Re: Objection to draft-ietf-6man-rfc4291bis-07.txt

David Farmer <farmer@umn.edu> Sat, 25 February 2017 20:40 UTC

Return-Path: <farmer@umn.edu>
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 9B230129535 for <ipv6@ietfa.amsl.com>; Sat, 25 Feb 2017 12:40:45 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -3.8
X-Spam-Level:
X-Spam-Status: No, score=-3.8 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_SORBS_SPAM=0.5, RP_MATCHES_RCVD=-0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=umn.edu
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 VKF6bcEHCZGa for <ipv6@ietfa.amsl.com>; Sat, 25 Feb 2017 12:40:43 -0800 (PST)
Received: from mta-p5.oit.umn.edu (mta-p5.oit.umn.edu [134.84.196.205]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id A0FDC1294DB for <ipv6@ietf.org>; Sat, 25 Feb 2017 12:40:43 -0800 (PST)
Received: from localhost (unknown [127.0.0.1]) by mta-p5.oit.umn.edu (Postfix) with ESMTP id 6D6CBC91 for <ipv6@ietf.org>; Sat, 25 Feb 2017 20:40:42 +0000 (UTC)
X-Virus-Scanned: amavisd-new at umn.edu
Received: from mta-p5.oit.umn.edu ([127.0.0.1]) by localhost (mta-p5.oit.umn.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id qBukuHSK44NO for <ipv6@ietf.org>; Sat, 25 Feb 2017 14:40:42 -0600 (CST)
Received: from mail-ua0-f197.google.com (mail-ua0-f197.google.com [209.85.217.197]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mta-p5.oit.umn.edu (Postfix) with ESMTPS id 2D381747 for <ipv6@ietf.org>; Sat, 25 Feb 2017 14:40:41 -0600 (CST)
Received: by mail-ua0-f197.google.com with SMTP id j56so29991190uaa.0 for <ipv6@ietf.org>; Sat, 25 Feb 2017 12:40:41 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=umn.edu; s=google; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=uhc9hoBcUXwaqC/2py7+JNpzuTrr/jJjbs6VwqJ7oD0=; b=Fcxh2B3hYDsLydbdW1H3wNwZHTGueSIzCmTo9FbHGaJX2vvo+Q9edLvF2dHRKMWb2C bxHsGUk5cp9vdyIbn86TzPKtHn2U0BO87SYu6V2cH7Iuo6s+C+InAeNFfy/mkW48Z199 oklmjcXv66fqENRCZGFIrLQrVu9tFpTDJmYxmrFl1rnkmyq8l9lCwQUyyPSMbKkLrhR9 d9pXp92zjj5mGwPW9z3T7fAN7B+Y9whs5Le6ZK8Mxk5P1Ovngd12FC2If5wPmVBqos+w XjbPPR2LyeUrJtnG64kuexy6g5DLYXok4gAzxaMJfyQTAItkc3E46PdugCekFj3GdNoP NQ3g==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=uhc9hoBcUXwaqC/2py7+JNpzuTrr/jJjbs6VwqJ7oD0=; b=FQc97I7jb6rtC1FCO0m9Ke76Gd0by7ekeVCSrgkEkEroS4FM+ex3yS/yQ2FPYvArpY FlBWRDGw5AP/H2fjq4yyYoLM44uK+Eu5pNmpxa5QcaIZELTsLqacvXCi2bvvwHKW/7lX AoCLME/WCmt4H+jJ1X89N477xMDLbqMealhkSF2Uo2uKEPVyR9fYnx13pKqUEFFhIs4M sYHvorrdJto3Z68f1kp5uY2IXgH5IF34Hb9D6HMAxjkACYINAJB0KyyojDCpPP1bgokg S57WpN48nl0CpZ1UwXoLSc+FSBSNukFdQnvnBXE5E5x9yaNUoQgJQIDq7tK9VeTneRi4 dBCA==
X-Gm-Message-State: AMke39nq+2WNyhWh2rugsc8V9//4a8vkBC2YMIhrlqdjXlBJHjdrxK/42P92pG1QxdtFR91JUYCEzXI6+rWHdP413hL5gEiELO/o/UEuq7ggw+jLkBqstD1PzVAP91m9krtRFlYkP9AovUEQIB0=
X-Received: by 10.176.6.10 with SMTP id f10mr3515952uaf.37.1488055241430; Sat, 25 Feb 2017 12:40:41 -0800 (PST)
X-Received: by 10.176.6.10 with SMTP id f10mr3515937uaf.37.1488055240819; Sat, 25 Feb 2017 12:40:40 -0800 (PST)
MIME-Version: 1.0
Received: by 10.103.89.71 with HTTP; Sat, 25 Feb 2017 12:40:40 -0800 (PST)
In-Reply-To: <de4988be-6031-08d9-84ce-21c3fa4f9bc9@gmail.com>
References: <20170223134026.GI5069@gir.theapt.org> <9277BC0B-04F3-4FC1-901E-F83A8F0E02D7@google.com> <58AF6429.70809@foobar.org> <902276E9-0521-4D4E-A42B-C45E64763896@google.com> <58AF726A.3040302@foobar.org> <F7C230DE-4759-4B78-ABF2-6799F85B3C62@google.com> <58B014F6.2040400@foobar.org> <6DA95097-8730-4353-A0C9-3EB4719EA891@google.com> <CAN-Dau0s04c=RV0Y8AGaxBPFui41TWPTB+5o0K2Lj-iah0An1w@mail.gmail.com> <CAL9jLaYirty22iGiEjEaYq3_KA1FZhxBTOBWuFOXQ9C-WPd5xQ@mail.gmail.com> <CAN-Dau0n6oFm538XdJOcuO1yg92BCDD3mBu5YfBVm_+g-gtcKA@mail.gmail.com> <CAL9jLaYO=uYgVfSZ0SoSe0SujJ1xgwEKE8WLzo_keJHywgXTtg@mail.gmail.com> <CAN-Dau1vJV5O_Ythp6THkAu4-YZXV82Upny1V+ybbjCVZQQX=A@mail.gmail.com> <27cce319-18ac-5c0e-3497-af92344f0062@gmail.com> <de4988be-6031-08d9-84ce-21c3fa4f9bc9@gmail.com>
From: David Farmer <farmer@umn.edu>
Date: Sat, 25 Feb 2017 14:40:40 -0600
Message-ID: <CAN-Dau0fq9eU71Od3oq9DRq1qLLMqiW-gr-oxgkc46Xo6hjE+Q@mail.gmail.com>
Subject: Re: Objection to draft-ietf-6man-rfc4291bis-07.txt
To: Brian E Carpenter <brian.e.carpenter@gmail.com>
Content-Type: multipart/alternative; boundary="94eb2c122e6c092d5a054960dc07"
Archived-At: <https://mailarchive.ietf.org/arch/msg/ipv6/N-BnwML0CX_0bDrXr72LsW9Dr10>
Cc: Alexandre Petrescu <alexandre.petrescu@gmail.com>, 6man WG <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: Sat, 25 Feb 2017 20:40:45 -0000

