[Bloat] Of interest: Comcast AQM Paper

[Neal Cardwell]

On Sat, Jul 31, 2021 at 3:27 PM Aaron Wood <woody77 at gmail.com> wrote:
>
> If we see that AQM appears to be not functioning as expected
>  for upstream connections on DOCSIS3.1, what's the right avenue
> for getting that resolved?  (and does that only apply to the
> Comcast-owned, vs. customer-owned, modems?)

FWIW, from the paper it sounds like not all Comcast cable modems
had/have PIE, which enabled the A/B experiment:

"10. Latency Measurement Results
As explained earlier, for two variants of XB6 cable modem gateway,
upstream DOCSIS-PIE AQM was enabled on the CGM4140COM (experiment)
variant but was not available on the TG3482G (control) variant during
the measurement period. The TG3482G variant used a buffer control
configuration that predated AQM in DOCSIS."

neal

>
> On Sat, Jul 31, 2021 at 10:50 AM Simon Barber <simon at superduper.net> wrote:
>>
>> Awesome to hear that you are turning this on both upstream and downstream. Do you know if the wifi stacks in your home routers also have AQM?
>>
>> Simon
>>
>>
>> > On Jul 30, 2021, at 10:28 PM, Livingood, Jason via Bloat <bloat at lists.bufferbloat.net> wrote:
>> >
>> > FYI that I will be presenting a lightning talk at the IRTF MAPRG meeting today at 17:30 ET (https://datatracker.ietf.org/meeting/111/materials/agenda-111-maprg). The talk links to a just-published paper at https://arxiv.org/abs/2107.13968 (click PDF link in upper right of page) that will likely be of interest to these two lists.
>> >
>> > High-level: turning on AQM in the cable modem (upstream queue) took working latency from around 250 ms to between 15-30 ms, which is actually kind of cool. ;-) AQM is turned on in all of our CMTSes (downstream queue) and in DOCSIS 3.1 modems (upstream queue).
>> >
>> > Have a nice weekend,
>> > Jason
>> >
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