ns limitations?

[Kristin Wright <kwright@cs.utah.edu>]

Hello,

Can anyone provide concrete examples of a computationsl 
limitation in ns or approximations of limitations based on 
empirical evidence? For example, has anyone had to limit 
the number of nodes in an experiment based on processing time? 

We're interested in including ns in a network testbed proposal. 
However, an "inherent limitations of simulators" argument 
continues to surface. After some discussion, it's clear that
none of us have a *concrete* idea of where the limitations
might be. We can imagine where some might exist, but we
cannot attach numbers to the scenarios. 
My own experience with ns has not revealed any
such limitations. 

(I've already pointed my colleagues to the ns 
publication web page for evidence of what simulations 
*can* be run.)

Thanks very much for any help. 

-kw