[v6ops] Clarification regarding CLAT and multiple interfaces (draft-ietf-v6ops-claton)
James Harr <jharr@internet2.edu> Wed, 21 January 2026 07:07 UTC
Return-Path: <jharr@internet2.edu>
X-Original-To: v6ops@mail2.ietf.org
Delivered-To: v6ops@mail2.ietf.org
Received: from localhost (localhost [127.0.0.1]) by mail2.ietf.org (Postfix) with ESMTP id 41477AAC7FFB for <v6ops@mail2.ietf.org>; Tue, 20 Jan 2026 23:07:13 -0800 (PST)
X-Virus-Scanned: amavisd-new at ietf.org
X-Spam-Flag: NO
X-Spam-Score: -1.897
X-Spam-Level:
X-Spam-Status: No, score=-1.897 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
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 dX1QEY_3BOrX for <v6ops@mail2.ietf.org>; Tue, 20 Jan 2026 23:07:12 -0800 (PST)
Received: from CY7PR03CU001.outbound.protection.outlook.com (mail-westcentralusazon11010052.outbound.protection.outlook.com [40.93.198.52]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-384) server-signature ECDSA (P-256) server-digest SHA256) (No client certificate requested) by mail2.ietf.org (Postfix) with ESMTPS id 26124AAC7FF4 for <v6ops@ietf.org>; Tue, 20 Jan 2026 23:07:12 -0800 (PST)
ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=FtNlMDSfeqVUoj0+MMV4pTQjXHDlg4LtwbC6XrtxTMm7oTACoYcPpEz/F2nmTo5MVxrDKdy/5v4AJlhC0HgwbOJzEuQYeHf2BKUrM8dxzjiobBBhV22lOlNCqTltDUQTKB08xWNhKdJTsUEq80Bfvo0G1lxP2grFnuxPQKGnSZq3x6h66EAXfq5D4pbR6bAxdfAU6QFqMP/tMhJC+q0DTUTnfmBUUjStNQb3zTKuBscs1Ya93RYakgtSwsEw2EeICtf5afCfp+QdHvZkE0vlUCg8k5B4S2kcW2mPJRiwIWqBcc9+1P3vf5urw1HnmoAHnajTVgCkkjmKUalIXiQzuA==
ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=VXJlZg01GUW7DAfDn7sXwQ0xat4kp6qvVEYHOuuNdEo=; b=TWfE7KL++ktDrAZ4fVIE/5Trj3rM8nKN6uTdMH12/Ek0Lw7cBLM60GuXBcg87HqV87Mw3UFU1nHhmY93Ttno2bRlqNAl+oNIoJjtioRjvOAC7HM7VZznPxtZyCyZpoQWd2ViA7vNYvK/El3daB3GioO6IVkA4c1jnUewHPWmmFGAJqBDEvk4rLrT4Bxhe+m90ZmjO8fuD1xcObVtYyI84br7Q08MDuOIo4P2FJAa9sLvj4y8lR5UevY/xU+6EL+rM8h0hK+1mN1CRhaL8TccLP9dQTqSbb3dxy/Dc0QnDwd0EHnSvIybcGPXe6KRg0HPk2SeZHKPNQI+CTPCgDxIXw==
ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=internet2.edu; dmarc=pass action=none header.from=internet2.edu; dkim=pass header.d=internet2.edu; arc=none
Received: from BY1PR22MB5517.namprd22.prod.outlook.com (2603:10b6:a03:4ad::9) by LV2PR22MB3629.namprd22.prod.outlook.com (2603:10b6:408:17b::10) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9542.9; Wed, 21 Jan 2026 07:07:02 +0000
Received: from BY1PR22MB5517.namprd22.prod.outlook.com ([fe80::49ed:737c:1dea:afad]) by BY1PR22MB5517.namprd22.prod.outlook.com ([fe80::49ed:737c:1dea:afad%4]) with mapi id 15.20.9542.008; Wed, 21 Jan 2026 07:07:02 +0000
From: James Harr <jharr@internet2.edu>
To: "v6ops@ietf.org" <v6ops@ietf.org>
Thread-Topic: Clarification regarding CLAT and multiple interfaces (draft-ietf-v6ops-claton)
Thread-Index: AQHciqJgA71NNpfHIEqqLZeK0dRD+Q==
Date: Wed, 21 Jan 2026 07:07:02 +0000
Message-ID: <BY1PR22MB5517A441C37CC61F79E99364EA96A@BY1PR22MB5517.namprd22.prod.outlook.com>
Accept-Language: en-US
Content-Language: en-US
X-MS-Has-Attach:
X-MS-TNEF-Correlator:
x-ms-reactions: allow
authentication-results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=internet2.edu;
x-ms-publictraffictype: Email
x-ms-traffictypediagnostic: BY1PR22MB5517:EE_|LV2PR22MB3629:EE_
x-ms-office365-filtering-correlation-id: 67ace18a-d303-4842-003b-08de58bbada0
x-ms-exchange-senderadcheck: 1
x-ms-exchange-antispam-relay: 0
x-microsoft-antispam: BCL:0;ARA:13230040|376014|10070799003|786006|1800799024|366016|41320700013|38070700021|8096899003|13003099007;
x-microsoft-antispam-message-info: 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
