[e2e] Why do we need TCP flow control (rwnd)?

David P. Reed dpreed at reed.com
Tue Jul 1 09:03:42 PDT 2008

Fred Baker wrote:
> We have not just predicted congestive collapse, we have experienced 
> it. Those events, the most well-known one being the collapse of the 56 
> KBPS NSFNet in 1987-1988 and the more recent instances being local 
> phenomena with under-provisioned networks, don't result from silly 
> assumptions. They originate from traffic from real applications with 
> real humans behind them on real networks.
I love real data.   From studying actual congestive collapses, one can 
figure out how to prevent them.   And this is exactly my point.   We 
need to understand what we understand, and explore what we don't yet 

Too often the "understanding we have" is based on the flimsiest of 
models, argued loudly by theorists whose only stake in the real is that 
they get paid per article published.  (this is not a slam on *all* 
theorists, just the ones who don't seek to validate their theories 
except by peer review by other theorists).

And often the "understanding we don't have" is disparaged by our 
community by declaring/defining it out of scope.   Thus, almost no one 
tries to understand app-level behavior because it's too hard to 
"standardize" the measurements.

Instead, we have the absurdity of publications by theorists of "optimal 
... algorithms" where the scope of the word "optimal" is limited to 
unnatural assumptions about unnatural acts.  But hey, it gets tenure.

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