Internet Y. Qu Internet-Draft Futurewei Technologies Intended status: Standards Track A. Lindem Expires: 1 January 2027 Arrcus, Inc. 30 June 2026 A YANG Data Model for OSPF Application-Specific Link Attributes and Flexible Algorithm draft-ietf-lsr-ospf-flex-algo-yang-09 Abstract This document defines a YANG data model to support OSPF Application- Specific Link Attributes and Flexible Algorithm. It also specifies the initial version of IANA-maintained YANG modules for IGP Algorithm Types, IGP Metric-Types, and IGP Link Attribute Applications. 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 January 2027. 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. Qu & Lindem Expires 1 January 2027 [Page 1] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 Table of Contents 1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 2. IANA IGP Algorithm Types Module . . . . . . . . . . . . . . . 3 3. IANA IGP Metric Types Module . . . . . . . . . . . . . . . . 5 4. IANA IGP Link Attribute Applications Module . . . . . . . . . 7 5. YANG Module for OSPF Application-Specific Link Attributes . . 10 6. YANG Module for OSPF Flexible Algorithm . . . . . . . . . . . 18 7. Security Considerations . . . . . . . . . . . . . . . . . . . 38 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 39 8.1. Registering YANG Modules . . . . . . . . . . . . . . . . 39 8.2. IANA IGP Algorithm Types Module . . . . . . . . . . . . . 40 8.3. IANA IGP Metric-Type Module . . . . . . . . . . . . . . . 41 8.4. IANA IGP Link Attribute Applications Module . . . . . . . 42 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 43 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 43 10.1. Normative References . . . . . . . . . . . . . . . . . . 43 10.2. Informative References . . . . . . . . . . . . . . . . . 46 Appendix A. Example OSPF Flex-Algo Configuration (XML) . . . . . 47 Appendix B. Example OSPF Flex-Algo Configuration (JSON) . . . . 49 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 50 1. Overview This document defines YANG [RFC7950] data modules augmenting the IETF OSPF YANG model [RFC9129], which itself augments the IETF Routing model [RFC8349], to provide support for both OSPF Flexible Algorithm as defined in [RFC9350] and OSPF Application-Specific Link Attributes as defined in [RFC9492]. Five YANG modules are defined in this document. The first is the initial version of the IANA-maintained YANG module for IGP Algorithm Types. The second module is the initial version of the IANA- maintained YANG module for IGP Metric-Type. The third module is the initial version of the IANA-maintained YANG module for IGP Link Attribute Application types. The fourth module is to support OSPF Application-Specific Link Attributes, and the fifth module augments the IETF OSPF YANG data model to support OSPF Flex Algorithm. The meanings of the symbols in the YANG tree diagrams are defined in [RFC8340]. Qu & Lindem Expires 1 January 2027 [Page 2] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 1.1. Requirements Language 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. 2. IANA IGP Algorithm Types Module IANA has created a registry titled "IGP Algorithm Types" under the "Interior Gateway Protocol (IGP) Parameters" registry group to identify Algorithm Types. Module iana-igp-algo-types is an IANA- maintained module, which defines the identities for the Algorithm Types as in the IANA "IGP Algorithm Types" registry. This module is maintained by IANA and will be updated if and when there is any change to the registry. This document defines the initial version of the IANA-maintained YANG module for Algorithm Types that mirrors the IANA "IGP Algorithm Types" registry [IANA-IGP-ALGO-Types]. This YANG module references [RFC8665]. file "iana-igp-algo-types@2026-03-30.yang" module iana-igp-algo-types { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:iana-igp-algo-types"; prefix iana-algo-types; organization "Internet Assigned Numbers Authority (IANA)"; contact "Internet Assigned Numbers Authority ICANN 12025 Waterfront Drive, Suite 300 Los Angeles, CA 90094-2536 United States of America Tel: +1 310 301 5800 "; description "The YANG module defines the identities for Interior Gateway Protocol (IGP) Algorithm Types. This YANG module is maintained by IANA and reflects the 'IGP Qu & Lindem Expires 1 January 2027 [Page 3] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 Algorithm Types' registry. Copyright (c) 2026 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Revised BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). All revisions of IETF and IANA published modules can be found at the YANG Parameters registry group (https://www.iana.org/assignments/yang-parameters). This initial version of this YANG module is part of RFC XXXX (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself for full legal notices. //RFC Ed.: replace XXXX with actual RFC number and remove this note The latest version of this YANG module is available at https://www.iana.org/assignments/yang-parameters."; revision 2026-03-30 { description "Initial Version"; reference "RFC XXXX: YANG Data Model for OSPF Application-Specific Link Attributes and Flexible Algorithm"; } identity algo-type { description "Base identity for IGP Algorithm Type. The algorithm types are defined in IANA IGP Algorithm Types registry."; } identity algo-spf { base algo-type; description "Shortest Path First (SPF) algorithm based on link metric."; reference "RFC 8665: OSPF Extensions for Segment Routing"; } Qu & Lindem Expires 1 January 2027 [Page 4] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 identity algo-strict-spf { base algo-type; description "Strict Shortest Path First (SPF) algorithm based on link metric."; reference "RFC 8665: OSPF Extensions for Segment Routing"; } } 3. IANA IGP Metric Types Module IANA has created a registry titled "IGP Metric-Type" under the "Interior Gateway Protocol (IGP) Parameters" registry group to identify Metric Types. Module iana-igp-metric-types is an IANA- maintained module, which defines the identities for the Metric Types as in the IANA "IGP Metric-Type" registry. This module is maintained by IANA and will be updated if and when there is any change to the registry. This document defines the initial version of the IANA-maintained YANG module for IGP metric types that mirrors the IANA "IGP Metric-Type" registry [IANA-IGP-Metric-Types]. This YANG module references [RFC3630], [RFC5305], [RFC7471], [RFC8570], [RFC9350], and [RFC9843]. file "iana-igp-metric-types@2026-03-30.yang" module iana-igp-metric-types { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:iana-igp-metric-types"; prefix iana-metric-types; organization "Internet Assigned Numbers Authority (IANA)"; contact "Internet Assigned Numbers Authority ICANN 12025 Waterfront Drive, Suite 300 Los Angeles, CA 90094-2536 United States of America Tel: +1 310 301 5800 "; description Qu & Lindem Expires 1 January 2027 [Page 5] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 "The YANG module defines the identities for Interior Gateway Protocol (IGP) Metric-Types. This YANG module is maintained by IANA and reflects the 'IGP Metric-Type' registry. Copyright (c) 2026 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Revised BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). All revisions of IETF and IANA published modules can be found at the YANG Parameters registry group (https://www.iana.org/assignments/yang-parameters). This initial version of this YANG module is part of RFC XXXX (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself for full legal notices. //RFC Ed.: replace XXXX with actual RFC number and remove this note The latest version of this YANG module is available at https://www.iana.org/assignments/yang-parameters."; revision 2026-03-30 { description "Initial Version"; reference "RFC XXXX: YANG Data Model for OSPF Application-Specific Link Attributes and Flexible Algorithm"; } identity metric-type { description "Base identity for IGP Metric-Type. The metric types are defined in IANA IGP Metric-Type registry."; } identity igp-metric { base metric-type; description "IGP Metric."; Qu & Lindem Expires 1 January 2027 [Page 6] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 reference "RFC9350: IGP Flexible Algorithm"; } identity min-unidirectional-link-delay { base metric-type; description "Min Unidirectional Link Delay as defined in RFC 8570 and Section 4.2 and RFC 