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

Gert Doering <gert@space.net> Tue, 16 February 2021 17:02 UTC

Return-Path: <gert@space.net>
X-Original-To: v6ops@ietfa.amsl.com
Delivered-To: v6ops@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 157003A0AAF for <v6ops@ietfa.amsl.com>; Tue, 16 Feb 2021 09:02:25 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.099
X-Spam-Level:
X-Spam-Status: No, score=-2.099 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, URIBL_BLOCKED=0.001] autolearn=unavailable autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=space.net
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 UIpZ24MIXcbk for <v6ops@ietfa.amsl.com>; Tue, 16 Feb 2021 09:02:21 -0800 (PST)
Received: from gatekeeper1-relay.space.net (gatekeeper1-relay.space.net [IPv6:2001:608:3:85::38]) (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 4A4833A0BFA for <v6ops@ietf.org>; Tue, 16 Feb 2021 09:02:17 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=space.net; i=@space.net; q=dns/txt; s=esa; t=1613494938; x=1645030938; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=wJWCDMkN+ya1MdEamvPp4kJJELeHmxhFmeHwcQ+YnVY=; b=BE4v+uciXydqSdusKuMTRiltTLrpB/rAQ/oIZi9k2W5mj1iyWOsb5thK jbrgvcqLgYrZmnNGCiotVmNMc5vPMho0ThYsqgBQBDdMjjFW8Dv9sXiUZ JUU2XvIdqx2N5hSTpWKMHvbBw/r7vZVcqgikE0nPZ/45C99m2klo07zhA 8Hym5opj536pCO4vS1pxVEGWrd+kakurLrw9us9wElBx2+rKJesrfi75P 49oE7fkJnh1MGNKL9NDInwliMCwvcSTWeg8ePAEpgCpKn9EZ0x3KyxIRm I6Dp+Ju8TsxmUh+J8ofzj9yJCS7LaDxK0NUMBtaMX6N1LZcrbi7NMJT3Q g==;
IronPort-SDR: FRbcUI8JpBJy/pbMn0XPv1v0S45r7fsdjwHnMxOqmZ7FvW3UH/vA+wQNjAu3Nfjo+YL0lpUksm gEuEfGPa1a/3kBPB6FH3rdLb8oDeXCvdxpE21aVcQRpzI0ogppOG0xXiq6ywkYbpebY/zCwken 7salbqdU5FgVh5WjiC0weSr77cB4kkM3PdjO42/t7tb/Z/LJsT2nTptjx4l72oBJVKA1YXZk2K A6L52hLS9pDHFj9r61aBTAlUvgdqKI+3kqs383h8KKxf7IyMHz+aULiqmrc1JjEppCuIxEwsHJ bbA=
X-SpaceNet-SBRS: None
Received: from mobil.space.net ([195.30.115.67]) by gatekeeper1-relay.space.net with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Feb 2021 18:02:13 +0100
X-Original-To: v6ops@ietf.org
Received: from mobil.space.net (localhost [IPv6:::1]) by mobil.space.net (Postfix) with ESMTP id 86E6F43B83 for <v6ops@ietf.org>; Tue, 16 Feb 2021 18:02:13 +0100 (CET)
X-SpaceNet-Relay: true
X-SpaceNet-Relay: true
X-SpaceNet-Relay: true
X-SpaceNet-Relay: true
Received: from moebius4.space.net (moebius4.space.net [IPv6:2001:608:2:2::251]) by mobil.space.net (Postfix) with ESMTP id 7088C43B7F; Tue, 16 Feb 2021 18:02:13 +0100 (CET)
Received: by moebius4.space.net (Postfix, from userid 1007) id 69FADF78D2; Tue, 16 Feb 2021 18:02:13 +0100 (CET)
Date: Tue, 16 Feb 2021 18:02:13 +0100
From: Gert Doering <gert@space.net>
To: Philip Homburg <pch-v6ops-10@u-1.phicoh.com>
Cc: v6ops@ietf.org, Gert Doering <gert@space.net>, "6man@ietf.org" <6man@ietf.org>
Message-ID: <YCv6lQDiseMUCOFd@Space.Net>
References: <6167230f-b32a-e995-c071-b6c199ac5d64@si6networks.com> <858465C5-F428-4B47-8549-FCC201143B0C@fugue.com> <6959c883-a255-5ab8-9027-e05d369af2ff@si6networks.com> <m1lC29B-0000MuC@stereo.hq.phicoh.net> <YCvkYXwTrSdQoe8Q@Space.Net> <F63054D3-59D0-47FA-AABF-98A18B8DFA6F@fugue.com> <YCvsVVkQc5zDJQVh@Space.Net> <D084D80B-66A3-4132-B111-31FC6A61A969@fugue.com> <YCvw1DC/eOKmoEYc@Space.Net> <m1lC3J8-0000JNC@stereo.hq.phicoh.net>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="KYI9O0hQSrkN66OP"
Content-Disposition: inline
In-Reply-To: <m1lC3J8-0000JNC@stereo.hq.phicoh.net>
Archived-At: <https://mailarchive.ietf.org/arch/msg/v6ops/Ffe0VnGtxXuPDOBZFEJii7rUNXQ>
Subject: Re: [v6ops] [EXTERNAL] Re: Scope of Unique Local IPv6 Unicast Addresses (Fwd: New Version Notification for draft-gont-6man-ipv6-ula-scope-00.txt)
X-BeenThere: v6ops@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: v6ops discussion list <v6ops.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/v6ops>, <mailto:v6ops-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/v6ops/>
List-Post: <mailto:v6ops@ietf.org>
List-Help: <mailto:v6ops-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/v6ops>, <mailto:v6ops-request@ietf.org?subject=subscribe>
X-List-Received-Date: Tue, 16 Feb 2021 17:02:25 -0000

Hi,

On Tue, Feb 16, 2021 at 05:34:38PM +0100, Philip Homburg wrote:
> >Linux, for example, will just pick one default gateway, usually "the one
> >from the RA received last".
> 
> I think Linux also honours the priority of the default router. 

It does, but that does not help much in the scenario "Router A connects
to ISP A, announces prefix from A, Router B connects to ISP B, and
announces prefix from B, and packets sourced from A or B needs to go
to the respective router".

> Playing
> with default router priorities and the preference value of slaac prefixes
> allows routers to steer traffic.
> 
> Of course that requires routers to coordinate... 

... and solves a different scenario ("primary ISP, backup ISP")...

The true greatness of dual-prefix multihoming, in my opinion, is 
"hosts get to decide which ISP to use", so a given host can decide
"I want to use ISP A for my web traffic, and ISP B for my voice traffic"
(by picking the corresponding source address).

Of course this is not there yet, because there is no guidance *how* to 
pick a proper source address in that scenario (and that leads to the
other problem of no guidance how to deal with "I picked GUA source A,
and can't reach my destination, so should I try GUA source B next?").


... and if we can't have the nice things, just using GUA + NPT66 on
the router will achieve the basic "I want to have two ISPs with failover
for my web traffic" just fine.

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

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