OPSAWG Y. Liu Internet-Draft L. Zhao Intended status: Standards Track ZTE Expires: 1 June 2026 28 November 2025 Export of IGP Flexible Algorithm Information in IPFIX draft-liu-opsawg-ipfix-igp-algo-00 Abstract This document introduces a new IPFIX information element (IE) to identify the IGP flexible algorithm information related with the Segment Identifier(SID) or the IPv4/IPv6 prefix. 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 1 June 2026. Copyright Notice Copyright (c) 2025 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. Liu & Zhao Expires 1 June 2026 [Page 1] Internet-Draft IPFIX for Flex-Algo November 2025 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. IGP Flexible Algorithm Information in IPFIX . . . . . . . . . 3 4. Operational Considerations . . . . . . . . . . . . . . . . . 4 5. Security Considerations . . . . . . . . . . . . . . . . . . . 4 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 7.1. Normative References . . . . . . . . . . . . . . . . . . 5 7.2. Informative References . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 1. Introduction [RFC9350] introduces the concept of Flexible Algorithm that allows IGPs (ISIS, OSPFv2 and OSPFv3) to compute constraint-based path over an SR-MPLS or an SRv6 network. In SR, the same prefix can be associated with multiple algorithms. [I-D.ietf-lsr-algorithm-related-adjacency-sid] comments that, besides the SR-MPLS prefix SID, the algorithm can be also included as part of an SR-MPLS Adjacency-SID advertisement in scenarios where multiple algorithm share the same link resource. [RFC9502] further extends IGP Flexible Algorithm so that it can be used with regular IPv4 and IPv6 forwarding. With IGP Flexible Algorithm, a physical network can be divided into multiple logical planes. For each Flex-Algorithm, the path is computed independently. Below are the typical use cases when monitoring a traffic flow in a network with IGP Flex-Algorithm enabled. * Which Flex-Algorithm is the SR-MPLS SID or the SRv6 SID locator belongs to ? * Which Flex-Algorithm is the IPv4/IPv6 prefix related with ? By only looking at the SR SID or the IP address itself, the above questions could not be answered. This document introduces a new IP Flow Information Export (IPFIX) information element (IE) to identify the IGP Flexible algorithm related with the SR segment identifier(SID) or the IPv4/IPv6 prefix. Liu & Zhao Expires 1 June 2026 [Page 2] Internet-Draft IPFIX for Flex-Algo November 2025 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], [RFC8402] and [RFC9350]. The following terms are used as defined in [RFC7011]: * IPFIX * IPFIX Information Elements * Metering Process * Template Record * Data Record * Collector The following terms are used as defined in [RFC8402]: * Segment Routing (SR) * Segment List * SRv6 * SR-MPLS * Segment Identifier (SID) The following terms are used as defined in [RFC9350]: * Flexible Algorithm 3. IGP Flexible Algorithm Information in IPFIX A new IE "flexAlgo" is defined in this document to identify the Flexible Algorithm information related with an SR-MPLS SID, an SRv6 locator or an IPv4/IPv6 prefix, the IE carries the value of the IGP Algorithm Types as in the IANA "IGP Algorithm Types" registry. Liu & Zhao Expires 1 June 2026 [Page 3] Internet-Draft IPFIX for Flex-Algo November 2025 Name: flexAlgo ElementID: TBD1 Description: The 8-bit value that represents an IGP Flexible Algorithm number related with an SR-MPLS SID, an SRv6 locator or an IPv4/IPv6 prefix. The Flexible Algorithm number are specified in the IANA "IGP Algorithm Types". Abstract Data Type: unsigned8 Data Type Semantics: identifier Additional Information: Specified in [RFC9350] and [RFC9502]. Reference: This document. 