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

Ted Lemon <> Sat, 13 February 2021 00:04 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 5E16E3A111E for <>; Fri, 12 Feb 2021 16:04:15 -0800 (PST)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -1.899
X-Spam-Status: No, score=-1.899 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, HTML_MESSAGE=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Authentication-Results: (amavisd-new); dkim=pass (2048-bit key)
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id DcKh8c6PA7iN for <>; Fri, 12 Feb 2021 16:04:12 -0800 (PST)
Received: from ( [IPv6:2607:f8b0:4864:20::836]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 913FC3A111A for <>; Fri, 12 Feb 2021 16:04:12 -0800 (PST)
Received: by with SMTP id v3so997728qtw.4 for <>; Fri, 12 Feb 2021 16:04:12 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20150623; h=from:message-id:mime-version:subject:date:in-reply-to:cc:to :references; bh=Hi9fxhNPJrO88+I6PFZRcc95g+nzqQXy38Zc8qCwUhk=; b=acV8t012kqWaJemfd67hGUPQlkfpPtKbvhfkrsj90SvW0B99Z0WgdSwvWjFZBJ8s7k P56iwFc+8bwNm6n4k3srC0w88jqCmnqVz20htLuN3mVdNFh0s3w1Glv+V58jocwqB1dE p1mYlNGY1C4B4hU9H8HFtmO4uOV0cSvCXYpLO2Ii/gq2R5iNCHiZOOlyZETP5Gn5N65t ShgQEdOeKitgq/jiRcceaQ43ZwiP0pOsQzoYdI7Fpnr902tpq9TlCXKVoGePWh2LuOgB R+sT0Fn+jk+KAAsrmZRCEtef9DgnnilZ87nM1jwA5+arZFBWq7LJs23C0x9JYY1dtHcE 13nw==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20161025; h=x-gm-message-state:from:message-id:mime-version:subject:date :in-reply-to:cc:to:references; bh=Hi9fxhNPJrO88+I6PFZRcc95g+nzqQXy38Zc8qCwUhk=; b=L0g4TucdepFAs2q52jyrdFP0vWucgAcMHDoY4EIMD53FHpsKpyZyYe2G02yHX5IwWC PX/qwH7xZgUgwCuYLkB0oghvbp2PEiu7yU1X2R//7DVI+XFy+IRi1t8vT3U08CYkgimF l9uAoE4aPBc4lfon4g5Ohkuq0uvKyEkXEs+rp5x4q3zHDEyKdTyWsI3SpJ8cNytZx3lE NLGxGBq7Z/kpon8f+SEzXv5LS6M5WznnqMJV0/XlDwJ+NECYBMst+rAPjcUYnYduZ9p8 mTZ35phPEyLJaGQZE/mILCdTYFk3Qs0bG8QL54WV1djhusJY3ey9dmcSR5LllJwZbttA 03EA==
X-Gm-Message-State: AOAM5301bUtxsfHDS56Wmh/XL2bv/p6qCB8Yu9PH3jKAfRgCRNnhShtu dHk/bhzrxq3aFwjH50UzDCXZSw==
X-Google-Smtp-Source: ABdhPJwtVSwTZsu8SWGWuljKRc4lHeWYLdt/uAF6Is9LeHYFhdIl34DVm+ZJkYvsVijLOBilrycWbQ==
X-Received: by 2002:ac8:5ac9:: with SMTP id d9mr4774309qtd.123.1613174651547; Fri, 12 Feb 2021 16:04:11 -0800 (PST)
Received: from ( []) by with ESMTPSA id x64sm1147215qte.45.2021. (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 12 Feb 2021 16:04:10 -0800 (PST)
From: Ted Lemon <>
Message-Id: <>
Content-Type: multipart/alternative; boundary="Apple-Mail=_0E29A213-4D79-47FF-9941-DFF77BDBF6A5"
Mime-Version: 1.0 (Mac OS X Mail 14.0 \(3654.\))
Date: Fri, 12 Feb 2021 19:04:09 -0500
In-Reply-To: <>
Cc: Fred Baker <>, IPv6 Operations <>, "" <>
To: Fernando Gont <>
References: <> <> <> <> <> <>
X-Mailer: Apple Mail (2.3654.
Archived-At: <>
Subject: Re: [v6ops] Scope of Unique Local IPv6 Unicast Addresses (Fwd: New Version Notification for draft-gont-6man-ipv6-ula-scope-00.txt)
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: v6ops discussion list <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Sat, 13 Feb 2021 00:04:15 -0000

On Feb 12, 2021, at 6:50 PM, Fernando Gont <> wrote:
> This, in away, is the question that this document somewhat raises:
> * What's "global scope" anyway?

Global scope is “you can forward it to the default route.”

> * And, given what we have right now, either the definition of scope is flawed (as in the scoped addressing architecture), or ULAs are not global, or both. :-)

RFC 4007 has a concept of “interfaces belonging to a zone,” and has a nice diagram with several organizations that we might say is a non-overlapping Venn diagram. But ULAs don’t have to have a non-overlapping Venn diagram. So they are global. And indeed there is no way to automatically determine (without configuration) which zone any given address belongs to. So in effect the only two scopes that can be automatically determined are “link local” and “global.” There can be no other scope, in the sense of a scope that can be automatically determined.

This doesn’t mean that RFC 4007 is useless, but what it does mean is that when we assign a scope to “ULA,” the only scope that makes sense is “global.”

So maybe a better question to ask is, why are we discussing this? What problem are we trying to solve?