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RE: NS versus OPNET Modeler
On Mon, 17 Jan 2000, James Scott wrote:
> hi heather,
>
> > I am negotiating a purchase of the OPNET Modeler software
> > and a friend reccommended NS. Any old or current OPNET
> > users? Who could give me feedback?
>
> i have used both opnet and ns. the question of which is
> the best tool would depend on the problem you're trying
> to solve and the skills of the person who is doing the
> work.
>
> the process model OpNET provides is a powerful tool,
> providing sort of a 4GL for building simulation models
> of specific nodal processes. additionally, the opnet i/o
> is top notch. and, if your work involves modelling ATM
> nodes, opnet is clearly the way to go. also, mil3 has
> recently provided a VHDL i/f for OpNET, which would be
> quite handy for cosimulation applications.
>
> i've found NS to be superior in the area of source traffic
> generation. while OpNET does provide a flexible mechanism
> for generating various types of source traffic, NS has a
> larger number of source traffic generators, in addition to
> contributed models for higher layer protocols (HTTP, etc).
> however, since OpNET provides an open API for source traffic
> generation, there is nothing prohibiting you from using NS
> generators to stimulate an OpNET model, depending on the
> level of sophistication possessed by the developer doing
> the work. in the past, i've written pareto models to
> stimulate OpNET process models. had i known of NS at the
> time, i could have saved some time by leveraging their
> pareto model <shrug>.
>
> in the area of routing, NS provides static and session-based
> routing using dijkstra, as well as dynamic routing using a
> distributed bellman-ford. by comparison, the OpNET tools
> provides just static routing.
Opnet also provides RIP and OSPF routing, as well multicast routing
recently. It is a more powerful simulation tool, the code is
well organized and the tool is good for demo.
But it has a bigger learning curve as trade-off.
> so, in summary, if you are modelling an IP network
> and interesting in things like queueing behavior and
> the interaction of higher-layer protocols on network
> performance, go with NS. you can use NS to model
> specific behaviors of proprietary h/w, but its perhaps
> not for the faint-of-heart.
>
> there are probably other areas where NS would be preferred,
> such as characterization of IP multicast and/or wireless IP,
> but i haven't had experience with these areas so will reserve
> comment. the above is just one man's opinion. both tools
> are QUITE useful, depending on the task at hand (as well as
> the size of your budget, and skills of your development crew).
>
> good luck!
>
> cheers,
>
> james
>