modeling protocol

[ahead <ahead@tm.net.my>]

Dear Sir,

I am final year (undergraduate) university student, I got a project. It
need to do the modeling for simulation the vechicle network protocols
(CAN and J1850) in order to known the characteristics of them (system
delay, transmission failure and throughput). May I known what simulator
(sofeware) I can use for my thesis project. Can I download from
internet? Is "NS" is suitable for my project?  

Actually, what is the way to do the protocol modeling and what the
things (like, parameters) I have to know before doing the simulation and
modeling.

Thanks a lot.

Sam
Ahead@tm.net.my