Re: [Lsr] [RTG-DIR] RtgDir Review: draft-ietf-isis-segment-routing-msd-15

"Acee Lindem (acee)" <acee@cisco.com> Wed, 03 October 2018 21:05 UTC

Return-Path: <acee@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 1335212F1AC; Wed, 3 Oct 2018 14:05:31 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -14.5
X-Spam-Level:
X-Spam-Status: No, score=-14.5 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIMWL_WL_MED=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HTML_MESSAGE=0.001, 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 uLOH1QsHVWrC; Wed, 3 Oct 2018 14:05:28 -0700 (PDT)
Received: from alln-iport-8.cisco.com (alln-iport-8.cisco.com [173.37.142.95]) (using TLSv1.2 with cipher DHE-RSA-SEED-SHA (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 36241128CB7; Wed, 3 Oct 2018 14:05:28 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=cisco.com; i=@cisco.com; l=70112; q=dns/txt; s=iport; t=1538600728; x=1539810328; h=from:to:cc:subject:date:message-id:references: in-reply-to:mime-version; bh=e5WBNy2QriQr/OXpwcuyE4RfAK6dp7COXzhpfg8ksiw=; b=OsOi/uC8YeMpFtOxcxGGwW09+cojsddfk99rl9LcwJD1hWUlN6azI915 UadxJ0D/dtJcEOHWv5PYX5zzFpTGOBkXYU1vElxSc84FOWjeA9evgxE+y MTDdrH+Enq0UeJm+01UXwa66sfcYm4SNXRNsrgpVSzUqUVaVmRblJQpYH o=;
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-Anti-Spam-Result: =?us-ascii?q?A0AGAABJLrVb/4wNJK1bGQEBAQEBAQE?= =?us-ascii?q?BAQEBAQcBAQEBAQGBUYEXd2Z/KAqDaogVjgEliGKNehSBZgsYAQqESQIXhAk?= =?us-ascii?q?hNBgBAwEBAgEBAm0cDIU4AQEBAQMBASFLBAcQAgEIEQMBAQEhAQYDAgICHwY?= =?us-ascii?q?LFAkIAgQOBYMhAYEdTAMVD6VHgS6HNg2CTAWLIReCAIERAScME4JMglZFAQE?= =?us-ascii?q?CAReBFAESAT8GEIJLMYImAogxCIERhDyFfoh5JCwJAoZHhliDHReBSoRiiTa?= =?us-ascii?q?MF3GIIgIRFIElHThkcXAVOyoBgkEJhXmFFIU+bwGLVoEfgR8BAQ?=
X-IronPort-AV: E=Sophos;i="5.54,337,1534809600"; d="scan'208,217";a="180119685"
Received: from alln-core-7.cisco.com ([173.36.13.140]) by alln-iport-8.cisco.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 03 Oct 2018 21:05:27 +0000
Received: from XCH-RTP-005.cisco.com (xch-rtp-005.cisco.com [64.101.220.145]) by alln-core-7.cisco.com (8.15.2/8.15.2) with ESMTPS id w93L5Qo4006171 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=FAIL); Wed, 3 Oct 2018 21:05:26 GMT
Received: from xch-rtp-015.cisco.com (64.101.220.155) by XCH-RTP-005.cisco.com (64.101.220.145) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Wed, 3 Oct 2018 17:05:25 -0400
Received: from xch-rtp-015.cisco.com ([64.101.220.155]) by XCH-RTP-015.cisco.com ([64.101.220.155]) with mapi id 15.00.1395.000; Wed, 3 Oct 2018 17:05:25 -0400
From: "Acee Lindem (acee)" <acee@cisco.com>
To: Bruno Decraene <bruno.decraene@orange.com>
CC: Routing Directorate <rtg-dir@ietf.org>, "draft-ietf-isis-segment-routing-msd@ietf.org" <draft-ietf-isis-segment-routing-msd@ietf.org>, "rtg-ads@ietf.org" <rtg-ads@ietf.org>, Alvaro Retana <aretana.ietf@gmail.com>, "lsr@ietf.org" <lsr@ietf.org>, Jeff Tantsura <jefftant.ietf@gmail.com>, "Les Ginsberg (ginsberg)" <ginsberg@cisco.com>, MEURIC Julien IMT/OLN <julien.meuric@orange.com>
Thread-Topic: [Lsr] [RTG-DIR] RtgDir Review: draft-ietf-isis-segment-routing-msd-15
Thread-Index: AQHUWw46HJBMIr9LnUmVD4nnvDM3nKUNjWFggAC5KoA=
Date: Wed, 3 Oct 2018 21:05:25 +0000
Message-ID: <107C953C-9823-4EA5-8901-D2B6CECCA253@cisco.com>
References: <F4955ED6-1FC9-4BD9-A3AE-CEAE3C474586@cisco.com> <20010_1538575635_5BB4CD13_20010_244_10_71d2bce7-864e-4292-a6fa-94313fb56b0e@OPEXCLILMA2.corporate.adroot.infra.ftgroup>
In-Reply-To: <20010_1538575635_5BB4CD13_20010_244_10_71d2bce7-864e-4292-a6fa-94313fb56b0e@OPEXCLILMA2.corporate.adroot.infra.ftgroup>
Accept-Language: en-US
Content-Language: en-US
X-MS-Has-Attach:
X-MS-TNEF-Correlator:
x-ms-exchange-messagesentrepresentingtype: 1
x-ms-exchange-transport-fromentityheader: Hosted
x-originating-ip: [10.116.152.198]
Content-Type: multipart/alternative; boundary="_000_107C953C98234EA58901D2B6CECCA253ciscocom_"
MIME-Version: 1.0
X-Outbound-SMTP-Client: 64.101.220.145, xch-rtp-005.cisco.com
X-Outbound-Node: alln-core-7.cisco.com
Archived-At: <https://mailarchive.ietf.org/arch/msg/lsr/aW9ulCoGcdnAyd3los8FsnS1uzw>
Subject: Re: [Lsr] [RTG-DIR] RtgDir Review: draft-ietf-isis-segment-routing-msd-15
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: Wed, 03 Oct 2018 21:05:32 -0000

