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

Lachlan Andrew lachlan.andrew at gmail.com
Tue Jul 1 11:35:44 PDT 2008

Greetings Detlef,

2008/7/1 Detlef Bosau <detlef.bosau at web.de>:
>> That raises the question: should we model access links or edge links,
>> or have separate models of each?
> We should read the chapter "introduction" which can be found in an
> arbitratry textbook on stochastic processes :-)
> Tyically, there are two statements.
> 1.: Markov processes and Poisson processes are nice, because they are easy
> do deal with.
> 2.: Nature and reality are naughty, because both are neither markovian nor
> poissonian.

Nature certainly isn't Markovian, but we're surrounded by laws of large numbers.

I certainly agree that we shouldn't build networks on beautiful theory
just because it is beautiful.  However, when the Poisson issue comes
up, I'm always reminded of the measurement study "Cluster Processes, a
Natural Language for Network Traffic" by Hohn, Veitch and Abry
which supports the model of Poisson flow arrivals.  These measurements
were for a lightly loaded link, but I haven't seen any contradictory
evidence on a heavily loaded (and highly multiplexed) link.  As
always, I'd be grateful for references to some.


Lachlan Andrew Dept of Computer Science, Caltech
1200 E California Blvd, Mail Code 256-80, Pasadena CA 91125, USA
Ph: +1 (626) 395-8820 Fax: +1 (626) 568-3603

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