Subject: Re: OPNET Simulation Code for MANET

From: Chip Elliott <[email-masked]>
Date: Thu, 19 Oct 2000 15:21:33 -0400

Hi Hossam,

Greetings! Yes, BBN has done a number of simulations of ad hoc networks
in OPNET. Unfortunately these are simulations for protocols that are now
being deployed into the US military and so we are not at libery to
release the source code.

However, I would be glad to answer your questions, to the best of my
ability. It is not entirely easy to choose between OPNET and ns-2 because
they have different strengths.

OPNET's main advantage is that it has a fairly large commercial base,
includes built-in features for modeling a number of existing kinds of
network technology, has reasonably good display graphics and and a
graphics-based user interface, and is fundamentally "object oriented"
which is a very good thing for network design. In our experience, it
seems essentially bug-free and does what it claims it will do. It has
some noticeably bad points, though. First, it is very expensive - enough
so that I doubt an academic department would really want to pay the
license fees. Second, it is rather slow and thus requires a fairly
high-powered machine for running good-size models. Third, its user
interface has seemed rather clunky to those of us at BBN who use it a
lot. Fourth, its implementations of TCP (etc) are nothing to write home
about and last I knew, its implementation of OSPF was downright buggy,
which is dangerous if you're trying to model behaviors of higher-level
protocols. Fifth, it is commercial software so you can't see or change
the source unless you are very good friends with MIL-3.

ns-2's main advantages are as follows. First, it is free. Second, it is
open-source. Third, it has historically had very good and extensive TCP
implementations, which thus allows you to observe higher-level protocol
behavior. Fourth, I think that most academic MANET researchers are using
ns-2 so you stand a chance of grabbing and importing their protocols. Its
disadvantages are that it's a fairly bare-bones system (very few frills
and built-in features compared to OPNET), that its graphics aren't quite
as pretty as OPNET, and that you'll have to do a few more things yourself
rather than have them handed to you on a silver platter.

On the whole, if it were me, I would choose ns-2. In fact, other groups
within BBN have used ns-2 for MANET research work and are quite happy
with it. In my view, it's something like the choice between Linux and
Windows 98, where ns-2 is Linux and OPNET is Windows 98. There's of
course a large element of personal preference involved, but on the whole
I think that ns-2 is a better match for MANET research.

Just my two cents but hope that it is useful.

Cheers,

-- Chip

PS. Why then, you might ask, did we pick OPNET? Well, we were required to
deliver an OPNET model under the terms of our contract. And that's not a
bad choice for the US military, since they can require OPNET models from
each of their subcontractors and then glue them together to make a really
big overall network model - all in OPNET. A far-sighted and laudable
goal, in my view. So I'm not complaining about OPNET, just saying it may
not be the best tool for your research. 

At 01:30 PM 10/19/00 -0400, you wrote: 

<excerpt>

<fontfamily><param>Arial</param><color><param>0000,0000,ffff</param><smaller>Chip,</smaller></color></fontfamily> 

<fontfamily><param>Arial</param><color><param>0000,0000,ffff</param><smaller>I
am a Ph.D. student in City University of New York (CUNY) working on MANET
and MIP. I have read from different sources (MANET WG, Mail Archive,
Papers,etc) that you and your colleagues at BBN have done some
simulations in MANET using OPNET on Dec '1998 or after. 

</smaller></color></fontfamily>

<fontfamily><param>Arial</param><color><param>0000,0000,ffff</param><smaller>As
you know, OPNET 7.0 now supports 802.11 MAC. It may be helpful to use
OPNET as a simulation tool since it has extra features (unified
visualization tool, easy to build and modify models, better reporting
tools, etc) than ns-2. However, I would appreciate if I can get these
OPNET codes Or can you help me to point to any OPNET MANET codes. Please,
advice if OPNET is better simulation tool than ns-2 since I have to
research works in both MobileIPv4/6 and MANET Unicast and Multicast
Routing Protocols.

