From owner-freebsd-net@FreeBSD.ORG Wed May 6 23:55:53 2009 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 0AC641065670 for ; Wed, 6 May 2009 23:55:53 +0000 (UTC) (envelope-from Jinmei_Tatuya@isc.org) Received: from mon.jinmei.org (mon.jinmei.org [IPv6:2001:4f8:3:36::162]) by mx1.freebsd.org (Postfix) with ESMTP id CEE598FC23 for ; Wed, 6 May 2009 23:55:51 +0000 (UTC) (envelope-from Jinmei_Tatuya@isc.org) Received: from jmb.jinmei.org (unknown [IPv6:2001:4f8:3:bb:217:f2ff:fee0:a91f]) by mon.jinmei.org (Postfix) with ESMTP id A80E233C5B; Wed, 6 May 2009 16:55:51 -0700 (PDT) Date: Wed, 06 May 2009 16:55:51 -0700 Message-ID: From: JINMEI Tatuya / =?ISO-2022-JP?B?GyRCP0BMQEMjOkgbKEI=?= To: Bob Van Zant In-Reply-To: References: User-Agent: Wanderlust/2.14.0 (Africa) Emacs/22.1 Mule/5.0 (SAKAKI) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Cc: "freebsd-net@freebsd.org" Subject: Re: IPv6 duplicate address detection X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 06 May 2009 23:55:54 -0000 At Wed, 06 May 2009 15:49:45 -0700, Bob Van Zant 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.