Re: [ns] ns limitation regarding network topology

[John Heidemann <johnh@ISI.EDU>]

>
>Hi,
>
>Is there any topology limitation while doing ns simulation ?
>
>I was trying to test the 300 node version of tutorial's
>"VI.1 Creating a larger topology".
>
>I've got error messages saying "unable to alloc 2480",
>and Segmentation error. (2480 is from my memory, might be 2400...)
>
>
>I've found that the error message was from Tcl (tclCkalloc.c:
>Tcl_Alloc()). Then I retry it with doing vmstat(8).
>My testing machine is NetBSD, and it says the machine has about
>300M. (avail memory = 349 MB)
>The vmstat at the failure was: (This shows the most avm)
>
>avm    fre    (size 1Kb)
>157788 184132
>
>I can't see the reason of memory allocation failed...
>
>Please help me...
>regards
>
>       yasu
>


Ns topology sizes are limited by memory (the simulator itself doesn't
impose some arbitrary other limit).

The message you report ("unable to alloc") is pretty clearly out
of memory.

Ns has been used to do much bigger scenarios (see the "debugging tips"
web page).

   -John Heidemann