7471 Section 4.2."; reference "RFC 7471: OSPF Traffic Engineering (TE) Metric Extensions RFC 8570: IS-IS Traffic Engineering (TE) Metric Extensions RFC 9350: IGP Flexible Algorithm"; } identity te-default-metric { base metric-type; description "Traffic Engineering Default Metric as defined in RFC 5305 Section 3.7 and Traffic Engineering Metric as defined in RFC3630, Section 2.5.5."; reference "RFC 3630: OSPF Traffic Engineering RFC 5305: IS-IS Traffic Engineering RFC 9350: IGP Flexible Algorithm"; } identity bandwidth-metric { base metric-type; description "Bandwidth metric."; reference "RFC 9843: IGP Flexible Algorithms: Bandwidth, Delay, Metrics, and Constraints, Sections 4 and 5"; } } 4. IANA IGP Link Attribute Applications Module IANA has created a registry titled "Link Attribute Application Identifiers" under the "Interior Gateway Protocol (IGP) Parameters" registry group to identify IGP application types with application- specific link attributes. Module iana-igp-link-attr-apps is an IANA- maintained module, which defines the identities for the link attribute application IDs as in the IANA "Link Attribute Application Identifiers" registry. Qu & Lindem Expires 1 January 2027 [Page 7] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 This module is maintained by IANA and will be updated if and when there is any change to the registry. This document defines the initial version of the IANA-maintained YANG module for IGP application types that mirrors the IANA "Link Attribute Application Identifiers" registry [IANA-Link-Attr-Apps]. This YANG module references [RFC9492]. file "iana-igp-link-attr-apps@2026-04-14.yang" module iana-igp-link-attr-apps { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:iana-igp-link-attr-apps"; prefix iana-link-attr-app; organization "Internet Assigned Numbers Authority (IANA)"; contact "Internet Assigned Numbers Authority ICANN 12025 Waterfront Drive, Suite 300 Los Angeles, CA 90094-2536 United States of America Tel: +1 310 301 5800 "; description "The YANG module defines the identities for Interior Gateway Protocol (IGP) Application IDs used for Link Attributes. This YANG module is maintained by IANA and reflects the 'Link Attribute Application Identifiers' registry. Copyright (c) 2026 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Revised BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). All revisions of IETF and IANA published modules can be found at the YANG Parameters registry group (https://www.iana.org/assignments/yang-parameters). Qu & Lindem Expires 1 January 2027 [Page 8] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 This initial version of this YANG module is part of RFC XXXX (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself for full legal notices. //RFC Ed.: replace XXXX with actual RFC number and remove this note The latest version of this YANG module is available at https://www.iana.org/assignments/yang-parameters."; revision 2026-04-14 { description "Initial Version"; reference "RFC XXXX: YANG Data Model for OSPF Application-Specific Link Attributes and Flexible Algorithm"; } identity igp-link-attr-app { description "Base identity for Standard Applications"; reference "RFC 9492: OSPF Application-Specific Link Attributes"; } identity rsvp-te-app { base igp-link-attr-app; description "RSVP Traffic Engineering (TE) Application - This corresponds to Bit 0 (R-BIT) in the Standard Application Bit Mask (SABM)."; reference "RFC 3630: Traffic Engineering (TE) for OSPFv2 RFC 5329: Traffic Engineering Extensions to OSPFv3"; } identity sr-policy-app { base igp-link-attr-app; description "Segment Routing (SR) Policy Application - This corresponds to Bit 1 (S-BIT) in the Standard Application Bit Mask (SABM)."; reference "RFC 8665: OSPF Extensions for Segment Routing RFC 8666: OSPFv3 Extensions for Segment Routing"; } identity lfa-app { Qu & Lindem Expires 1 January 2027 [Page 9] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 base igp-link-attr-app; description "Loop-Free Alternative (LFA) Application - This corresponds to Bit 2 (F-BIT) in the Standard Application Bit Mask (SABM)."; reference "RFC 8102: Remote-LFA Node Protection and Manageability RFC 9855: Topology Independent Fast Reroute Using Segment Routing"; } identity flex-algo-app { base igp-link-attr-app; description "Flexible Algorithm Application - This corresponds to Bit 3 (X-BIT) in the Standard Application Bit Mask (SABM)."; reference "RFC 9350: IGP Flexible Algorithm, Section 12."; } } 5. YANG Module for OSPF Application-Specific Link Attributes This document defined a YANG module for OSPF Application-Specific Link Attributes (ASLA) as defined in [RFC9492]. The module augments OSPF router configuration with support for the ASLA operation mode, enabling interoperability during the transition from legacy advertisements to ASLA. In addition, both OSPFv2 and OSPFv3 LSAs are augmented to include the TLVs defined in[RFC9492]. As far as whether or not an application-specific link atttribute is included, only legacy attributes that are defined in [RFC9129] are included. Additional atttributes will be included in these TLVs when the augmentations for the corresponding legacy attributes are added. This YANG module references [RFC8349], [RFC9129], [RFC9350], [RFC9492], and [RFC9587] . module: ietf-ospf-link-attr augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf: +--rw ospf-link-attr +--rw (link-attr-op-mode)? +--:(legacy) Qu & Lindem Expires 1 January 2027 [Page 10] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 | +--rw legacy? empty +--:(transition) | +--rw transition? empty +--:(app-specific) +--rw app-specific? empty augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf/ospf:areas /ospf:area/ospf:interfaces/ospf:interface: +--rw ospf-asla +--rw interface-asla* [link-attr-app] +--rw link-attr-app identityref +--rw te-metric? te-types:te-metric +--rw admin-group? te-types:admin-group augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf/ospf:areas /ospf:area/ospf:database/ospf:area-scope-lsa-type /ospf:area-scope-lsas/ospf:area-scope-lsa/ospf:version /ospf:ospfv2/ospf:ospfv2/ospf:body/ospf:opaque /ospf:extended-link-opaque/ospf:extended-link-tlv: +--ro app-specific-link-attr-sub-tlvs +--ro asla-sub-tlvs* [] +--ro sabm | +--ro sabm-bit* identityref +--ro udabm +--ro link-attributes-sub-tlvs +--ro te-metric? te-types:te-metric +--ro admin-group? te-types:admin-group +--ro unknown-tlvs +--ro unknown-tlv* [] +--ro type? uint16 +--ro length? uint16 +--ro value? yang:hex-string augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf/ospf:areas /ospf:area/ospf:database/ospf:area-scope-lsa-type /ospf:area-scope-lsas/ospf:area-scope-lsa/ospf:version /ospf:ospfv3/ospf:ospfv3/ospf:body /ospfv3-e-lsa:e-router/ospfv3-e-lsa:e-router-tlvs /ospfv3-e-lsa:link-tlv: +--ro app-specific-link-attr-sub-tlvs +--ro asla-sub-tlvs* [] +--ro sabm | +--ro sabm-bit* identityref +--ro udabm +--ro link-attributes-sub-tlvs +--ro te-metric? te-types:te-metric +--ro admin-group? te-types:admin-group +--ro unknown-tlvs Qu & Lindem Expires 1 January 2027 [Page 11] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 +--ro unknown-tlv* [] +--ro type? uint16 +--ro length? uint16 +--ro value? yang:hex-string file "ietf-ospf-link-attr@2026-06-03.yang" module ietf-ospf-link-attr { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-ospf-link-attr"; prefix ospf-link-attr; import ietf-routing { prefix rt; reference "RFC 8349: A YANG Data Model for Routing Management (NMDA Version)"; } import ietf-te-types { prefix te-types; reference "RFC 8776: Common YANG Data Types for Traffic Engineering."; } import ietf-ospf { prefix ospf; reference "RFC 9129: YANG Data Model for the OSPF Protocol"; } import ietf-ospfv3-extended-lsa { prefix ospfv3-e-lsa; reference "RFC 9587: YANG Data Model for OSPFv3 Extended Link State Advertisements (LSAs)"; } import iana-igp-link-attr-apps { prefix iana-link-attr-apps; reference "RFC XXXX: YANG Data Model for OSPF Application-Specific Link Attributes and Flexible Algorithm"; } organization "IETF LSR - Link State Routing Working Group"; contact "WG Web: WG List: Author: Yingzhen Qu Qu & Lindem Expires 1 January 2027 [Page 12] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 Author: Acee Lindem "; description "This YANG module defines the configuration and operational state for OSPF application specific link attributes feature as defined in RFC 9492. This YANG model conforms to the Network Management Datastore Architecture (NMDA) as described in RFC 8342. Copyright (c) 2026 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Revised BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX; see the RFC itself for full legal notices. 