Subject: network simulation software?

From: "Wang Hui" <[email-masked]>
Date: Fri, 23 Mar 2001 10:56:10 +0800

Hi folks here,

I am about to set up a small Network Simulation lab as to do some network protocol simulations.
The first thing to do is to choose the software and its platform.   But as for me, I have no experience of working on it,  so I have no idea of that.  Anyone has any idea?  Which network software is popular among this field?  Could you drop me a message?  Or give me some web links?

Thanks in advance.

-Wang Hui.

---

From: [email-masked]
Date: Fri, 23 Mar 2001 12:13:57 -0500

> network protocol simulations.

Congratulations, and good luck.

> The first thing to do is to choose the software and its platform.

No, the *first* thing to do is understand *what* you're trying to simulate
and *why*.

Are you trying to understand the protocol at all?  You'd probably be
better off spending the time and effort reading a good book on the
subject, or doing a literature search for research papers already done.

Are you trying to understand a *specific aspect* of a *specific protocol*?
For instance, "failure modes of the SMTP protocol when communicating with
a node that implements the protocol improperly" (I've studied *that* enough
myself)? Or are you trying to understand oscillation modes in BGP flaps
(which I don't understand well, except as they apply to queue management
for an SMTP server - when the routes are flapping, you start piling up
queues).

If so, you need to specify what protocol, and what aspect,
you're studying.  The question you are asking will make a difference in the
tools you will need to answer it.

> But as for me, I have no experience of working on it,  so I have no idea
> of that.  Anyone has any idea?

Idea: Get up to speed on it before trying to do simulations.  Or at least
figure out something more specific than "I've been told to set up a lab".

Starting out without a clear goal in mind guarantees failure.  Among other
things, lack of a clear goal means you can't tell when you've suceeded.

> ...............................  Which network software is popular among
> this field?  Could you drop me a message?  Or give me some web links?

The network software is *totally* *irrelevant* until you understand
what you're trying to do.

				Valdis Kletnieks
				Operating Systems Analyst
				Virginia Tech

---

From: Ping Pan <[email-masked]>
Date: Fri, 23 Mar 2001 18:27:05 -0800

Try ns-2: http://www.isi.edu/nsnam/ns/. It's quite easy.
Also I think this is also good if you like UNIX,
http://www.eecs.harvard.edu/networking/simulator.html

Wang Hui wrote:
> The first thing to do is to choose the software and its platform.   But as for me, I have no experience
> of working on it,  so I have no idea of that.  Anyone has any idea?  Which network software is popular among > this field?  Could you drop me a message?  Or give me some web links?
> 
> Thanks in advance.
> 
> -Wang Hui.

--
Ping Pan

---

From: Scott Michel <[email-masked]>
Date: Mon, 26 Mar 2001 18:49:52 -0800

> Try ns-2: http://www.isi.edu/nsnam/ns/. It's quite easy.

Uhhh... yeah. Right. Sure. This statement should be taken with a great
grain of salt and requires proper investigation of the ns-users mailing
list for newbie FAQs.

Depends on what level you want to simulate. If you're at layers 3 and
below, it's good. If you're above layer 3, it can be a righteous burr
under the saddle.

---

From: Lloyd Wood <[email-masked]>
Date: Tue, 27 Mar 2001 13:55:04 +0100 (BST)

> grain of salt and requires proper investigation of the ns-users mailing

of which there is just one, saying 'read the webpages' for the most
part.

> below, it's good. If you're above layer 3, it can be a righteous burr

Other way around, surely?

Over the past few years ns has been growing down the stack and
gradually fleshing out some very limited and abstracted MAC/physical
support. You still can't do multicast over wireless, for example -
nothing over layer 3 in that - and the split between disparate sets of
C++ routing code and OTcl routing code is unfortunate.

The strength of ns lies in its one-way TCP suite - and that's layer 4.
Many academic ns simulation papers have the complex basic topology of:

      TCP     TCP
       O---O---O
           ^ some fancy queuing thing here

and don't touch anything below layer 3; links are presumed serial.

Segmentation and reassembly and header/packet size fudgings throw off
stuff below layer 3 entirely... the amount of adjustment needed to
e.g. generate meaningful BER curves for TCP traffic from propagation
effects upward is significant.

You only think ns is difficult for above layer 3 because that's all
you're trying to use it for. Let me assure you that if you try to use
ns for work above -and- below layer 3 you'll have a much more
considered perspective.

if you want to use ns for TCP stuff across serial links, you'll
probably be fine. Beyond that, all bets are off; ns has a lot of
built-in abstractions that get in the way of using it for engineering
with real physical quantities at the lower layers, and you have to
appreciate its limitations to get useful results out.

L.

<[email-masked]>PGP<http://www.ee.surrey.ac.uk/Personal/L.Wood/>

---

From: "Davide Careglio" <[email-masked]>
Date: Fri, 30 Mar 2001 00:11:25 +0200

Dear Wang,

I used a network modelling language called TeD (Telecommunication
Description Language, http://www.cc.gatech.edu/computing/pads/teddoc.html)
for 1-2 years and is not bad, but it has programming limitations. Try SSFNet
(www.ssfnet.org), its (I suppose) directed successor.

Regards,
Davide
_______________________________________
Davide Careglio

UPC Universitat Politècnica de Catalunya
Departament d'Arquitectura de Computadores
Jordi Girona, 1-3, D6 008 (Campus Nord)
08034 Barcelona (Spain)

Phone: +34 93 4017182      Fax: +34 93 4017055
E-Mail: [email-masked]

----- Original Message -----
From: "Wang Hui" <[email-masked]>
To: "[email-masked]" <[email-masked]>
Cc: <[email-masked]>
Sent: Friday, March 23, 2001 4:56 AM
Subject: network simulation software?

> The first thing to do is to choose the software and its platform.   But as
for me, I have no experience of working on it,  so I have no idea of that.
Anyone has any idea?  Which network software is popular among this field?
Could you drop me a message?  Or give me some web links?