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

[Jim Gettys <jg@freedesktop.org>]

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On Mon, Nov 26, 2012 at 9:22 AM, Michael Richardson <mcr@sandelman.ca>wrote:

>
> >>>>> "Dave" == Dave Taht <dave.taht@gmail.com> writes:
>     Dave> to move the fq_codel algorithm into the cable modem, OR to have
> the
>     Dave> cable modem exert flow control like ADSL modems do. Then have the
>     Dave> smarter device (the router) then do smarter queuing.
>
> I was unaware that DSL models were doing this... is this with GbE
> ethernet level XON/XOFF?   Should I assume that any DSL model with less
> than a GbE sync doesn't/can't have it?  Any brands you'd like to
> acknowledge?
>

We don't know that all DSL modems do this.

However, in corresponding with Michael Tremer about his results (documented
here
http://planet.ipfire.org/post/ipfire-2-13-tech-preview-fighting-bufferbloat),
it appears that a DSL modem commonly used in Germany does implement
Ethernet flow control (or he could not have gotten the results he reports
there at all; all he did was turn on fq_codel on the x86 geode router he is
using for IPfire).  Whether this is "standard" in DSL modems, I have no
clue (anyone want to plow through DSL standards documents?).


I've been unable to find a supplier in the U.S. for this particular DSL
modem.  Short of bidding on ebay in Europe, I was defeated (despite there
being 10's of millions of them in Germany); this isn't too surprising, as
the modem is supplied by the carrier in this case.

Note that I'm testing a DGN3500 this week with John Crispin (blogic) which
has an integrated Lantiq DSL chip (along with Atheros radios) running
fq_codel that John maintains.  That may be a better option for DSL, as it
can be purchased easily via Amazon.  Wish us luck (though John's early data
looks really nice).
                              - Jim


> --
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>  firewalls  [
> ]   Michael Richardson, Sandelman Software Works, Ottawa, ON    |net
> architect[
> ] mcr@sandelman.ottawa.on.ca http://www.sandelman.ottawa.on.ca/
>
> |device driver[
>    Kyoto Plus: watch the video <http://www.youtube.com/watch?v=kzx1ycLXQSE
>
> >
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