan Ceuleers]

On 13/01/2022 00:42, Dave Taht wrote:
> My 1st question is - are there any ONTs that actually do do pause
> frames? Or providers that configure for them?

In my (limited) experience most network operators want ONTs to be
transparent to pause frames.

> My second is - what is a cheap way to setup a lab to emulate a good,
> common, version of gpon e2e?

I'm not aware of a cheap way. You need an OLT and a few ONTs.

> Third - what OS do these things run? Who makes a "good" one?

Linux. But forwarding is offloaded so not dealt with by the Linux
networking stack.

Re: [Bloat] ONTs and ITU - T G.988

[Dave Taht]

On Thu, Jan 13, 2022 at 7:28 AM Jan Ceuleers <jan.ceuleers@gmail.com> wrote:
>
> On 13/01/2022 00:42, Dave Taht wrote:
> > My 1st question is - are there any ONTs that actually do do pause
> > frames? Or providers that configure for them?
>
> In my (limited) experience most network operators want ONTs to be
> transparent to pause frames.

so the pause frames originate at the ISP not at the ONT?

>
> > My second is - what is a cheap way to setup a lab to emulate a good,
> > common, version of gpon e2e?
>
> I'm not aware of a cheap way. You need an OLT and a few ONTs.
>
> > Third - what OS do these things run? Who makes a "good" one?
>
> Linux. But forwarding is offloaded so not dealt with by the Linux
> networking stack.

I kind of moved this thread over to cerowrt-devel where I've found a
SFP and ONU running linux,
among other things.
>
> _______________________________________________
> Bloat mailing list
> Bloat@lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/bloat



-- 
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