



OPSAWG                                                            Y. Liu
Internet-Draft                                              China Mobile
Intended status: Standards Track                                  C. Lin
Expires: 6 December 2026                            New H3C Technologies
                                                                Z. Zhang
                                                         ZTE Corporation
                                                             4 June 2026


    Export of BIER Information in IP Flow Information Export (IPFIX)
                     draft-ll-opsawg-ipfix-bier-01

Abstract

   This document introduces new IP Flow Information Export (IPFIX)
   Information Elements (IEs) to identify a set of information related
   to Bit Index Explicit Replication (BIER) such as data contained in
   BIER header that traffic is being forwarded with.

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 6 December 2026.

Copyright Notice

   Copyright (c) 2026 IETF Trust and the persons identified as the
   document authors.  All rights reserved.











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   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 Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  New IPFIX BIER Information Elements . . . . . . . . . . . . .   3
   4.  Operation on bierEncapType  . . . . . . . . . . . . . . . . .   5
   5.  Sample Use Cases  . . . . . . . . . . . . . . . . . . . . . .   5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
     7.1.  IPFIX Information Elements  . . . . . . . . . . . . . . .   6
       7.1.1.  bierTTL . . . . . . . . . . . . . . . . . . . . . . .   6
       7.1.2.  bierEncapType . . . . . . . . . . . . . . . . . . . .   7
       7.1.3.  bierVersion . . . . . . . . . . . . . . . . . . . . .   7
       7.1.4.  bierBSL . . . . . . . . . . . . . . . . . . . . . . .   8
       7.1.5.  bierEntropy . . . . . . . . . . . . . . . . . . . . .   8
       7.1.6.  bierOAMSection  . . . . . . . . . . . . . . . . . . .   9
       7.1.7.  bierDSCP  . . . . . . . . . . . . . . . . . . . . . .   9
       7.1.8.  bierNextProtocol  . . . . . . . . . . . . . . . . . .  10
       7.1.9.  bierBFIRid  . . . . . . . . . . . . . . . . . . . . .  10
       7.1.10. bierBitString . . . . . . . . . . . . . . . . . . . .  11
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  11
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  12
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   [RFC8279] introduces a novel multicast data packet forwarding
   architecture known as "Bit Index Explicit Replication" (BIER).  This
   architecture achieves optimal forwarding within a "multicast domain"
   without relying on explicit tree-building protocols or requiring
   intermediate nodes to maintain per-flow state.  Currently, BIER
   technology has been widely adopted in modern data centers and large-
   scale networks, significantly enhancing the efficiency and
   scalability of multicast transmission.

   [RFC8296] defines the encapsulation of BIER header that provides the
   information needed to support the BIER forwarding procedures.




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   This document specifies new IPFIX Information Elements (IEs) within
   the "IPFIX Information Elements" registry [RFC7012], for BIER
   purposes.  These IEs are used to export the main parameters of BIER
   flow.  This function can be used to collect statistics on the BIER
   flow receiving at a current node; and obtain node statistics
   information of the BIER flow.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

   This document makes use of the terms defined in [RFC7011].

   The following terms are used as defined in [RFC7011]:

   *  IPFIX

   *  IPFIX Information Elements

   The following terms are used as defined in [RFC8296]:

   *  TC

   *  TTL

   *  BFR

   *  BIFT

   *  BFIR

   *  BFER

   *  BSL

   *  SD

   *  SI

3.  New IPFIX BIER Information Elements

   This section specifies the new IPFIX BIER IEs.





