Subject: RE: [manet] IP addresses in MANET

From: "Mullen, John P. (Contractor)" <[email-masked]>
Date: Thu, 27 Jun 2002 07:28:55 -0600

Hi Dario,

I agree that using some form of hierarchal addressing scheme can improve
routing efficiency in moderately large MANETs.

The IP address in the Internet is hierarchal.  Each node is given an address
that reflects its position in the topology of the Internet, much as State
and City reflects a person's location within the US.  This allows for
efficient routing, as you point out, by reducing the need for propagating
local detail to other routers.  

Because Internet nodes do not typically move a lot, a node can be given a
permanent address.  The problem with the MANET is that because the nodes are
in motion, any hierarchal clustering would have to be dynamic in order to
aid routing.  If MANET nodes have permanent addresses, it is simple to know
which node to look for, but not where to look for it.  On the other hand, if
a node is given an address that reflects its location in the net, then the
system has to resolve that address with a more permanent label.

The analogy I use is that you are trying to find someone who is staying in a
hotel.  You may know the city and the hotel name, but at some point you end
up talking to the front desk to find out which room Joe Smith is staying in.
Joe's name (plus some other information) is a permanent label, but you need
to know more information to find him.  The desk clerk performs the final
"address" resolution.

Another way to look at this is the IP addresses perform two functions:  1)
they uniquely identify a node, and 2) they allow efficient routing by
encoding a clustering scheme.  In a MANET, these two functions are distinct.

In the general MANET, we are not able to bind a real IP address to a
cluster.  A cluster reflects a configuration of the dynamic topology.  It
has no permanent identity or even assurance of existence.  As the nodes
within the MANET move, clusters split and merge.  The roles of a given node
change.  A node may be a cluster head one minute and a guest in a different
cluster the next.  If we assign a IP address to a location, then what
happens if two clusters move into that location?  What if no clusters are in
a location?  (If we have fixed locations we can reference, we do have a
simpler problem, but this is not guaranteed in a MANET).  Worse than that, a
specific node will be given different IP addresses as it moves through the
topology.  This complicates the problem of identification.

So far, one scheme I've seen involves giving each node a permanent IP
address plus a MANET suffix.  The suffix is used to find the node and the IP
address to identify it.  Alternatively, one can propagate throughout the net
(either proactively or on demand) a cross-reference table that matches up IP
and MANET addresses.

This is not to say that binding IP addresses to a cluster or locality will
not work in some situations.  However, that would be a special situation
and, some would say, not a MANET, but a stub network, instead.

John Mullen

-----Original Message-----
From: Dario Bottazzi [mailto:[email-masked]]
Sent: Tuesday, June 25, 2002 10:24 AM
To: [email-masked]
Subject: [manet] IP addresses in MANET

In my opinion some addressing scheme inspired from Virtual IP would be
really 
useful in MANET framework: we might think to bind real IP addresses to the 
locality (or to a cluster) and this could reduce most of the network traffic

related to routing management. (Routing tables would change with a lower 
frequency) 
If the Virtual IP (the name of the node) doesn't change even iin the case of

a migration it is possible for the others to track its movement and to use 
the services it shows as soon as it reconnects somewhere into the MANET.  
Is it meaningfull? I'd like to have your opinion...
regards 
     Dario

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---

From: Dario Bottazzi <[email-masked]>
Date: Thu, 27 Jun 2002 16:39:05 +0200

Dr. Mullen
     thank you for the clear and deep answer you have given me. I agree that 
my approach isn't general but I think that it maight fit many real life 
situations.  I think that the approach I have expressed (it's only an 
idea...) shows two interesting points:

- We have to think to cluster (o locality aware) solutions
- It might be possible to bind the IP to the location (and assign it 
dynamically) and to keep "something" (a second address) fixed. If I search 
for Mario Rossi in any hotel in Bologna, I know that he can change hotel... 
but the person I am looking for is always Mario. 

