Internet-Draft IPFIX MPLS Segment Routing Information September 2021
Graf Expires 22 March 2022 [Page]
Network Working Group
Intended Status:
T. Graf

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


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 used within a Segment Routing domain. In particular, this document defines five code points for the IPFIX mplsTopLabelType Information Element for PCE, IS-IS, OSPFv2, OSPFv3, and BGP MPLS Segment Routing extensions.

Status of This Memo

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

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This Internet-Draft will expire on 22 March 2022.

Table of Contents

1. Introduction

Four routing protocol extensions, OSPFv2 Extensions [RFC8665], OSPFv3 Extensions [RFC8666], IS-IS Extensions [RFC8667], BGP Prefix Segment Identifiers (Prefix-SIDs) [RFC8669] and one Path Computation Element Communication Protocol (PCEP) Extension [RFC8664] have been defined to be able to propagate Segment Routing (SR) 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 in dimensional data modelling to account traffic to MPLS SR label dimensions within a Segment Routing domain.

In [RFC7012], the Information Element (IE) mplsTopLabelType(46) identifies which MPLS control plane protocol allocated the top-of-stack label in the MPLS label stack. Section 7.2 of [RFC7012] creates the "IPFIX MPLS label type (Value 46)" subregistry [IANA-IPFIX] where MPLS label type 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 five new code points to the IPFIX IE mplsTopLabelType(46) for PCE, IS-IS, OSPFv2, OSPFv3 and BGP Prefix-SID, it is possible to identify which traffic is being forwarded based upon which MPLS SR control plane protocol is in use.

A typical use case 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 Appendix A of [RFC8661].

Another use case is to monitor MPLS control plane migrations from dynamic BGP labels [RFC8277] to BGP Prefix-SIDs [RFC8669]. For example, the motivation and benefits for such a migration in large-scale data centers are described in [RFC8670].

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

By looking at the MPLS label value itself, it is not always clear as to which label protocol it belongs. This is because they may share the same label allocation range. This is, for example, the case for IGP-Adjacency SIDs, LDP and dynamic BGP labels.

3. IANA Considerations

This document requests IANA to allocate the following code points in the existing subregistry "IPFIX MPLS label type (Value 46)" under the "IPFIX Information Elements" registry [RFC7012] available at [IANA-IPFIX].

      | Value |          Description           |      Reference       |
      | TBD1  | Path Computation Element       | [RFC-to-be], RFC8664 |
      | TBD2  | OSPFv2 Segment Routing         | [RFC-to-be], RFC8665 |
      | TBD3  | OSPFv3 Segment Routing         | [RFC-to-be], RFC8666 |
      | TBD4  | IS-IS Segment Routing          | [RFC-to-be], RFC8667 |
      | TBD5  | BGP Segment Routing Prefix-SID | [RFC-to-be], RFC8669 |

      Table 1: Updates to "IPFIX MPLS label type (Value 46)" subregistry

Note to the RFC-Editor:

Note IANA:

4. Operational Considerations

In the IE mplsTopLabelType(46), the BGP code point 4 refers to the label value in MP_REACH_NLRI path attribute described in Section 2 of [RFC8277], while the BGP Segment Routing Prefix-SID code point TBD5 corresponds to the label index value in the Label-Index TLV described in Section 3.1 of [RFC8669]. These values are thus used for those distinct purposes.

5. Security Considerations

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

6. Acknowledgements

I would like to thank 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, Qin Wu and Matthias Arnold for their review and valuable comments. Many thanks also to Robert Wilton for the AD review. Thanks to Alvaro Retana, Eric Vyncke and Benjamin Kaduk for the IESG review.

7. References

7.1. Normative References

Claise, B., Ed. and B. Trammell, Ed., "Information Model for IP Flow Information Export (IPFIX)", RFC 7012, DOI 10.17487/RFC7012, , <>.

7.2. 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", Work in Progress, Internet-Draft, draft-ali-spring-sr-traffic-accounting-05, , <>.
"IANA, IPFIX MPLS label type (Value 46)", <>.
Rosen, E., "Using BGP to Bind MPLS Labels to Address Prefixes", RFC 8277, DOI 10.17487/RFC8277, , <>.
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, , <>.
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, , <>.
Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W., and J. Hardwick, "Path Computation Element Communication Protocol (PCEP) Extensions for Segment Routing", RFC 8664, DOI 10.17487/RFC8664, , <>.
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, , <>.
Psenak, P., Ed. and S. Previdi, Ed., "OSPFv3 Extensions for Segment Routing", RFC 8666, DOI 10.17487/RFC8666, , <>.
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, , <>.
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, , <>.
Filsfils, C., Ed., Previdi, S., Dawra, G., Aries, E., and P. Lapukhov, "BGP Prefix Segment in Large-Scale Data Centers", RFC 8670, DOI 10.17487/RFC8670, , <>.

Author's Address

Thomas Graf
Binzring 17
CH-8045 Zurich