[Cake] Advantages to tightly tuning latency

[Thibaut]

> Le 22 avr. 2020 à 00:44, Dave Taht <dave.taht at gmail.com> a écrit :
> 
> On Tue, Apr 21, 2020 at 3:33 PM Jonathan Morton <chromatix99 at gmail.com> wrote:
>> 
>>> On 22 Apr, 2020, at 1:25 am, Thibaut <hacks at slashdirt.org> wrote:
>>> 
>>> My curiosity is piqued. Can you elaborate on this? What does free.fr do?
>> 
>> They're a large French ISP.  They made their own CPE devices, and debloated both them and their network quite a while ago.  In that sense, at least, they're a model for others to follow - but few have.
>> 
>> - Jonathan Morton
> 
> they are one of the few ISPs that insisted on getting full source code
> to their DSL stack, and retained the chops to be able to modify it. I
> really admire their revolution v6 product. First introduced in 2010,
> it's been continuously updated, did ipv6 at the outset, got fq_codel
> when it first came out, and they update the kernel regularly. All
> kinds of great features on it, and ecn is enabled by default for those
> also (things like samba). over 3 million boxes now I hear....
> 
> with <1ms of delay in the dsl driver, they don't need to shape, they
> just run at line rate using three tiers of DRR that look a lot like
> cake. They shared their config with me, and before I lost heart for
> future internet drafts, I'd stuck it here:
> 
> https://github.com/dtaht/bufferbloat-rfcs/blob/master/home_gateway_queue_management/middle.mkd <https://github.com/dtaht/bufferbloat-rfcs/blob/master/home_gateway_queue_management/middle.mkd>

Very interesting, thanks. I wonder if they trickled down these improvements to the older V5: I had to plug my old V5 back after my DSLAM was moved to native IPV6 (I couldn’t find how to talk to it over VDSL2 modem, as I did before the switch), and though there was a massive drop in uplink bandwidth (from 10Mbps VDSL2 to 1Mbps ADSL), I noticed that I no longer needed cake on the router wan interface. Latency remained very well controlled without having to do anything special. In fact, enabling cake with the previous settings was wrecking havoc! (Maybe it interfered with whatever Free is doing in the box).

> Occasionally they share some data with me. Sometimes I wish I lived in
> paris just so I could have good internet! (their fiber offering is
> reasonably buffered (not fq_codeled) and the wifi... maybe I can get
> them to talk about what they did)

You don’t have to live in Paris to enjoy good internet: I’m currently stranded in the countryside and I enjoy a better connection than many a Parisian, thanks to a public/private FTTH network that appears to be very well handled by my current ISP (K-Net) :)

> When free.fr shipped fq_codel 2 months after we finalized it, I
> figured the rest of the world was only months behind. How hard is it
> to add 50 lines of BQL oriented code to a DSL firmware?

Heh.

Cheers,
Thibaut
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