Hi Bruno,

On Oct 3, 2018, at 10:07 AM, bruno.decraene@orange.com<mailto:bruno.decraene@orange.com> wrote:

Hi Acee,


From: Acee Lindem (acee) [mailto:acee@cisco.com]


Hey Bruno, Jeff, Les,

Have we agreed on the precise definition of “label imposition”?
Thanks for asking.
Not so far.
We don’t necessarily need to agree on a precision definition of “label imposition”. In my latest email (a few hours ago), I proposed to reuse the phrasing from RFC 3031, which does not use that term. If we are fine with using RFC 3031 terms, that would be fine for me.

Since the MSD type has always been defined in terms of “Imposition” in both the OSPF and IS-IS MSD drafts, I think it would be better to clarify any ambiguities the text Les quotes below.

Of course, we don’t want to get too bogged down in semantics as has happened in the past: https://www.youtube.com/watch?v=-P8IYKxpqG0

Thanks,
Acee



Thanks,
--Bruno


Thanks,
Acee

From: Lsr <lsr-bounces@ietf.org<mailto:lsr-bounces@ietf.org>> on behalf of Bruno Decraene <bruno.decraene@orange.com<mailto:bruno.decraene@orange.com>>
Date: Wednesday, October 3, 2018 at 4:37 AM
To: Jeff Tantsura <jefftant.ietf@gmail.com<mailto:jefftant.ietf@gmail.com>>
Cc: Routing Directorate <rtg-dir@ietf.org<mailto:rtg-dir@ietf.org>>, "draft-ietf-isis-segment-routing-msd@ietf.org<mailto:draft-ietf-isis-segment-routing-msd@ietf.org>" <draft-ietf-isis-segment-routing-msd@ietf.org<mailto:draft-ietf-isis-segment-routing-msd@ietf.org>>, "rtg-ads@ietf.org<mailto:rtg-ads@ietf.org>" <rtg-ads@ietf.org<mailto:rtg-ads@ietf.org>>, Alvaro Retana <aretana.ietf@gmail.com<mailto:aretana.ietf@gmail.com>>, "lsr@ietf.org<mailto:lsr@ietf.org>" <lsr@ietf.org<mailto:lsr@ietf.org>>, "Les Ginsberg (ginsberg)" <ginsberg@cisco.com<mailto:ginsberg@cisco.com>>, MEURIC Julien IMT/OLN <julien.meuric@orange.com<mailto:julien.meuric@orange.com>>
Subject: Re: [Lsr] [RTG-DIR] RtgDir Review: draft-ietf-isis-segment-routing-msd-15

Jeff,

From: Jeff Tantsura [mailto:jefftant.ietf@gmail.com]
Sent: Tuesday, October 02, 2018 8:28 PM
To: DECRAENE Bruno IMT/OLN; Alvaro Retana; MEURIC Julien IMT/OLN; Les Ginsberg (ginsberg)
Cc: rtg-ads@ietf.org<mailto:rtg-ads@ietf.org>; lsr@ietf.org<mailto:lsr@ietf.org>; rtg-dir@ietf.org<mailto:rtg-dir@ietf.org>; draft-ietf-isis-segment-routing-msd@ietf.org<mailto:draft-ietf-isis-segment-routing-msd@ietf.org>
Subject: RE: [RTG-DIR] RtgDir Review: draft-ietf-isis-segment-routing-msd-15

Gents,

I’m 100% with Les here, going into platform/asic specifics within this document would inevitably create ambiguity.
Absolutely.
And nobody is asking for this.

