Subject: RE: DAD

From: "Bound, Jim" <[email-masked]>
Date: Tue, 17 May 2005 07:26:46 -0400

It should be done for normal commercial links and consumer networks
(houses) wired (fixed) and wireless (fixed).  The execution cost is not
that great in those networks for what one gets to verify EUI's are
unique.  But, for Mission Critical Secure Defense wireless Networks DAD
can be avoided if in fact the EUI's are guaranteed to be unique on such
devices, especially for MANETs. Some time soon I will post draft to
MANET or Autoconfig MANET work that depicts the use of pre-DAD, boot
operation of radio, and then post-DAD after boot operation of radio, and
that the post-DAD operation is not needed in some cases.  This would be
an implementation choice, and IPv6 addrconf standard is clear that DAD
is required. Thus, the risk of implementation of such a net would have
to assume interoperability and uniqueness of the EUI responsibility.
There is also Optimistic DAD that can be used for commercial mobile
devices on wireless networks, one should review and check.  But, today I
am aware of no implementations that do not implement DAD or have
implemented Optimistic DAD (but there are folks on this list that can
correct me if Optimistic DAD has been implemented???).

/jim

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]] On 
> Behalf Of giuseppe
> Sent: Tuesday, May 17, 2005 1:48 AM
> To: [email-masked]
> Subject: DAD
> 
> In IPv6 stateless address autoconfiguration, how is it 
> possible that the 
> generated address could be duplicated?
> The MAC that host appends to the link prefix is unique, isn't it?
> Replies appreciated
> G
> 
> -- 
> ----------------------
> ----------------------
> Giuseppe De Marco, Ph.D.
> 
> Dipartimento di Ingegneria 
> dell'Informazione e Ingegneria Elettrica
> DIIIE, University of Salerno
> via ponte don Melillo 1, Fisciano, Salerno
> tel: +39 089 964012
> email: [email-masked]
> 
> Department of Information and 
> Communication Engineering 
> Faculty of Information Engineering 
> Fukuoka Institute of Technology (FIT)
> 3-30-1 Wajiro-Higashi, Higashi-ku, Fukuoka 811-0295 
> Japan
> email: [email-masked]
> --------------------
> 
> 
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---

From: "Nick 'Sharkey' Moore" <[email-masked]>
Date: Wed, 18 May 2005 08:17:09 +1000

> correct me if Optimistic DAD has been implemented???).

Optimistic DAD is in the Standards Track queue now.
We implemented it for Linux as part of the development process, and
I'll make the patch available again soon ... I'm working on other
things until the IESG/etc comments come back, then I'll update the
patch and release.  Some vendors have expressed their interest in
implementing once it is nailed down in an RFC.

Linux, at least, can be set up to not run DAD very simply by setting
the DAD retransmits parameter to 0.  Whether this is a good idea is
another matter.

There's some discussion of the original poster's question in the
OptiDAD draft: see draft-ietf-ipv6-optimistic-dad-05.txt

cheers,

-----Nick