[Cerowrt-devel] [Cerowrt-users] QOS settings vs speedboost and random bandwidth

Dave Taht dave.taht at gmail.com
Mon Nov 26 03:32:34 EST 2012

there are not presently a lot of cerowrt-users members, so I'm cc-ing

On Mon, Nov 26, 2012 at 12:20 AM, Marc MERLIN <marc at 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.


> 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)?


> 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.

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.

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

> 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.
> 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/
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> Cerowrt-users at lists.bufferbloat.net
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Dave Täht

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

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