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Date: Wed, 06 May 2009 15:06:48 -0700
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From: JINMEI Tatuya / =?ISO-2022-JP?B?GyRCP0BMQEMjOkgbKEI=?=
	<Jinmei_Tatuya@isc.org>
To: Bob Van Zant <bob@veznat.com>
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References: <C625D61C.224AD%bob@veznat.com>
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Cc: "freebsd-net@freebsd.org" <freebsd-net@freebsd.org>
Subject: Re: IPv6 duplicate address detection
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At Tue, 05 May 2009 11:40:12 -0700,
Bob Van Zant <bob@veznat.com> wrote:
> 
> I'm working on a piece of software that, among other things, allows an
> administrator to easily configure IPv6 interfaces on a FreeBSD host. I've
> run into a problem where whenever I reconfigure an interface with an IPv6
> address FreeBSD marks the new address as being a duplicate.
> 
> The problem is that I'm following RFC 2461 [1] in that I send an unsolicited
> neighbor advertisement to ff02::1 immediately after configuring the
> interface.

I'm afraid we need clarification first...what do you mean by
"reconfigure an interface with an IPv6 address"?  Do you mean adding a
new IPv6 address to an interface?  If so, I'm not sure why you
referred to the following part of RFC2461 (btw the RFC was updated by
RFC4861):

> [1] RFC 2461 section 7.2.6 paragraph 1:
> 
>    In some cases a node may be able to determine that its link-layer
>    address has changed (e.g., hot-swap of an interface card) and may
>    wish to inform its neighbors of the new link-layer address quickly.

this example talks about the case where the link-layer address changes
for an existing address, not where a new address is configured.

Could you elaborate?

---
JINMEI, Tatuya
Internet Systems Consortium, Inc.