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 (RFC 2119) (RFC 8174) when, and only when, they appear in all capitals, as shown here."; revision 2026-06-30 { description "Initial version"; reference "RFC XXXX: A YANG Data Model for OSPF Application-Specific Link Attributes and Flexible Algorithm"; } grouping ospf-te-link-attrs { description "OSPF Application-Specific Link Attributes (ASLA) inherited from the base OSPF TE attributes"; leaf te-metric { type te-types:te-metric; description "TE metric."; reference Qu & Lindem Expires 1 January 2027 [Page 13] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 "RFC 3630 - Traffic Engineering (TE) Extensions to OSPFv2"; } leaf admin-group { type te-types:admin-group; description "Administrative Group / Resource Class/Color."; reference "RFC 3630 - Traffic Engineering (TE) Extensions to OSPFv2"; } reference "RFC 3630 - Traffic Engineering (TE) Extensions to OSPFv2"; } grouping app-specific-link-attr-sub-tlvs { description "OSPF Application-Specific Link Attributes (ASLA) sub-TLV. The ASLA sub-TLV is a sub-TLV of the OSPFv2 Extended Link TLV (RFC7684) and OSPFv3 Router-Link TLV (RFC8362)."; container app-specific-link-attr-sub-tlvs { description "Application-Specific Link Attributes sub-TLV."; list asla-sub-tlvs { container sabm { leaf-list sabm-bit { type identityref { base iana-link-attr-apps:igp-link-attr-app; } description "Standard Application Identifier Bit Mask bits. This leaf-list contains identities for the bits which are set to 1 in the SABM field."; } description "Standard Application Identifier Bit Mask."; reference "RFC 9492: OSPF Application-Specific Link Attributes, Section 5"; } container udabm { description "User Defined Application Identifier Bit Mask (UDABM). This container is intended to be augmented by documents defining user-defined application identifiers. Each such augmentation SHOULD add a leaf-list of identityref type whose base identity represents the user-defined Qu & Lindem Expires 1 January 2027 [Page 14] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 application, following the same pattern as the 'sabm-bit' leaf-list. Refer to RFC 9479, Section 3 for the on-wire encoding of the UDABM field."; reference "RFC 9492: OSPF Application-Specific Link Attributes, Section 5"; } container link-attributes-sub-tlvs { uses ospf-te-link-attrs; uses ospf:unknown-tlvs; description "Link Attributes sub-TLVs."; } description "List of application-Specific Link Attributes sub-TLVs."; } } reference "RFC 9492: OSPF Application-Specific Link Attributes"; } /* Configuration */ augment "/rt:routing/rt:control-plane-protocols" + "/rt:control-plane-protocol/ospf:ospf" { when "../rt:type = 'ospf:ospfv2' or " + "../rt:type = 'ospf:ospfv3'" { description "This augments the OSPF routing protocol when used."; } description "This augments OSPF protocol configuration with application-specific link attributes."; container ospf-link-attr { choice link-attr-op-mode { default "app-specific"; leaf legacy { type empty; description "Only send legacy advertisements, and no ASLA advertisement."; } leaf transition { type empty; description "Send both application-specific and legacy advertisements."; } Qu & Lindem Expires 1 January 2027 [Page 15] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 leaf app-specific { type empty; description "Only send application-specific advertisements."; } description "Link attributes mode. Default to app-specific mode for consistent with implementations. This is the enablement knob for ASLA advertisement at the protocol level. Please refer to Section 12.3 of RFC9492 for details."; } description "Link attributes operation mode."; reference "RFC 9492 - OSPF Application-Specific Link Attributes, Section 12.3."; } } augment "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/ospf:ospf/" + "ospf:areas/ospf:area/ospf:interfaces/ospf:interface" { when "derived-from(/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/rt:type, 'ospf:ospfv2') or " + "derived-from(/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/rt:type, 'ospf:ospfv2')" { description "This augments the OSPF interface configuration."; } description "This augments OSPF interface configuration with Application Specific Link Attributes (ASLA)."; container ospf-asla { list interface-asla { key "link-attr-app"; leaf link-attr-app { type identityref { base iana-link-attr-apps:igp-link-attr-app; } description "Application-specific attributes. Note that when encoded, applications with identical attributes may be included in the same sub-TLV."; } uses ospf-te-link-attrs; description "ASLA interface configuration."; } Qu & Lindem Expires 1 January 2027 [Page 16] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 description "Application specific link attributes configuration."; } } /* Database */ augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol/" + "ospf:ospf/ospf:areas/" + "ospf:area/ospf:database/" + "ospf:area-scope-lsa-type/ospf:area-scope-lsas/" + "ospf:area-scope-lsa/ospf:version/ospf:ospfv2/" + "ospf:ospfv2/ospf:body/ospf:opaque/" + "ospf:extended-link-opaque/ospf:extended-link-tlv" { when "derived-from(/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/rt:type, 'ospf:ospfv2')" { description "This augmentation is only valid for OSPFv2."; } description "OSPF Application-Specific Link Attributes (ASLA) sub-TLV is a sub-TLV of OSPFv2 Extended Link TLV (RFC7684)."; uses app-specific-link-attr-sub-tlvs; } augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol/" + "ospf:ospf/ospf:areas/ospf:area/ospf:database/" + "ospf:area-scope-lsa-type/ospf:area-scope-lsas/" + "ospf:area-scope-lsa/ospf:version/ospf:ospfv3/" + "ospf:ospfv3/ospf:body/ospfv3-e-lsa:e-router/" + "ospfv3-e-lsa:e-router-tlvs/ospfv3-e-lsa:link-tlv" { when "derived-from(/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/rt:type, 'ospf:ospfv3')" { description "This augmentation is only valid for OSPFv3 E-Router LSAs"; } description "Augment OSPFv3 Area scope router-link TLV."; uses app-specific-link-attr-sub-tlvs; } } Qu & Lindem Expires 1 January 2027 [Page 17] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 6. YANG Module for OSPF Flexible Algorithm This document defines a YANG module for OSPF Flexible Algorithm as defined in [RFC9350]. It is an augmentation of the OSPF base model. The module augments OSPF router configuration with support flexible algorithms. In addition, both the OSPFv2 and OSPFv3 link-state databases are augmented to include the TLVs defined in[RFC9350]. This YANG module references [RFC8349], [RFC9129], [RFC9350], [RFC9587], and [I-D.ietf-teas-yang-te]. module: ietf-ospf-flex-algo augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf: +--rw ospf-flex-algo +--rw flex-algo* [algo-number] +--rw algo-number uint8 +--rw advertise-definition? boolean +--rw admin-groups | {te-types:named-extended-admin-groups}? | +--rw exclude-admin-group? | | te-types:extended-admin-group | +--rw include-any-admin-group? | | te-types:extended-admin-group | +--rw include-all-admin-group? | te-types:extended-admin-group +--rw exclude-srlgs* te-types:srlg +--rw calc-type? identityref +--rw metric-type? identityref +--rw prefix-metric! +--rw priority? uint8 augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf/ospf:areas /ospf:area/ospf:interfaces/ospf:interface /ospf:database/ospf:link-scope-lsa-type /ospf:link-scope-lsas/ospf:link-scope-lsa/ospf:version /ospf:ospfv2/ospf:ospfv2/ospf:body/ospf:opaque /ospf:ri-opaque: +--ro fad-tlvs +--ro fad-tlv* [] +--ro algo-number? uint8 +--ro metric-type? identityref +--ro calc-type? identityref +--ro priority? uint8 +--ro fa-ex-ag-sub-tlv | +--ro extended-admin-group? Qu & Lindem Expires 1 January 2027 [Page 18] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 | te-types:extended-admin-group +--ro fa-in-any-ag-sub-tlv | +--ro extended-admin-group? | te-types:extended-admin-group +--ro fa-in-all-ag-sub-tlv | +--ro extended-admin-group? | te-types:extended-admin-group +--ro fad-flags-sub-tlv | +--ro fad-flags* identityref +--ro fa-ex-srlg-sub-tlv | +--ro srlgs* te-types:srlg +--ro unknown-tlvs +--ro unknown-tlv* [] +--ro type? uint16 +--ro length? uint16 +--ro value? yang:hex-string augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf/ospf:areas /ospf:area/ospf:database/ospf:area-scope-lsa-type /ospf:area-scope-lsas/ospf:area-scope-lsa/ospf:version /ospf:ospfv2/ospf:ospfv2/ospf:body/ospf:opaque /ospf:ri-opaque: +--ro fad-tlvs +--ro fad-tlv* [] +--ro algo-number? uint8 +--ro metric-type? identityref +--ro calc-type? identityref +--ro priority? uint8 +--ro fa-ex-ag-sub-tlv | +--ro extended-admin-group? | te-types:extended-admin-group +--ro fa-in-any-ag-sub-tlv | +--ro extended-admin-group? | te-types:extended-admin-group +--ro fa-in-all-ag-sub-tlv | +--ro extended-admin-group? | te-types:extended-admin-group +--ro fad-flags-sub-tlv | +--ro fad-flags* identityref +--ro fa-ex-srlg-sub-tlv | +--ro srlgs* te-types:srlg +--ro unknown-tlvs +--ro unknown-tlv* [] +--ro type? uint16 +--ro length? uint16 +--ro value? yang:hex-string augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf/ospf:database Qu & Lindem Expires 1 January 2027 [Page 19] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 /ospf:as-scope-lsa-type/ospf:as-scope-lsas /ospf:as-scope-lsa/ospf:version/ospf:ospfv2 /ospf:ospfv2/ospf:body/ospf:opaque/ospf:ri-opaque: +--ro fad-tlvs +--ro fad-tlv* [] +--ro algo-number? uint8 +--ro metric-type? identityref +--ro calc-type? identityref +--ro priority? uint8 +--ro fa-ex-ag-sub-tlv | +--ro extended-admin-group? | te-types:extended-admin-group +--ro fa-in-any-ag-sub-tlv | +--ro extended-admin-group? | te-types:extended-admin-group +--ro fa-in-all-ag-sub-tlv | +--ro extended-admin-group? | te-types:extended-admin-group +--ro fad-flags-sub-tlv | +--ro fad-flags* identityref +--ro fa-ex-srlg-sub-tlv | +--ro srlgs* te-types:srlg +--ro unknown-tlvs +--ro unknown-tlv* [] +--ro type? uint16 +--ro length? uint16 +--ro value? yang:hex-string augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf/ospf:areas /ospf:area/ospf:interfaces/ospf:interface /ospf:database/ospf:link-scope-lsa-type /ospf:link-scope-lsas/ospf:link-scope-lsa/ospf:version /ospf:ospfv3/ospf:ospfv3/ospf:body /ospf:router-information: +--ro fad-tlvs +--ro fad-tlv* [] +--ro algo-number? uint8 +--ro metric-type? identityref +--ro calc-type? identityref +--ro priority? uint8 +--ro fa-ex-ag-sub-tlv | +--ro extended-admin-group? | te-types:extended-admin-group +--ro fa-in-any-ag-sub-tlv | +--ro extended-admin-group? | te-types:extended-admin-group +--ro fa-in-all-ag-sub-tlv | +--ro extended-admin-group? Qu & Lindem Expires 1 January 2027 [Page 20] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 | te-types:extended-admin-group +--ro fad-flags-sub-tlv | +--ro fad-flags* identityref +--ro fa-ex-srlg-sub-tlv | +--ro srlgs* te-types:srlg +--ro unknown-tlvs +--ro unknown-tlv* [] +--ro type? uint16 +--ro length? uint16 +--ro value? yang:hex-string augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf/ospf:areas /ospf:area/ospf:database/ospf:area-scope-lsa-type /ospf:area-scope-lsas/ospf:area-scope-lsa/ospf:version /ospf:ospfv3/ospf:ospfv3/ospf:body /ospf:router-information: +--ro fad-tlvs +--ro fad-tlv* [] +--ro algo-number? uint8 +--ro metric-type? identityref +--ro calc-type? identityref +--ro priority? uint8 +--ro fa-ex-ag-sub-tlv | +--ro extended-admin-group? | te-types:extended-admin-group +--ro fa-in-any-ag-sub-tlv | +--ro extended-admin-group? | te-types:extended-admin-group +--ro fa-in-all-ag-sub-tlv | +--ro extended-admin-group? | te-types:extended-admin-group +--ro fad-flags-sub-tlv | +--ro fad-flags* identityref +--ro fa-ex-srlg-sub-tlv | +--ro srlgs* te-types:srlg +--ro unknown-tlvs +--ro unknown-tlv* [] +--ro type? uint16 +--ro length? uint16 +--ro value? yang:hex-string augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf/ospf:database /ospf:as-scope-lsa-type/ospf:as-scope-lsas /ospf:as-scope-lsa/ospf:version/ospf:ospfv3 /ospf:ospfv3/ospf:body/ospf:router-information: +--ro fad-tlvs +--ro fad-tlv* [] +--ro algo-number? uint8 Qu & Lindem Expires 1 January 2027 [Page 21] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 +--ro metric-type? identityref +--ro calc-type? identityref +--ro priority? uint8 +--ro fa-ex-ag-sub-tlv | +--ro extended-admin-group? | te-types:extended-admin-group +--ro fa-in-any-ag-sub-tlv | +--ro extended-admin-group? | te-types:extended-admin-group +--ro fa-in-all-ag-sub-tlv | +--ro extended-admin-group? | te-types:extended-admin-group +--ro fad-flags-sub-tlv | +--ro fad-flags* identityref +--ro fa-ex-srlg-sub-tlv | +--ro srlgs* te-types:srlg +--ro unknown-tlvs +--ro unknown-tlv* [] +--ro type? uint16 +--ro length? uint16 +--ro value? yang:hex-string augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf/ospf:areas /ospf:area/ospf:interfaces/ospf:interface /ospf:database/ospf:link-scope-lsa-type /ospf:link-scope-lsas/ospf:link-scope-lsa/ospf:version /ospf:ospfv2/ospf:ospfv2/ospf:body/ospf:opaque /ospf:extended-prefix-opaque/ospf:extended-prefix-tlv: +--ro fapm-sub-tlvs +--ro fapm-sub-tlv* [] +--ro algo-number? uint8 +--ro fapm-flags* identityref +--ro metric? uint32 augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf/ospf:areas /ospf:area/ospf:database/ospf:area-scope-lsa-type /ospf:area-scope-lsas/ospf:area-scope-lsa/ospf:version /ospf:ospfv2/ospf:ospfv2/ospf:body/ospf:opaque /ospf:extended-prefix-opaque/ospf:extended-prefix-tlv: +--ro fapm-sub-tlvs +--ro fapm-sub-tlv* [] +--ro algo-number? uint8 +--ro fapm-flags* identityref +--ro metric? uint32 augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf/ospf:database /ospf:as-scope-lsa-type/ospf:as-scope-lsas /ospf:as-scope-lsa/ospf:version/ospf:ospfv2 Qu & Lindem Expires 1 January 2027 [Page 22] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 /ospf:ospfv2/ospf:body/ospf:opaque /ospf:extended-prefix-opaque/ospf:extended-prefix-tlv: +--ro fapm-sub-tlvs +--ro fapm-sub-tlv* [] +--ro algo-number? uint8 +--ro fapm-flags* identityref +--ro metric? uint32 augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf/ospf:areas /ospf:area/ospf:database/ospf:area-scope-lsa-type /ospf:area-scope-lsas/ospf:area-scope-lsa/ospf:version /ospf:ospfv3/ospf:ospfv3/ospf:body /ospfv3-e-lsa:e-inter-area-prefix /ospfv3-e-lsa:e-inter-prefix-tlvs /ospfv3-e-lsa:inter-prefix-tlv: +--ro fapm-sub-tlvs +--ro fapm-sub-tlv* [] +--ro algo-number? uint8 +--ro fapm-flags* identityref +--ro metric? uint32 augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf/ospf:database /ospf:as-scope-lsa-type/ospf:as-scope-lsas /ospf:as-scope-lsa/ospf:version/ospf:ospfv3 /ospf:ospfv3/ospf:body/ospfv3-e-lsa:e-as-external /ospfv3-e-lsa:e-external-tlvs /ospfv3-e-lsa:external-prefix-tlv: +--ro fapm-sub-tlvs +--ro fapm-sub-tlv* [] +--ro algo-number? uint8 +--ro fapm-flags* identityref +--ro metric? uint32 augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf/ospf:areas /ospf:area/ospf:database/ospf:area-scope-lsa-type /ospf:area-scope-lsas/ospf:area-scope-lsa/ospf:version /ospf:ospfv2/ospf:ospfv2/ospf:body/ospf:opaque: +--ro eia-asbr-opaque +--ro eia-asbr-tlv | +--ro asbr-rtr-id? rt-types:router-id | +--ro faam-sub-tlvs | | +--ro faam-sub-tlv* [] | | +--ro algo-number? uint8 | | +--ro metric? uint32 | +--ro unknown-tlvs | +--ro unknown-tlv* [] | +--ro type? uint16 | +--ro length? uint16 Qu & Lindem Expires 1 January 2027 [Page 23] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 | +--ro value? yang:hex-string +--ro unknown-tlvs +--ro unknown-tlv* [] +--ro type? uint16 +--ro length? uint16 +--ro value? yang:hex-string augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf/ospf:areas /ospf:area/ospf:database/ospf:area-scope-lsa-type /ospf:area-scope-lsas/ospf:area-scope-lsa/ospf:version /ospf:ospfv3/ospf:ospfv3/ospf:body /ospfv3-e-lsa:e-inter-area-router /ospfv3-e-lsa:e-inter-router-tlvs /ospfv3-e-lsa:inter-router-tlv: +--ro faam-sub-tlvs +--ro faam-sub-tlv* [] +--ro algo-number? uint8 +--ro metric? uint32 notifications: +---n flex-algo-not-supported +--ro routing-protocol-name? leafref +--ro algo-number? uint8 file "ietf-ospf-flex-algo@2026-06-30.yang" module ietf-ospf-flex-algo { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-ospf-flex-algo"; prefix ospf-flex-algo; import ietf-routing { prefix rt; reference "RFC 8349: A YANG Data Model for Routing Management (NMDA Version)"; } import ietf-routing-types { prefix rt-types; reference "RFC 8294: Common YANG Data Types for the Routing Area"; } import ietf-te-types { prefix te-types; reference "RFC 8776: Common YANG Data Types for Traffic Engineering."; } import ietf-ospf { Qu & Lindem Expires 1 January 2027 [Page 24] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 prefix ospf; reference "RFC 9129: YANG Data Model for the OSPF Protocol"; } import ietf-ospfv3-extended-lsa { prefix ospfv3-e-lsa; reference "RFC 9587: YANG Data Model for OSPFv3 Extended Link State Advertisements (LSAs)"; } import iana-igp-algo-types { prefix iana-algo-types; reference "IANA IGP Algorithm Types registry, ."; } import iana-igp-metric-types { prefix iana-metric-type; reference "IANA IGP Metric-Type registry, ."; } organization "IETF LSR - Link State Routing Working Group"; contact "WG Web: WG List: Author: Yingzhen Qu Author: Acee Lindem "; description "The YANG module defines the configuration and operational state for OSPF Flexible Algorithm as defined in RFC 9350. Copyright (c) 2026 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Revised BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). Qu & Lindem Expires 1 January 2027 [Page 25] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 This version of this YANG module is part of RFC XXXX; see the RFC itself for full legal notices. 