ATM and NS

[scooper@nmsu.edu]

I would like to add to the ATM/NS discussion.

For the past year I have been working with a modified version of NS
for my ATM research.  I looked at the contributions made by others
and found that they didn't use the NS event engine like I wanted NS
to do.

My code is *NOT* ready for prime-time.  However, for those who are looking
at NS for supporting ATM, there are some issues that you may
want to consider.

In my implementation, I had to re-write the classifier so that IP
packets turned into ATM cells.  This is much like a segmentation
and reassemble process.

Second, you will have to implement any ATM AAL activities.  I found
it best to do this at segmentation.

I've been working with Available bit rate, so I had to include Resource
Management cells in the segmentation process.

And, the most difficult part I have found is putting ATM smarts in
the router nodes via the classifier.  When a node receives and ATM cell,
the routing nodes needs to manage cell jitter, peak arrival rate, etc.


I still use everything else of NS.  I have found NS to be a good product
to conduct my ATM research, but it isn't a walk in the park.  You will
have to do some customizations to use the NS engine.

I hope this helps

Shaun Cooper
scooper@nmsu.edu