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   bierTTL
      The value of the TTL field in the BIER header (Section 2 of
      [RFC8296]).  This IE indicates the incoming Time to Live (TTL)
      when a BIER packet is received.

   bierEncapType
      This IE indicates what type of BIER packet encapsulation is used.
      There are currently three encapsulation methods for BIER packets:
      Ethernet encapsulation, defined in [RFC8296]; MPLS encapsulation,
      also defined in [RFC8296]; and IPv6-based encapsulation, defined
      in [I-D.ietf-bier-bierin6].

   bierVersion
      The version of the BIER header (Section 2 of [RFC8296]).

   bierBSL
      The value of the BSL field in the BIER header (Section 2 of
      [RFC8296]).  This IE indicates the length in bits of the BitString
      defined in the BIER header (Section 2 of [RFC8296]).

   bierEntropy
      The value of the Entropy field in the BIER header (Section 2 of
      [RFC8296]).  It is can be used for load-balancing purposes.

   bierOAMSection
      The OAM and Rsv field from the BIER header (Section 2 of
      [RFC8296]).

   bierDSCP
      The value of the DSCP field in the BIER header (Section 2 of
      [RFC8296]).  In Non-MPLS networks, it is used to hold a
      Differentiated Services Codepoint [RFC2474].

   bierNextProtocol
      The next protocol defined in the Proto field of the BIER header
      (Section 2 of [RFC8296]).  It identifies the type of the payload
      following the BIER header.

   bierBFIRid
      The value of the BFIR-id field in the BIER header (Section 2 of
      [RFC8296]).  It indicates the BFR-id of the BFIR in the SD to
      which the packet has been assigned.

   bierBitString
      The BitString field defined in the BIER header (Section 2 of
      [RFC8296]).  Together with the packet's SI and SD, it identifies
      the destination BFERs for this packet.




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4.  Operation on bierEncapType

   The `bierEncapType` cannot be directly obtained from the BIER Header;
   it must be derived from the corresponding encapsulation method.

   Different encapsulation types guide BIER packets through different
   forwarding table entries.  For the Collector, knowing the
   encapsulation type of the BIER packet is helpful for statistical
   analysis or statistical purposes regarding the corresponding
   forwarding patterns.

   BIER packets can be directly encapsulated using the Ethernet type.
   In this case, the BIER header is directly encapsulated with Ethernet
   type 0xAB37.  BIER packets can also be encapsulated using an MPLS
   label stack.  The label at the bottom of the stack guides the BIER
   packet to find the corresponding MPLS forwarding table entry.  The
   definitions of Ethernet type and MPLS encapsulation are both in
   [RFC8296].  BIER packets can also be encapsulated in IPv6 format.  In
   this mode, the BIER header is encapsulated after the IPv6 header.
   This method is defined in [I-D.ietf-bier-bierin6].

   The node, based on the specific encapsulation information of the
   received BIER message and other IEs in the message header, sends it
   to the Collector so that the Collector can perform further statistics
   and analysis.

5.  Sample Use Cases

   The IPFIX IEs defined in the Section 3, and some existing IP packet
   header information [IANA-IPFIX] provide answers to the following
   questions (amongst others).

   *  Whether the IP packet is a BIER packet?

   *  Whether the BIER packet is from an MPLS network?

   *  What is the incoming TTL of the BIER packet?

   *  What is BIER version used by the BIER packet?

   *  What is the type of the payload following the BIER header in the
      BIER packet?

   *  What is the destination BFERs for the BIER packet?







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6.  Security Considerations

   There exists no extra security considerations other than those
   already discussed in Section 11 of [RFC7011] and Section 8 of
   [RFC7012].

7.  IANA Considerations

7.1.  IPFIX Information Elements

   This document requests IANA to add new IPFIX BIER IEs to the "IPFIX
   Information Elements" registry [RFC7012] available at [IANA-IPFIX].

   Table 1 lists the new IPFIX BIER IEs:

         +============+=============================+===============+
         | Element ID | Name                        | Reference     |
         +============+=============================+===============+
         | TBD1       | bierTTL                     | This document |
         +------------+-----------------------------+---------------+
         | TBD2       | bierEncapType               | This document |
         +------------+-----------------------------+---------------+
         | TBD3       | bierVersion                 | This document |
         +------------+-----------------------------+---------------+
         | TBD4       | bierBSL                     | This document |
         +------------+-----------------------------+---------------+
         | TBD5       | bierEntropy                 | This document |
         +------------+-----------------------------+---------------+
         | TBD6       | bierOAMSection              | This document |
         +------------+-----------------------------+---------------+
         | TBD7       | bierDSCP                    | This document |
         +------------+-----------------------------+---------------+
         | TBD8       | bierNextProtocol            | This document |
         +------------+-----------------------------+---------------+
         | TBD9       | bierBFIRid                  | This document |
         +------------+-----------------------------+---------------+
         | TBD10      | bierBitString               | This document |
         +------------+-----------------------------+---------------+

