[Cake] inbound cake or fq_codel shaping fails on cable on netflix reno

[Dave Taht]

hmmm... And wow, does this modem have difficulty with udp

Summary of ping test run 'hping3-cake-docsis' (at 2018-07-21 22:22:14.758201):

                           avg       median     # data pts
 Ping (ms) ICMP :        26.50        23.20 ms        2395
 Ping (ms) UDP  :         1.02        44.21 ms          47 # That's
like a bazillion percent packet loss and explains why irtt is having
such difficulty.

Thank you very much for clues as to what's being going south in my
lab. I had no idea this problem at this low layer was so common:

http://badmodems.com/Forum/app.php/badmodems

On Sat, Jul 21, 2018 at 3:13 PM Dave Taht <dave.taht at gmail.com> wrote:
>
> wow. That is the best dslreports test result for cable I have ever had.
>
> with hping3 -2 -d 0 -s 10080 -k -p 80 -i u150 96.120.89.153
>
> http://www.dslreports.com/speedtest/36209937
>
> Without:
>
> http://www.dslreports.com/speedtest/36210095
>
> You say a different cablemodem does better without hping3 running? which? :)
>
> Most of my production gear is based on an older arris modem (which is
> quite good), most of my test gear is a bunch of netgear (free) modems
> and service I got free from my time working for comcast.
>
> I haven't got around to springing for a docsis 3.1 modem yet (they are
> awfully pricy).
> On Sat, Jul 21, 2018 at 2:37 PM Dave Taht <dave.taht at gmail.com> wrote:
> >
> > or, another way we might look at it is there is very little we can do
> > as the cmts has to have data in it in order to burst schedule the mac
> > for the next string of packets, much like how fq_codel for wifi has
> > "one in the hardware, one ready to go", a cmts has at least one in the
> > hardware (per channel? a multiple? what?).
> >
> > or I could be on drugs entirely. And this thread did start with
> > fast.com misbehaving badly regardless of the shaper in place or not,
> > which is not what I'm looking at now.  I need to setup a 45ms rtt
> > test...
> >
> > anyway, as per your suggestion, the latency gets MUCH better with your
> > hping3 idea running, which implies that we've  been fooled all along
> > by the rrul test. On the other hand, I think this will hurt other
> > cable modems on the same wire. On the gripping hand, I'm happier
> > knowing that with a busier network, docsis cable, when shaped, gets
> > better, and that I should junk my existing test cablemodem due to the
> > persistent spikes I see.
> >
> > I wonder if it's the sent path or the return path shattering latency
> > so well? I wonder if hping3 would count against your badwidth cap?
> >
> > going back to trying to figure out why fast.com is so gnarly
> > On Sat, Jul 21, 2018 at 2:18 PM Arie <nospam at ariekanarie.nl> wrote:
> > >
> > > I had a similar issue with my previous cable modem, whatever I shaped to didn't matter, I still had long delays. I "fixed" it by continuously sending a stream of empty UDP packets upstream:
> > >
> > > hping3 -2 -d 0 -s 10080 -k -p 80 -i u150 IP-OF-FIRST-OUTSIDE-CABLE-HOP-HERE
> > >
> > > On 21 July 2018 at 22:36, Dave Taht <dave.taht at gmail.com> wrote:
> > >>
> > >> This is my "inbound trying to shape a cable connection" smoking gun.
> > >> The delay curve is the same
> > >> shaping the 110mbit cmts down to 85mbit OR 55mbit.
> > >>
> > >> _______________________________________________
> > >> Cake mailing list
> > >> Cake at lists.bufferbloat.net
> > >> https://lists.bufferbloat.net/listinfo/cake
> > >>
> > >
> >
> >
> > --
> >
> > Dave Täht
> > CEO, TekLibre, LLC
> > http://www.teklibre.com
> > Tel: 1-669-226-2619
>
>
>
> --
>
> Dave Täht
> CEO, TekLibre, LLC
> http://www.teklibre.com
> Tel: 1-669-226-2619



-- 

Dave Täht
CEO, TekLibre, LLC
http://www.teklibre.com
Tel: 1-669-226-2619