IETF Logo Mail Archive

[IPv6]Re: [v6ops] Re: New draft: "The IPv6 Loopback Address Prefix"

Gert Doering <gert@space.net> Wed, 26 November 2025 09:06 UTC

Return-Path: <gert@space.net>
X-Original-To: ipv6@mail2.ietf.org
Delivered-To: ipv6@mail2.ietf.org
Received: from localhost (localhost [127.0.0.1]) by mail2.ietf.org (Postfix) with ESMTP id 876D690ECA43 for <ipv6@mail2.ietf.org>; Wed, 26 Nov 2025 01:06:31 -0800 (PST)
X-Virus-Scanned: amavisd-new at ietf.org
X-Spam-Flag: NO
X-Spam-Score: -2.1
X-Spam-Level:
X-Spam-Status: No, score=-2.1 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001] autolearn=unavailable autolearn_force=no
Authentication-Results: mail2.ietf.org (amavisd-new); dkim=pass (2048-bit key) header.d=space.net
Received: from mail2.ietf.org ([166.84.6.31]) by localhost (mail2.ietf.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id zo4diU_3jrjj for <ipv6@mail2.ietf.org>; Wed, 26 Nov 2025 01:06:31 -0800 (PST)
Received: from gatekeeper3-relay.space.net (gatekeeper3-relay.space.net [IPv6:2001:608:3:85::43]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail2.ietf.org (Postfix) with ESMTPS id E0C3090ECA1B for <ipv6@ietf.org>; Wed, 26 Nov 2025 01:06:30 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=space.net; i=@space.net; q=dns/txt; s=esa; t=1764147991; x=1795683991; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=8uSxUwa/DxA0LVZjZYqYHWI6ip7O0QcLmQYp3ZWnTWk=; b=A/Jb5Js9wA98+CJvdeUzgm9xF7rR+bM9KXgiiu5CaROSwWOvOJM7QiCE kPzODVRu/HkkjJMStLEuvnpNvwgW/jL5jwfLisIpOrS07gYl2sTmSjDd7 TrMdN65+K6AOxtoRxTgIYmNs6P4G70Y/PPRbnS0pLDdzdpISNnab1zVfI BGzUUMoJ12PDQCkwjwB9WqNqhbWaj4a1B5yey9d+NWhT5RFXdhmJkLNfG VdOwy+Qrgm+29USKRR+17b7CF/jMRiCge+vH5BnBVxIgihx9xu2gAcBkT 8n7WCoCVzEaks43hAZ06YhXAjZHKS36azu/eH9NTfabNYdWUKEBQlRnoK g==;
X-CSE-ConnectionGUID: MfXiYgApSZKWzYVUJUOWJg==
X-CSE-MsgGUID: Nl3xcHCaTp21aPgyilV8Dg==
X-SpaceNet-SBRS: None
Received: from mobil.space.net ([195.30.115.67]) by gatekeeper3-relay.space.net with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Nov 2025 10:06:19 +0100
X-Original-To: ipv6@ietf.org
Received: from mobil.space.net (localhost [IPv6:::1]) by mobil.space.net (Postfix) with ESMTP id 6AB10181B165 for <ipv6@ietf.org>; Wed, 26 Nov 2025 10:06:19 +0100 (CET)
X-SpaceNet-Relay: true
Received: from moebius6.space.net (moebius6.space.net [IPv6:2001:608:2:2::251]) by mobil.space.net (Postfix) with ESMTP id 50D51181054E; Wed, 26 Nov 2025 10:06:19 +0100 (CET)
Received: by moebius6.space.net (Postfix, from userid 1007) id 4EBDA65B14; Wed, 26 Nov 2025 10:06:19 +0100 (CET)
Date: Wed, 26 Nov 2025 10:06:19 +0100
From: Gert Doering <gert@space.net>
To: Mark Smith <markzzzsmith@gmail.com>
Message-ID: <aSbDC6wo80tmRmZ2@Space.Net>
References: <CAHw9_i+b=uZozstCAm1Kr52Pj-_Y_aCndHc0e703rMUr9va=iA@mail.gmail.com> <CAO42Z2xsGuZ+5V8SadxRRkeeL7owm35F9MO8owAcWwfi9Q6nFw@mail.gmail.com> <F04C4F2A-C664-4B68-875B-C4C6CF3B6C64@gmail.com> <CAO42Z2x85B3Cn87QZQqhDef28Pfp_ukWqNO71Ucg=Jyut_NEkA@mail.gmail.com> <aSaruUCUeKMEa-I_@Space.Net> <CAO42Z2wZKaY8pcpgByyDcr=+59OhbO=fVsdLzdivwF+CnK0nqA@mail.gmail.com>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="vIevsz1FxRRMjjV0"
Content-Disposition: inline
In-Reply-To: <CAO42Z2wZKaY8pcpgByyDcr=+59OhbO=fVsdLzdivwF+CnK0nqA@mail.gmail.com>
Message-ID-Hash: KPHRCJOUG2RCXFUPUSWLWVII75QU7AYI
X-Message-ID-Hash: KPHRCJOUG2RCXFUPUSWLWVII75QU7AYI
X-MailFrom: gert@space.net
X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; header-match-ipv6.ietf.org-0; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header
CC: Gert Doering <gert@space.net>, Geoff Huston <gih902@gmail.com>, IPv6 <ipv6@ietf.org>, IPv6 Operations <v6ops@ietf.org>
X-Mailman-Version: 3.3.9rc6
Precedence: list
Subject: [IPv6]Re: [v6ops] Re: New draft: "The IPv6 Loopback Address Prefix"
List-Id: "IPv6 Maintenance Working Group (6man)" <ipv6.ietf.org>
Archived-At: <https://mailarchive.ietf.org/arch/msg/ipv6/bTTrRglDH8rTSWcrsalyqbhzXWw>
List-Archive: <https://mailarchive.ietf.org/arch/browse/ipv6>
List-Help: <mailto:ipv6-request@ietf.org?subject=help>
List-Owner: <mailto:ipv6-owner@ietf.org>
List-Post: <mailto:ipv6@ietf.org>
List-Subscribe: <mailto:ipv6-join@ietf.org>
List-Unsubscribe: <mailto:ipv6-leave@ietf.org>