      Table 1: New BIER IEs in the "IPFIX Information Elements" Registry

7.1.1.  bierTTL

   ElementID:  TBD1

   Name:  bierTTL

   Abstract Data Type:  unsigned8



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   Data Type Semantics:  default

   Status:  current

   Description:  The value of the TTL field in the BIER header.  This
      Information Element indicates the incoming TTL when a BIER packet
      is received.

   Units:  hops

   Additional Information:  See Section 2 of [RFC8296] for more details
      about the TTL fields.

   Reference:  [this document]

7.1.2.  bierEncapType

   ElementID:  TBD2

   Name:  bierEncapType

   Abstract Data Type:  unsigned8

   Data Type Semantics:  default

   Status:  current

   Description:  This IE indicates the encapsulation type of BIER
      packet.  When the value is set to 0, it indicates Ethernet
      encapsulation; when the value is set to 1, it indicates MPLS
      encapsulation; when the value is set to 2, it indicates IPv6
      encapsulation.

   Reference:  [this document]

7.1.3.  bierVersion

   ElementID:  TBD3

   Name:  bierVersion

   Abstract Data Type:  unsigned8

   Data Type Semantics:  identifier

   Status:  current

   Description:  The version value of the Ver field in the BIER header.



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      This Information Element encodes only the 4 bits of the Ver field.
      Therefore, its value may range from 0 to 0xF.

   Additional Information:  See Section 2 of [RFC8296] for more details
      about the Ver field of the BIER header.

   Reference:  [this document]

7.1.4.  bierBSL

   ElementID:  TBD4

   Name:  bierBSL

   Abstract Data Type:  unsigned8

   Data Type Semantics:  default

   Status:  current

   Description:  The value of the BSL field in the BIER header.  This
      Information Element indicates the length in bits of the BitString
      defined in the BIER header.

      This Information Element encodes only the 4 bits of the BSL field.
      Therefore, its value may range from 0 to 15.

   Additional Information:  See Section 2 of [RFC8296] for more details
      about the BSL field of the BIER header.

   Reference:  [this document]

7.1.5.  bierEntropy

   ElementID:  TBD5

   Name:  bierEntropy

   Abstract Data Type:  unsigned32

   Data Type Semantics:  default

   Status:  current

   Description:  The value of the Entropy field in the BIER header.
      This Information Element indicates the function of load-balancing.





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      This Information Element encodes only the 20 bits of the Entropy
      field.  Therefore, its value may range from 0 to 0xFFFFF.

   Additional Information:  See Section 2 of [RFC8296] for more details
      about the Entropy field of the BIER header.

   Reference:  [this document]

7.1.6.  bierOAMSection

   ElementID:  TBD6

   Name:  bierOAMSection

   Abstract Data Type:  unsigned8

   Data Type Semantics:  flags

   Status:  current

   Description:  The OAM and Rsv field from the BIER header.

                    0 1 2 3 4 5 6 7
                   +-+-+-+-+-+-+-+-+
                   |OAM|Rsv|no care|
                   +-+-+-+-+-+-+-+-+

                   Bits 0-1: OAM field.
                   Bits 2-3: Rsv field, unused.
                   Bits 4-7: No care, value is irrelevent.

   Additional Information:  See Section 2 of [RFC8296] for more details
      about the OAM and Rsv field of the BIER header.

   Reference:  [this document]

7.1.7.  bierDSCP

   ElementID:  TBD7

   Name:  bierDSCP

   Abstract Data Type:  unsigned8

   Data Type Semantics:  identifier

   Status:  current




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   Description:  The value of the DSCP field in the BIER header.  In
      Non-MPLS networks, it is used to hold a Differentiated Services
      Codepoint.

      This Information Element encodes only the 6 bits of the DSCP
      field.  Therefore, its value may range from 0 to 63.

