[e2e] Is sanity in NS2?

[Roland Bless]

Hi Richard,

Richard Gold wrote:

> It's great to see work like this being done. Thank you for releasing
> your work to the community. However, I wonder how well this release will

The work started also as a first proof of concept: Is it possible
to integrate a nearly unmodified version of an existing real OS network
stack implementation into a simulator?

> be supported. Is there a development team, someone responsible for
> maintenance and bugfixes, updating it for recent OS/tools, a roadmap for
> the future? Getting a simulator out the door is extremely important, but

Good point. We must differentiate between OMNeT++ (the simulation kernel
itself) and OppBSD. OppBSD was the outcome of a master thesis and is
currently not a big project by itself, so we do not have dedicated
resources assigned to it. However, I supervise a student who is
upgrading it to FreeBSD 5.3 and who should integrate IPv6 and Mobile
IPv6. So we do have some kind of a roadmap. If you found bugs, we are
happy to  include your fixes into our public accessible subversion
repository. :-) But we do not have a dedicated support team...

> it's also critical what happens to it after it is released. If there is
> no community around it, then it will just be abandoned. I have heard

Yep.

> good things about SSFNet, for example, but the latest release was Jan
> 2004 and as far as I can tell there is no-one continuing this work. I
> hope that I am just mis-informed. Rightly or not, this severely
> discourages me from using the simulator. This is the one thing that ns2
> has going for it: it's still actively maintained and probably will be in
> the future too. Whether or not this is a good thing is left as an
> exercise to the reader...

As speaking for the simulation kernel OMNeT++:
there is active support and development for OMNeT++ since several years
by its main author Andras Varga. He is very responsive if there are
problems/bugs or feature requests. However, because he is really
eager to improve his simulator, he is working 100% of the time for it.
In order to prevent starving to death, Andras provides the commercial
variant OMNEST. OMNeT++ comes with an academic public license (see
http://www.omnetpp.org/external/license.php) and it is open source,
which is really important if you suspect that there is a bug in the
simulator and you want to fix it immediately.

There are several models under construction in the OMNeT++ community.
In this respect it is possibly comparable to ns-2: some models are easy
to use and written well, others should better be rewritten from scratch.
But it's really the same for all simulators: how far can you trust the
model and its implementation? So usually you have to validate it, and,
in this respect: the larger the community the better.

> This is, of course, an extremely difficult issue to solve. Can we make
> it part of the networking research community program to build and
> maintain a good toolkit for doing research?

This was really a purpose of ns, right?
(http://www.isi.edu/~johnh/PAPERS/Bajaj99a.html)
However, depending on what you are simulating, there are possibly better
and slimmer alternatives to ns-2.

Regards,
 Roland