On Mon, Nov 26, 2012 at 3:32 AM, Dave Taht <dave.taht@gmail.com> wrote:
there are not presently a lot of cerowrt-users members, so I'm cc-ing
cerowrt-devel.

On Mon, Nov 26, 2012 at 12:20 AM, Marc MERLIN <marc@merlins.org> wrote:
> I'm setting up QOS as explained in the FAQ
> http://www.bufferbloat.net/projects/cerowrt/wiki/FAQ
 

>
> Not surprisingly
> speednest.net
 
gives me 33Mbit/7.65Mbit while dslreports.com/speedtest
 
gives
> me a meager 16.2Mbit/2.5Mbit (for a line that's supposed to be 22Mbit/5Mbit).

Yes, you get a boost for about 10 seconds.

> I understand the queuing and that if I put too high a number, I'll fill
> queues and end up with bad latency.

yep.

>
> At the same time, am I correct that if I put numbers that are lower than
> what I can really get when the line doesn't suck, I'll cap myself to those
> numbers (here 16.2Mbit instead of 22Mbit or so)?


yep.

>
> Is it also possible for linux/cerowrt to dynmically detect the queuing/delay
> in my cable modem and dynamically adjust the QOS values to limit buffering
> on the comcast side without throttling me down to lower than what the line
> can do at any given time?

Nope. The right answer is to not have to rate shape in the router, but
to move the fq_codel algorithm into the cable modem, OR to have the
cable modem exert flow control like ADSL modems do. Then have the
smarter device (the router) then do smarter queuing.

There are other dynamic bandwidth effects on a cable network that
result in more widely varying backend bandwidth.

Yes, and under conditions of overall network congestion, if you are using your link at a high fraction (> 80% or so, IIRC), they may also take some action after an extended period (something like 10-15 minutes), as part of their protocol neutral congestion management system.

There are also physical effects (temperature) that can cause some bandwidth variation.
 

A little birdie tells me that the cable modem guys are on this...
speedboost is a good idea but the only way to not lose it is to move
the smarts around.

Yup.  It's a good feature and it's sad to have to defeat it (unless someone does a Powerboost emulator). 

That said, it does seem possible to develop a speedboost emulator on
the router that would give you most of the benefit.

The details of at least Comcast's "Powerboost" may be documented in the RFC published describing their provisioning.   I don't have the RFC handy.  I think the algorithm they use is described there, even if the exact parameters for a particular provisioning tier is not...


>
> I'm also a bit concerned of what happens when comcasts ups my bandwidth
> without telling me (they do that sometimes) and me never finding out if I
> have a static QOS value in cerowrt.

They certainly tell you in the advertising spam that we all delete ;-(.
                         - Jim
 
>
> Can others advise?
>
> Thanks,
> Marc
> --
> "A mouse is a device used to point at the xterm you want to type in" - A.S.R.
> Microsoft is to operating systems ....
>                                       .... what McDonalds is to gourmet cooking
> Home page: http://marc.merlins.org/
 

> _______________________________________________
> Cerowrt-users mailing list
> Cerowrt-users@lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/cerowrt-users
 




--
Dave Täht

Fixing bufferbloat with cerowrt: http://www.teklibre.com/cerowrt/subscribe.html
 

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