Subject: Duplicate address detection

From: Francis Dupont <[email-masked]>
Date: Fri, 19 May 2000 13:57:02 +0200

I need to know if you (mainly implementors) agree with this statement:
if the source address of a neighbor solicitation is the unspecified
address, this implies that the solicitation is from a node performing DAD
for the target address of the solicitation.

Regards

[email-masked]

PS: reference are RFC 2461 and 2462 (ND and autoconf).
PPS: the real question is to know if the procedure proposed in the
I-D 12 (last) about mobile IPv6 when a mobile returns at home and
doesn't know the link-layer address of the home agent is a DAD
or not.
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From: Mohan Parthasarathy <[email-masked]>
Date: Fri, 19 May 2000 11:03:09 -0700 (PDT)

> for the target address of the solicitation.
Agreed.  
> doesn't know the link-layer address of the home agent is a DAD
It will be considered as a DAD. Why can't the MN send out a
unsolicited neighbor advertisement with the over-ride flag
set so that everybody including the home agent can update
their caches ? If it is a proxy entry it could even delete
the entry. Then learning home agents link layer address
is simple.

-mohan

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From: Francis Dupont <[email-masked]>
Date: Sat, 20 May 2000 16:50:41 +0200

Agreed.  

=> I've looked at KAME sources and comments show KAME people should agree too.

   their caches ?

=> I can see two objections :
 - the home agent doesn't update its cache (ie this is not in the
   semantics of unsolicited/overriding NAs (*))
 - the mobile MUST send it after home deregistration (end of page 95)

If it is a proxy entry it could even delete the entry. Then learning
home agents link layer address is simple.

=> (*) there is a security issue there, home registration is authenticated
and should not be partially undone by a simple neighbor discovery packet.
I don't believe there is an agreement about changeing the proxy advertisement
mechanism in order to make this (overriding of proxy entries by a suitable NA)
works but I agree it is a simple solution...

Regards

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From: Mohan Parthasarathy <[email-masked]>
Date: Mon, 22 May 2000 18:21:41 -0700 (PDT)

>    semantics of unsolicited/overriding NAs (*))

RFC2461 section 7.2.6  does talk about unsolicited/overriding NAs.
Why would not the home agent update its cache entry ?

> works but I agree it is a simple solution...
Ok. If the mobile node solicits for the home agents link layer address
with a proper source address (not unspecified) i.e its home address,
why would the home agent consider it as a duplicate ? The draft
seems to mention that HA will consider it as a duplicate as it
is defending for the mobile node. But, unless the source is unspecified
this should not happen.

-mohan