RFC 8571

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

📅 published March 2019, from ietf

RFC 8571: BGP-LS Advertisement of IGP Traffic Engineering Performance Metric Extensions 💖

Okay bestie, let's get into RFC 8571 🎀 It's a Standards Track document from March 2019 (ISSN 2070-1721), so this is real protocol stuff that implementers actually build against 💅

The editor is L. Ginsberg, Ed. from Cisco Systems, Inc. The co-authors are S. Previdi (no affiliation is listed in this header), Q. Wu from Huawei, J. Tantsura from Apstra, Inc., and C. Filsfils from Cisco Systems, Inc. 🦋 The header doesn't list any "Obsoletes" or "Updates" entries, so it doesn't replace or modify another document in this header block 🌸

The document is published by the Internet Engineering Task Force (IETF) and is listed as RFC 8571 in the Request for Comments series ✨

Abstract

So the whole point is this: it defines new BGP - Link State (BGP-LS) TLVs 💜 Those TLVs carry the IGP Traffic Engineering Metric Extensions that are defined in the IS-IS and OSPF protocols. Basically, it's how traffic engineering metrics get passed around through BGP-LS 🧚

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. 🍓

Copyright Notice

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 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
   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 ✨

Okay so the setup is this 🦋 BGP - Link State (BGP-LS) [RFC7752] defines Network Layer Reachability Information (NLRI) and attributes so it can carry link-state information. The new BGP-LS Link Attribute TLVs are needed so that it can carry the Traffic Engineering Metric Extensions defined in [RFC8570] and [RFC7471]. It's giving "the pieces finally fit together" 💅

2. Link Attribute TLVs for TE Metric Extensions 🌸

Here's the lineup. 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

The TLV formats are described in detail in the following subsections. These 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

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

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

Part 1 is done, bestie 🌈✨ Part 2 picks up with the bandwidth TLVs and everything after them 💖

2.8. Mappings to IGP Source Sub-TLVs ✨

okay so this section is the matching guide 🗺️ it shows which Link Attribute TLVs from this doc line up with the advertisements the IGPs already send out. For OSPFv2 and OSPFv3, those advertisements live in [RFC7471]. For IS-IS, they live in [RFC8570]. 💅

Here's the mapping table, so you can see the sub-TLV numbers side by side:

   +---------------------------------------+----------+----------------+
   | 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 🔐

okay this part is SERIOUS bestie, so read it carefully 🥺

Procedures and protocol extensions defined in this document do not affect the BGP security model. For a discussion of BGP security, see the "Security Considerations" section of [RFC4271]. You should also check out [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 carry 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. 🔒✨

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]. So no extra danger from these new TLVs, just the same stuff that was already there 💜

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>. 🦋

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. Thank you Ketan, you're literally a legend 👑

Contributors ✨

The following people have contributed substantially to this document and should be considered coauthors. Iconic behavior from both of them 💖

   Saikat Ray
   Individual
   Email: raysaikat@gmail.com

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

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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