On Sat, Feb 25, 2017 at 1:15 PM, Brian E Carpenter <
brian.e.carpenter@gmail.com> wrote:

> On 25/02/2017 23:02, Alexandre Petrescu wrote:
> ...
> > I would agree if I read "/64 was RECOMMENDED in the past".
>
> That would be a lie, since until now it was 'required' in the text.
>
> > I would not agree if I read "/64 is NOT RECOMMENDED".
>
> But nobody is suggesting that (in RFC 2119 it is equal to SHOULD NOT).
>
> > I would not agree if I read "/64 is RECOMMENDED".
>
> There I think you are wrong. It is the value that today allows portable
> interoperable host software (on IEEE 802.1 or 802.11 media) so it is, in
> fact, the only plausible default that we can suggest. 'Recommended' leaves
> plenty of space that 'required' does not.
>
>     Brian
>

So we can't simply say "/64 subnet prefixes are RECOMMENDED" or "64 bit
IIDs are REQUIRED", depending on the context of the discussion it is
actually both.

I think we are trying to say 64 is the default subnet prefix length and IID
length, and should be used most of the time, and other non-64 subnet prefix
lengths and IID lengths can be use when necessary in special cases.
However, 64 can only be an effective default, if every implementation of
IPv6 actually supports it.

Therefore, "/64 subnet prefixes are operationally RECOMMENDED" and "all
implementations of IPv6 are REQUIRED to support 64 bit IIDs".

What Chris and I were discussing is what is the proper statement about
non-64 subnet prefix lengths and IID lengths?  I don't think non-64
lengths can be "REQUIRED" because some implementations of IPv6 only support
64 as the subnet prefix length and IID length.  This is not right or wrong,
it is just a fact we have to live with. So that leaves either "OPTIONAL" or
"RECOMMENDED" for support of non-64 lengths.  I started with "OPTIONAL" but
said I'd consider "RECOMMENDED".

Thinking about this a bit more; I think the non-64 lengths should be
"OPTIONAL for host implementations of IPv6 to support", "RECOMMENDED for
router implementations of IPv6 to support", "operational use of /127 subnet
prefixes for point-to-point router links is RECOMMENDED", and by
implication, but doesn't need to be said explicitly, the operational use of
other non-64 lengths is NOT RECOMMENDED, but not prohibited or limited in
any way either.

Thanks.

-- 
===============================================
David Farmer               Email:farmer@umn.edu
Networking & Telecommunication Services
Office of Information Technology
University of Minnesota
2218 University Ave SE        Phone: 612-626-0815
Minneapolis, MN 55414-3029   Cell: 612-812-9952
===============================================