Network Working Group                                            T. Graf
Internet-Draft                                                  Swisscom
Intended status: Standards Track                          March 24, 2021
Expires: September 25, 2021

        Export of MPLS Segment Routing Label Type Information in
                   IP Flow Information Export (IPFIX)


   This document introduces additional code points in the
   mplsTopLabelType Information Element for IS-IS, OSPFv2, OSPFv3 and
   BGP MPLS Segment Routing (SR) extensions to enable Segment Routing
   label protocol type information in IP Flow Information Export

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  MPLS Segment Routing Top Label Type . . . . . . . . . . . . .   2
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   Besides BGP-4 [RFC8277], LDP [RFC5036] and BGP VPN [RFC4364], four
   new routing-protocols, OSPFv2 Extensions [RFC8665], OSPFv3 Extensions
   [RFC8666], IS-IS Extensions [RFC8667] and BGP Prefix-SID [RFC8669]
   have been added to the list of routing-protocols able to propagate
   Segment Routing labels for the MPLS data plane [RFC8660].

   Traffic Accounting in Segment Routing Networks
   [I-D.ali-spring-sr-traffic-accounting] describes how IPFIX can be
   leveraged to account traffic to MPLS Segment Routing label dimensions
   within a Segment Routing domain.

   In the Information Model for IP Flow Information Export IPFIX
   [RFC7012], the information element mplsTopLabelType(46) describes
   which MPLS control plane protocol allocated the top-of-stack label in
   the MPLS label stack.  RFC 7012 section 7.2 [RFC7012] describes the
   "IPFIX MPLS label type (Value 46)" sub-registry [IANA-IPFIX-IE46]
   where new code points should be added.

2.  MPLS Segment Routing Top Label Type

   By introducing four new code points to information element
   mplsTopLabelType(46) for IS-IS, OSPFv2, OSPFv3 and BGP Prefix-SID,
   when Segment Routing with one of these four routing protocols is
   deployed, we get insight into which traffic is being forwarded based
   on which MPLS control plane protocol.

   A typical use case scenario is to monitor MPLS control plane
   migrations from LDP to IS-IS or OSPF Segment Routing.  Such a
   migration can be done node by node as described in RFC8661 [RFC8661]

   Another use case is the monitoring of a migration to a Seamless MPLS
   SR [I-D.hegde-spring-mpls-seamless-sr] architecture where prefixes
   are propagated with dynamic BGP labels according to RFC8277

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   [RFC8277], BGP Prefix-SID according to RFC8669 [RFC8669] and used for
   the forwarding between IGP domains.  Adding an additional layer into
   the MPLS data plane to above described use case.

   Both use cases can be verified by using mplsTopLabelType(46),
   mplsTopLabelIPv4Address(47), mplsTopLabelStackSection(70) and
   forwardingStatus(89) dimensions to get insights into

   o  how many packets are forwarded or dropped

   o  if dropped, for which reasons

   o  the MPLS provider edge loopback address and label protocol

   By looking at the MPLS label value itself, it is not always clear as
   to which label protocol it belongs, since they could potentially
   share the same label allocation range.  This is the case for IGP-
   Adjacency SID's, LDP and dynamic BGP labels as an example.

3.  IANA Considerations

   This document specifies four additional code points for IS-IS,
   OSPFv2, OSPFv3 and BGP Prefix-SID Segment Routing extension in the
   existing sub-registry "IPFIX MPLS label type (Value 46)" of the
   "IPFIX Information Elements" and one new "IPFIX Information Element"
   with a new sub-registry in the "IP Flow Information Export (IPFIX)
   Entities" name space.

       | Value|       Description              | Reference |  Requester  |
       | TBD1 | OSPFv2 Segment Routing         |  RFC8665  | [RFC-to-be] |
       | TBD2 | OSPFv3 Segment Routing         |  RFC8666  | [RFC-to-be] |
       | TBD3 | IS-IS Segment Routing          |  RFC8667  | [RFC-to-be] |
       | TBD4 | BGP Segment Routing Prefix-SID |  RFC8669  | [RFC-to-be] |

 Figure 1: Updates to "IPFIX MPLS label type (Value 46)" SubRegistry

   Note to IANA:

   o  Please assign TBD1 to 4 to the next available numbers according to
      the "IPFIX MPLS label type (Value 46)" sub-registry
      [IANA-IPFIX-IE46] procedure.

