[ns] strange "invalid command" error (bug?) when simulating

[Richard Mortier <Richard.Mortier@cl.cam.ac.uk>]

Hi,

I'm trying to rerun a set of simulations that I previously had
working, as far as I'm aware using the same versions of NS &
associated libraries, compilers, CPUs, etc, etc.  However, the
simulation frequently produces the following error (after
approx. 150s simulated time):

"""

ns: _o6912 produce 17.0: invalid command name "_o6912"
    while executing
"_o6912 produce 17.0"

"""

...with the _oxxxx value being different for different values of
various simulation parameters and seeds.  If I try and print out
"[ info class ]" on that object, it appears to be an "Agent/TCP"
in the same way that the previously created ~6000 (in this case)
were.  I'm not running out of memory, or other resources as far
as I can see.

I'm using NS 2.1b4 (I'm trying to avoid porting some code to
2.1b6 at the moment), Otcl 1.0a3, tclcl 1.0b8 and tcl/tk8.0p2
which I believe are all interoperating versions.  gcc/g++ 2.8.1
is being used to build on a RedHat 5.2/Linux 2.2.2 machine.

So -- anyone any ideas as to what might be causing this?  It's
probably something obvious that I'm missing, but I'm really
stumped at the moment (and given that it takes about 10mins. to
reproduce it each time, debugging it is going to be slow :-( ).
The error is being printed as a result of calling
init.tcl:unknown, if that's any help.

Cheers,

--
Richard Mortier                 --------------------
-----------------        ------ Computer Laboratory,
rmm1002@cam.ac.uk  ----- University of Cambridge, UK
mort@ieee.org ---- http://www.cl.cam.ac.uk/~rmm1002/