[Cake] Trouble with CAKE

Thibaut hacks at slashdirt.org
Fri Dec 13 09:21:58 EST 2019

Hi Sebastian,

December 13, 2019 3:15 PM, "Sebastian Moeller" <moeller0 at gmx.de> wrote:

> Hi Thibaut,
> so ADSL is both special and precious, may I recommend to follow the instructions on
> https://github.com/moeller0/ATM_overhead_detector? 

I will give it a try.

> This will either confirm the overhead settings,
> or more likely "explode" if the freeebox truely tunnels all IPv4 data through IPv6.

It does, this is a confirmed fact (and in fact trying to connect with my VDSL modem the DSLAM only speaks IPv6: I could tcpdump encapsulated frames from the BR containing IPv4 data that were destined to other subscribers - an unpleasant side effect of map-t "shared IPv4": by default free splits every IPv4 between 4 subscriber (by splitting the port range). You have to actively ask for a "full stack IP" to turn that off).

> In both cases
> the results should be interesting. As a quick test, what is the textual output from the "Share Your
> Results" box on https://www.speedguide.net/analyzer.php?

I'll report when the buildslave is done uploading :)

> I would not be amazed if the issue might be related to having a whoping 40 bytes more of
> unaccounted for per-packet-overhead (in combination with ATM/AAL5's lovely per packet padding). But
> that might all be moot if it is/was caused by a kernel issue.



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