Re: [v6ops] A proposal for draft-ietf-6man-rfc4291bis-07 - interpretations of the "sum"

Fernando Gont <fgont@si6networks.com> Tue, 07 March 2017 17:11 UTC

Return-Path: <fgont@si6networks.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 5A191129533 for <ipv6@ietfa.amsl.com>; Tue, 7 Mar 2017 09:11:18 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.9
X-Spam-Level:
X-Spam-Status: No, score=-1.9 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id bnIEh91PZzrE for <ipv6@ietfa.amsl.com>; Tue, 7 Mar 2017 09:11:16 -0800 (PST)
Received: from fgont.go6lab.si (fgont.go6lab.si [IPv6:2001:67c:27e4::14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 589BD1294EA for <ipv6@ietf.org>; Tue, 7 Mar 2017 09:11:16 -0800 (PST)
Received: from [192.168.3.83] (unknown [181.165.116.69]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by fgont.go6lab.si (Postfix) with ESMTPSA id 1945E8033A; Tue, 7 Mar 2017 18:11:11 +0100 (CET)
Subject: Re: [v6ops] A proposal for draft-ietf-6man-rfc4291bis-07 - interpretations of the "sum"
To: Sander Steffann <sander@steffann.nl>, Alexandre Petrescu <alexandre.petrescu@gmail.com>
References: <CAN-Dau17q_BrUuzfvB1mLDt6p5UxYikphWaHpa8VQ2L-3kx-DA@mail.gmail.com> <ABE47051-FBFC-460F-89B0-FFD451410F7B@google.com> <m1cjviu-0000EYC@stereo.hq.phicoh.net> <5BC57F0E-50FD-4452-853F-A08291C91EB1@google.com> <m1ck5mu-0000GaC@stereo.hq.phicoh.net> <5B4AFF50-8CA9-4134-8CE2-A383DB5F8BF5@google.com> <m1ckxfo-0000IMC@stereo.hq.phicoh.net> <225F639E-27C1-4408-BC2B-26500929049B@google.com> <CAOSSMjUR203+hYFBrFBrj9Xkjux3o7fYNd4y9kNyxwpLxF11ew@mail.gmail.com> <6D825351-7F43-4540-89AB-48DC2B5E92E3@google.com> <CAOSSMjUP6m-L1iNhE=BxHW+7hvt4YsZgxxtVn+qmgEVS9HeStA@mail.gmail.com> <CAJE_bqfpE-NWwG12S4CXM+ZnHdHHH31-y+_+pYhuCuq2FtqZ4w@mail.gmail.com> <6f532a72-a142-5d84-f351-c38cba5230d! d@gmail.c om> <5773AF65-4E7E-43B6-BCB1-26F6E9CD3C60@steffann.nl! > <fdc3fa b6-fdcb-f390-e6ea-d9e49edacf52@gmail.com> <7A10E8D9-02F4-4D1C-B422-86ACCAABCB38@steffann.nl> <b86627e7-3668-304f-f1 2e-71ad3bfd6f7a@gmail.com> <1F674D50-1C89-444C-A617-C528951F80EC@steffann.nl>
From: Fernando Gont <fgont@si6networks.com>
X-Enigmail-Draft-Status: N1110
Message-ID: <e250c3a9-083f-01ea-8361-b42f8d20d730@si6networks.com>
Date: Tue, 7 Mar 2017 13:51:19 -0300
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0
MIME-Version: 1.0
In-Reply-To: <1F674D50-1C89-444C-A617-C528951F80EC@steffann.nl>
Content-Type: text/plain; charset=windows-1252
Content-Transfer-Encoding: 7bit
Archived-At: <https://mailarchive.ietf.org/arch/msg/ipv6/sU4wYcZn2_zqhh0aQBQEs-Fm5oI>
Cc: ipv6@ietf.org
X-BeenThere: ipv6@ietf.org
X-Mailman-Version: 2.1.17
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: <https://mailarchive.ietf.org/arch/browse/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: Tue, 07 Mar 2017 17:11:18 -0000

On 03/07/2017 01:38 PM, Sander Steffann wrote:
> Hi,
> 
>>> In step 3 the N rightmost bits of that are overwritten with the
>>> N-bits-long IID.
>>
>> YEs, that covers the 64bit rightmost part.  But that does not say what
>> to put between /10 and /64.
> 
> Yes it does. In whatever way you read it those bits contain 0.

Fully agreed.

That aside, when you learn link-locals via some APIs in BSDs, you'll
find that some of such bits are non-zero -- that's because they leverage
the requirement for them to be zero, and use such bits to store e.g. the
interface index. (it was one of my WTH moments when coding tools :-) ).

Thanks!

Cheers,
-- 
Fernando Gont
SI6 Networks
e-mail: fgont@si6networks.com
PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492