This week we covered congestion control (with a brief mention of latest ideas of CUBIC and BBR) and scheduling (work conserving, max min fairness, and round robin with various tweaks, as well as queue management, with another appearance of "randomness" as a useful trick).
My analogy for the overall system that is TCP + IP is that it is like a bicycle, with a chain connecting two sets of gears - you can change gear at each end to change rate/speed, but the wheels slip (forwarding) and the chain is made of soggy bread (end to end rate).
IP forwarding+scheduling is like the bit where the rubber hits the road, and the foot on the pedal is like the sender, while the force backwards from friction, skidding and effort is the flow & congestion control.
Now loosely couple the chains of 10 billion bikes and riders and roads, and run them anything from 1 to a billion RPM...
and make the road surface out of jelly. and take a chain link out, or put on in every now and then (re-routing)...
and many of the bikes are penny farthings but some are jetskis (i.e. not everyone is running the same algorithm, either at IP level or end-to-end/TCP level).
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