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IDR Working Group                                                Z. Wang
Internet-Draft                                                     Q. Wu
Intended status: Standards Track                                  Huawei
Expires: May 19, 2021                                        J. Tantsura
                                                            Apstra, Inc.
                                                           K. Talaulikar
                                                           Cisco Systems
                                                       November 15, 2020


 Distribution of Traffic Engineering Extended Admin Groups using BGP-LS
                   draft-ietf-idr-eag-distribution-13

Abstract

   Administrative groups are link attributes (commonly referred to as
   "colors" or "link colors") advertised by link state protocols (e.g.
   ISIS or OSPF) and used for traffic engineering.  These administrative
   groups were initially defined as 32 bit masks.  As network usage
   grew, these 32 bit masks were found to constrain traffic engineering.
   Therefore, link state protocols (ISIS, OSPF) were expanded to
   advertise a variable length administrative group.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on May 19, 2021.

Copyright Notice

   Copyright (c) 2020 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of



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   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   2
   2.  Advertising Extended Administrative Groups in BGP-LS  . . . .   3
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   5.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   4
   6.  Normative References  . . . . . . . . . . . . . . . . . . . .   4
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   Administrative groups (commonly referred to as "colors" or "link
   colors") are link attributes that are advertised by link state
   protocols like IS-IS [RFC5305], OSPFv2 [RFC3630] and OSPFv3 [RFC5329]
   for traffic engineering use-cases.  The BGP-LS advertisement is
   encoded using the Administrative Group (color) TLV 1088 as defined in
   [RFC7752].

   These administrative groups are defined as a fixed-length 32-bit
   bitmask.  As networks grew and more use-cases were introduced, the
   32-bit length was found to be constraining and hence extended
   administrative groups (EAG) were introduced in the IS-IS and OSPFv2
   link state routing protocols [RFC7308].

   This document specifies extensions to BGP-LS for advertisement of the
   extended administrative groups.

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.








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2.  Advertising Extended Administrative Groups in BGP-LS

   This document defines extensions that enable BGP-LS speakers to
   signal the EAG of links in a network to a BGP-LS consumer of network
   topology such as a centralized controller.  The centralized
   controller can leverage this information in traffic engineering
   computations and other use-cases.  When a BGP-LS speaker is
   originating the topology learnt via link-state routing protocols like
   OSPF or IS-IS, the EAG information of the links is sourced from the
   underlying extensions as defined in [RFC7308].  The BGP-LS speaker
   may also advertise the EAG information for the local links of a node
   when not running any link-state IGP protocol e.g. when running BGP as
   the only routing protocol.

   EAG of a link is encoded in a new Link Attribute TLV [RFC7752] using
   the following format:

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |              Type             |             Length            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    Extended Administrative Groups (variable)                 //
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

            Figure 1: Extended Administrative Groups TLV Format

   Where:

   o  Type: 1173

   o  Length: variable length which represents the total length of the
      value field.  The length value must MUST be multiple of 4.  If the
      length is not a multiple of 4, the TLV must be considered
      malformed.

   o  Value: one or more sets of 32-bit bitmasks that indicate the
      administrative groups (colors) that are enable on the link when
      those specific bits are set.

   The EAG TLV is an optional TLV.  The existing AG TLV 108 and the EAG
   TLV defined in this document MAY be advertised together.  The
   semantics of the EAG and the backward compatibility aspects of EAG
   with respect to the AG are handled as described in the Backward
   Compatibility section of [RFC7308].






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3.  IANA Considerations

   This document requests assigning code-point from the registry "BGP-LS
   Node Descriptor, Link Descriptor, Prefix Descriptor, and Attribute
   TLVs" based on table below.  Early allocation for these code-points
   have been done by IANA.

    +------------+-------------------------------+-------------------+
    | Code Point |   Description                 | IS-IS TLV/Sub-TLV |
    +------------+-------------------------------+-------------------+
    |   1173     | Extended Administrative Group |      22/14        |
    +------------+-------------------------------+-------------------+


4.  Security Considerations

   The extensions in this document advertise same administrative group
   information specified via [RFC7752] but as a larger/extended value
   and hence does not introduce security issues beyond those discussed
   in [RFC7752] and [I-D.ietf-idr-rfc7752bis] .

5.  Acknowledgments

   The authors gratefully acknowledge the review by Eric Osborne and Les
   Ginsberg.

6.  Normative References

   [I-D.ietf-idr-rfc7752bis]
              Talaulikar, K., "Distribution of Link-State and Traffic
              Engineering Information Using BGP", draft-ietf-idr-
              rfc7752bis-04 (work in progress), September 2020.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC3630]  Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
              (TE) Extensions to OSPF Version 2", RFC 3630,
              DOI 10.17487/RFC3630, September 2003,
              <https://www.rfc-editor.org/info/rfc3630>.

   [RFC5305]  Li, T. and H. Smit, "IS-IS Extensions for Traffic
              Engineering", RFC 5305, DOI 10.17487/RFC5305, October
              2008, <https://www.rfc-editor.org/info/rfc5305>.





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   [RFC5329]  Ishiguro, K., Manral, V., Davey, A., and A. Lindem, Ed.,
              "Traffic Engineering Extensions to OSPF Version 3",
              RFC 5329, DOI 10.17487/RFC5329, September 2008,
              <https://www.rfc-editor.org/info/rfc5329>.

   [RFC7308]  Osborne, E., "Extended Administrative Groups in MPLS
              Traffic Engineering (MPLS-TE)", RFC 7308,
              DOI 10.17487/RFC7308, July 2014,
              <https://www.rfc-editor.org/info/rfc7308>.

   [RFC7752]  Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
              S. Ray, "North-Bound Distribution of Link-State and
              Traffic Engineering (TE) Information Using BGP", RFC 7752,
              DOI 10.17487/RFC7752, March 2016,
              <https://www.rfc-editor.org/info/rfc7752>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

Authors' Addresses

   Zitao Wang
   Huawei
   101 Software Avenue, Yuhua District
   Nanjing, Jiangsu  210012
   China

   Email: wangzitao@huawei.com


   Qin Wu
   Huawei
   101 Software Avenue, Yuhua District
   Nanjing, Jiangsu  210012
   China

   Email: bill.wu@huawei.com


   Jeff Tantsura
   Apstra, Inc.

   Email: jefftant.ietf@gmail.com







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   Ketan Talaulikar
   Cisco Systems

   Email: ketant@cisco.com















































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