[Bloat] ADSL, ATM drivers, bloat, education & confusion

Sebastian Moeller moeller0 at gmx.de
Sat Jun 6 11:04:48 EDT 2015


Hi Jonathan, hi Kevin, hi list,

On June 6, 2015 3:53:43 PM GMT+02:00, Jonathan Morton <chromatix99 at gmail.com> wrote:
>Ideally, one would read the raw sync rate out of the modem (there has
>to be
>a way to do that, since it is able to report it in the web interface),
>and
>use that to set cake's bandwidth parameter.

        Unfortunately ISPs more and more implement a throttle/policed? at the BRAS level which in essence supersedes the link rate, but does not seem to be universally reported. If ISPs would actually use this in a way that keeps utilization high but latency increase low all would be dandy, just alas they might be trying but at least not all of them succeed. So people should start out at the modems link rates but should be prepared to reduce the shaped rates until latency under load seems bounded to acceptable levels...

Best Regards
        Sebastian 

 You could update it
>periodically using "tc qdisc change ...".
>
>You will need to set the overhead calculation correctly, probably using
>"pppoa-vcmux" or similar, depending on precisely what encapsulation
>your
>ISP uses. If you're not confident about that, specify "conservative" to
>begin with. Once you have that, you can experiment to see how much you
>need
>to reduce the raw sync rate to achieve full bottleneck control -
>hopefully
>not much, at most 1%.
>
>The same approach would also work for inbound if necessary, except that
>you
>would need to reduce the raw sync rate rather more.
>
>- Jonathan Morton
>
>
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