Subject: Re: [manet] NS-2

From: "Michael Roberts" <[email-masked]>
Date: Mon, 23 Jun 2003 14:57:57 -0400

Andrew,

I haven't used ns, so I can only give you half an answer, but I'd advise you
to take a hard look at OPNET.  We've used it extensively and had good
results on several ad hoc routing studies comprising both unicast and
multicast traffic.

In addition to basic tool features (model architecture, UI, programming
library, debug support, etc), you'll want to consider a few unique things
about ad hoc nets and how the different models/environments deal with
disconnects from the standard "wired" IP paradigm:

1) Ad Hoc nodes are typically both routers and source/sinks as opposed to
being either one or the other.

2) Ad Hoc nodes are "one armed".  This means that they usually want to route
traffic back out the same interface on which it arrived (i.e. the router has
only "one arm" that connects to the network).  This is a pretty unusual
situation for wired nets.

3) Standard address and subnet assignments don't really make sense in the
wireless world where link connectivity is dynamic and you have asymmetric
broadcast groups (e.g. B can send to A and C, but A can only send to B, and
C can only send to B).

4) ARP modeling is a big sub-problem.  Three general options here:
promiscuous mode, customized functionality, or standard functionality, any
of which have issues.

Regarding OPNET, #1 isn't usually a problem because of code re-use in the
standard IP library (the same processes are used in workstation models that
are used in routers).  #2 can create some legacy restrictions since the
original models were designed with wired nets in mind, but these problems
have been simple to fix.  #3 and #4 are tougher, since there is no
acknowledged best approach to these problems (which might be just the kind
of thing that you are going to be studying).  You'll definitely want to see
how these issues are handled in the ns models for comparison.

All of our work has required modifications the standard OPNET models to
address one or more of the issues above.  The new DSR model (and others
coming) from OPNET will probably reduce the amount of customization
necessary for our ad hoc work, but we haven't had a chance to fully assess
it yet.

Regards,
 
Michael Roberts
Highland Systems, Inc.

_______________________________________________
manet mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/manet

---

From: ng jiahui <[email-masked]>
Date: Mon, 23 Jun 2003 17:52:45 -0700 (PDT)

Hi;

    Hi, can i know when i have set up the AODV-UU
testbed then does any one has setup one PC as a
gateway successfully as i do not think i set it up
correctly by typing the command:
            aodvd -w -i eth1
 and can kindly guide me on this. 

2nd qn: Can i know if i have 3 laptops connected
wirelessly and 1 of it has eth0 connected to
LAN/internet and eth1 connected to a wireless access
point. When all 3 laptops are run aodvd, i notice that
the other 2 laptops can ping one another but not ping
external network like the internet (example: ping
google.com), only the one that has eth0 connected to
LAN can access internet. Can anyone help me on this?

Thanks in advance =)  

Regards; 
Jiahui

__________________________________
Do you Yahoo!?
SBC Yahoo! DSL - Now only $29.95 per month!
http://sbc.yahoo.com