Having suffered with poor upstream latency under load (aka 'bufferbloat') for years, as have VM's other customers, I was interested to read a paper[1] today by Flickinger et al.
The paper refers to a newer upstream active queue management, Proportional Integral Controller Enhanced - known colloquially as DOCSIS-PIE. More specifically, the paper discusses the impact of implementing DOCSIS-PIE on a (Comcast) DOCSIS network during the COVID-19 pandemic, when everyone started working and schooling from home, thus adding unprecedented latency and load to networks.
A rollout by Comcast with two modems, one with AQM/PIE enabled and one without, showed a difference in upstream latency under load to the order of 15ms (with PIE) vs 250ms (without PIE). A rather staggering difference! I certainly don't see behaviour as good as that on VM, hence the thread/question.
More importantly, the paper goes on to cite that:
In 2014, CableLabs included PIE as the official AQM in the DOCSIS 3.1 specifications as a mandatory feature for the CMTS and cable modems (PIE was also added as an optional feature for earlier generation DOCSIS 3.0 cable modems). At the same time, CableLabs required that DOCSIS 3.1 CMTS equipment support AQM as well but left the algorithm choice to the vendor.
Given it's mandatory in the standard/specification, I'm assuming this is something that VM has enabled for the downstream DOCSIS 3.1 channel on Gig1? What of the other DOCSIS 3 channels, which are optional?
(Edit: I'm asking about the CMTS and the CPE here.)
There's scant information out there on the VM network core, and this is the only place I know of to ask such a question despite the fact the forum is clearly not geared to this type of discussion (regrettably).
I'd be interested to hear a definitive reply back from someone at VM, and I do understand that the forum team will likely need to bounce this over to someone at networks for comment.
It'd be nice to finally have a connection that doesn't collapse into a crippled mess of high latency because someone's phone is backing up to iCloud, when I'm trying to (for example) make a video call or waiting for elements to render on a website. As it is, currently I'm just implementing fq_codel on my OpenBSD router (and running cake+bbr on my *nix boxes). But what of VM's end?
[1] Improving Latency with Active Queue Management (AQM) During COVID-19
By Allen Flickinger, Carl Klatsky, Atahualpa Ledesma, Jason Livingood, Sebnem Ozer
https://arxiv.org/ftp/arxiv/papers/2107/2107.13968.pdf