Hi,

On Wed, Nov 26, 2025 at 07:20:17PM +1100, Mark Smith wrote:
> On Wed, 26 Nov 2025 at 18:26, Gert Doering <gert@space.net> wrote:
> > On Wed, Nov 26, 2025 at 11:03:20AM +1100, Mark Smith wrote:
> > > On Wed, 26 Nov 2025 at 10:19, Geoff Huston <gih902@gmail.com> wrote:
> > > > thanks Mark - except that you should  substitute the /32 to a /96 as I got confused between my left and my right!
> > > >
> > >
> > > One of my use cases, which I think I hinted to but didn't specifically
> > > state, was multiple loopback interfaces on a node.
> > >
> > > On Cisco routers you can create multiple loopback interfaces. I've
> > > done that so that I could have say a management loopback interface and
> > > address, a BGP session loopback interface and address and then other
> > > loopback interfaces and addresses for other functions such as an
> > > L2TPv2 end point, RADIUS service client address etc.. Those loopback
> > > interface addresses were all announced into the routing protocol (or
> > > not depending on function).
> >
> > This is a very different thing from what the draft proposes to establish.
> >
> > You are basically deliberately choosing and assigning routable addresses
> > to "non physical" device interfaces, for externally-reachable functions
> > (and this is a very reasonable thing to do, so "all the router people"
> > do it, and "all the anycast service people" do it as well...).
> >
> 
> Yes. I mentioned it to demonstrate that I think a larger loopback
> prefix should be big enough to support multiple loopback interfaces
> within a host.

I find this very hard to understand.

Why would "there is a larger loopback prefix, used only for machine-internal
communication" have any relevance to "I use multiple loopback interfaces with
manually configured routable IP addresses"?

Why would "having multiple loopback interfaces out of the well-known 
machine-internal loopback address space" have any relevance to anything?

Gert Doering
        -- NetMaster
-- 
have you enabled IPv6 on something today...?

SpaceNet AG                      Vorstand: Sebastian v. Bomhard,
                                           Karin Schuler, Sebastian Cler
Joseph-Dollinger-Bogen 14        Aufsichtsratsvors.: A. Grundner-Culemann
D-80807 Muenchen                 HRB: 136055 (AG Muenchen)
Tel: +49 (0)89/32356-444         USt-IdNr.: DE813185279

v2.40.4 | Report a Bug | By Email | System Status