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   o  Please replace the [RFC-to-be] with the RFC number assigned to
      this document.

   Note to RFC-editor:

   o  Please remove above two IANA notes.

4.  Security Considerations

   There exists no extra security considerations regarding the
   allocation of these new IPFIX information elements compared to
   RFC7012 [RFC7012].

5.  Acknowledgements

   I would like to thank to the IE doctors, Paul Aitken and Andrew
   Feren, as well Benoit Claise, Loa Andersson, Tianran Zhou, Pierre
   Francois, Bruno Decreane, Paolo Lucente, Hannes Gredler, Ketan
   Talaulikar, Sabrina Tanamal, Erik Auerswald and Sergey Fomin for
   their review and valuable comments.

6.  References

6.1.  Normative References

   [RFC7012]  Claise, B., Ed. and B. Trammell, Ed., "Information Model
              for IP Flow Information Export (IPFIX)", RFC 7012,
              DOI 10.17487/RFC7012, September 2013,

6.2.  Informative References

              Filsfils, C., Talaulikar, K., Sivabalan, S., Horneffer,
              M., Raszuk, R., Litkowski, S., Voyer, D., and R. Morton,
              "Traffic Accounting in Segment Routing Networks", draft-
              ali-spring-sr-traffic-accounting-04 (work in progress),
              February 2020.

              Hegde, S., Bowers, C., Xu, X., Gulko, A., Bogdanov, A.,
              Uttaro, J., Jalil, L., Khaddam, M., and A. Alston,
              "Seamless Segment Routing", draft-hegde-spring-mpls-
              seamless-sr-04 (work in progress), January 2021.

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              "IANA IP Flow Information Export (IPFIX) Information
              Element #46 SubRegistry",

   [RFC4364]  Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
              Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February
              2006, <>.

   [RFC5036]  Andersson, L., Ed., Minei, I., Ed., and B. Thomas, Ed.,
              "LDP Specification", RFC 5036, DOI 10.17487/RFC5036,
              October 2007, <>.

   [RFC8277]  Rosen, E., "Using BGP to Bind MPLS Labels to Address
              Prefixes", RFC 8277, DOI 10.17487/RFC8277, October 2017,

   [RFC8660]  Bashandy, A., Ed., Filsfils, C., Ed., Previdi, S.,
              Decraene, B., Litkowski, S., and R. Shakir, "Segment
              Routing with the MPLS Data Plane", RFC 8660,
              DOI 10.17487/RFC8660, December 2019,

   [RFC8661]  Bashandy, A., Ed., Filsfils, C., Ed., Previdi, S.,
              Decraene, B., and S. Litkowski, "Segment Routing MPLS
              Interworking with LDP", RFC 8661, DOI 10.17487/RFC8661,
              December 2019, <>.

   [RFC8665]  Psenak, P., Ed., Previdi, S., Ed., Filsfils, C., Gredler,
              H., Shakir, R., Henderickx, W., and J. Tantsura, "OSPF
              Extensions for Segment Routing", RFC 8665,
              DOI 10.17487/RFC8665, December 2019,

   [RFC8666]  Psenak, P., Ed. and S. Previdi, Ed., "OSPFv3 Extensions
              for Segment Routing", RFC 8666, DOI 10.17487/RFC8666,
              December 2019, <>.

   [RFC8667]  Previdi, S., Ed., Ginsberg, L., Ed., Filsfils, C.,
              Bashandy, A., Gredler, H., and B. Decraene, "IS-IS
              Extensions for Segment Routing", RFC 8667,
              DOI 10.17487/RFC8667, December 2019,

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   [RFC8669]  Previdi, S., Filsfils, C., Lindem, A., Ed., Sreekantiah,
              A., and H. Gredler, "Segment Routing Prefix Segment
              Identifier Extensions for BGP", RFC 8669,
              DOI 10.17487/RFC8669, December 2019,

Author's Address

   Thomas Graf
   Binzring 17
   Zurich  8045


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