is it possible?
can anybody here their experience?
Thank you. 
No one?
Please help…
I guess the real question should be what kind of network topology you’re trying to simulate. I admit my limited experience with network simulations like GTnetS because I’ve generally learned first by dry classroom lectures, then applied to real hardware.
Since OSPFD is the default algorithm within just about any LAN, I’d assume that type of network topology would implement OSPFD by default. If you’re setting up and routing between multiple networks, then my guess is that the simulator would route using a different method or algorithm (most likely BGP).
If you want specific information and not guesswork I’d recommend you find a mail list or discussion board for GTnetS.
Just some observations without actually testing on GTnetS and HTH,
Tony