





Internet Engineering Task Force (IETF)                  L. Ginsberg, Ed.
Request for Comments: 8571                           Cisco Systems, Inc.
Category: Standards Track                                     S. Previdi
ISSN: 2070-1721                                                    Q. Wu
                                                                  Huawei
                                                             J. Tantsura
                                                            Apstra, Inc.
                                                             C. Filsfils
                                                     Cisco Systems, Inc.
                                                              March 2019


               BGP - Link State (BGP-LS) Advertisement of
         IGP Traffic Engineering Performance Metric Extensions

Abstract

   This document defines new BGP - Link State (BGP-LS) TLVs in order to
   carry the IGP Traffic Engineering Metric Extensions defined in the
   IS-IS and OSPF protocols.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8571.

















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Copyright Notice

   Copyright (c) 2019 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
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   publication of this document.  Please review these documents
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   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
   2. Link Attribute TLVs for TE Metric Extensions ....................3
      2.1. Unidirectional Link Delay TLV ..............................3
      2.2. Min/Max Unidirectional Link Delay TLV ......................4
      2.3. Unidirectional Delay Variation TLV .........................4
      2.4. Unidirectional Link Loss TLV ...............................5
      2.5. Unidirectional Residual Bandwidth TLV ......................5
      2.6. Unidirectional Available Bandwidth TLV .....................6
      2.7. Unidirectional Utilized Bandwidth TLV ......................6
      2.8. Mappings to IGP Source Sub-TLVs ............................7
   3. Security Considerations .........................................7
   4. IANA Considerations .............................................8
   5. References ......................................................8
      5.1. Normative References .......................................8
      5.2. Informative References .....................................9
   Acknowledgements ...................................................9
   Contributors .......................................................9
   Authors' Addresses ................................................10

1.  Introduction

   BGP - Link State (BGP-LS) [RFC7752] defines Network Layer
   Reachability Information (NLRI) and attributes in order to carry
   link-state information.  New BGP-LS Link Attribute TLVs are required
   in order to carry the Traffic Engineering Metric Extensions defined
   in [RFC8570] and [RFC7471].








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2.  Link Attribute TLVs for TE Metric Extensions

   The following new Link Attribute TLVs are defined:

       TLV Code Point                 Value
      --------------------------------------------------------
       1114              Unidirectional Link Delay

       1115              Min/Max Unidirectional Link Delay

       1116              Unidirectional Delay Variation

       1117              Unidirectional Link Loss

       1118              Unidirectional Residual Bandwidth

       1119              Unidirectional Available Bandwidth

       1120              Unidirectional Utilized Bandwidth

   TLV formats are described in detail in the following subsections.
   TLV formats follow the rules defined in [RFC7752].

2.1.  Unidirectional Link Delay TLV

   This TLV advertises the average link delay between two directly
   connected IGP link-state neighbors.  The semantics and values of the
   fields in the TLV are described in [RFC8570] and [RFC7471].

     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              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |A|  RESERVED   |                   Delay                       |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                 Figure 1

   where:

   Type:  1114

   Length:  4







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2.2.  Min/Max Unidirectional Link Delay TLV

   This TLV advertises the minimum and maximum delay values between two
   directly connected IGP link-state neighbors.  The semantics and
   values of the fields in the TLV are described in [RFC8570] and
   [RFC7471].

     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              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |A| RESERVED    |                   Min Delay                   |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |   RESERVED    |                   Max Delay                   |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                 Figure 2

   where:

   Type:  1115

   Length:  8

2.3.  Unidirectional Delay Variation TLV

   This TLV advertises the average link delay variation between two
   directly connected IGP link-state neighbors.  The semantics and
   values of the fields in the TLV are described in [RFC8570] and
   [RFC7471].

     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              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |  RESERVED     |               Delay Variation                 |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                 Figure 3

   where:

   Type:  1116

   Length:  4




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2.4.  Unidirectional Link Loss TLV

   This TLV advertises the loss (as a packet percentage) between two
   directly connected IGP link-state neighbors.  The semantics and
   values of the fields in the TLV are described in [RFC8570] and
   [RFC7471].

     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              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |A|  RESERVED   |                  Link Loss                    |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                 Figure 4

   where:

   Type:  1117

   Length:  4

2.5.  Unidirectional Residual Bandwidth TLV

   This TLV advertises the residual bandwidth between two directly
   connected IGP link-state neighbors.  The semantics and values of the
   fields in the TLV are described in [RFC8570] and [RFC7471].

     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              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                          Residual Bandwidth                   |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                 Figure 5

   where:

   Type:  1118

   Length:  4







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2.6.  Unidirectional Available Bandwidth TLV

   This TLV advertises the available bandwidth between two directly
   connected IGP link-state neighbors.  The semantics and values of the
   fields in the TLV are described in [RFC8570] and [RFC7471].

     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              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                      Available Bandwidth                      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                 Figure 6

   where:

   Type:  1119

   Length:  4

2.7.  Unidirectional Utilized Bandwidth TLV

   This TLV advertises the bandwidth utilization between two directly
   connected IGP link-state neighbors.  The semantics and values of the
   fields in the TLV are described in [RFC8570] and [RFC7471].

     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              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                     Utilized Bandwidth                        |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                 Figure 7

   where:

   Type:  1120

   Length:  4








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2.8.  Mappings to IGP Source Sub-TLVs

   This section documents the mappings between the Link Attribute TLVs
   defined in this document and the corresponding advertisements sourced
   by the IGPs.

