[e2e] Estimating MS windows RTO equation

[francesco@net.infocom.uniroma1.it]

Quoting Detlef Bosau <detlef.bosau at web.de>:

> Marco Mellia wrote:
> > 
> > We are working on the same topic, identifying packet anomalies (e.g.
> > retransmissions) in a TCP flow from passive measurement.
> > If you are interested, here are the links on the papers that we'll be
> > presented in June at ICC
> 
> 
> It would be interesting to see whether you will create a trace "what are
> spurious timeouts" in GPRS ;-) *SCNR*
> 
> To be serious: It would not be interesting to understand, what an SRTO
> really _is_, but it would be helpful to see, whether those practically
> occur.
> If you look at the technical report "TCP Spurious Timeout estimation in
> an operational GPRS/UMTS network" by 
> Francesco Vacirca, Thomas Ziegler and Eduard Hasenleithner, the authors
> do passive measurements of the particular anomalie "spurious timeout"
> and end up in the observation that these do hardly occur in reality. If
> this is correct, particularly the importance of SRTO
> has been drastically overestimated during the past few years.
> 

Our results cannot be considered as general but refer to the monitored UMTS/GPRS
network. It would be interesting to see other results from different
networks...

The details about the algorithm for the SRTO estimation and the results for the
monitored network can be found here:
http://userver.ftw.at/~ziegler/FTW-TR-2005-008.pdf

whereas the patch for tcptrace with the algorithm can be downloaded from:
http://userver.ftw.at/~vacirca/

Francesco


> So, what I think would be particularly interesting in a work like yours
> is that we are able to discrimate important problems from
> non important / neglectible ones.
> 
> It´s perhaps not that important to have an "OS identifying mechanism".
> IIRC there are quite a few papers around on this matter
> and to my understanding, this is more some kind of (necessary! and
> sophisticated!) debugging than "pure science".
> 
> However, it is very important to find out whether e.g. SRTO are reality
> or not. Spoken more drastically: If someone rides
> the SRTO horse once again, does he ride a dead horse?
> 
> This question is somewhat off topic for this thread, however I´m very
> interested in this topic. BTW: My personal expectation
> is that SRTO _ARE_ a dead horse.
> 
> Detlef
> 
> -- 
> Detlef Bosau
> Galileistrasse 30
> 70565 Stuttgart
> Mail: detlef.bosau at web.de
> Web: http://www.detlef-bosau.de
> Mobile: +49 172 681 9937
> 




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