[Rpm] lightweight active sensing of bandwidth and buffering

[Dave Taht]

For about 2 years now the cake w-adaptive bandwidth project has been
exploring techniques to lightweightedly sense  bandwidth and buffering
problems. One of my favorites was their discovery that ICMP type 13
got them working OWD from millions of ipv4 devices!

They've also explored leveraging ntp and multiple other methods, and
have scripts available that do a good job of compensating for 5g and
starlink's misbehaviors.

They've also pioneered a whole bunch of new graphing techniques, which
I do wish were used more than single number summaries especially in
analyzing the behaviors of new metrics like rpm, samknows, ookla, and
RFC9097 - to see what is being missed.

There are thousands of posts about this research topic, a new post on
OWD just went by here.

https://forum.openwrt.org/t/cake-w-adaptive-bandwidth/135379/793

and of course, I love flent's enormous graphing toolset for simulating
and analyzing complex network behaviors.