4. Operational Considerations When used for monitoring SR-MPLS traffic flows, the IE "flexAlgo" indicates the IGP flexible algorithm of the active SR-MPLS prefix/ adjacency SID or the IGP prefix related with the SR-MPLS SID, as in [RFC8665], [RFC9350] and [I-D.ietf-lsr-algorithm-related-adjacency-sid]. And the "flexAlgo" is valid when the value of IE "IPFIX MPLS label type (Value 46)"[RFC9160] in the data record is 7 (OSPFv2 Segment Routing), 8 (OSPFv3 Segment Routing) or 9(IS-IS Segment Routing). In the absence of the IE "IPFIX MPLS label type" in the IPFIX template record, how to process the "flexAlgo" is implementation specific. When used for monitoring SRv6 traffic flows, the IE "flexAlgo" indicates the IGP algorithm related with the locator of the active SRv6 SID as in [RFC9350], [RFC9352] and [RFC9513]. And the "flexAlgo" is valid when the value of IE "IPFIX IPv6 SRH Segment Type (Value 500)"[RFC9487] in the data record is 3 (OSPFv3 Segment Routing) or 4 (IS-IS Segment Routing). In the absence of the "IPFIX IPv6 SRH Segment Type", how to process the "flexAlgo" is implementation specific. When monitoring pure IPv4/IPv6 traffic flows, the IE "flexAlgo" can be used to indicate the IGP algorithm related with the destination IPv4/IPv6 address or the IPv4/IPv6 next hop address. 5. Security Considerations There are no additional security considerations regarding allocation of these new IPFIX IEs compared to [RFC7012]. Liu & Zhao Expires 1 June 2026 [Page 4] Internet-Draft IPFIX for Flex-Algo November 2025 Other security considerations for IGP flexible algorithmin [RFC9350] and [RFC9502] apply to this document. 6. IANA Considerations This document requests IANA to create a new IE under the "IPFIX Information Elements" registry [RFC7012] available at [IANA-IPFIX]. +-------+--------------------------------+ |Element| Name | Reference | | ID | | | +-------+-----------------+--------------+ | TBD1 | flexAlgo |This document | +-------+-----------------+--------------+ 7. References 7.1. Normative References [IANA-IPFIX] IANA, "IP Flow Information Export (IPFIX) Entities", . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [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, . [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., Decraene, B., Litkowski, S., and R. Shakir, "Segment Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, July 2018, . Liu & Zhao Expires 1 June 2026 [Page 5] Internet-Draft IPFIX for Flex-Algo November 2025 [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, . [RFC9350] Psenak, P., Ed., Hegde, S., Filsfils, C., Talaulikar, K., and A. Gulko, "IGP Flexible Algorithm", RFC 9350, DOI 10.17487/RFC9350, February 2023, . [RFC9502] Britto, W., Hegde, S., Kaneriya, P., Shetty, R., Bonica, R., and P. Psenak, "IGP Flexible Algorithm in IP Networks", RFC 9502, DOI 10.17487/RFC9502, November 2023, . 7.2. Informative References [I-D.ietf-lsr-algorithm-related-adjacency-sid] Chen, R., Peng, S., Talaulikar, K., and P. Psenak, "Algorithm Related IGP-Adjacency SID Advertisement", Work in Progress, Internet-Draft, draft-ietf-lsr-algorithm- related-adjacency-sid-08, 16 October 2025, . [RFC8665] 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, December 2019, . [RFC9160] Graf, T., "Export of MPLS Segment Routing Label Type Information in IP Flow Information Export (IPFIX)", RFC 9160, DOI 10.17487/RFC9160, December 2021, . [RFC9352] Psenak, P., Ed., Filsfils, C., Bashandy, A., Decraene, B., and Z. Hu, "IS-IS Extensions to Support Segment Routing over the IPv6 Data Plane", RFC 9352, DOI 10.17487/RFC9352, February 2023, . [RFC9487] Graf, T., Claise, B., and P. Francois, "Export of Segment Routing over IPv6 Information in IP Flow Information Export (IPFIX)", RFC 9487, DOI 10.17487/RFC9487, November 2023, . Liu & Zhao Expires 1 June 2026 [Page 6] Internet-Draft IPFIX for Flex-Algo November 2025 [RFC9513] Li, Z., Hu, Z., Talaulikar, K., Ed., and P. Psenak, "OSPFv3 Extensions for Segment Routing over IPv6 (SRv6)", RFC 9513, DOI 10.17487/RFC9513, December 2023, . Authors' Addresses Yao Liu ZTE Nanjing China Email: liu.yao71@zte.com.cn Liman Zhao ZTE Email: zhao.liman@zte.com.cn Liu & Zhao Expires 1 June 2026 [Page 7]