Subject: IP address autoconfiguration

From: "Charles E. Perkins" <[email-masked]>
Date: Sat, 12 Feb 2000 16:06:38 -0800

Hello,

The subject of address autoconfiguration has come up in the past
on this mailing list.  I am wondering whether there would be any
problem with using the zerconf approach, of just having a node
pick at random an address from the class B network prefix 169.254/16
(don't sue me if that's not exactly the right number, I don't have
the document here).  The node would, of course, have to check that
no one was using the address, but that could be done by the simple
method of sending a RREQ for the randomly chosen IP address.

In general, I think that RREQ/RREP replaces ARP in ad hoc
networks (at least it should with AODV).  And, similarly, it
should replace DAD (Duplicate Address Detection) for IPv6
ad hoc networks.

Unless there is some problem with this, I will write this up
as an explicit provision for AODV.  It seems almost trivial,
as long as we don't go into security or DNS update issues.

Regards,
Charlie P.

---

From: Laura Feeney <[email-masked]>
Date: Sun, 13 Feb 2000 23:56:38 +0100

Hello,

I am wondering whether there might be an issue in the case where two
manets, each with its own set of unique addresses, come into contact.
One way this could happen - even within a single "administrative
manet" - is a temporary partition and subsequent address assignments
in the new sub-manets.  (If two *independent* 50-node manet's combine,
the odds of a collision are about 4%.)

Perhaps the zeroconf approach is intended more for the case where
nodes join a network (169.254/16)?  I don't think the multi-segment
zeroconf draft gives you much help, as it assumes that there is one
true router (192.168/16) to assign addresses.  

If it is necessary to reconfigure a node's IP address to correct a
duplication, you may also need to be a little careful specifying how
routing table entries pointing to the node that no longer has the
address are cleaned up.  (Maybe both nodes should relinquish the
address?)

Unfortunately, I don't have a more helpful suggestion.

Best regards,
Laura

>>>>> "Charles E. Perkins" <[email-masked]> writes:

Charles> Hello,

Charles> The subject of address autoconfiguration has come up in the
Charles> past on this mailing list.  I am wondering whether there
Charles> would be any problem with using the zerconf approach, of just
Charles> having a node pick at random an address from the class B
Charles> network prefix 169.254/16 (don't sue me if that's not exactly
Charles> the right number, I don't have the document here).  The node
Charles> would, of course, have to check that no one was using the
Charles> address, but that could be done by the simple method of
Charles> sending a RREQ for the randomly chosen IP address.

Charles> In general, I think that RREQ/RREP replaces ARP in ad hoc
Charles> networks (at least it should with AODV).  And, similarly, it
Charles> should replace DAD (Duplicate Address Detection) for IPv6 ad
Charles> hoc networks.

Charles> Unless there is some problem with this, I will write this up
Charles> as an explicit provision for AODV.  It seems almost trivial,
Charles> as long as we don't go into security or DNS update issues.

Charles> Regards, Charlie P.

-- 
Laura Marie Feeney				[email-masked]
Visiting Researcher				http://www.sics.se/
Computer and Network Architectures Lab	 	Tel: +46 8 633 15 09 
Swedish Institute of Computer Science		Mobile: +46 70 246 56 63     
Box 1263, SE-164 29 KISTA, SWEDEN		Fax: +46 8 751 72 30

---

From: Miguel Sanchez <[email-masked]>
Date: Mon, 14 Feb 2000 13:56:43 +0100

Hi,

What we want is automatic IP configuration of network nodes. Don't we?
However, just a challenge/response to determine if a randomly generated
IP address (in the proper range, I'm not suing anybody :) can only be
successful if we can guarantee that ad-hoc network is not partition at
the moment you send the RREQ for cheching nobody is using this new
address.

So I think this could be a risky approach that could lead, sometimes, to
duplicate addresses.

However,  I don't have a better idea.

Kind regards,

Miguel Sanchez

--
Miguel Sanchez Lopez                            |       [email-masked]
Universidad Politecnica de Valencia             | voice:+3496 387 9700
Camino de Vera, 14                              | fax:  +3496 387 7579
46071 VALENCIA (Spain)                          |