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

Detlef Bosau detlef.bosau at web.de
Thu Jul 3 14:01:08 PDT 2008

guol at cs.bu.edu wrote:
>> Good rant.
>> And I coudln't agree more.
>> Only one problem remains.... And that's a very honest question:
>> If we agree upon some facts:
>> - Poisson processes and Markov prossesses are of little use in
>> networking research,
> I don't think this has been agreed upon. 

Change the words to: "If we agreed upon...."

However, I think the meaning of my comment can be understood.

> I believe the concensus is that
> Markovian model under-estimates variability existing in the current
> Internet/human behavior. But these processes are definitely very valuable
> in that they give ways to estimate, at least qualitatively, the effect of
> variability to networking systems.

I don't have the precise definition of a Markov-process in mind.

However: When you consider the complete definition and carefully study 
each detail, you may understand my doubts about this model.
The parts of the definition are indeed quite strong.

"Being markovian" is nothing what happens by chance.

>> - Analysis is not really helpful (and frankly spoken, I hardly believe
>> those analytical TCP models, which are around),
> Again I think they are very helpful to get insights

The most obvious flaw, I've seen in all analytical models I've seen so 
far is that I do not see, how packet loss and missing ACKs are modeled.

In addition, often you'll find infinite queues.

My point was that there is no simple, obviously correct "single" way to 
go, when we want to understand networks.

Detlef Bosau                          Mail:  detlef.bosau at web.de
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