   For OSPFv2 and OSPFv3, the advertisements are defined in [RFC7471].
   For IS-IS, the advertisements are defined in [RFC8570].

   +---------------------------------------+----------+----------------+
   | Attribute Name                        |  IS-IS   | OSPFv2/OSPFv3  |
   |                                       | Sub-TLV  |   Sub-TLV      |
   +---------------------------------------+----------+----------------+
   | Unidirectional Link Delay             |   33     |     27         |
   +---------------------------------------+----------+----------------+
   | Min/Max Unidirectional Link Delay     |   34     |     28         |
   +---------------------------------------+----------+----------------+
   | Unidirectional Delay Variation        |   35     |     29         |
   +---------------------------------------+----------+----------------+
   | Unidirectional Link Loss              |   36     |     30         |
   +---------------------------------------+----------+----------------+
   | Unidirectional Residual Bandwidth     |   37     |     31         |
   +---------------------------------------+----------+----------------+
   | Unidirectional Available Bandwidth    |   38     |     32         |
   +---------------------------------------+----------+----------------+
   | Unidirectional Utilized Bandwidth     |   39     |     33         |
   +---------------------------------------+----------+----------------+

                                 Figure 8

3.  Security Considerations

   Procedures and protocol extensions defined in this document do not
   affect the BGP security model.  See the "Security Considerations"
   section of [RFC4271] for a discussion of BGP security.  Also, refer
   to [RFC4272] and [RFC6952] for analyses of security issues for BGP.
   Security considerations for acquiring and distributing BGP-LS
   information are discussed in [RFC7752].

   The TLVs introduced in this document are used to propagate the
   Traffic Engineering Metric Extensions defined in [RFC8570] and
   [RFC7471].  These TLVs represent the state and resource availability
   of the IGP link.  It is assumed that the IGP instances originating
   these TLVs will support all the required security and authentication
   mechanisms (as described in [RFC8570] and [RFC7471]) in order to
   prevent any security issues when propagating the TLVs into BGP-LS.





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   The advertisement of the link attribute information defined in this
   document presents no additional risk beyond that associated with the
   existing link attribute information already supported in [RFC7752].

4.  IANA Considerations

   IANA has made assignments in the "BGP-LS Node Descriptor, Link
   Descriptor, Prefix Descriptor, and Attribute TLVs" registry for the
   new Link Attribute TLVs as listed below:

       TLV Code Point    Description
      --------------------------------------------------------
       1114              Unidirectional Link Delay

       1115              Min/Max Unidirectional Link Delay

       1116              Unidirectional Delay Variation

       1117              Unidirectional Link Loss

       1118              Unidirectional Residual Bandwidth

       1119              Unidirectional Available Bandwidth

       1120              Unidirectional Utilized Bandwidth

5.  References

5.1.  Normative References

   [RFC7471]  Giacalone, S., Ward, D., Drake, J., Atlas, A., and S.
              Previdi, "OSPF Traffic Engineering (TE) Metric
              Extensions", RFC 7471, DOI 10.17487/RFC7471, March 2015,
              <https://www.rfc-editor.org/info/rfc7471>.

   [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>.

   [RFC8570]  Ginsberg, L., Ed., Previdi, S., Ed., Giacalone, S., Ward,
              D., Drake, J., and Q. Wu, "IS-IS Traffic Engineering (TE)
              Metric Extensions", RFC 8570, DOI 10.17487/RFC8570,
              March 2019, <https://www.rfc-editor.org/info/rfc8570>.






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5.2.  Informative References

   [RFC4271]  Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
              Border Gateway Protocol 4 (BGP-4)", RFC 4271,
              DOI 10.17487/RFC4271, January 2006,
              <https://www.rfc-editor.org/info/rfc4271>.

   [RFC4272]  Murphy, S., "BGP Security Vulnerabilities Analysis",
              RFC 4272, DOI 10.17487/RFC4272, January 2006,
              <https://www.rfc-editor.org/info/rfc4272>.

   [RFC6952]  Jethanandani, M., Patel, K., and L. Zheng, "Analysis of
              BGP, LDP, PCEP, and MSDP Issues According to the Keying
              and Authentication for Routing Protocols (KARP) Design
              Guide", RFC 6952, DOI 10.17487/RFC6952, May 2013,
              <https://www.rfc-editor.org/info/rfc6952>.

Acknowledgements

   The authors wish to acknowledge comments from Ketan Talaulikar.

Contributors

   The following people have contributed substantially to this document
   and should be considered coauthors:

      Saikat Ray
      Individual
      Email: raysaikat@gmail.com

      Hannes Gredler
      RtBrick Inc.
      Email: hannes@rtbrick.com


















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Authors' Addresses

   Les Ginsberg (editor)
   Cisco Systems, Inc.
   United States of America

   Email: ginsberg@cisco.com


   Stefano Previdi
   Huawei
   Italy

   Email: stefano@previdi.net


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

   Email: bill.wu@huawei.com


   Jeff Tantsura
   Apstra, Inc.
   United States of America

   Email: jefftant.ietf@gmail.com


   Clarence Filsfils
   Cisco Systems, Inc.
   Brussels
   Belgium

   Email: cfilsfil@cisco.com













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