[Ns-developers] Real world TCP stacks in ns-2

[Sam Jansen]

I talked to Tom Henderson earlier about my work incorporating real world
network stacks in ns-2. Basically, what I've done is extracted the relevant
bits of some open source kernels (Linux 2.4.x, 2.6.x, FreeBSD, OpenBSD and
also lwIP) all allowed them to be used as TCP agents in ns-2. I also do some
work to allow multiple instances of each stack to be instantiated and
communicate independently.

This has turned out to be a reasonably large project. The build system in
particular ended up being quite complex and the system has to include 
all the
source for each network stack.

I'd like to see this as part of ns-2, but I'm a little unsure how this 
should
proceed. There are a few hurdles:

* Licences: each network stack I use has a different open source 
licence. My
own code is supposedly under a different open source-ish license still, 
I need
to coordinate with my research group a little more to figure out exactly 
what.

* Dependencies: I have a parser module with requires flex/bison and my
current build system uses scons (www.scons.org). The latter at least 
could be
replaced, but would take a significant amount of work.

* Some of the stacks are quite
dependent on compilers and architectures. Almost all of them currently will
only compile on i386 and I'm not sure that all reasonable versions of 
gcc will
work. I'd like to get past the architecture problem in the future, but this
requires a bit of time I have yet to be able to justify. The system only
really builds on Linux and FreeBSD because those are the only systems I've
ever tested on.

It seems that ns-2 is currently finding it's feet using the open source
development model; time to throw some more questions out there:

How should my project be incorporated, if at all, and what restrictions are
there going to be on it? I'm quite happy to spend some more time getting my
work up to date to make it of use to the general ns-2 community.

For anyone who is interested in the inner workings of this project, you can
have a look at my old and very dated document

        http://www.wand.net.nz/pubDetail.php?id=199

or the rather thin webpages at

        http://www.wand.net.nz/~stj2/nsc/

-- 
Sam Jansen                                           sam at wand.net.nz 
Wand Network Research Group             http://www.wand.net.nz/~stj2