[ns] Unofficial ns enhancement

[Martin Westhead <M.Westhead@epcc.ed.ac.uk>]

Folks,

A group of us at EPCC in Edinburgh  have recently completed a Cisco
funded project to try and enhance the scaling of ns. We chose to work on
simplifying to otcl-C++ interface in order to improve memory efficiency
and robustness. 

You can find the results of our efforts at:

http://www.epcc.ed.ac.uk/intersim/ns

our benchmarks demonstrate we were able to successfully reduce the
memory requirements for large simulations by over 50% on small
simulations and this figure improved as the simulation size increased.
At the same time we also brought down the initialisation time. Overall
we believe the code is also more robust. 

This ns version will run unmodified ns-2 Tcl scripts but does not
support all the functionality of the full ns release. We were only able
to include basic components (Nodes, Links, TCP, HTTP, FTP, TCP/IP
packets). The process of moving models over is semi-automatic and you
should find a perl script and documentation on how to do it in the
release.

I believe the ns team is looking at the question of incorporating these
changes into the main release. It is not clear whether this will happen
or not and there is a significant amount of work involved in moving over
all the existing models. 

Our code is distributed under the same terms as the main ns release, so
you are free to pick it up and use it as you like providing copyright
notices are maintained. We would be interested in feedback on the tool
but unfortunately have no effort to put into supporting this package.

Let me know how you get on.

Cheers,

Martin



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Dr Martin D. Westhead | <M.Westhead@epcc.ed.ac.uk> 
                      | http://www.epcc.ed.ac.uk/~martinwe 
Principal Consultant  | phone : +44 (0)131 650 5958       
    Research          | mobile: +44 (0)7050 193530
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