Export of MPLS Segment Routing Label Type Information in IP Flow Information Export (IPFIX)
draft-ietf-opsawg-ipfix-mpls-sr-label-type-02

Network Working Group                                            T. Graf
Internet-Draft                                                  Swisscom
Intended status: Standards Track                           June 22, 2021
Expires: December 24, 2021

        Export of MPLS Segment Routing Label Type Information in
                   IP Flow Information Export (IPFIX)
             draft-ietf-opsawg-ipfix-mpls-sr-label-type-02

Abstract

   This document introduces new IP Flow Information Export (IPFIX) code
   points to identify which traffic is being forwarded based on which
   MPLS control plane protocol is in use within a Segment Routing
   domain.  In particular, this document defines four code points for
   the IPFIX mplsTopLabelType Information Element for IS-IS, OSPFv2,
   OSPFv3, and BGP MPLS Segment Routing extensions.

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   the Trust Legal Provisions and are provided without warranty as
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Table of Contents

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

1.  Introduction

   Four new routing protocol extensions, OSPFv2 Extensions [RFC8665],
   OSPFv3 Extensions [RFC8666], IS-IS Extensions [RFC8667] and BGP
   Prefix-SID [RFC8669] have been defined as routing protocols that are
   able to propagate Segment Routing labels for the MPLS data plane
   [RFC8660].

   Also [I-D.ali-spring-sr-traffic-accounting] describes how IP Flow
   Information Export [RFC7012] can be leveraged to account traffic to
   MPLS Segment Routing label dimensions within a Segment Routing
   domain.

   In [RFC7012], the information element mplsTopLabelType(46) describes
   which MPLS control plane protocol allocated the top-of-stack label in
   the MPLS label stack.  Section 7.2 of [RFC7012] describes the "IPFIX
   MPLS label type (Value 46)" sub-registry [IANA-IPFIX-IE46] where new
   code points should be added.  This document defines new code points
   to address typical use cases that are discussed in Section 2.

2.  MPLS Segment Routing Top Label Type

   By introducing four new code points to the IPFIX 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, it is possible to identify into which traffic is being
   forwarded based on which MPLS control plane protocol is in use.

   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]
   Appendix A.

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   Another use case scenario is to monitor MPLS control plane migrations
   from dynamic BGP labels [RFC8277] to BGP Prefix-SID [RFC8669] in
   context of Seamless MPLS SR described in Section 4.6 of
   [I-D.hegde-spring-mpls-seamless-sr].

   Both use cases can be verified by using mplsTopLabelType(46),
   mplsTopLabelIPv4Address(47), mplsTopLabelIPv6Address(140),
   mplsTopLabelStackSection(70) and forwardingStatus(89) IEs to infer

   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, for example, the
   case for IGP-Adjacency SID's, LDP and dynamic BGP labels.

3.  IANA Considerations

   IANA is requested to allocate four code points in the existing sub-
   registry "IPFIX MPLS label type (Value 46)" of the "IPFIX Information
   Elements" registry for IS-IS, OSPFv2, OSPFv3 and BGP Prefix-SID
   Segment Routing extensions.

       -------------------------------------------------------------------
       | 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 replace TBD1 - TBD4 with the values allocated by IANA

   o  Please remove above two IANA notes.

4.  Operational Considerations

   In the information element mplsTopLabelType(46), the BGP code point 4
   refers to the label value in MP_REACH_NLRI path attribute described
   in Section 2 of [RFC8277], and the BGP Segment Routing Prefix-SID
   code point TBD4 to the label index value in the Label-Index TLV
   described in Section 3.1 of [RFC8669].

5.  Security Considerations

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

6.  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, Sergey Fomin, Mohamed
   Boucadair, Tom Petch and Qin Wu for their review and valuable
   comments.

7.  References

7.1.  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,
              <https://www.rfc-editor.org/info/rfc7012>.

7.2.  Informative References

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   [I-D.ali-spring-sr-traffic-accounting]
              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-05 (work in progress),
              April 2021.

   [I-D.hegde-spring-mpls-seamless-sr]
              Hegde, S., Bowers, C., Xu, X., Gulko, A., Bogdanov, A.,
              Uttaro, J., Jalil, L., Khaddam, M., Alston, A., and L. M.
              Contreras, "Seamless SR Problem Statement", draft-hegde-
              spring-mpls-seamless-sr-05 (work in progress), February
              2021.

   [IANA-IPFIX-IE46]
              "IANA IP Flow Information Export (IPFIX) Information
              Element #46 SubRegistry",
              <https://www.iana.org/assignments/ipfix/ipfix.xhtml#ipfix-
              mpls-label-type>.

   [RFC8277]  Rosen, E., "Using BGP to Bind MPLS Labels to Address
              Prefixes", RFC 8277, DOI 10.17487/RFC8277, October 2017,
              <https://www.rfc-editor.org/info/rfc8277>.

   [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,
              <https://www.rfc-editor.org/info/rfc8660>.

   [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, <https://www.rfc-editor.org/info/rfc8661>.

   [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,
              <https://www.rfc-editor.org/info/rfc8665>.

   [RFC8666]  Psenak, P., Ed. and S. Previdi, Ed., "OSPFv3 Extensions
              for Segment Routing", RFC 8666, DOI 10.17487/RFC8666,
              December 2019, <https://www.rfc-editor.org/info/rfc8666>.

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   [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,
              <https://www.rfc-editor.org/info/rfc8667>.

   [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,
              <https://www.rfc-editor.org/info/rfc8669>.

Author's Address

   Thomas Graf
   Swisscom
   Binzring 17
   Zurich  8045
   Switzerland

   Email: thomas.graf@swisscom.com

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