Re: [Lsr] Suresh Krishnan's No Objection on draft-ietf-lsr-isis-rfc7810bis-04: (with COMMENT)

"Les Ginsberg (ginsberg)" <ginsberg@cisco.com> Thu, 20 December 2018 04:36 UTC

Return-Path: <ginsberg@cisco.com>
X-Original-To: lsr@ietfa.amsl.com
Delivered-To: lsr@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id D3DA3130F4C; Wed, 19 Dec 2018 20:36:42 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -14.565
X-Spam-Level:
X-Spam-Status: No, score=-14.565 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.065, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, RCVD_IN_DNSWL_HI=-5, SPF_PASS=-0.001, URIBL_BLOCKED=0.001, USER_IN_DEF_DKIM_WL=-7.5] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (1024-bit key) header.d=cisco.com
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 wTyaFq0-oZJO; Wed, 19 Dec 2018 20:36:40 -0800 (PST)
Received: from alln-iport-5.cisco.com (alln-iport-5.cisco.com [173.37.142.92]) (using TLSv1.2 with cipher DHE-RSA-SEED-SHA (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id C9134130E26; Wed, 19 Dec 2018 20:36:39 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=cisco.com; i=@cisco.com; l=3506; q=dns/txt; s=iport; t=1545280600; x=1546490200; h=from:to:cc:subject:date:message-id:references: in-reply-to:content-transfer-encoding:mime-version; bh=tPpqQCtObL6MjcGiA+paCCJHlxerYrEqlSsQI6xVmx0=; b=hmePTRWVnurSSnaz6kLTwfvtV/CBaPAJPa2nyZFpvqPtEyazMOPT5sQg ke6XtrewMXSgt+sbby/OF1GVH3FUOIr0pLkNL6EMuB9bHWnVToOYeDNE/ 8cR5twyFpx4ZGN4hAVbFN0XUm8spReW5zOSN7iNrS1Rxt99pcXUoIglMG g=;
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-Anti-Spam-Result: =?us-ascii?q?A0ADAAC9Gxtc/4YNJK1kGQEBAQEBAQE?= =?us-ascii?q?BAQEBAQcBAQEBAQGBUQQBAQEBAQsBggNmgQInCoNziBmOCYNFhVCOSBSBZws?= =?us-ascii?q?BASOESQIXKoIqIjQJDQEDAQECAQECbRwMhTwBAQEBAyMRRQwEAgEIEQQBAQM?= =?us-ascii?q?CJgICAh8RFQgIAgQBDQUIgxuBaQMVD6c4gS+EQUCDAw2CGAWBC4s0F4FAP4E?= =?us-ascii?q?RgxKCV0cCAQIBgSoBEgGDJ4JXAolGAQOBdopaimozCQKHDochgykggV6FH4M?= =?us-ascii?q?xhyuJSIR6gROKCAIRFIEnHzhlWBEIcBWDJ4JQiEyFP0ExAYwogR+BHwEB?=
X-IronPort-AV: E=Sophos;i="5.56,375,1539648000"; d="scan'208";a="215126285"
Received: from alln-core-12.cisco.com ([173.36.13.134]) by alln-iport-5.cisco.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 20 Dec 2018 04:36:38 +0000
Received: from XCH-RCD-009.cisco.com (xch-rcd-009.cisco.com [173.37.102.19]) by alln-core-12.cisco.com (8.15.2/8.15.2) with ESMTPS id wBK4acZ2017636 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=FAIL); Thu, 20 Dec 2018 04:36:38 GMT
Received: from xch-aln-001.cisco.com (173.36.7.11) by XCH-RCD-009.cisco.com (173.37.102.19) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Wed, 19 Dec 2018 22:36:37 -0600
Received: from xch-aln-001.cisco.com ([173.36.7.11]) by XCH-ALN-001.cisco.com ([173.36.7.11]) with mapi id 15.00.1395.000; Wed, 19 Dec 2018 22:36:37 -0600
From: "Les Ginsberg (ginsberg)" <ginsberg@cisco.com>
To: Suresh Krishnan <suresh@kaloom.com>, The IESG <iesg@ietf.org>
CC: "draft-ietf-lsr-isis-rfc7810bis@ietf.org" <draft-ietf-lsr-isis-rfc7810bis@ietf.org>, "Ketan Talaulikar (ketant)" <ketant@cisco.com>, "aretana.ietf@gmail.com" <aretana.ietf@gmail.com>, "lsr-chairs@ietf.org" <lsr-chairs@ietf.org>, "Ketan Talaulikar (ketant)" <ketant@cisco.com>, "lsr@ietf.org" <lsr@ietf.org>
Thread-Topic: Suresh Krishnan's No Objection on draft-ietf-lsr-isis-rfc7810bis-04: (with COMMENT)
Thread-Index: AQHUmBSG6Rzyix0Lm0yLgi4C8qB8xaWHCCqg
Date: Thu, 20 Dec 2018 04:36:37 +0000
Message-ID: <fdce9dee40c1440587f87618e9accd0d@XCH-ALN-001.cisco.com>
References: <154527669905.1822.11138986536679857134.idtracker@ietfa.amsl.com>
In-Reply-To: <154527669905.1822.11138986536679857134.idtracker@ietfa.amsl.com>
Accept-Language: en-US
Content-Language: en-US
X-MS-Has-Attach:
X-MS-TNEF-Correlator:
x-ms-exchange-transport-fromentityheader: Hosted
x-originating-ip: [10.24.112.6]
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: base64
MIME-Version: 1.0
X-Outbound-SMTP-Client: 173.37.102.19, xch-rcd-009.cisco.com
X-Outbound-Node: alln-core-12.cisco.com
Archived-At: <https://mailarchive.ietf.org/arch/msg/lsr/uKvwkTcCgb57rq5Jmvryr4nObvc>
Subject: Re: [Lsr] Suresh Krishnan's No Objection on draft-ietf-lsr-isis-rfc7810bis-04: (with COMMENT)
X-BeenThere: lsr@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Link State Routing Working Group <lsr.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/lsr>, <mailto:lsr-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/lsr/>
List-Post: <mailto:lsr@ietf.org>
List-Help: <mailto:lsr-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/lsr>, <mailto:lsr-request@ietf.org?subject=subscribe>
X-List-Received-Date: Thu, 20 Dec 2018 04:36:43 -0000

