Subject: Re: [ippm] thoughts on reordering draft (-08)

From: Michał Przybylski <[email-masked]>
Date: Tue, 01 Feb 2005 09:36:10 +0100

Hello Mark,

> I disagree with that phrasing (but, maybe not the intent).  If my
> application only sends one packet every 10 seconds then there is no way
> that a stress test can predict the "possible" reordering my application
> will observe.  I would buy that sending at line rate may provide an
> upper bound on the amount of reordering that *some* application could
> conceivably observe.  And, that might be useful.  But, I think trying to
> tie such a notion to any "particular application" is very thorny and
> quite tenuous. 

I agree with you. Definitely you will not observe reordering at 0,1pps ;-)

We have some experience with guys like CERN (ATLAS) and VLBI, they 
really send large data streams - we've got to conclusions (after some 
practical experiments) that it's good to know for example, what is the 
reordering of "line speed" streams, what is the "maximum non reordered 
single stream flow speed", etc.... They were just trying to develop the 
application, so that kind of information was really useful at the 
application development stage (decide how many simultaneous flows, flow 
speed, packet sizes etc).

Anyway, we can easily get to the conclusion that *line speed* testing is 
just an example of *line speed* application.

So we shall specify that *line speed testing* is intended for obtaining 
network characteristics for particular user only (user line speed may 
differ from network line speed), while *testing using application trace* 
is the way to assess the probable reordering for the particular application.

All the best,

Michal

> 
> allman
> 
> 
> --
> Mark Allman -- ICIR -- http://www.icir.org/mallman/
> 
> 
> 

-- 
______________________________________________________________________
Michal Przybylski         Network Research and Development
[email-masked]     Poznan Supercomputing and Networking Center
+48 61 858 20 27          http://www.man.poznan.pl
______________________________________________________________________

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