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Export of BIER Information in IP Flow Information Export (IPFIX)
Export of BIER Information in IP Flow Information Export (IPFIX)
draft-ll-opsawg-ipfix-bier-00
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| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Yisong Liu , Changwang Lin | ||
| Last updated | 2026-01-22 | ||
| RFC stream | (None) | ||
| Intended RFC status | (None) | ||
| Formats | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
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draft-ll-opsawg-ipfix-bier-00
OPSAWG Y. Liu
Internet-Draft China Mobile
Intended status: Standards Track C. Lin
Expires: 26 July 2026 New H3C Technologies
22 January 2026
Export of BIER Information in IP Flow Information Export (IPFIX)
draft-ll-opsawg-ipfix-bier-00
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
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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 26 July 2026.
Copyright Notice
Copyright (c) 2026 IETF Trust and the persons identified as the
document authors. All rights reserved.
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.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. New IPFIX BIER Information Elements . . . . . . . . . . . . . 3
4. Sample Use Cases . . . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
6.1. IPFIX Information Elements . . . . . . . . . . . . . . . 5
6.1.1. bierBIFTidSection . . . . . . . . . . . . . . . . . . 6
6.1.2. bierTTL . . . . . . . . . . . . . . . . . . . . . . . 7
6.1.3. bierFromMPLSNetwork . . . . . . . . . . . . . . . . . 7
6.1.4. bierVersion . . . . . . . . . . . . . . . . . . . . . 8
6.1.5. bierBSL . . . . . . . . . . . . . . . . . . . . . . . 8
6.1.6. bierEntropy . . . . . . . . . . . . . . . . . . . . . 9
6.1.7. bierOAMSection . . . . . . . . . . . . . . . . . . . 9
6.1.8. bierDSCP . . . . . . . . . . . . . . . . . . . . . . 10
6.1.9. bierNextProtocol . . . . . . . . . . . . . . . . . . 10
6.1.10. bierBFIRid . . . . . . . . . . . . . . . . . . . . . 11
6.1.11. bierBitString . . . . . . . . . . . . . . . . . . . . 11
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
7.1. Normative References . . . . . . . . . . . . . . . . . . 12
7.2. Informative References . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
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.
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.
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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.
bierBIFTidSection
The BIFT-id, TC, and S fields defined in the initial three octets
of the BIER header (Section 2 of [RFC8296]).
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.
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bierFromMPLSNetwork
This IE indicates whether the BIER packet is from an MPLS network.
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.
4. 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?
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* 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?
5. Security Considerations
There exists no extra security considerations other than those
already discussed in Section 11 of [RFC7011] and Section 8 of
[RFC7012].
6. IANA Considerations
6.1. 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:
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+============+=============================+===============+
| Element ID | Name | Reference |
+============+=============================+===============+
| TBD1 | bierBIFTidSection | This document |
+------------+-----------------------------+---------------+
| TBD2 | bierTTL | This document |
+------------+-----------------------------+---------------+
| TBD3 | bierFromMPLSNetwork | This document |
+------------+-----------------------------+---------------+
| TBD4 | bierVersion | This document |
+------------+-----------------------------+---------------+
| TBD5 | bierBSL | This document |
+------------+-----------------------------+---------------+
| TBD6 | bierEntropy | This document |
+------------+-----------------------------+---------------+
| TBD7 | bierOAMSection | This document |
+------------+-----------------------------+---------------+
| TBD8 | bierDSCP | This document |
+------------+-----------------------------+---------------+
| TBD9 | bierNextProtocol | This document |
+------------+-----------------------------+---------------+
| TBD10 | bierBFIRid | This document |
+------------+-----------------------------+---------------+
| TBD11 | bierBitString | This document |
+------------+-----------------------------+---------------+
Table 1: New BIER IEs in the "IPFIX Information Elements" Registry
6.1.1. bierBIFTidSection
ElementID: TBD1
Name: bierBIFTidSection
Abstract Data Type: octetArray
Data Type Semantics: identifier
Status: current
Description: The BIFT-id, TC, and S fields defined in the initial
three octets of the BIER header. The size of this information
Element is 3 octets.
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0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BIFT-id | TC |S|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
BIFT-id: BIFT id, 20 bits
TC: Traffic Class, 3 bits
S: Set to 1, 1 bit
Additional Information: See Section 2 of [RFC8296] for more details
about the BIFT-id, TC, and S fields.
Reference: [this document]
6.1.2. bierTTL
ElementID: TBD2
Name: bierTTL
Abstract Data Type: unsigned8
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]
6.1.3. bierFromMPLSNetwork
ElementID: TBD3
Name: bierFromMPLSNetwork
Abstract Data Type: boolean
Data Type Semantics: default
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Status: current
Description: This IE indicates whether the BIER packet is from an
MPLS network.
Additional Information: In MPLS networks, the Nibble field of the
BIER header MUST be set to the binary value 0101. In Non-MPLS
networks, the Nibble field is set to the binary value 0000.
Therefore, the Nibble field can be used to identify whether a BIER
packet is from an MPLS network. See Section 2 of [RFC8296] for
more details.
Reference: [this document]
6.1.4. bierVersion
ElementID: TBD4
Name: bierVersion
Abstract Data Type: unsigned8
Data Type Semantics: identifier
Status: current
Description: The version value of the Ver field in the BIER header.
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]
6.1.5. bierBSL
ElementID: TBD5
Name: bierBSL
Abstract Data Type: unsigned8
Data Type Semantics: default
Status: current
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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]
6.1.6. bierEntropy
ElementID: TBD6
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.
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]
6.1.7. bierOAMSection
ElementID: TBD7
Name: bierOAMSection
Abstract Data Type: unsigned8
Data Type Semantics: flags
Status: current
Description: The OAM and Rsv field from the BIER header.
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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]
6.1.8. bierDSCP
ElementID: TBD8
Name: bierDSCP
Abstract Data Type: unsigned8
Data Type Semantics: identifier
Status: current
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]
6.1.9. bierNextProtocol
ElementID: TBD9
Name: bierNextProtocol
Abstract Data Type: unsigned8
Data Type Semantics: identifier
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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]
6.1.10. bierBFIRid
ElementID: TBD10
Name: bierBFIRid
Abstract Data Type: unsigned16
Data Type Semantics: identifier
Status: current
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]
6.1.11. bierBitString
ElementID: TBD11
Name: bierBitString
Abstract Data Type: octetArray
Data Type Semantics: identifier
Status: current
Description: The BitString field defined in the BIER header.
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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]
7. References
7.1. Normative References
[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>.
[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>.
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[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>.
7.2. 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
Changwang Lin
New H3C Technologies
8 Yongjia North Road
Beijing
Haidian District, 100094
China
Email: linchangwang.04414@h3c.com
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