x-forefront-antispam-report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:BY1PR22MB5517.namprd22.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(376014)(10070799003)(786006)(1800799024)(366016)(41320700013)(38070700021)(8096899003)(13003099007);DIR:OUT;SFP:1101;
x-ms-exchange-antispam-messagedata-chunkcount: 2
x-ms-exchange-antispam-messagedata-0: 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
x-ms-exchange-antispam-messagedata-1: q1R3qSaZ8W/9XjDCNPugsyY3EYmFueWN6GA=
Content-Type: multipart/alternative; boundary="_000_BY1PR22MB5517A441C37CC61F79E99364EA96ABY1PR22MB5517namp_"
MIME-Version: 1.0
X-OriginatorOrg: internet2.edu
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-AuthSource: BY1PR22MB5517.namprd22.prod.outlook.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 67ace18a-d303-4842-003b-08de58bbada0
X-MS-Exchange-CrossTenant-originalarrivaltime: 21 Jan 2026 07:07:02.7846 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 78ea4b46-9f08-4ef5-949b-2dae057c55d8
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-CrossTenant-userprincipalname: shHvVgZITToUqtKP5pYJp0gR/GdQh3VGIqhz6DYalEfB4M+pBIJIKpNS71nGQ/V5Mkc9A8o/2CNDK2DvCtw3iA==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: LV2PR22MB3629
Message-ID-Hash: J2MA34TTPLEMTTVB5XJH7B2NX4T235CP
X-Message-ID-Hash: J2MA34TTPLEMTTVB5XJH7B2NX4T235CP
X-MailFrom: jharr@internet2.edu
X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; header-match-v6ops.ietf.org-0; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header
X-Mailman-Version: 3.3.9rc6
Precedence: list
Subject: [v6ops] Clarification regarding CLAT and multiple interfaces (draft-ietf-v6ops-claton)
List-Id: v6ops discussion list <v6ops.ietf.org>
Archived-At: <https://mailarchive.ietf.org/arch/msg/v6ops/OzFpjbqVb4X6Ziq6ZjqcbaxPhqM>
List-Archive: <https://mailarchive.ietf.org/arch/browse/v6ops>
List-Help: <mailto:v6ops-request@ietf.org?subject=help>
List-Owner: <mailto:v6ops-owner@ietf.org>
List-Post: <mailto:v6ops@ietf.org>
List-Subscribe: <mailto:v6ops-join@ietf.org>
List-Unsubscribe: <mailto:v6ops-leave@ietf.org>
Regarding https://datatracker.ietf.org/doc/draft-ietf-v6ops-claton/ section 5, The section says 5. Disabling CLAT It is possible that after a CLAT instance has started, native IPv4 connectivity becomes available (e.g., an IPv4 address received via DHCP). Unless explicitly configured otherwise, the node MUST disable CLAT immediately upon obtaining a native IPv4 default gateway. Does it matter whether the IPv4 default route is on the same interface that the CLAT is running on? Admittedly, it's an odd corner-case, but it might be worth clarifying for OS maintainers. Based on my reading of section 4 and how it says to use multiple CLAT instances when multiple interfaces are involved, it would follow that the CLAT must only disable in the presence of an IPv4 default route on the same interface as the CLAT. 4. Enabling CLAT A node may have multiple IPv6-only interfaces (for example, a mobile phone can be connected to an IPv6-only Wi-Fi network and to an IPv6-only mobile network). The node MAY choose to enable CLAT on a subset of its interfaces connected to networks equipped with PLAT. In that case the node MUST run an independent, dedicated CLAT instance on each interface the node chooses to enable CLAT on. Consequently, each CLAT instance MUST install a separate default IPv4 route on each CLAT-enabled interface. Let me know if this makes sense and/or if I should suggest a clarification to the draft. Cheers! -- James Harr