Network Working Group                                            T. Graf
Internet-Draft                                                  Swisscom
Intended status: Informational                          18 February 2022
Expires: 22 August 2022


             Export of Segment Routing IPv6 Information in
                   IP Flow Information Export (IPFIX)
                  draft-tgraf-opsawg-ipfix-srv6-srh-01

Abstract

   This document introduces new IP Flow Information Export (IPFIX)
   information elements to identify the SRv6 Segment Routing Header
   dimensions and SRv6 Control Plane Protocol that traffic is being
   forwarded with.

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   This Internet-Draft will expire on 22 August 2022.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  IPFIX Information Elements  . . . . . . . . . . . . . . . . .   2
   3.  Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Appendix A.  IPFIX Encoding Example . . . . . . . . . . . . . . .   7
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   A new type of Routing Extension Header called Segment Routing Header
   (SRH) is defined by [RFC8754] which is used for applying Segment
   Routing (SR) on the IPv6 data plane.

   Three routing protocol extensions, OSPFv3 Extensions
   [I-D.li-lsr-ospfv3-srv6-extensions], IS-IS Extensions
   [I-D.ietf-lsr-isis-srv6-extensions], BGP Prefix Segment Identifiers
   (Prefix-SIDs) [I-D.ietf-bess-srv6-services] and one Path Computation
   Element Communication Protocol (PCEP) Extension
   [I-D.ietf-pce-segment-routing-ipv6] have been defined to propagate
   Segment Identifiers (SIDs) for the IPv6 data plane.

   This document defines seven new IPFIX Information Elements (IEs) and
   two new subregistries within the "IPFIX Information Elements"
   registry [RFC7012], respectively for the new SRH dimensions and
   routing protocol and PCEP extensions.

2.  IPFIX Information Elements

   This section defines and describes the new IPFIX IEs.

   ipv6SRHFlags
      8-bit flags defined in the SRH.

   ipv6SRHTag
      16-bit tag field defined in the SRH that marks a packet as part of
      a class or group of packets sharing the same set of properties.

   ipv6SRHSegment
      128-bit IPv6 address that represents an SRv6 segment.





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   ipv6SRHSegmentList
      Ordered basicList [RFC6313] of zero or more 128-bit IPv6 addresses
      in the SRH that represents the SRv6 segment list.  The Segment
      List is encoded starting from the active segment of the SR Policy.

   ipv6SRHSegmentsLeft
      8-bit unsigned integer defining the number of route segments
      remaining to reach the end of the segment list.

   ipv6SRHSection
      Exposes the SRH and its TLV's as defined in section 2 of [RFC8754]
      as series of n octets.

   ipv6SRHSegmentType
      Name of the routing protocol or PCEP extension from where the
      active SRv6 segment has been learned from.

3.  Use Cases

   By using ipv6SRHSegmentList(TBD4), ipv6SRHSegmentsLeft (TBD5),
   ipv6SRHSegment1Type(TBD7) and forwardingStatus(89) it is possible to
   identify

   *  how many packets are forwarded or dropped

   *  if dropped, for which reasons,

   *  identify the control plane protocol which defined the active
      segment,

   *  the SRv6 segment list and

   *  how many SRv6 segments are left.

4.  IANA Considerations

   This document requests IANA to create new IEs and two new
   subregistries called ""IPFIX IPv6 SRH Flags (TBD1)" and IPFIX IPv6
   SRH Segment type (TBD5)" under the "IPFIX Information Elements"
   registry [RFC7012] available at [IANA-IPFIX] and assign the following
   code initial points.










