Re: [v6ops] Scope of Unique Local IPv6 Unicast Addresses (Fwd: New Version Notification for draft-gont-6man-ipv6-ula-scope-00.txt)

Fernando Gont <fgont@si6networks.com> Sat, 13 February 2021 16:21 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 E465A3A0DE4; Sat, 13 Feb 2021 08:21:51 -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, NICE_REPLY_A=-0.001, SPF_HELO_NONE=0.001, 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 Zooglzivo9VK; Sat, 13 Feb 2021 08:21:48 -0800 (PST)
Received: from fgont.go6lab.si (fgont.go6lab.si [91.239.96.14]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 0A9353A0DDE; Sat, 13 Feb 2021 08:21:47 -0800 (PST)
Received: from [IPv6:2800:810:464:2b9:1c77:acfc:e6a8:1311] (unknown [IPv6:2800:810:464:2b9:1c77:acfc:e6a8:1311]) (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 26AEE2801BB; Sat, 13 Feb 2021 16:21:42 +0000 (UTC)
Subject: Re: [v6ops] Scope of Unique Local IPv6 Unicast Addresses (Fwd: New Version Notification for draft-gont-6man-ipv6-ula-scope-00.txt)
To: Ted Lemon <mellon@fugue.com>
Cc: IPv6 Operations <v6ops@ietf.org>, "6man@ietf.org" <6man@ietf.org>
References: <160989494094.6024.7402128068704112703@ietfa.amsl.com> <6fe3a45e-de65-9f88-808d-ea7e2abdcd16@si6networks.com> <F4E00812-E366-4520-AE17-7BB46E28D575@gmail.com> <CAN-Dau3iOjjU+FLpdtA7nqfKRX+sjjSanAU8U-O3pH-k5nSoig@mail.gmail.com> <a3fbfb94-90ae-961c-a2ab-33ade27e074e@si6networks.com> <5D1FBC37-1024-4300-AFA5-19F329E9F1D1@fugue.com>
From: Fernando Gont <fgont@si6networks.com>
Message-ID: <0bf57925-fb85-7af8-32ce-e2adb2d3226a@si6networks.com>
Date: Sat, 13 Feb 2021 13:09:43 -0300
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.1
MIME-Version: 1.0
In-Reply-To: <5D1FBC37-1024-4300-AFA5-19F329E9F1D1@fugue.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Archived-At: <https://mailarchive.ietf.org/arch/msg/ipv6/d5Qj2wyPN9zhtvirxW8NRu7GOZw>
X-BeenThere: ipv6@ietf.org
X-Mailman-Version: 2.1.29
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, 13 Feb 2021 16:21:52 -0000

Hi, Ted,

On 13/2/21 11:54, Ted Lemon wrote:
> On Feb 13, 2021, at 4:19 AM, Fernando Gont <fgont@si6networks.com 
> <mailto:fgont@si6networks.com>> wrote:
>> Well, whether we call it out or not, as per RFC4007:
>>
>>              scope(LL) < scope(ULA) < scope(GUA)
>>
>> So it's more about acknowledging facts than about introducing or 
>> needing a new scope.  The same applies to the addresses you mentioned 
>> before.
> 
> No. scope(LL) < scope(ULA) and scope(LL) < scope(GUA) but scope(ULA) ? 
> scope(GUA). That is, any particular ULA may or may not be global in scope.


  [RFC4007] defines the scope of an address as:

       "[the] topological span within which the address may be used as a
       unique identifier for an interface or set of interfaces"


You cannot attest that any ULA is globally unique. They are randomized, 
in a de-centralized manner, without any sort of coordination (i.e., no 
global registry).

If they were "global scope", the "topological span" would be "the 
Internet". And when you compute the birthday paradoz for *all* ULA-based 
networks in the Internet, you actually get sort of a guarantee that your 
prefix is being used elsewhere.




> The problem with admin scope is that it’s not a definitional scope, but 
> rather an operational scope.

But it still plays nicely with the above definition of scope....



> Which may be the problem—we are using the 
> term “scope” when that’s not specific enough—we could mean “by 
> definition” or “in practice” scope, but we aren’t making that clear. 

The definition of scope (and of global scope) are quite clear in 
RFC4007: "uniqueness of the address in the topological span that 
represents the scope"

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