Re: DHCPv6 address used when M or O bit is set

Karl Auer <> Wed, 04 April 2012 22:41 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id E7A7521F84FF for <>; Wed, 4 Apr 2012 15:41:51 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -1.999
X-Spam-Status: No, score=-1.999 tagged_above=-999 required=5 tests=[BAYES_00=-2.599, J_CHICKENPOX_21=0.6]
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id XYCNpu9Ep4Ki for <>; Wed, 4 Apr 2012 15:41:51 -0700 (PDT)
Received: from (unknown [IPv6:2001:44b8:8060:ff02:300:1:6:5]) by (Postfix) with ESMTP id 8189521F84F4 for <>; Wed, 4 Apr 2012 15:41:48 -0700 (PDT)
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-Anti-Spam-Result: ApIBANrMfE+WZX+7/2dsb2JhbAANOIVNtW4BAQEEI2YLGCoCAlcZsESRTo0rggyBGAShGYdz
Received: from (HELO []) ([]) by with ESMTP; 05 Apr 2012 08:11:45 +0930
Subject: Re: DHCPv6 address used when M or O bit is set
From: Karl Auer <>
In-Reply-To: <>
References: <> <>
Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"; boundary="=-1+KZZxJrI1uEvVbRsZ/e"
Date: Thu, 05 Apr 2012 08:41:38 +1000
Message-ID: <1333579298.11943.532.camel@karl>
Mime-Version: 1.0
X-Mailer: Evolution 2.30.3
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: "IPv6 Maintenance Working Group \(6man\)" <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Wed, 04 Apr 2012 22:41:52 -0000

On Wed, 2012-04-04 at 16:12 +0200, Fernando Gont wrote:
> I'm curious about why the corresponding text was removed. In particular
> when at the time (2007) the DNS options was not yet widely implemented,
> and hence you *needed* DHCPv6 to learn the addresses of recursive DNS
> servers dynamically.

Me too!

The RFC4862 says

   "Removed the text regarding the M and O flags, considering the
    maturity of implementations and operational experiences.
    ManagedFlag and OtherConfigFlag were removed accordingly. (Note
    that this change does not mean the use of these flags is

The only way I can interpret this is "people are doing whatever the hell
they like with these flags, and some of those implementations are pretty
well-established, so we are not going to try to define how the flags
should be used because no matter what we say, it will conflict with the
way someone out there is doing things. However, people should definitely
still use these flags! We aren't taking them away, we're just refusing
to define how they should be used."

It seems a strange thing to say, so maybe my interpretation is wrong :-)

Regards, K.

Karl Auer (

GPG fingerprint: AE1D 4868 6420 AD9A A698 5251 1699 7B78 4EEE 6017
Old fingerprint: DA41 51B1 1481 16E1 F7E2 B2E9 3007 14ED 5736 F687