Subject: Re: [manet] ARP in MANETS

From: "yasser lotfy" <[email-masked]>
Date: Wed, 26 Apr 2006 08:41:42 -0500

How do you know a "quite" station exist?

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From: "Gabi Kliot" <[email-masked]>
Date: Wed, 26 Apr 2006 17:11:03 +0200

Hi

I am not a 802.11 expert, but as far as I remember, in IBSS mode there is a
beacon message being sent periodically (every 100-200 millisecond or so) by
mobile stations.
This beacon is not being sent by the same station every time, but each time
other station is picked probabilistically to send the beacon (just number of
milliseconds before next beacon every station must wake up and pick the slot
out of next X slots in which it must transmit the beacon. If another station
transmitted before me - I will cancel the beacon timer).

So basically MAC mechanism guarantees (probabilistically)  that every
station sends beacons periodically and that way no station will stay silent
forever.

Of course, if the station does not use the standard 802.11 MAC and it is
selfish and avoids sending beacons - others will not know about it. But who
wants to communicate with this selfish station anyway. :)

Gabriel Kliot

> -----Original Message-----
> From: yasser lotfy [mailto:[email-masked]] 
> Sent: Wednesday, April 26, 2006 3:42 PM
> Cc: manet
> Subject: Re: [manet] ARP in MANETS
> 
> 
>

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From: "Val Naumov" <[email-masked]>
Date: Wed, 26 Apr 2006 16:51:15 +0200

Hi all,

> How do you know a "quite" station exist?
ARP-exchange precedes a unicast packet transmission. But in ad hoc network, 
a host A, before deciding to send a unicast message to another host B, must 
first receive any packet from B (any kind of broadcast: e.g., HELLO-message, 
route request, etc; OR a unicast packet).

ARP is in deed harmful for MANET. In addition to the paper that Seung 
pointer to, in the
paper "Scalability of Routing Methods in Ad Hoc Networks" we suggest a 
revised role of ARP in wireless ad hoc network that simplifies communication 
between hosts and improves the performance of any routing protocol, 
especially in scenarios with high mobility of hosts (constantly changing 
neighborhood). Routing protocols that are mostly based on unicast packet 
transmissions (e.g., geographic routing protocols) benefit most from 
omitting the ARP-exchange.

If you are interested, the paper is:
V. Naumov,  T. Gross,  Scalability of Routing Methods in Ad Hoc Networks, 
Performance Evaluation, Elsevier Science, 62(1-4):193-209, October 2005
http://www.lst.inf.ethz.ch/research/publications/PERFORMANCE_2005.html

Regards,

Val

----- Original Message ----- 
From: "yasser lotfy" <[email-masked]>
Cc: "manet" <[email-masked]>
Sent: Wednesday, April 26, 2006 3:41 PM
Subject: Re: [manet] ARP in MANETS

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From: Ali Hamidian <[email-masked]>
Date: Wed, 26 Apr 2006 17:09:18 +0200

Hi,

I'm not arguing for ARP - am just try to understand things :-) .

Since there is no IP address in the beacon frame, you can't use it to 
map IP addresses to MAC addresses. Therefore, to go back to the previous 
question. listening to the wireless media is not good enough so there 
should be some way to request other node's MAC addresses.

I've read the paper "ARP Considered Harmful" and think that it suggests 
an interesting approach.

Kind regards
Ali

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Department of Communication Systems, Lund University

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