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 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 6 December 2026. Copyright Notice Copyright (c) 2026 IETF Trust and the persons identified as the document authors. All rights reserved. Liu, et al. Expires 6 December 2026 [Page 1] Internet-Draft Export of BIER in IPFIX June 2026 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. Liu, et al. Expires 6 December 2026 [Page 2] Internet-Draft Export of BIER in IPFIX June 2026 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. Liu, et al. Expires 6 December 2026 [Page 3] Internet-Draft Export of BIER in IPFIX June 2026 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. Liu, et al. Expires 6 December 2026 [Page 4] Internet-Draft Export of BIER in IPFIX June 2026 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? Liu, et al. Expires 6 December 2026 [Page 5] Internet-Draft Export of BIER in IPFIX June 2026 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 Liu, et al. Expires 6 December 2026 [Page 6] Internet-Draft Export of BIER in IPFIX June 2026 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. Liu, et al. Expires 6 December 2026 [Page 7] Internet-Draft Export of BIER in IPFIX June 2026 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. Liu, et al. Expires 6 December 2026 [Page 8] Internet-Draft Export of BIER in IPFIX June 2026 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 Liu, et al. Expires 6 December 2026 [Page 9] Internet-Draft Export of BIER in IPFIX June 2026 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 Liu, et al. Expires 6 December 2026 [Page 10] Internet-Draft Export of BIER in IPFIX June 2026 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, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . Liu, et al. Expires 6 December 2026 [Page 11] Internet-Draft Export of BIER in IPFIX June 2026 [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, . [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, . [RFC7012] Claise, B., Ed. and B. Trammell, Ed., "Information Model for IP Flow Information Export (IPFIX)", RFC 7012, DOI 10.17487/RFC7012, September 2013, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [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, . [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, . 8.2. Informative References [IANA-IPFIX] "IP Flow Information Export (IPFIX) Entities", n.d., . Authors' Addresses Yisong Liu China Mobile 32 Xuanwumen West Street Beijing Xicheng District, 100053 China Email: liuyisong@chinamobile.com Liu, et al. Expires 6 December 2026 [Page 12] Internet-Draft Export of BIER in IPFIX June 2026 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 Liu, et al. 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