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 (RFC 2119) (RFC 8174) when, and only when, they appear in all capitals, as shown here."; revision 2026-06-30 { description "Initial Version"; reference "RFC XXXX: A YANG Data Model for OSPF Application-Specific Link Attributes and Flexible Algorithm"; } /* Identities */ identity fad-flags { description "Base identity for OSPF FAD flags."; reference "RFC 9350: IGP Flexible Algorithm, Section 7"; } identity m-flag { base fad-flags; description "M-flag in the Flex-Algorithm Definition (FAD) flags sub-TLV. When this flag is present in the fad-flags leaf-list, the Flex-Algorithm-specific prefix metric is used for inter-area and external prefix calculation. Note that this flag is not applicable to prefixes advertised as SRv6 locators."; reference "RFC 9350: IGP Flexible Algorithm, Section 7.4"; } identity fapm-flags { description "Base identity for OSPF flex-algo prefix metric flags."; reference "RFC 9350: IGP Flexible Algorithm"; } identity e-bit { base fapm-flags; description Qu & Lindem Expires 1 January 2027 [Page 26] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 "External metric, if set, the metric specified is a type 2 external metric."; reference "RFC 9350: IGP Flexible Algorithm"; } /* Groupings */ grouping fad-tlvs { container fad-tlvs { list fad-tlv { leaf algo-number { type uint8; description "Flex-algo number - A value not in the inclusive range of 128-255 is an invalid FAD TLV specification. There should only be a single FAD TLV per algorithm number."; } leaf metric-type { type identityref { base iana-metric-type:metric-type; } description "Type of metric to be used during the calculation."; } leaf calc-type { type identityref { base iana-algo-types:algo-type; } description "IGP algorithm types, value from 0 to 127 as defined under 'Interior Gateway Protocol (IGP) Parameter' by IANA."; } leaf priority { type uint8; description "Priority of the advertisement."; } container fa-ex-ag-sub-tlv { leaf extended-admin-group { type te-types:extended-admin-group; description "Extended administrative group as defined in RFC 7308."; } description "The flex-algo exclude admin group sub-tlv."; Qu & Lindem Expires 1 January 2027 [Page 27] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 } container fa-in-any-ag-sub-tlv { leaf extended-admin-group { type te-types:extended-admin-group; description "Extended administrative group as defined in RFC 7308."; } description "The flex-algo include-any admin group sub-tlv."; } container fa-in-all-ag-sub-tlv { leaf extended-admin-group { type te-types:extended-admin-group; description "Extended administrative group as defined in RFC 7308."; } description "The flex-algo include-all admin group sub-tlv."; } container fad-flags-sub-tlv { leaf-list fad-flags { type identityref { base fad-flags; } description "Flex-algo definition flags list."; } description "OSPF flex-algo definition flags."; } container fa-ex-srlg-sub-tlv { leaf-list srlgs { type te-types:srlg; description "SRLG value as defined in RFC 4203."; } description "The flex-algo exclude SRLG sub-tlv."; } uses ospf:unknown-tlvs; description "List of flex-algo definition TLVs."; } description "OSPF Flexible Algorithm Definition TLV."; } Qu & Lindem Expires 1 January 2027 [Page 28] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 description "OSPF Flexible Algorithm Definition (FAD) TLV."; reference "RFC 9350: IGP Flexible Algorithm"; } grouping fapm-sub-tlvs { container fapm-sub-tlvs { list fapm-sub-tlv { leaf algo-number { type uint8; description "Flex-algo number - A value not in the inclusive range of 128-255 is an invalid FAD TLV specification."; } leaf-list fapm-flags { type identityref { base fapm-flags; } description "Flex-algo prefix metric flags list."; } leaf metric { type uint32; description "Prefix metric."; } description "List of flex-algo prefix sub-tlvs."; } description "Flex-algo prefix metric sub-tlvs."; } description "Flexible Algorithm Prefix Metric (FAPM) sub-TLVs."; reference "RFC 9350: IGP Flexible Algorithm"; } grouping faam-sub-tlvs { container faam-sub-tlvs { list faam-sub-tlv { leaf algo-number { type uint8; description "Flex-algo number - A value not in the inclusive range of 128-255 is an invalid FAAM Sub-TLV specification."; } Qu & Lindem Expires 1 January 2027 [Page 29] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 leaf metric { type uint32; description "Prefix metric."; } description "List of faam sub-tlvs."; } description "Flexible Algorithm ASBR Metric (FAAM) Sub-TLVs."; } description "Flexible Algorithm ASBR Metric (FAAM) Sub-TLVs."; reference "RFC 9350: IGP Flexible Algorithm"; } /* Management */ augment "/rt:routing/rt:control-plane-protocols" + "/rt:control-plane-protocol/ospf:ospf" { when "../rt:type = 'ospf:ospfv2' or " + "../rt:type = 'ospf:ospfv3'" { description "This augments the OSPF routing protocol when used."; } description "This augments OSPF protocol with Flexible Algorithm."; container ospf-flex-algo { list flex-algo { key "algo-number"; leaf algo-number { type uint8 { range "128..255"; } description "An identifier associated with the Flexible Algorithm Definition."; } leaf advertise-definition { type boolean; default "true"; description "Enable to advertise the flex-algo definition."; } container admin-groups { if-feature "te-types:named-extended-admin-groups"; Qu & Lindem Expires 1 January 2027 [Page 30] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 leaf exclude-admin-group { type te-types:extended-admin-group; description "Exclude rule used during the flex-algo path computation."; } leaf include-any-admin-group { type te-types:extended-admin-group; description "The flex-algo include-any admin group. Note that the presence of more than one Include-Any Extended Admin Group will result in an invalid FAD TLV."; } leaf include-all-admin-group { type te-types:extended-admin-group; description "The flex-algo include-all admin group. Note that the presence of more than one Include-All Extended Admin Group will result in an invalid FAD TLV."; } description "Specify links for the flex-algo path computation."; } leaf-list exclude-srlgs { type te-types:srlg; description "Shared Risk Link Groups (SRLGs) to be excluded during the flex-algo path computation."; } leaf calc-type { type identityref { base iana-algo-types:algo-type; } default "iana-algo-types:algo-spf"; description "Calcuation-type. Value from 0-127 inclusive from the IANA 'IGP Algorithm Types' registry defined under the 'Interior Gateway Protocol (IGP) Parameters' registry."; } leaf metric-type { type identityref { base iana-metric-type:metric-type; } default "iana-metric-type:igp-metric"; description "Type of metric to be used during the calculation."; } container prefix-metric { Qu & Lindem Expires 1 January 2027 [Page 31] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 presence "Use flex-algo specific prefix metric."; description "Use flex-algo prefix metric."; } leaf priority { type uint8; description "Priority of the advertisement."; } description "List of flex-algo configurations."; } description "Flexible Algorithm configuration."; } } /* Database */ augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol/" + "ospf:ospf/ospf:areas/ospf:area/" + "ospf:interfaces/ospf:interface/ospf:database/" + "ospf:link-scope-lsa-type/ospf:link-scope-lsas/" + "ospf:link-scope-lsa/ospf:version/ospf:ospfv2/" + "ospf:ospfv2/ospf:body/ospf:opaque/ospf:ri-opaque" { when "../../../../../../../../../../../../../" + "rt:type = 'ospf:ospfv2'" { description "This augmentation is only valid for OSPFv2."; } description "Flex-algo definition TLVs for OSPFv2 type 9 opaque RI LSA."; uses fad-tlvs; } augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol/" + "ospf:ospf/ospf:areas/" + "ospf:area/ospf:database/" + "ospf:area-scope-lsa-type/ospf:area-scope-lsas/" + "ospf:area-scope-lsa/ospf:version/ospf:ospfv2/" + "ospf:ospfv2/ospf:body/ospf:opaque/ospf:ri-opaque" { when "../../../../../../../../../../../" + "rt:type = 'ospf:ospfv2'" { description "This augmentation is only valid for OSPFv2."; } Qu & Lindem Expires 1 January 2027 [Page 32] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 description "Flex-algo definition TLVs for OSPFv2 type 10 opaque RI LSA."; uses fad-tlvs; } augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol/" + "ospf:ospf/ospf:database/" + "ospf:as-scope-lsa-type/ospf:as-scope-lsas/" + "ospf:as-scope-lsa/ospf:version/ospf:ospfv2/" + "ospf:ospfv2/ospf:body/ospf:opaque/ospf:ri-opaque" { when "../../../../../../../../../" + "rt:type = 'ospf:ospfv2'" { description "This augmentation is only valid for OSPFv2."; } description "Flex-algo definition TLVs for OSPFv2 type 11 opaque RI LSA."; uses fad-tlvs; } augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol/" + "ospf:ospf/ospf:areas/ospf:area/" + "ospf:interfaces/ospf:interface/ospf:database/" + "ospf:link-scope-lsa-type/ospf:link-scope-lsas/" + "ospf:link-scope-lsa/ospf:version/ospf:ospfv3/" + "ospf:ospfv3/ospf:body/ospf:router-information" { when "../../../../../../../../../../../../" + "rt:type = 'ospf:ospfv3'" { description "This augmentation is only valid for OSPFv3."; } description "Flex-algo definition TLVs for OSPFv3 Router Information (RI) LSA."; uses fad-tlvs; } augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol/" + "ospf:ospf/ospf:areas/" + "ospf:area/ospf:database/" + "ospf:area-scope-lsa-type/ospf:area-scope-lsas/" + "ospf:area-scope-lsa/ospf:version/ospf:ospfv3/" + "ospf:ospfv3/ospf:body/ospf:router-information" { when "../../../../../../../../../../" + "rt:type = 'ospf:ospfv3'" { Qu & Lindem Expires 1 January 2027 [Page 33] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 description "This augmentation is only valid for OSPFv3."; } description "Flex-algo definition TLVs for OSPFv3 Router Information (RI) LSA."; uses fad-tlvs; } augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol/" + "ospf:ospf/ospf:database/" + "ospf:as-scope-lsa-type/ospf:as-scope-lsas/" + "ospf:as-scope-lsa/ospf:version/ospf:ospfv3/" + "ospf:ospfv3/ospf:body/ospf:router-information" { when "../../../../../../../../" + "rt:type = 'ospf:ospfv3'" { description "This augmentation is only valid for OSPFv3."; } description "Flex-algo definition TLVs for OSPFv3 Router Information LSA."; uses fad-tlvs; } augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol/" + "ospf:ospf/ospf:areas/ospf:area/" + "ospf:interfaces/ospf:interface/ospf:database/" + "ospf:link-scope-lsa-type/ospf:link-scope-lsas/" + "ospf:link-scope-lsa/ospf:version/ospf:ospfv2/" + "ospf:ospfv2/ospf:body/ospf:opaque/" + "ospf:extended-prefix-opaque/ospf:extended-prefix-tlv" { when "../../../../../../../../../../../../../../" + "rt:type = 'ospf:ospfv2'" { description "This augmentation is only valid for OSPFv2."; } description "Flex-algo prefix metric sub-TLVs for OSPFv2 extended prefix TLV in type 9 opaque LSA."; uses fapm-sub-tlvs; } augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol/" + "ospf:ospf/ospf:areas/" + "ospf:area/ospf:database/" Qu & Lindem Expires 1 January 2027 [Page 34] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 + "ospf:area-scope-lsa-type/ospf:area-scope-lsas/" + "ospf:area-scope-lsa/ospf:version/ospf:ospfv2/" + "ospf:ospfv2/ospf:body/ospf:opaque/" + "ospf:extended-prefix-opaque/ospf:extended-prefix-tlv" { when "../../../../../../../../../../../../" + "rt:type = 'ospf:ospfv2'" { description "This augmentation is only valid for OSPFv2."; } description "Flex-algo prefix metric sub-TLVs for OSPFv2 extended prefix TLV in type 10 opaque LSA."; uses fapm-sub-tlvs; } augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol/" + "ospf:ospf/ospf:database/" + "ospf:as-scope-lsa-type/ospf:as-scope-lsas/" + "ospf:as-scope-lsa/ospf:version/ospf:ospfv2/" + "ospf:ospfv2/ospf:body/ospf:opaque/" + "ospf:extended-prefix-opaque/" + "ospf:extended-prefix-tlv" { when "../../../../../../../../../../" + "rt:type = 'ospf:ospfv2'" { description "This augmentation is only valid for OSPFv2."; } description "Flex-algo prefix metric sub-TLVs for OSPFv2 extended prefix TLV in type 11 opaque LSA."; uses fapm-sub-tlvs; } /* Flex-algo prefix metric Sub-TLV in OSPFv3 Inter-Area Prefix TLV */ augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol/" + "ospf:ospf/ospf:areas/ospf:area/ospf:database/" + "ospf:area-scope-lsa-type/ospf:area-scope-lsas/" + "ospf:area-scope-lsa/ospf:version/ospf:ospfv3/" + "ospf:ospfv3/ospf:body/ospfv3-e-lsa:e-inter-area-prefix/" + "ospfv3-e-lsa:e-inter-prefix-tlvs/" + "ospfv3-e-lsa:inter-prefix-tlv" { when "../../../../../../../../../../../../" + "rt:type = 'ospf:ospfv3'" { description Qu & Lindem Expires 1 January 2027 [Page 35] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 "This augmentation is only valid for OSPFv3 E-Router LSAs"; } uses fapm-sub-tlvs; description "OSPFv3 Area-Scoped Inter-Area Prefix TLV."; } /* Flex-algo prefix metric Sub-TLV in OSPFv3 External Prefix TLV */ augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol/" + "ospf:ospf/ospf:database/" + "ospf:as-scope-lsa-type/ospf:as-scope-lsas/" + "ospf:as-scope-lsa/ospf:version/ospf:ospfv3/" + "ospf:ospfv3/ospf:body/ospfv3-e-lsa:e-as-external/" + "ospfv3-e-lsa:e-external-tlvs/" + "ospfv3-e-lsa:external-prefix-tlv" { when "../../../../../../../../../../" + "rt:type = 'ospf:ospfv3'" { description "This augmentation is only valid for OSPFv3."; } uses fapm-sub-tlvs; description "OSPFv3 AS-Scoped External Prefix TLV."; } /* OSPFv2 Extended Inter-Area ASBR LSA */ augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol/" + "ospf:ospf/ospf:areas/" + "ospf:area/ospf:database/" + "ospf:area-scope-lsa-type/ospf:area-scope-lsas/" + "ospf:area-scope-lsa/ospf:version/ospf:ospfv2/" + "ospf:ospfv2/ospf:body/ospf:opaque" { when "../../../../../../../../../../" + "rt:type = 'ospf:ospfv2'" { description "This augmentation is only valid for OSPFv2."; } description "OSPFv2 Extended Inter-Area ASBR LSA in type 10 opaque LSA."; container eia-asbr-opaque { container eia-asbr-tlv { leaf asbr-rtr-id { Qu & Lindem Expires 1 January 2027 [Page 36] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 type rt-types:router-id; description "The OSPF Router ID of the ASBR."; } uses faam-sub-tlvs; uses ospf:unknown-tlvs; description "EIA-ASBR TLV, used to advertise additional attributes associated with the reachability of an ASBR."; } uses ospf:unknown-tlvs; description "OSPFv2 Extended Inter-Area (EIA-ASBR) opaque LSA."; } } /* FAAM Sub-TLV in OSPFv3 Inter-Area-Router TLV */ augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol/" + "ospf:ospf/ospf:areas/ospf:area/ospf:database/" + "ospf:area-scope-lsa-type/ospf:area-scope-lsas/" + "ospf:area-scope-lsa/ospf:version/ospf:ospfv3/" + "ospf:ospfv3/ospf:body/ospfv3-e-lsa:e-inter-area-router/" + "ospfv3-e-lsa:e-inter-router-tlvs/" + "ospfv3-e-lsa:inter-router-tlv" { when "../../../../../../../../../../../../" + "rt:type = 'ospf:ospfv3'" { description "This augmentation is only valid for OSPFv3 Inter-Area-Router TLV."; } uses faam-sub-tlvs; description "OSPFv3 Area-Scoped Inter-Area-Router TLV."; } /* Notification */ notification flex-algo-not-supported { leaf routing-protocol-name { type leafref { path "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/rt:name"; } description "Name of the OSPF instance."; } Qu & Lindem Expires 1 January 2027 [Page 37] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 leaf algo-number { type uint8; description "Flex-algo identifier which is not supported by the OSPF instance. A value not in the inclusive range of 128-255 is indicative of an invalid FAD algorithm specification."; } description "This notification is sent when an OSPF instance does not support this flex-algo."; } } 7. Security Considerations The YANG modules defined in this document are designed to be accessed via