Re: [Starlink] FQ_Codel

[Stuart Cheshire <cheshire@apple.com>]

On 8 Jun 2022, at 12:12, warren ponder <wponder11@gmail.com> wrote:

> So this is really helpful. Is it fair to say then that end users with SQM and fq_codel on a Starlink connection should essentially not turn on SQM.and.just leave it off?

My advice is that people should have SQM (e.g., fq_codel) enabled anywhere it is available. For devices that aren’t the bottleneck hop on a path it won’t make any difference, but it won’t hurt. And if the network topology is such that it does become the bottleneck hop, even briefly, SQM will avoid having a big queue build up there.

One example is Wi-Fi. If you have 50Mb/s Internet service and 802.11ac Wi-Fi in the house, your Wi-Fi is unlikely to be the bottleneck. But if you walk out to the garden and the Wi-Fi rate drops to 40Mb/s, then suddenly bufferbloat in the AP can bite you, leading to bi-modal network usability, that abruptly falls off a cliff the moment your Wi-Fi rate drops below your Internet service rate. I think this is a large part of the reason behind the enthusiasm these days for “mesh” Wi-Fi systems -- you need to blanket your home with sufficient density of Wi-Fi access points to ensure that they never become the bottleneck hop and expose their incompetent queue management. If you get 11Mb/s in the garden that should be plenty to stream music, but throw in some egregious bufferbloat and a perfectly good 11Mb/s rate becomes unusably bad. Ironically, if you pay more for faster Internet service then the problem gets worse, not better, because the effective usable range of your bufferbloated Wi-Fi access points shrinks as the rate coming into the house goes up.

Stuart Cheshire