Hi Jonathan,

Thanks for the quick reply.

December 13, 2019 3:02 PM, "Jonathan Morton" <[email protected]> wrote:

>> On 13 Dec, 2019, at 3:43 pm, Thibaut <[email protected]> wrote:
>> 
>> I've been using CAKE on my DSL-connected Linux router for the last few 
>> years, and it worked well
>> until very recently. Two things happened:
>> 
>> 1) My ISP (French "Free") switched my DSLAM to native IPv6, which for the 
>> time being means that I
>> had to revert to using their set-top-box (Freebox) instead of the VDSL2 
>> model I was using in bridge
>> mode until then (CAKE in "bridged-ptm ether-vlan" mode)
>> 2) I upgraded my router from 3.16 (Devuan Jessie) to 4.9 (Devuan ASCII)
>> 
>> Since then, no matter which setup I use, I cannot get CAKE to work as 
>> intended. Specifically, any
>> long-standing best effort stream (such as a remote rsync) will be throttled 
>> to a near grinding halt
>> even though there is no other significant traffic going on. Some random 
>> bursts can be seen (with
>> iftop) but nothing ever gets close to half the maximum bandwidth. This is 
>> notably affecting the
>> OpenWRT buildbots I'm hosting on this link.
> 
> Old kernels, including 4.9 series, tend to be more problematic than the 
> latest ones. If you can, I
> would recommend updating to a 5.x series kernel, in which Cake is an upstream 
> feature. I won't
> presume to guess how best to achieve that with your distro.

Indeed. Given this is a relatively "security-sensitive" setup, I'd rather not 
diverge from distro (or run "unstable" for that matter).
Still, CAKE was previously working Just Fine(TM) on an even older kernel: 
3.16...
 
> The good news is that Free.fr is among the relatively few ISPs who have 
> actively tackled
> bufferbloat themselves. As a workaround while you sort this out, you should 
> get reasonable
> performance just from using the Freebox directly.

Well, probably not with the antiquated Freebox model I have: a v5. I would also 
very much like to drop it to be able to connect again at VDSL2 speeds (I was 
getting 50/10 instead of the current 20/1) and save 75% on power usage (the 
Freebox is power hungry). But that's orthogonal to the current issue :)

What I could do for a test is temporarily revert back to the previous 
3.16/Jessie setup (I have kept a backup) and see if I can reproduce the same 
behavior there, in which case I think that would definitely point in the 
general direction of a bad interaction with the Freebox tunnel?

Best,
Thibaut
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