Date: Wed, 06 May 2009 16:55:51 -0700 From: JINMEI Tatuya / =?ISO-2022-JP?B?GyRCP0BMQEMjOkgbKEI=?= <Jinmei_Tatuya@isc.org> To: Bob Van Zant <bob@veznat.com> Cc: "freebsd-net@freebsd.org" <freebsd-net@freebsd.org> Subject: Re: IPv6 duplicate address detection Message-ID: <m2ljp9vla0.wl%Jinmei_Tatuya@isc.org> In-Reply-To: <C6276219.226C1%bob@veznat.com> References: <m2prelvqbr.wl%Jinmei_Tatuya@isc.org> <C6276219.226C1%bob@veznat.com>
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At Wed, 06 May 2009 15:49:45 -0700, Bob Van Zant <bob@veznat.com> wrote: > > 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): > We have a crude form of NIC pairing in our software. We allow someone to > logically pair two interfaces together. This is implemented by `ifconfig > down` both interfaces, configure them both the same, then `ifconfig up` the > primary interface. We then monitor the link state of the primary interface. > If the state goes to down, we `ifconfig down` the primary NIC and then > `ifconfig up` the secondary NIC. This has the effect of changing the link > layer address associated with a given IPv6 address. After we do this we send > out the unsolicited NA to update whatever switch we're plugged into. Okay, thanks for the explanation. But I still don't understand one thing: why is DAD triggered for the address on the secondary NIC? Unless someone has changed the code recently, the FreeBSD (KAME-derived) IPv6 stack shouldn't trigger DAD for an existing address simply because the interface becomes 'up' (this behavior may be debatable per se, but that's a different question). Did you perhaps make the address "tentative" by hand after configuring the address? --- JINMEI, Tatuya Internet Systems Consortium, Inc.
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