Re: Feedback on draft-gont-6man-stable-privacy-addresses-01 (was: Re: Consensus call on adopting:....)

Washam Fan <washam.fan@gmail.com> Sat, 14 April 2012 06:25 UTC

Return-Path: <washam.fan@gmail.com>
X-Original-To: ipv6@ietfa.amsl.com
Delivered-To: ipv6@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 4311C21F8666 for <ipv6@ietfa.amsl.com>; Fri, 13 Apr 2012 23:25:03 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -3.599
X-Spam-Level:
X-Spam-Status: No, score=-3.599 tagged_above=-999 required=5 tests=[BAYES_00=-2.599, RCVD_IN_DNSWL_LOW=-1]
Received: from mail.ietf.org ([12.22.58.30]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id PzIOvQVfZLVv for <ipv6@ietfa.amsl.com>; Fri, 13 Apr 2012 23:25:02 -0700 (PDT)
Received: from mail-wg0-f44.google.com (mail-wg0-f44.google.com [74.125.82.44]) by ietfa.amsl.com (Postfix) with ESMTP id 4072621F8664 for <ipv6@ietf.org>; Fri, 13 Apr 2012 23:24:45 -0700 (PDT)
Received: by wgbdr13 with SMTP id dr13so2508236wgb.13 for <ipv6@ietf.org>; Fri, 13 Apr 2012 23:24:44 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=CMullx28O4fcUsZL3SRIAF7ORsRmUJ0TrAWRTysl87I=; b=h8/kBMXiCKSPct9TKvC4XI5LhJolfwYaH62Iw6Ypc2Zp7y0WS1Zzma5pBBDkHFZMls wSKylE79HxDGmH5JRJLuPIteC0lMG4s6nP1fdd1jIo2mBQdC58j1IjLzuDHR1+3wQbYL oxGqk9MS5VXDe18qOrC5l4ui6HosahfI/QG1t6HMEFFExBTqYyenW4mq10nwQIMI/Jl9 W6F3UuT/SMrOlyozAJzDH3gdjw2Mspt5Hnt+urkWhtqKIvahSrMMECS7VvTVAgTwVhHD AsydP2liWyXl9M0fi6nYKMX40Ncrt7kr1GTVscemSYEANylwfsE9ojYE2WEBosdEal7H K+Ng==
MIME-Version: 1.0
Received: by 10.180.102.129 with SMTP id fo1mr2116123wib.6.1334384684300; Fri, 13 Apr 2012 23:24:44 -0700 (PDT)
Received: by 10.216.191.41 with HTTP; Fri, 13 Apr 2012 23:24:44 -0700 (PDT)
In-Reply-To: <1334363774.3945.541.camel@karl>
References: <E7607B61-9889-43A9-B86B-133BD4238BA2@gmail.com> <1334276068.3945.408.camel@karl> <4F882A44.3080305@si6networks.com> <1334363774.3945.541.camel@karl>
Date: Sat, 14 Apr 2012 14:24:44 +0800
Message-ID: <CAAuHL_BCv2q=hDjTLmiviLoRRTbbyU+aSSQ0ETbDDQk==YfmLQ@mail.gmail.com>
Subject: Re: Feedback on draft-gont-6man-stable-privacy-addresses-01 (was: Re: Consensus call on adopting:....)
From: Washam Fan <washam.fan@gmail.com>
To: Karl Auer <kauer@biplane.com.au>
Content-Type: text/plain; charset="ISO-8859-1"
Cc: ipv6@ietf.org
X-BeenThere: ipv6@ietf.org
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: "IPv6 Maintenance Working Group \(6man\)" <ipv6.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/ipv6>, <mailto:ipv6-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/ipv6>
List-Post: <mailto:ipv6@ietf.org>
List-Help: <mailto:ipv6-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/ipv6>, <mailto:ipv6-request@ietf.org?subject=subscribe>
X-List-Received-Date: Sat, 14 Apr 2012 06:25:03 -0000

Hi,

>> > 5: Duplicate address detection is not mentioned explicitly, but probably
>> > should be - what happens if a host does DAD and determines that its
>> > stable address is already in use?
>>
>> Address configuration fails.
>
> That should be in the spec.
>
>> That said, if deemed appropriate, one could include one additional byte,
>> "DAD" in the hash function, which is initialized to 0, and that is
>> incremented by 1 if the host wants to try a different address if/when
>> DAD fails.
>>
>> If we do that, the implementations should probably cache the resulting
>> address, such that it is stable. (otherwise the resulting address might
>> change if the same node was brought up while the node with the
>> conflicting address is off).
>
> This may not be possible on systems with no onboard storage, and makes
> things much more complicated.

+1. And the storage or filesystem could have been damaged.

> I suggest that if DAD fails, then
> autoconfiguration should just fail (at least as regards stable
> addresses).
>
So what is the next step if the autoconfiguration fails? static
configure? If yes. Will the next reboot try autoconfiguration again?
If yes, you may have non-stable addresses within the same network. If
no, when you move to another network you should explicitly revoke the
static configuration and enable autoconfiguration again.

I think the author should clarify this DAD failure issue in the next version.

THanks,
washam