[e2e] a few questions on TCP mechanism

[Michael Welzl]

> >b. If the only source of feedback is the destination
> >point, how is it possible for me to:
> >1. adjust my window size in T < RTT
> 
> In general, you shouldn't.  As I understand control theory, if you adjust
> in times smaller than the RTT, your control loop is unstable.

Great that you bring this up: it's something that I never really
understood - how does this thinking translate to TCP, which
updates the rate with every ACK it gets (a lot more often than
once per RTT)? Is TCP actually interpolating?

Cheers,
Michael