Cheers
--Bruno



Cheers,
Jeff
On Oct 2, 2018, 11:20 AM -0700, Les Ginsberg (ginsberg) <ginsberg@cisco.com<mailto:ginsberg@cisco.com>>, wrote:

Bruno –

Trimming the thread…

[Les2:] Label imposition is meant to cover both the SWAP operation and the PUSH operation. In the example you provided above where a label stack of “12” is replaced by a label stack of “14,15” the number of labels “imposed” is 2.
[Bruno2] In that case, I definitely think that the discussion was useful and that this point needs to be clarified in the document.
Whether you choose to call that (1 POP, 2 PUSH) or (1 SWAP, 1 PUSH)  or simply a SWAP isn’t relevant here (though it might matter to folks like the RFC 3031 authors).

With that ibn mind, here is proposed text:

“Base MPLS Imposition MSD (BMI-MSD) signals the total number of MPLS
   labels which can be imposed, including all service/transport/special
   labels.  Imposition includes swap and/or push operations.

If the advertising router performs label imposition in the context of
   the ingress interface, it is not possible to meaningfully advertise
   per link values.  In such a case only the Node MSD SHOULD be
   advertised.”

[Bruno2] Given that the term “imposition” does not seem to be defined within the IETF, I would still favor a formal definition not using it. e.g. “BMI-MSD advertises the ability to increase the depth of the label stack by BMI-MSD labels”.
Alternatively, I’d propose the following rewording which seems clearer to me:
OLD: Imposition includes swap and/or push operations.
NEW: A swap operation counts as an imposition of one label; just like one push operation.

[Les3:] This gets into implementation specific issues that I would really like to avoid.
For example, some implementations perform one and only one  “operation”. Conceptually that may involve a swap and a push – but from the internal implementation POV it is simply one operation. And this may be true regardless of how many labels are involved. Other implementations might perform this in several discrete steps. The language we use here should not imply anything about how many labels are associated with a specific operation.

The term “increase” isn’t accurate because in the case of a swap there is no increase, yet the label which is replaced is counted.

https://tools.ietf.org/html/rfc3031#section-3.10 is relevant here.

The term “imposition” is generic – and as Alvaro has pointed out is used in RFC 4221. And the language proposed above does define the relationship between “swap and push” and “imposition”.

I appreciate your desire for clarity – and I am still open to new language – but at this point I still think what I proposed is  the most accurate.

   Les



Thanks,
--Bruno


_________________________________________________________________________________________________________________________



Ce message et ses pieces jointes peuvent contenir des informations confidentielles ou privilegiees et ne doivent donc

pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu ce message par erreur, veuillez le signaler

a l'expediteur et le detruire ainsi que les pieces jointes. Les messages electroniques etant susceptibles d'alteration,

Orange decline toute responsabilite si ce message a ete altere, deforme ou falsifie. Merci.



This message and its attachments may contain confidential or privileged information that may be protected by law;

they should not be distributed, used or copied without authorisation.

If you have received this email in error, please notify the sender and delete this message and its attachments.

As emails may be altered, Orange is not liable for messages that have been modified, changed or falsified.

Thank you.

_________________________________________________________________________________________________________________________

Ce message et ses pieces jointes peuvent contenir des informations confidentielles ou privilegiees et ne doivent donc
pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu ce message par erreur, veuillez le signaler
a l'expediteur et le detruire ainsi que les pieces jointes. Les messages electroniques etant susceptibles d'alteration,
Orange decline toute responsabilite si ce message a ete altere, deforme ou falsifie. Merci.

This message and its attachments may contain confidential or privileged information that may be protected by law;
they should not be distributed, used or copied without authorisation.
If you have received this email in error, please notify the sender and delete this message and its attachments.
As emails may be altered, Orange is not liable for messages that have been modified, changed or falsified.
Thank you.


_______________________________________________
Lsr mailing list
Lsr@ietf.org<mailto:Lsr@ietf.org>
https://www.ietf.org/mailman/listinfo/lsr