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   +-------+--------------------+------------+-----------+-------------+
   |Element|       Name         |  Abstract  | Data Type |  Reference  |
   |   ID  |                    |  Data Type | Semantics |             |
   +-------+--------------------+------------+-------------------------+
   | TBD1  | ipv6SRHFlag        | unsigned8  | flags     | [RFC-to-be],|
   |       |                    |            |           | RFC8754     |
   +-------+--------------------+------------+-------------------------+
   | TBD2  | ipv6SRHTag         | unsigned16 | identifier| [RFC-to-be],|
   |       |                    |            |           | RFC8754     |
   +-------+--------------------+------------+-------------------------+
   | TBD3  | ipv6SRHSegment     | ipv6address| default   | [RFC-to-be],|
   |       |                    |            |           | RFC8754     |
   +-------+--------------------+------------+-------------------------+
   | TBD4  | ipv6SRHSegmentList | basiclist  | list      | [RFC-to-be],|
   |       |                    |            |           | RFC8754     |
   +-------+--------------------+------------+-------------------------+
   | TBD5  | ipv6SRHSegmentsLeft| unsigned8  | quantity  | [RFC-to-be],|
   |       |                    |            |           | RFC8754     |
   +-------+--------------------+------------+-------------------------+
   | TBD6  | ipv6SRHSection     | octetArray | default   | [RFC-to-be] |
   +-------+--------------------+------------+-------------------------+
   | TBD7  | ipv6SRHSegmentType | unsigned8  | identifier| [RFC-to-be] |
   +-------+--------------------+------------+-------------------------+

     Table 1: Creates IEs in the "IPFIX Information Elements" registry

   +--------+-------------------+--------------------------------------+
   | Value  |    Description    |              Reference               |
   +--------+-------------------+--------------------------------------+
   | 0-7    | Unassigned        |                                      |
   +--------+-------------------+--------------------------------------+

         Table 2: Creates "IPFIX IPv6 SRH Flags (TBD1)" subregistry


















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   +-------+--------------------+--------------------------------------+
   | Value |     Description    |              Reference               |
   +-------+--------------------+--------------------------------------+
   | TBD8  | Unknown            | [RFC-to-be]                          |
   |       |                    |                                      |
   +-------+--------------------+--------------------------------------+
   | TBD9  | Path Computation   | [RFC-to-be],                         |
   |       | Element            | draft-ietf-pce-segment-routing-ipv6  |
   +-------+--------------------+--------------------------------------+
   | TB10  | OSPFv3             | [RFC-to-be],                         |
   |       | Segment Routing    | draft-li-ospf-ospfv3-srv6-extensions |
   +-------+--------------------+--------------------------------------+
   | TBD11 | IS-IS              | [RFC-to-be]                          |
   |       | Segment Routing    | draft-ietf-lsr-isis-srv6-extensions  |
   +-------+--------------------+--------------------------------------+
   | TBD12 | BGP Segment        | [RFC-to-be],                         |
   |       | Routing Prefix-SID | draft-ietf-bess-srv6-services        |
   +-------+--------------------+--------------------------------------+

     Table 3: Creates "IPFIX IPv6 SRH Segment type (TBD7)" subregistry

   Note to the RFC-Editor:

   *  Please replace TBD1 - TBD12 with the values allocated by IANA

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

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 Pierre Francois, Yao Liu, Paolo Lucente and
   Benoit Claise for their review and valuable comments.

7.  References

7.1.  Normative References

   [RFC6313]  Claise, B., Dhandapani, G., Aitken, P., and S. Yates,
              "Export of Structured Data in IP Flow Information Export
              (IPFIX)", RFC 6313, DOI 10.17487/RFC6313, July 2011,
              <https://www.rfc-editor.org/info/rfc6313>.





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   [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

   [I-D.ietf-bess-srv6-services]
              Dawra, G., Filsfils, C., Talaulikar, K., Raszuk, R.,
              Decraene, B., Zhuang, S., and J. Rabadan, "SRv6 BGP based
              Overlay Services", Work in Progress, Internet-Draft,
              draft-ietf-bess-srv6-services-11, 16 February 2022,
              <https://www.ietf.org/archive/id/draft-ietf-bess-srv6-
              services-11.txt>.

   [I-D.ietf-lsr-isis-srv6-extensions]
              Psenak, P., Filsfils, C., Bashandy, A., Decraene, B., and
              Z. Hu, "IS-IS Extensions to Support Segment Routing over
              IPv6 Dataplane", Work in Progress, Internet-Draft, draft-
              ietf-lsr-isis-srv6-extensions-18, 20 October 2021,
              <https://www.ietf.org/archive/id/draft-ietf-lsr-isis-srv6-
              extensions-18.txt>.

   [I-D.ietf-pce-segment-routing-ipv6]
              Li, C., Negi, M., Sivabalan, S., Koldychev, M.,
              Kaladharan, P., and Y. Zhu, "PCEP Extensions for Segment
              Routing leveraging the IPv6 data plane", Work in Progress,
              Internet-Draft, draft-ietf-pce-segment-routing-ipv6-11, 10
              January 2022, <https://www.ietf.org/internet-drafts/draft-
              ietf-pce-segment-routing-ipv6-11.txt>.