Suresh -

Inline.

> -----Original Message-----
> From: Suresh Krishnan <suresh@kaloom.com>;
> Sent: Wednesday, December 19, 2018 7:32 PM
> To: The IESG <iesg@ietf.org>;
> Cc: draft-ietf-lsr-isis-rfc7810bis@ietf.org; Ketan Talaulikar (ketant)
> <ketant@cisco.com>;; aretana.ietf@gmail.com; lsr-chairs@ietf.org; Ketan
> Talaulikar (ketant) <ketant@cisco.com>;; lsr@ietf.org
> Subject: Suresh Krishnan's No Objection on draft-ietf-lsr-isis-rfc7810bis-04:
> (with COMMENT)
> 
> Suresh Krishnan has entered the following ballot position for
> draft-ietf-lsr-isis-rfc7810bis-04: No Objection
> 
> When responding, please keep the subject line intact and reply to all
> email addresses included in the To and CC lines. (Feel free to cut this
> introductory paragraph, however.)
> 
> 
> Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html
> for more information about IESG DISCUSS and COMMENT positions.
> 
> 
> The document, along with other ballot positions, can be found here:
> https://datatracker.ietf.org/doc/draft-ietf-lsr-isis-rfc7810bis/
> 
> 
> 
> ----------------------------------------------------------------------
> COMMENT:
> ----------------------------------------------------------------------
> 
> * Backward compatibility
> 
> There is text in Appendix A that provides guidance to implementers on how
> to
> handle TLVs with length 5 from RFC7810. I think this would be much more
> helpful
> inside the main body of the document. I was wondering how the backward
> compatibility was handled until I read through the Appendix that lists the
> *diffs*.
> 

[Les:] I REALLY do not want to do this.

There is no intent to legitimize two different encodings. Implementations which encoded the problematic sub-TLVs with a length of 5 and a reserved byte were wrong - though obviously based on the flawed text in RFC 7810 it wasn't easy for a reader to realize that.

The obligation is on the implementations which used the 5 byte encoding to correct themselves and use the 4 byte encoding.
There is no obligation on conformant implementations to be "generous" and allow for interoperating with implementations which used the 5 byte encodings.
There might be business value in doing so - but that is outside the purview of specification. We use the appendix only to suggest that "generosity" be considered.

The main body of the document should not be cluttered with this. It needs to serve as the normative specification independent of the prior existence of RFC 7810.

   Les