Subject: [manet] promiscious mode in MANET

From: [email-masked]
Date: Wed, 30 Mar 2005 05:22:05 +0200

Hi all,

I'm currently reading some papers about mibehaviors detection in MANET. The
basic technique used is that each node enters in promiscious mode and monitors
its neighbors.

I'm wondering... What are the consequences on performance and routing if all the
nodes in a MANET are in promiscious mode?

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From: Baker Fred <[email-masked]>
Date: Wed, 30 Mar 2005 08:12:19 -0800

On Mar 29, 2005, at 7:22 PM, [email-masked] wrote:
> I'm wondering... What are the consequences on performance and routing 
> if all the nodes in a MANET are in promiscious mode?

That really depends on a lot of things. If the manet node is correctly 
implemented, nothing should happen whatsoever.

The wired comparison is to a host on an Ethernet. A router is, if you 
will, a host that retransmits what it receives at the network layer. A 
correctly functioning router does so in a way that it gets a datagram 
closer to its destination. An Ethernet switch is, if you will, an 
Ethernet device that retransmits what it receives, and a correctly 
functioning one does so according to certain algorithms as well. When 
you couple an Ethernet Switch with a host (which is how you manage the 
things) or with a router, the traffic that goes to layer three is that 
which was addressed to the host or router at layer 2, and it behaves at 
layer 3 just like a host or router. If you break that, though, then the 
router will attempt to forward the traffic, resulting in duplication 
(perhaps massive duplication) of the traffic.

When you say that the manet node is operating in promiscuous mode for 
the purpose of observation of its neighbors, I have to believe that you 
mean it is receiving all traffic it can hear at layer 2, giving to its 
own layer 3 that which belongs to its own layer 3, and recording the 
rest. That is not incorrect operation. No datagram will get sent by 
that machine that would not have been sent by a non-promiscuous node. 
An RMON Probe is an example of such a device; what it does is measure 
the behavior around it and report back to a network management system 
on the nodes in its vicinity.