   [I-D.li-lsr-ospfv3-srv6-extensions]
              Li, Z., Hu, Z., Cheng, D., Talaulikar, K., and P. Psenak,
              "OSPFv3 Extensions for SRv6", Work in Progress, Internet-
              Draft, draft-li-lsr-ospfv3-srv6-extensions-00, 15 January
              2020, <https://www.ietf.org/archive/id/draft-li-lsr-
              ospfv3-srv6-extensions-00.txt>.

   [IANA-IPFIX]
              "IANA, "IP Flow Information Export (IPFIX) Entities"",
              <https://www.iana.org/assignments/ipfix/ipfix.xhtml>.

   [RFC8754]  Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J.,
              Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
              (SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020,
              <https://www.rfc-editor.org/info/rfc8754>.





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Appendix A.  IPFIX Encoding Example

   In this section an example is provided to show the encoding format
   for the newly introduced IEs.

   +-----+------+-----+--------+---------------------------------------|
   | SRH | SRH  | SRH | Segment|             Segment List              |
   | Nr  | Flags| Tag | Type   |                                       |
   +-----+------+-----+--------+---------------------------------------+
   | 1   | 0    | 123 | IS-IS  | 2001:db8::1, 2001:db8::2, 2001:db8::3 |
   +-----+------+-----+--------+---------------------------------------+
   | 2   | 0    | 456 | IS-IS  | 2001:db8::4, 2001:db8::5              |
   +-----+------+-----+--------+---------------------------------------+
   | 3   | 0    | 789 | IS-IS  | 2001:db8::6                           |
   +-----+------+-----+--------+---------------------------------------+

        Table 4: 3 observed SRH headers and their routing protocol

A.1.  Template Record

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          SET ID = 2           |       Length = 41             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      Template ID = 256        |      Field Count = 4          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|     ipv6SRHFlags = TBD2     |      Field Length = 1         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|      ipv6SRHTag = TBD3      |      Field Length = 2         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|  ipv6SRHSegmentType = TBD6  |      Field Length = 1         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|    ipv6SRHSegment = TBD4    |      Field Length = 16        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|  ipv6SRHSegmentList = TBD6  |      Field Length = 0xFFFF    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                  Table 4: Template Record Encoding Format


   In this example, the Template ID is 256, which will be used in the
   Data Record.  The field length for ipv6SRHSegmentList is 0xFFFF,
   which means the length of this IE is variable, and the actual length
   of this IE is indicated by the List Length field in the basicList
   format as per [RFC6313].





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A.2.  Data Set

   The data set is represented as follows:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         SET ID = 256          |           Length = 136        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | ipv6SRHFlags  |        ipv6SRHTag = 123       | ipv6SRHSegment|
      | = 0           |                               | Type = TBD11  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      255      |        List Length = 53       |semantic=      |
      |               |                               |ordered        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     ipv6SRHSegment = TBD4     |        Field Length = 16      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Segment List[0] = 2001:db8::1  (16 bytes)         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Segment List[1] = 2001:db8::2  (16 bytes)         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Segment List[2] = 2001:db8::3  (16 bytes)         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | ipv6SRHFlags  |        ipv6SRHTag = 456       | ipv6SRHSegment|
      | = 0           |                               | Type = TBD11  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      255      |        List Length = 37       |semantic=      |
      |               |                               |ordered        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     ipv6SRHSegment = TBD4     |        Field Length = 16      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Segment List[0] = 2001:db8::4  (16 bytes)         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Segment List[1] = 2001:db8::5  (16 bytes)         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | ipv6SRHFlags  |        ipv6SRHTag = 789       | ipv6SRHSegment|
      | = 0           |                               | Type = TBD11  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      255      |        List Length = 21       |semantic=      |
      |               |                               |ordered        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     ipv6SRHSegment = TBD4     |        Field Length = 16      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Segment List[0] = 2001:db8::6  (16 bytes)         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Table 5: Data Set Encoding Format




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Author's Address

   Thomas Graf
   Swisscom
   Binzring 17
   CH-8045 Zurich
   Switzerland
   Email: thomas.graf@swisscom.com











































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