YANG-based management protocols, such as NETCONF [RFC6241] and RESTCONF [RFC8040]. These protocols have to use a secure transport layer (e.g., SSH [RFC4252], TLS [I-D.ietf-tls-rfc8446bis], and QUIC [RFC9000]) and have to use mutual authentication. The Network Configuration Access Control Model (NACM) [RFC8341] provides the means to restrict access for particular NETCONF or RESTCONF users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and content. There are a number of data nodes defined in this YANG module that are writable/creatable/deletable (i.e., "config true", which is the default). All writable data nodes are likely to be reasonably sensitive or vulnerable in some network environments. Write operations (e.g., edit-config) and delete operations to these data nodes without proper protection or authentication can have a negative effect on network operations. The following subtrees and data nodes have particular sensitivities/vulnerabilities: /ospf:ospf/ospf-link-attr/link-attr-op-mode - Modification to the protocol operation mode may result in traffic disruption. /ospf:ospf/flex-algo - Modification to flex-algo configuration could be used to mount a DoS attack. For example, changing of calc-type may result in routing loops. /ospf:area/ospf:interfaces/ospf:interface/ospf-asla/ - Modification to the ASLA link attributes could result in the disruption or rerouting of traiffic. Qu & Lindem Expires 1 January 2027 [Page 38] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 Some of the readable data nodes in this YANG module may be considered sensitive or vulnerable in some network environments. It is thus important to control read access (e.g., via get, get-config, or notification) to these data nodes. Specifically, the following subtrees and data nodes have particular sensitivities/ vulnerabilities: Both module ietf-ospf-flex-algo and module ietf-ospf-link-attr augments base OSPF module Link State Database (LSDB) with various TLVs. Knowledge of these data nodes can be used to attack other routers in the OSPF domain. These attacks are documented in [RFC9129]. The YANG modules defined in this document do not include any RPC or action operations. Hence, there are no security considerations associated with these YANG constructs. 8. IANA Considerations 8.1. Registering YANG Modules This document registers URIs in the IETF XML registry [RFC3688]. Following the format in [RFC3688], the following registrations are requested to be made: URI: urn:ietf:params:xml:ns:yang:iana-igp-algo-types Registrant Contact: The IESG. XML: N/A, the requested URI is an XML namespace. URI: urn:ietf:params:xml:ns:yang:iana-igp-metric-types Registrant Contact: The IESG. XML: N/A, the requested URI is an XML namespace. URI: urn:ietf:params:xml:ns:yang:iana-igp-link-attr-apps Registrant Contact: The IESG. XML: N/A, the requested URI is an XML namespace. URI: urn:ietf:params:xml:ns:yang:ietf-ospf-link-attr Registrant Contact: The IESG. XML: N/A, the requested URI is an XML namespace. URI: urn:ietf:params:xml:ns:yang:ietf-ospf-flex-algo Registrant Contact: The IESG. XML: N/A, the requested URI is an XML namespace. This document registers the YANG modules in the YANG Module Names registry [RFC6020]. Qu & Lindem Expires 1 January 2027 [Page 39] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 name: iana-igp-algo-types Maintained by IANA? Y namespace: urn:ietf:params:xml:ns:yang:iana-igp-algo-types prefix: iana-algo-types reference: RFC XXXX name: iana-igp-metric-types Maintained by IANA? Y namespace: urn:ietf:params:xml:ns:yang:iana-igp-metric-types prefix: iana-metric-types reference: RFC XXXX name: iana-igp-link-attr-app Maintained by IANA? Y namespace: urn:ietf:params:xml:ns:yang:iana-igp-link-attr-apps prefix: iana-link-attr-app reference: RFC XXXX name: ietf-ospf-link-attr Maintained by IANA? N namespace: urn:ietf:params:xml:ns:yang:ietf-ospf-link-attr prefix: ospf-link-attr reference: RFC XXXX name: ietf-ospf-flex-algo Maintained by IANA? N namespace: urn:ietf:params:xml:ns:yang:ietf-ospf-flex-algo prefix: ospf-flex-algo reference: RFC XXXX 8.2. IANA IGP Algorithm Types Module This document defines the initial version of the IANA-maintained "iana-igp-algo-types" YANG module (Section 2). The most recent version of the YANG module is available from the "YANG Parameters" registry [IANA-YANG-Parameters]. IANA is requested to add this note to the registry: | New values must not be directly added to the "iana-algo-types" | YANG module. They must instead be added to the "IGP Algorithm | Types" registry in the "Interior Gateway Protocol (IGP) | Parameters" registry group. Qu & Lindem Expires 1 January 2027 [Page 40] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 When a value is added to the "IGP Algorithm Types" registry, a new "identity" statement needs to be added to the "iana-igp-algo-types" YANG module. The name of the "identity" MUST be the name as provided in the registry. The "identity" statement should have the following sub-statements defined: "base": contains "algo-type". "description": Replicates the description from the registry. "reference": Replicates the reference(s) from the registry with the title of the document(s) added. When the "iana-igp-algo-types" YANG module is updated, a new "revision" statement with a unique revision date must be added in front of the existing revision statements. The "revision" statement MUST contain both "description" and "reference" substatements as follows. The "description" substatement captures what changed in the revised version. Typically, the description enumerates the changes such as updpates to existing entries (e.g., update a description or a reference) or notes which identities were added or had their status changed (e.g., deprecated, discouraged, or obsoleted). The "reference" substatement points specifically to the published module (i.e., IANA_FOO_URL_With_REV). It may also point to an authoritative event triggering the update to the YANG module. In all cases, this event is cited from the underlying IANA registry. If the update is triggered by an RFC, that RFC must also be included in the "reference" substatement. IANA is requested to add this note to [IANA-IGP-ALGO-Types]: | When this registry is modified, the YANG module "iana-igp-algo- | types" Section 2 must be updated as defined in RFC XXXX. 8.3. IANA IGP Metric-Type Module This document defines the initial version of the IANA-maintained "iana-igp-metric-types" YANG module (Section 3). The most recent version of the YANG module is available from the "YANG Parameters" registry [IANA-YANG-Parameters]. IANA is requested to add this note to the registry: | New values must not be directly added to the "iana-igp-metric- | types" YANG module. They must instead be added to the "IGP | Metric-Type" registry in the "Interior Gateway Protocol (IGP) | Parameters" registry group. Qu & Lindem Expires 1 January 2027 [Page 41] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 When a value is added to the "IGP Metric-Type" registry, a new "identity" statement needs to be added to the "iana-igp-metric-types" YANG module. The name of the "identity" MUST be the name as provided in the registry. The "identity" statement should have the following sub-statements defined: "base": contains "metric-type". "description": Replicates the description from the registry. "reference": Replicates the reference(s) from the registry with the title of the document(s) added. When the "iana-igp-metric-types" YANG module is updated, a new "revision" statement with a unique revision date must be added in front of the existing revision statements. The "revision" statement MUST contain both "description" and "reference" substatements as follows. The "description" substatement captures what changed in the revised version. Typically, the description enumerates the changes such as updpates to existing entries (e.g., update a description or a reference) or notes which identities were added or had their status changed (e.g., deprecated, discouraged, or obsoleted). The "reference" substatement points specifically to the published module (i.e., IANA_FOO_URL_With_REV). It may also point to an authoritative event triggering the update to the YANG module. In all cases, this event is cited from the underlying IANA registry. If the update is triggered by an RFC, that RFC must also be included in the "reference" substatement. IANA is requested to add this note to [IANA-IGP-Metric-Types]: | When this registry is modified, the YANG module "iana-metric- | types" Section 3 must be updated as defined in RFC XXXX. 8.4. IANA IGP Link Attribute Applications Module This document defines the initial version of the IANA-maintained "iana-igp-link-attr-apps" YANG module (Section 4). The most recent version of the YANG module is available from the "YANG Parameters" registry [IANA-YANG-Parameters]. IANA is requested to add this note to the registry: | New values must not be directly added to the "iana-igp-link-attr- | apps" YANG module. They must instead be added to the "Link | Attribute Application IDs" registry in the "Interior Gateway | Protocol (IGP) Parameters" registry group. Qu & Lindem Expires 1 January 2027 [Page 42] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 When a value is added to the "Link Attribute Application IDs" registry, a new "identity" statement needs to be added to the "iana- igp-link-attr-apps" YANG module. The name of the "identity" MUST be the name as provided in the registry. The "identity" statement should have the following sub-statements defined: "base": contains "igp-link-attr-app". "description": Replicates the description from the registry. "reference": Replicates the reference(s) from the registry with the title of the document(s) added. When the "iana-igp-link-attr-apps" YANG module is updated, a new "revision" statement with a unique revision date must be added in front of the existing revision statements. The "revision" statement MUST contain both "description" and "reference" substatements as follows. The "description" substatement captures what changed in the revised version. Typically, the description enumerates the changes such as updpates to existing entries (e.g., update a description or a reference) or notes which identities were added or had their status changed (e.g., deprecated, discouraged, or obsoleted). The "reference" substatement points specifically to the published module (i.e., IANA_FOO_URL_With_REV). It may also point to an authoritative event triggering the update to the YANG module. In all cases, this event is cited from the underlying IANA registry. If the update is triggered by an RFC, that RFC must also be included in the "reference" substatement. IANA is requested to add this note to [IANA-Link-Attr-Apps]: | When this registry is modified, the YANG module "iana-igp-link- | attr-apps" must be updated as defined in RFC XXXX Section 4 . 9. Acknowledgements Thanks to Dhruv Dhody for his detailed YANG doctors review. Thanks to Adrian Farrel for his OPS directorate review. Thanks to Renato Westphal for his review and comments. 10. References 10.1. Normative References Qu & Lindem Expires 1 January 2027 [Page 43] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 [I-D.ietf-teas-yang-te] Saad, T., Gandhi, R., Liu, X., Beeram, V. P., and I. Bryskin, "A YANG Data Model for Traffic Engineering Tunnels, Label Switched Paths, and Interfaces", Work in Progress, Internet-Draft, draft-ietf-teas-yang-te-44, 26 March 2026, . [IANA-IGP-ALGO-Types] IANA, "IGP Algorithm Types", . [IANA-IGP-Metric-Types] IANA, "IGP Metric-Type", . [IANA-Link-Attr-Apps] IANA, "Link Attribute Application Identifiers", . [IANA-YANG-Parameters] IANA, "YANG Module Names", . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering (TE) Extensions to OSPF Version 2", RFC 3630, DOI 10.17487/RFC3630, October 2003, . [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004, . [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic Engineering", RFC 5305, DOI 10.17487/RFC5305, October 2008, . [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010, . Qu & Lindem Expires 1 January 2027 [Page 44] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 [RFC7471] Giacalone, S., Ward, D., Drake, J., Atlas, A., and S. Previdi, "OSPF Traffic Engineering (TE) Metric Extensions", RFC 7471, DOI 10.17487/RFC7471, March 2015, . [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, March 2018, . [RFC8349] Lhotka, L., Lindem, A., and Y. Qu, "A YANG Data Model for Routing Management (NMDA Version)", RFC 8349, DOI 10.17487/RFC8349, March 2018, . [RFC8570] Ginsberg, L., Ed., Previdi, S., Ed., Giacalone, S., Ward, D., Drake, J., and Q. Wu, "IS-IS Traffic Engineering (TE) Metric Extensions", RFC 8570, DOI 10.17487/RFC8570, March 2019, . [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, . [RFC9129] Yeung, D., Qu, Y., Zhang, Z., Chen, I., and A. Lindem, "YANG Data Model for the OSPF Protocol", RFC 9129, DOI 10.17487/RFC9129, October 2022, . [RFC9350] Psenak, P., Ed., Hegde, S., Filsfils, C., Talaulikar, K., and A. Gulko, "IGP Flexible Algorithm", RFC 9350, DOI 10.17487/RFC9350, February 2023, . [RFC9492] Psenak, P., Ed., Ginsberg, L., Henderickx, W., Tantsura, J., and J. Drake, "OSPF Application-Specific Link Attributes", RFC 9492, DOI 10.17487/RFC9492, October 2023, . Qu & Lindem Expires 1 January 2027 [Page 45] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 [RFC9587] Lindem, A., Palani, S., and Y. Qu, "YANG Data Model for OSPFv3 Extended Link State Advertisements (LSAs)", RFC 9587, DOI 10.17487/RFC9587, June 2024, . [RFC9843] Hegde, S., Britto, W., Shetty, R., Decraene, B., Psenak, P., and T. Li, "IGP Flexible Algorithms: Bandwidth, Delay, Metrics, and Constraints", RFC 9843, DOI 10.17487/RFC9843, September 2025, . 10.2. Informative References [I-D.ietf-tls-rfc8446bis] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", Work in Progress, Internet-Draft, draft- ietf-tls-rfc8446bis-14, 13 September 2025, . [RFC4252] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH) Authentication Protocol", RFC 4252, DOI 10.17487/RFC4252, January 2006, . [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., and A. Bierman, Ed., "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011, . [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, . [RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, . [RFC8792] Watsen, K., Auerswald, E., Farrel, A., and Q. Wu, "Handling Long Lines in Content of Internet-Drafts and RFCs", RFC 8792, DOI 10.17487/RFC8792, June 2020, . [RFC9000] Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based Multiplexed and Secure Transport", RFC 9000, DOI 10.17487/RFC9000, May 2021, . Qu & Lindem Expires 1 January 2027 [Page 46] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 Appendix A. Example OSPF Flex-Algo Configuration (XML) The following is an example configuration for OSPF Flexible Algorithm using the YANG model defined in this document. Note: '\' line wrapping per [RFC8792]. Qu & Lindem Expires 1 January 2027 [Page 47] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 true blue 1.1.1.1 \ ospf:ospfv2 OSPFv2 0.0.0.0 200 blue \ iana-metric-types:igp-metric \ iana-algo-types:algo-spf 100 Qu & Lindem Expires 1 January 2027 [Page 48] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 Appendix B. Example OSPF Flex-Algo Configuration (JSON) The following is the same example configuration for OSPF Flexible Algorithm as in the previous section in JSON format using the YANG model defined in this document. { "te": { "enable": "true", "globals": { "named-admin-groups": { "named-admin-group": { "name": "blue" } } }, "_xmlns": "urn:ietf:params:xml:ns:yang:ietf-te" } } { "routing": { "router-id": "1.1.1.1", "control-plane-protocols": { "control-plane-protocol": { "type": { "_xmlns:ospf": "urn:ietf:params:xml:ns:yang:ietf-ospf", "__text": "ospf:ospfv2" }, "name": "OSPFv2", "ospf": { "areas": { "area": { "area-id": "0.0.0.0" } }, "ospf-flex-algo": { "flex-algo": { "algo-number": "200", "admin-groups": { "exclude-admin-groups": "blue" }, "metric-type": { "_xmlns:iana-metric-types": "urn:ietf:params:xml:ns:\ yang:iana-igp-metric-types", "__text": "iana-metric-types:igp-metric" }, "calc-type": { "_xmlns:iana-algo-types": "urn:ietf:params:xml:ns:\ Qu & Lindem Expires 1 January 2027 [Page 49] Internet-Draft OSPF ASLA and Flex-Algo YANG June 2026 yang:iana-igp-algo-types", "__text": "iana-algo-types:algo-spf" }, "prefix-metric": "", "priority": "100" }, "_xmlns": "urn:ietf:params:xml:ns:yang:\ ietf-ospf-flex-algo" }, "_xmlns": "urn:ietf:params:xml:ns:yang:ietf-ospf" } } }, "_xmlns": "urn:ietf:params:xml:ns:yang:ietf-routing" } } Authors' Addresses Yingzhen Qu Futurewei Technologies United States of America Email: yingzhen.ietf@gmail.com Acee Lindem Arrcus, Inc. United States of America Email: acee.ietf@gmail.com Qu & Lindem Expires 1 January 2027 [Page 50]