</smaller></color></fontfamily>

<fontfamily><param>Arial</param><color><param>0000,0000,ffff</param><smaller>I
definitely appreciate your help regarding this
issue.</smaller></color></fontfamily> 

<fontfamily><param>Arial</param><color><param>0000,0000,ffff</param><smaller>Thanks</smaller></color></fontfamily> 

<fontfamily><param>Arial</param><color><param>0000,0000,ffff</param><smaller>/Hossam</smaller></color></fontfamily> 

</excerpt><<<<<<<<

---

From: [email-masked]
Date: Thu, 19 Oct 2000 15:42:02 -0400

Hi Chip,

I appreciate very much your quick reply. I understand the code release
issue. I also understand your recommendations and I agree on most of them.
It is still a tough choice for me since:
1. CUNY (our school) has a license for it. It is already purchased and
installed.
2. It is installed in a high-power Sun Server.
3. I have a colleague who is an expert in OPNET 7.0 (2 years experience) who
will help me in my research (Please, see below a brief description).
4. He did a lot of work in TCP simulations.
5. He has a lot of friends in MIL-3 since he has been coordinating with them
for more than 1.5 years.
*. I also agree with your ns-2 recommendations.

My research is (briefly): "MANET Internet Access". However, I designed a
modified MIP (backward compatible) to work with any MANET unicast protocol.
There are lot of value-added features within this developed protocol. I am
in a situation to start simulation to prove the applicability of this new
protocol. Since I need MIP (to change the source and add to it) + several
MANET unitcast protocols (to run the simulation against) + other reasons,
ns-2 looks like the best simulation vehicle for me (I am a Unix fan and
Microsoft hater !!!).

Thanks again for your time.
/Hossam

> -----Original Message-----
> From:	Chip Elliott [SMTP:[email-masked]]
> Sent:	Thursday, October 19, 2000 3:22 PM
> To:	[email-masked]
> Cc:	[email-masked]
> Subject:	Re: OPNET Simulation Code for MANET
> 
> 
> Hi Hossam, 
> 
> Greetings! Yes, BBN has done a number of simulations of ad hoc networks in
> OPNET. Unfortunately these are simulations for protocols that are now
> being deployed into the US military and so we are not at libery to release
> the source code. 
> 
> which is a very good thing for network design. In our experience, it seems
> essentially bug-free and does what it claims it will do. It has some
> noticeably bad points, though. First, it is very expensive - enough so
> that I doubt an academic department would really want to pay the license
> fees. Second, it is rather slow and thus requires a fairly high-powered
> machine for running good-size models. Third, its user interface has seemed
> rather clunky to those of us at BBN who use it a lot. Fourth, its
> implementations of TCP (etc) are nothing to write home about and last I
> knew, its implementation of OSPF was downright buggy, which is dangerous
> if you're trying to model behaviors of higher-level protocols. Fifth, it
> is commercial software so you can't see or change the source unless you
> are very good friends with MIL-3. 
> 
> within BBN have used ns-2 for MANET research work and are quite happy with
> it. In my view, it's something like the choice between Linux and Windows
> 98, where ns-2 is Linux and OPNET is Windows 98. There's of course a large
> element of personal preference involved, but on the whole I think that
> ns-2 is a better match for MANET research. 
> 
> big overall network model - all in OPNET. A far-sighted and laudable goal,
> in my view. So I'm not complaining about OPNET, just saying it may not be
> the best tool for your research.  
> 
> 
> 	Chip,  
> 	I am a Ph.D. student in City University of New York (CUNY) working
> on MANET and MIP. I have read from different sources (MANET WG, Mail
> Archive, Papers,etc) that you and your colleagues at BBN have done some
> 	As you know, OPNET 7.0 now supports 802.11 MAC. It may be helpful to
> use OPNET as a simulation tool since it has extra features (unified
> 	I definitely appreciate your help regarding this issue.  
> 
> 	Thanks  
> 	/Hossam  
> 
> 
> <<<< 
>