[Idr] Regd encoding of ISIS SRMS range inside BGP-LS

"Ketan Talaulikar (ketant)" <ketant@cisco.com> Wed, 14 June 2017 13:22 UTC

Return-Path: <ketant@cisco.com>
X-Original-To: idr@ietfa.amsl.com
Delivered-To: idr@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id C555212EA54; Wed, 14 Jun 2017 06:22:31 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -14.523
X-Spam-Level:
X-Spam-Status: No, score=-14.523 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, RCVD_IN_DNSWL_HI=-5, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, RP_MATCHES_RCVD=-0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-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 gfTlH5S2TeA1; Wed, 14 Jun 2017 06:22:30 -0700 (PDT)
Received: from rcdn-iport-9.cisco.com (rcdn-iport-9.cisco.com [173.37.86.80]) (using TLSv1.2 with cipher DHE-RSA-SEED-SHA (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id D12531294FF; Wed, 14 Jun 2017 06:22:29 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=cisco.com; i=@cisco.com; l=2405; q=dns/txt; s=iport; t=1497446549; x=1498656149; h=from:to:subject:date:message-id: content-transfer-encoding:mime-version; bh=s8XRQt7F0x9uwU9Dda3nOnR2GmtIdA8g2RIfzvIsGZ4=; b=BYBubBmgAmorPIrPzjjygLHuCd6s4gu8ucKFbLvD6ARq2R3L3YwtwgWm bU+hzD6sgbZhNQ5HbtUtgJN7oO3Z+yhIg29CKWnxzI/hJhIrsZRvaaI+9 /cCMC+ZFlcxcQx1JJYuMvIh2W7AJ/Oui2qGgE+o6WmLN3/s3HfhkeIT95 c=;
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-Anti-Spam-Result: A0DHAAAROEFZ/5RdJa1eGgEBAQECAQEBAQgBAQEBg1higRSOB6d9ghEuiEc/GAECAQEBAQEBAWsohVlRAT5CJgEEARqKJBCwXIs9AQEBAQEFAQEBAQEBHQWGYoFfgyKEVIYJBZ5HAoFdhU2MHZISlHkBHziBCnQVhVQcgWaJZIENAQEB
X-IronPort-AV: E=Sophos;i="5.39,340,1493683200"; d="scan'208";a="255532465"
Received: from rcdn-core-12.cisco.com ([173.37.93.148]) by rcdn-iport-9.cisco.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 14 Jun 2017 13:22:29 +0000
Received: from XCH-ALN-009.cisco.com (xch-aln-009.cisco.com [173.36.7.19]) by rcdn-core-12.cisco.com (8.14.5/8.14.5) with ESMTP id v5EDMSDh018228 (version=TLSv1/SSLv3 cipher=AES256-SHA bits=256 verify=FAIL); Wed, 14 Jun 2017 13:22:29 GMT
Received: from xch-aln-008.cisco.com (173.36.7.18) by XCH-ALN-009.cisco.com (173.36.7.19) with Microsoft SMTP Server (TLS) id 15.0.1210.3; Wed, 14 Jun 2017 08:22:28 -0500
Received: from xch-aln-008.cisco.com ([173.36.7.18]) by XCH-ALN-008.cisco.com ([173.36.7.18]) with mapi id 15.00.1210.000; Wed, 14 Jun 2017 08:22:28 -0500
From: "Ketan Talaulikar (ketant)" <ketant@cisco.com>
To: "draft-ietf-idr-bgp-ls-segment-routing-ext@ietf.org" <draft-ietf-idr-bgp-ls-segment-routing-ext@ietf.org>, idr wg <idr@ietf.org>, "isis-wg@ietf.org" <isis-wg@ietf.org>
Thread-Topic: Regd encoding of ISIS SRMS range inside BGP-LS
Thread-Index: AdLlEM4AVzQrPMyyReCuHg+F0wsdMg==
Date: Wed, 14 Jun 2017 13:22:28 +0000
Message-ID: <d7a9067191e64b34bf3d53c9b7c699fd@XCH-ALN-008.cisco.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: [10.65.62.182]
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
Archived-At: <https://mailarchive.ietf.org/arch/msg/idr/qUuCuh3jPGCyoSyEKuM8Mb2bVU8>
Subject: [Idr] Regd encoding of ISIS SRMS range inside BGP-LS
X-BeenThere: idr@ietf.org
X-Mailman-Version: 2.1.22
Precedence: list
List-Id: Inter-Domain Routing <idr.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/idr>, <mailto:idr-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/idr/>
List-Post: <mailto:idr@ietf.org>
List-Help: <mailto:idr-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/idr>, <mailto:idr-request@ietf.org?subject=subscribe>
X-List-Received-Date: Wed, 14 Jun 2017 13:22:32 -0000

Hello All,

Needed some clarification from the authors and implementers of BGP-LS on Sec 3.4 of the https://tools.ietf.org/html/draft-ietf-idr-bgp-ls-segment-routing-ext-01#page-26 

It currently states ...

3.4.  Advertisement of a range of IS-IS SR bindings

   The advertisement of a range of IS-IS SR bindings has following
   rules:

      In IS-IS the Mapping Server binding ranges are advertised using
      the Binding TLV.  The IS-IS Binding TLV is encoded in the BGP-LS
      Prefix Attribute Range TLV as defined in Section 2.3.5 using the
      Binding Sub-TLV as defined in Section 2.3.6.  The flags in the
      Range TLV are all set to zero on transmit and ignored on
      reception.  The range value from the original IS-IS Binding TLV is
      encoded in the Range TLV "Range" field.

My understanding what that the encoding for ISIS is done with Range TLV + Prefix-SID sub-TLV (very similar to how it is specified in Sec 3.3 for OSPF). However the language is indirectly referring to the Prefix-SID sub-TLV by saying  "using the Binding Sub-TLV".

This may give an impression that the encoding for ISIS is done as Range TLV + Binding TLV + Prefix-SID sub-TLV and differently than done for OSPF. It would be clearer if the ISIS sec 3.4 were to also use similar language as OSPF sec 3.3. Would like to propose something like below:

3.4.  Advertisement of a range of IS-IS SR bindings

   The advertisement of a range of IS-IS SR bindings has following
   rules:

      In IS-IS the Mapping Server binding ranges are advertised using
      the IS-IS Binding TLV
      ([I-D.ietf-isis-segment-routing-extensions]).  The IS-IS Binding
      TLV is encoded in the BGP-LS Prefix Attribute Range TLV as defined
      in Section 2.3.4.
      The flags in the Range TLV are all set to zero on transmit and
      ignored on reception.  The range value from the original IS-IS
      Binding TLV is encoded in the Range TLV "Range" field. The
      Prefix-SID from the original ISIS Prefix SID Sub-TLV is encoded
      using the BGP-LS Prefix Attribute Prefix-SID as defined in
      Section 2.3.1 with the flags set according to the definition in
     [I-D.ietf-isis-segment-routing-extensions]

I would also like to check if anyone has implemented the encoding of ISIS SRMS range using the Binding SID TLV.

Thanks,
Ketan