[ns] Release of Parallel/Distributed ns (PDns)

[George Riley <riley@cc.gatech.edu>]

Hello Everyone,

The COMPASS (COMposable and PArallel Simulations of internetworkS)
research group at Georgia Tech College of Computing would like to make
available our "Parallel and Distributed ns" (PDns) to the ns user
community.  The COMPASS and PDns research efforts are funded in part by
the National Science Foundation.  Information on downloading and compiling
the release can be found at:

http://www.cc.gatech.edu/computing/compass/pdns/index.html

The PDns release consists mostly of extensions to ns version 2.1b6a
(additional c++ and tcl modules), a comprehensive runtime library for
implementing parallel simulations, and a few very small changes to the
actual ns code itself (distributed as "diff" scripts).

Why would anyone want to use PDns?  The most compelling reason at this
juncture is to simulate larger models. If you have a simulation that is
simply too big (in terms of memory usage) to be run on a single system,
PDns gives an almost linear increase in available memory when running on
multiple systems.  So if your model is at the memory limits of a single
system with 200 nodes defined, you should theoretically be able to
simulate 1600 nodes on 8 systems.

You may also get some speedup in the overall execution time of your
simulation.  The amount of runtime speedup achieved by any parallel
simulation is largely dependent on what is being simulated, and cannot be
accurately predicted.  Your mileage may vary depending on your network
models.

We are releasing the code with the following caveats:

1) This is the version 0.1 release, and has seen limited testing here
   at Georgia Tech.

2) You need to modify your model somewhat for parallel execution.
   The web page given above describes how this is done.

3) PDns uses a "Runtime Infrastructure" known as RTIKIT for
   intersystem communications.  This PDns release has been
   tested on Intel/Solaris using TCP/IP, on Intel/Linux using
   TCP/IP, and on Sparc/Solaris using both TCP/IP and Myrinet.  The
   RTIKIT also supports shared memory message passing on SGI Origin, 
   but PDns has not been integrated or tested on SGI.

We are actively working on the next release of PDns, which will
simplify the effort of running a parallel simulation.
This work is in progress with an expected release in about 6 months.

Feel free to contact George Riley (riley@cc.gatech.edu) with any
questions or comments.

Good Luck!
George

					
			-George F. Riley (riley@cc.gatech.edu)