   Additional Information:  See Section 2 of [RFC8296] for more details
      about the DSCP field of the BIER header.

   Reference:  [this document]

7.1.8.  bierNextProtocol

   ElementID:  TBD8

   Name:  bierNextProtocol

   Abstract Data Type:  unsigned8

   Data Type Semantics:  identifier

   Status:  current

   Description:  The next protocol defined in the Proto field of the
      BIER header.  This Information Element identifies the type of the
      payload following the BIER header.

      This Information Element encodes only the 6 bits of the Proto
      field.  Therefore, its value may range from 0 to 63.

   Additional Information:  See Section 2 of [RFC8296] for more details
      about the Proto field of the BIER header.

   Reference:  [this document]

7.1.9.  bierBFIRid

   ElementID:  TBD9

   Name:  bierBFIRid

   Abstract Data Type:  unsigned16

   Data Type Semantics:  identifier

   Status:  current




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   Description:  The value of the BFIR-id field in the BIER header.
      This Information Element identifies the BFR-id of the BFIR in the
      SD to which the packet has been assigned.

   Additional Information:  See Section 2 of [RFC8296] for more details
      about the BFIR-id field of the BIER header.

   Reference:  [this document]

7.1.10.  bierBitString

   ElementID:  TBD10

   Name:  bierBitString

   Abstract Data Type:  octetArray

   Data Type Semantics:  identifier

   Status:  current

   Description:  The BitString field defined in the BIER header.
      Together with the packet's SI and SD, this information Element
      identifies the destination BFERs for this packet.

   Additional Information:  See Section 2 of [RFC8296] for more details
      about the BitString field of the BIER header.

   Reference:  [this document]

8.  References

8.1.  Normative References

   [I-D.ietf-bier-bierin6]
              Zhang, Z., Zhang, Z. J., Wijnands, I., Mishra, M. P.,
              Bidgoli, H., and G. S. Mishra, "Supporting BIER in IPv6
              Networks (BIERin6)", Work in Progress, Internet-Draft,
              draft-ietf-bier-bierin6-13, 23 February 2026,
              <https://datatracker.ietf.org/doc/html/draft-ietf-bier-
              bierin6-13>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.





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   [RFC2474]  Nichols, K., Blake, S., Baker, F., and D. Black,
              "Definition of the Differentiated Services Field (DS
              Field) in the IPv4 and IPv6 Headers", RFC 2474,
              DOI 10.17487/RFC2474, December 1998,
              <https://www.rfc-editor.org/info/rfc2474>.

   [RFC7011]  Claise, B., Ed., Trammell, B., Ed., and P. Aitken,
              "Specification of the IP Flow Information Export (IPFIX)
              Protocol for the Exchange of Flow Information", STD 77,
              RFC 7011, DOI 10.17487/RFC7011, September 2013,
              <https://www.rfc-editor.org/info/rfc7011>.

   [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>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8279]  Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A.,
              Przygienda, T., and S. Aldrin, "Multicast Using Bit Index
              Explicit Replication (BIER)", RFC 8279,
              DOI 10.17487/RFC8279, November 2017,
              <https://www.rfc-editor.org/info/rfc8279>.

   [RFC8296]  Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A.,
              Tantsura, J., Aldrin, S., and I. Meilik, "Encapsulation
              for Bit Index Explicit Replication (BIER) in MPLS and Non-
              MPLS Networks", RFC 8296, DOI 10.17487/RFC8296, January
              2018, <https://www.rfc-editor.org/info/rfc8296>.

8.2.  Informative References

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

Authors' Addresses

   Yisong Liu
   China Mobile
   32 Xuanwumen West Street
   Beijing
   Xicheng District, 100053
   China
   Email: liuyisong@chinamobile.com



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   Changwang Lin
   New H3C Technologies
   8 Yongjia North Road
   Beijing
   Haidian District, 100094
   China
   Email: linchangwang.04414@h3c.com


   Zheng Zhang
   ZTE Corporation
   Nanjing
   China
   Email: zhang.zheng@zte.com.cn





































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