Subject: [manet] one way hash in SAODV

From: zhen <[email-masked]>
Date: Thu, 2 Jan 2003 18:27:45 -0400

surely it prevents hop counts from being decremented, still it can be 
incremented arbitrarily. Say some node is on the best route, it increments the 
hop-count many many times-proper as it thinks, of course, won't that cause the 
optimal route is rejected so as to cause some waste of resources.

Is this right? any idea with the extent of wasting?

best

Zhen

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From: Manel Guerrero Zapata <[email-masked]>
Date: Tue, 07 Jan 2003 13:10:56 +0200

Yeah, you are right.

I recomend to look to the papers about SAODV in:

http://ant.eupvg.upc.es/~tarom/saodv.html

specially the updated version of the paper I presented in WiSe:

http://ant.eupvg.upc.es/~tarom/guerrero_wise_2002.ps.gz

In the section #3 (Requirements) of this paper you can see that
prevention against DoS is not one of the requirements of SAODV.
(For more detailed analysis of the limitations of the hash approach
look to the section #5.3.5 (Analysis).)
So if you want some kind of protection against DoS you should look
somewhere else.

BUT, in my opinion it makes no sense to try protect the routing layer
because if I want to do a DoS, I'll do it at physical or link layer
(where it is much more easy and routing protocol independent).
So let's do not waste resources to try to partialy protect something
that the bad boys are gonna attack from another layer.

There are some manet protocols that claim that they protect against
DoS (partialy or totaly). IMHO, they are just protecting _some_ of the
windows of the third flour, letting any enemy get in through
the main door that is in the basement. (sorry for the lousy metafora) ;)

Regards,

	Manel Guerrero

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From: feng zhu <[email-masked]>
Date: Fri, 10 Jan 2003 07:29:35 -0800 (PST)

Hi,
Can we say that ...

The node, on some (maybe the best) route, which
increments the hop-count many many times-proper as it
thinks, is a malicious node. 

The responsibility of SAODV and other secure routing
protocols is only to find a (maybe the best - shortest
or fastest) available route. So the route most likely
does not(or should not) includes the malicious nodes.

If some malicious node is on a route, it increments
the hop-count many many times-proper as it thinks,
then that only cause the route, which including this
malicious node, is rejected. It just means that this
rount is not the best available route because it
include a melicious node.

Best,
--Feng

> Is this right? any idea with the extent of wasting?

=====
==============================
ZHU, Feng
[email-masked]
http://www.ccs.neu.edu/home/zhufeng/security_manet.html

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From: Mingyan Liu <[email-masked]>
Date: Sat, 11 Jan 2003 22:59:16 -0500 (EST)

Hi, 

You may be interested in our recent paper on the random 
waypoint model that is going to appear in Infocom 2003:
http://www.eecs.umich.edu/~mingyan/pub/random-waypoint.pdf

Abstract --
This study examines the random waypoint model widely used
in the simulation studies of mobile ad hoc networks. Our 
findings show that this model fails to provide a steady 
state in that the average nodal speed consistently decreases
over time, and therefore should not be directly used for 
simulation. We show how unreliable results can be obtained
by using this model. In particular, certain ad hoc routing
metrics can drop by as much as 40% over the course of a 
900-second simulation using the random waypoint model. 
We give both an intuitive and a formal explanation for 
this phenomenon. We also propose a simple fix of the
problem and discuss a few alternatives. Our modified random
waypoint model is able to reach a steady state and simulation
results are presented. 

-mingyan

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From: "Jeff Boleng" <[email-masked]>
Date: Mon, 13 Jan 2003 21:37:44 +0900

Interesting paper, and a very thorough treatment of the topic.  I am
compelled to point out a few things (possibly a type of rebuttal).

Not everyone assumes that the Random Waypoint Model must range speed in
(0,Vmax].  In fact, all our research ranges speed in [Vmin, Vmax] when we
use the Random Waypoint.  Furthermore, we usually keep Vmin and Vmax within
ten percent of Vavg.  We have never published a result using 0 as Vmin for
all velocity cases.

Very early on in our research we realized that setdest wouldn't work for us.
We developed our own mobility generator (called mobgen) which allows much
more flexibility, and avoids the problem of all nodes being paused for
<pause time> seconds at the beginning of the simulation.  This code is
available to everyone, and we have distributed it widely since our WCMC
journal paper, which you cite.

I should also not that your references [1], [2], [3], and [4] are not the
only comparisons of MANET protocols.  In fact there is an important paper
from Mobicom '99 by Per Johansson et al, and our work from Infocom:

T. Camp, J. Boleng, B. Williams, L. Wilcox, and W. Navidi, Performance
Comparison of Two Location Based Routing Protocols for Ad Hoc Networks,
Proceedings of the IEEE Infocom, pp.1678-1687, 2002

available at http://toilers.mines.edu/papers/Infocom02.pdf.  In this paper,
as our others, we use a speed of +/- 10% of Vavg and the random waypoint
mobility model.  We also simulate 2000 seconds of operation and discard the
first 1000 seconds as has been standard practice for us for some time.

I have other comments on your paper but will not include everything here.
Please contact me if you are interested.

One final thing is to answer your summary of our WCMC paper on mobility
models.  Figure 4 in our paper (your reference [7]) does not show "a stable
mean but an increased variance over larger time scales", and cannot be
"suggestive of decreased movement of nodes..." because we don't use zero as
Vmin.  In fact, for this plot, speed ranged from 9-11 with a mean of 10.  We
use this figure as an example of why we discard initial time in the
simulation.  In essence, we "warm-up" the simulation.  The necessity to do
this was first discovered after discussions with Dr. Royer at a conference,
but is related to the reasons outlined in your references [6] and [9].

We are quite clear about our simulation parameters in all our papers, and a
careful reading will reveal that our speed ranges between [Vmin,Vmax] where
Vmin=0.9*Vavg and Vmax=1.1*Vavg.

Respectfully,

Jeff Boleng
[email-masked]

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]On Behalf Of
Mingyan Liu
Sent: Sunday, January 12, 2003 12:59 PM
To: [email-masked]
Subject: [manet] random waypoint model

Hi,

Abstract --

-mingyan