[e2e] Are we doing sliding window in the Internet?

Craig Partridge craig at aland.bbn.com
Mon Jan 7 08:19:38 PST 2008

Hi Dave:

I think you're understating the TCP innovation/intuition in important
ways.  The starting point of the TCP innovations was to view a TCP
connection as a control loop and to ask what the correct behavior of
the control loop was under certain impulses.  As you observe, this
approach rapidly led to the conclusion that for the impulse of
loss due to congestion, the answer was "send less" rather than "send more."

In that light, when someone shows up and says "hey, I've got a TCP innovation"
in the absence of understanding they are dealing with a control loop, there's
justified skepticism.

At the same time, I agree with you that in the current world (where we have
little understanding of what is flowing over our networks), we have only a
primitive guess about what new kinds of impulses our TCP control loops are
experiencing and what they should do.  This observation, of course,
applies to lots of other network traffic too (much of which also can be
modeled as some kind of control theory structure).



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