Anyway I will read again the answer you gave me. 

many thanks 
     dario

> The analogy I use is that you are trying to find someone who is staying in
> a hotel.  You may know the city and the hotel name, but at some point you
> end up talking to the front desk to find out which room Joe Smith is
> staying in. Joe's name (plus some other information) is a permanent label,
> but you need to know more information to find him.  The desk clerk performs
> the final "address" resolution.
>
> happens if two clusters move into that location?  What if no clusters are
> in a location?  (If we have fixed locations we can reference, we do have a
> simpler problem, but this is not guaranteed in a MANET).  Worse than that,
> a specific node will be given different IP addresses as it moves through
> the topology.  This complicates the problem of identification.
>
> address plus a MANET suffix.  The suffix is used to find the node and the
> IP address to identify it.  Alternatively, one can propagate throughout the
> net (either proactively or on demand) a cross-reference table that matches
> up IP and MANET addresses.
>

---

From: Dario Bottazzi <[email-masked]>
Date: Thu, 27 Jun 2002 16:39:05 +0200

Dr. Mullen

many thanks 
     dario

---

From: Rex Buddenberg <[email-masked]>
Date: Thu, 27 Jun 2002 10:33:02 -0700

>local detail to other routers.

John,

I find the database language appropriate for describing the problem. 
IP addresses are data structures that are not fully normalized.  IP 
addresses tell you two things, not one (which would be fully 
normalized):
   - identity
   - location (your point about hierarchical)

In the wired internet, you move to a new location, you get a new IP 
address.  Even though your identity is unchanged.

Mobile IP is one method for getting around that, but I think that 
Charlie would agree that that's not a thorough enough solution for 
MANETs of any scale.

-- 
b

---

From: Rex Buddenberg <[email-masked]>
Date: Thu, 27 Jun 2002 10:33:02 -0700

John,

-- 
b

---

From: Kuldip Singh Pabla <[email-masked]>
Date: Thu, 27 Jun 2002 11:17:24 -0700

Hi

Forgive me for my limited knowledge of this working group. I have been
following this discussion for the last few days and thought of
expressing my views and have questions.

IMO, adhocism is adhocism - its not planned or organized. For e.g. if I
become a part of a small group/conf./gathering in a pure adhoc manner
for a short while. Moreover, MANET is not trying to address Mobile IP.
Am I right!

o In this case, where would I get my permanent IP address from? 
o Moreover, Internet is already running out of IP addresses, so, how
would each and every 802.11 enabled device get its unique IP address?
o I agree with some of you that unlike a wired device, a MANET device is
mobile. So, an IP address is only serving as an Identity of the device
and not its location info. So, a virtual IP address or an ID could be
more meaningful than an IP address.
o Also, in a wired planet, its easier to detect address conflicts, in a
wireless world, it would be tough to detect a conflict. MANET may
already be addressing this issue, if so, I would be interested in
pointers to this info.

-Kuldip

-- 
Kuldip Singh Pabla
Peer-2-Peer Networking

---

From: Kuldip Singh Pabla <[email-masked]>
Date: Thu, 27 Jun 2002 11:17:24 -0700

Hi

-Kuldip

-- 
Kuldip Singh Pabla
Peer-2-Peer Networking

---

From: "Charles E. Perkins" <[email-masked]>
Date: Thu, 27 Jun 2002 11:40:35 -0700

Hello folks,

So little time just now ...

> for a short while. Moreover, MANET is not trying to address Mobile IP.

That would match my view.  Mobile IP requires infrastructure, and
manet does not.

> o In this case, where would I get my permanent IP address from?

Anywhere you like -- or, you may try to autoconfigure one according
to the IPv4 and/or IPv6 draft(s) that have been submitted.

> would each and every 802.11 enabled device get its unique IP address?

The abovementioned drafts offer solutions, but of course I would
suggest that the IPv6 version is better at offering enough addresses.

> more meaningful than an IP address.

But protocols work on bits, not meanings.

> already be addressing this issue, if so, I would be interested in

The conflict MAY be irrelevant for temporary addresses used in networks
that are never connected to each other or the Internet.

> > Charlie would agree that that's not a thorough enough solution for

What I would rather say is that Mobile IP can be used when there
is infrastructure, and mobile ad hoc networks need solutions for
cases when there is no infrastructure.  However, as it turns out,
the latter solution is still useful with Mobile IP if the ad hoc
network has connectivity to the Internet.

Regards,
Charlie P.

---

From: "Charles E. Perkins" <[email-masked]>
Date: Thu, 27 Jun 2002 11:40:35 -0700

Hello folks,

Regards,
Charlie P.