From owner-freebsd-net@FreeBSD.ORG Thu May 7 00:18:02 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 1D9801065673 for ; Thu, 7 May 2009 00:18:02 +0000 (UTC) (envelope-from bob@veznat.com) Received: from mail.ttora.com (mail.ttora.com [208.75.243.236]) by mx1.freebsd.org (Postfix) with ESMTP id C7C0B8FC0C for ; Thu, 7 May 2009 00:18:01 +0000 (UTC) (envelope-from bob@veznat.com) DomainKey-Signature: s=two; d=veznat.com; c=nofws; q=dns; h=X-MID:X-IronPort-AV:X-IronPort-AV:Received:User-Agent: Date:Subject:From:To:CC:Message-ID:Thread-Topic: Thread-Index:In-Reply-To:Mime-version:Content-type: Content-transfer-encoding; b=Xpwmvkqj0ug3HmC+B1OGuK3MLfM/Iom7XUVpqNx5JT+ThThl+HjPbu3c 4xRH4sr6DCEaSTMph8oXJQ8/pYBgb4b+OrNY4deIjYK1FE4fU02GkI7n6 6firoHSf2nGmqiq45Sz0+LtKK4FJEpDOk6D3+xeR6Jx4QKJze5VlhfALq 8=; DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=veznat.com; i=bob@veznat.com; q=dns/txt; s=one; t=1241655482; x=1273191482; h=from:sender:reply-to:subject:date:message-id:to:cc: mime-version:content-transfer-encoding:content-id: content-description:resent-date:resent-from:resent-sender: resent-to:resent-cc:resent-message-id:in-reply-to: references:list-id:list-help:list-unsubscribe: list-subscribe:list-post:list-owner:list-archive; z=From:=20Bob=20Van=20Zant=20|Subject:=20R e:=20IPv6=20duplicate=20address=20detection|Date:=20Wed, =2006=20May=202009=2017:17:52=20-0700|Message-ID:=20|To:=20=20JINMEI=20Tatuya=20/ =20=3D?ISO-2022-JP?B?GyRCP0BMQEMjOkgbKEI=3D?=3D=0D=0A=20< Jinmei_Tatuya@isc.org>|CC:=20"freebsd-net@freebsd.org"=20 |Mime-version:=201.0 |Content-transfer-encoding:=207bit|In-Reply-To:=20; bh=xvHCEu4ir8SNO2hQmSK2olYLxy3AJGQdGXLM1dyQw4M=; b=j0HmI0rhnQFrGs1DWMTJdEmNAlSWYlleag3yzhXSb/gmGtV0frY7ge/f fJJ0q5RvpoXBzc1l1osNLURc8u3yHFGlkpTkZddvbKWEoCRZ7aRKW6Vys qdFQujB5GZ41O7SGQggAHp/s+BQYdUhj4amI0q/FUQt2qjKjEO/M0e8JH s=; X-MID: 1017051 X-IronPort-AV: E=McAfee;i="5300,2777,5607"; a="1017051" X-IronPort-AV: E=Sophos;i="4.40,305,1239001200"; d="scan'208";a="1017051" Received: from nat.ironport.com (HELO [173.37.10.6]) ([63.251.108.100]) by mail.ttora.com with ESMTP/TLS/DES-CBC3-SHA; 06 May 2009 17:17:56 -0700 User-Agent: Microsoft-Entourage/12.12.0.080729 Date: Wed, 06 May 2009 17:17:52 -0700 From: Bob Van Zant To: JINMEI Tatuya / =?ISO-2022-JP?B?GyRCP0BMQEMjOkgbKEI=?= Message-ID: Thread-Topic: IPv6 duplicate address detection Thread-Index: AcnOqUKpin67QKJAakqfrjpw4WmQmw== In-Reply-To: Mime-version: 1.0 Content-type: text/plain; charset="ISO-2022-JP" Content-transfer-encoding: 7bit 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: Thu, 07 May 2009 00:18:02 -0000 I never actually tested the NIC pairing scenario and was only testing the naive "add a new IP, fire off an unsolicited NA for that IP." I did just test the NIC pairing and you are right, if the interface is down when it is configured we don't run DAD. Which does seem weird but that would be a different thread. I guess that changes my question quite a bit. If you randomly fire off an unsolicited NA right after configuring an interface should that cause a DAD failure? -Bob On 5/6/09 4:55 PM, "JINMEI Tatuya / 神明達哉" wrote: > 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.