[Cerowrt-devel] comcast provisioned rates?

Dave Taht dave.taht at gmail.com
Sat Apr 19 14:40:37 EDT 2014

On Sat, Apr 19, 2014 at 11:16 AM,  <dpreed at reed.com> wrote:
> Very good.   So the idea, rather than Comcast implementing codel or
> something proper in the DOCSIS 3.0 systems they have in the field, is to
> emulate power boost to "impedance match" the add-on router-based codel
> approach to some kind of knowledge of what the DOCSIS CMTS buffering state
> looks like....


is mandated in DOCSIS 3.1 modems.

The ECO has gone out for DOCSIS 3.0 as well.

Pie is tightly intertwined with the powerboost capable scheduler.

The powerboost feature is viewed

> And of course nothing can be done about "downstream" bufferbloat in the
> Comcast DOCSIS deployment.

I have seen promising noises from Arris at least, on the CMTS side, and
had posted some of their thinking from the last meeting of the society
of cable engineers on one of our mailing lists fairly recently, which
induced no comment.


They had come up with a variant of red, called "LRED", and a nifty enhancement
to SFQ, but hadn't got as far as grokking that queue length and packet
together were a better answer.

I would certainly like the overall level of overbuffering in CMTSes to be
reduced which is something the cable providers could do today, and that
certainly bugs me.

> So instead of fixing Comcast's stuff "correctly", we end up with a literal
> "half measure".

The cable ISP industry as a whole is slave to their equipment makers.
cablelabs only has dominion over the cable modem side.

What the world needs is better long distance media types not designed
by former telecoms, and designed for packet data.

If you thought cable was complex and had bad ideas
in it, see gpon, also. Or moca, or various powerline standards.

What my hope has been has been that the increasingly common
hybrid cable modem/wireless gateways would gain fq_codel support and manage
both the up and downstreams themselves, thus bypassing the
slow to update million dollar head end portion of the industry

I'd like something as powerful and as loved as the revolution V6 box
to appear.

I'm not holding my breath.

Apple could do it right.

> Who does Comcast buy its CMTS gear from, and if it has a Heartbleed bug,
> maybe some benevolent hacker should just fix it for them?

There are only 3 makers of CMTS gear - cisco, arris, and a third company
from china whose name I forget.

> It's now been 2 years since Comcast said they were deploying a fix.  Was
> that just them hoping the critics would dissipate their time and effort?

Competition is needed. I'm rooting for gfiber to provide some.

> And is Comcast still using its Sandvine DPI gear?

No idea. I certainly see an aweful lot of packets remarked CS1.

> I'm afraid that monopolists really don't care.  Even friendly-sounding ones.
> Especially when they can use their technical non-deployments to get paid
> more by Netflix.

Well, grump, I am fair minded. Netflix's business model has always been
to colocate their servers within the ISP itself with things like the


It makes a rediculous amount of sense to do so, and is a cost savings
to both ISP and netflix on external bandwidth, but somebody still has to
cover the rack space, hardware, and electricity no matter where located.

> On Saturday, April 19, 2014 1:57pm, "Dave Taht" <dave.taht at gmail.com> said:
>> The features of the PowerBoost feature are well documented at this
>> point. A proper
>> emulation of them is in the ns2 code. It has been a persistent feature
>> request, to
>> add support to some Linux rate shaper to properly emulate PowerBoost,
>> but no funding
>> ever arrived.
>> Basically you get 10 extra megabytes above the base rate at whatever
>> rate the line
>> can sustain before it settles back to the base rate.
>> You can also see that as presently implemented, at least on a short
>> RTT path, the feature
>> does not prevent bufferbloat.
>> http://snapon.lab.bufferbloat.net/~cero2/jimreisert/results.html
>> I'd like a faster, less cpu intense rate shaper than sch_htb in
>> general, and powerboost emulation would be nice.
>> On Sat, Apr 19, 2014 at 9:38 AM, Aaron Wood <woody77 at gmail.com> wrote:
>> > Based on these results:
>> >
>> > http://snapon.lab.bufferbloat.net/~cero2/jimreisert/results.html
>> >
>> > And talking off-list with Jim, I think that the "PowerBoost" is above
>> > the
>> > quoted rate, as the 24/4 service hits >36Mbps TCP data rate. I'm
>> definitely
>> > sad that using SQM in the router instead of the modem loses features
>> > like
>> > that. But I'll just be happy to have upload over 1Mbps again.
>> >
>> > I do know that the FCC was cracking down on advertised vs. actual rates,
>> > and
>> > started a "measuring broadband in America" project:
>> >
>> > http://www.fcc.gov/measuring-broadband-america
>> >
>> > -Aaron
>> >
>> >
>> > On Sat, Apr 19, 2014 at 6:21 PM, <dpreed at reed.com> wrote:
>> >>
>> >> As a non-Comcast-customer, I am curious too. I had thought their
>> "boost"
>> >> feature allowed temporary rates *larger* than the quoted "up to" rates.
>> >> (but I remember the old TV-diagonal games and disk capacity games,
>> >> where
>> any
>> >> way to get a larger number was used in the advertising, since the FTC
>> didn't
>> >> have a definition that could be applied).
>> >>
>> >>
>> >>
>> >> I wonder if some enterprising lawyer might bring the necessary consumer
>> >> fraud class-action before the FTC to get clear definitions of the
>> numbers?
>> >> It's probably too much to ask for Comcast to go on the record with a
>> precise
>> >> definition.
>> >>
>> >>
>> >>
>> >>
>> >>
>> >> On Saturday, April 19, 2014 8:55am, "Aaron Wood"
>> <woody77 at gmail.com> said:
>> >>
>> >> I'm setting up new service in the US, and I'm currently assuming that
>> all
>> >> of Comcast's rates are "boosted" rates, not the "provisioned" rates.
>> >> So if they quote 50/10Mbps, I assume that's not what will need to be
>> >> set
>> >> in SQM with CeroWRT.
>> >> Does anyone have good info on the "provisioned" rates that go with each
>> of
>> >> the Comcast tiers?
>> >> Basically, I'm trying to get to an apples-to-apples comparison with
>> >> Sonic.net DSL (I'll be close enough to the CO to run in Annex M "upload
>> >> priority" mode and get ~18/2 service).
>> >> Thanks,
>> >> Aaron
>> >
>> >
>> >
>> > _______________________________________________
>> > Cerowrt-devel mailing list
>> > Cerowrt-devel at lists.bufferbloat.net
>> > https://lists.bufferbloat.net/listinfo/cerowrt-devel
>> >
>> --
>> Dave Täht
>> NSFW:
>> https://w2.eff.org/Censorship/Internet_censorship_bills/russell_0296_indecent.article

Dave Täht

NSFW: https://w2.eff.org/Censorship/Internet_censorship_bills/russell_0296_indecent.article

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