Internet Y. Qu Internet-Draft Futurewei Technologies Intended status: Standards Track A. Lindem Expires: 1 November 2026 M. Joshi Arrcus, Inc. 30 April 2026 YANG Data Model for IS-IS Application-Specific Link Attributes and Flexible Algorithm draft-ietf-lsr-isis-flex-algo-yang-08 Abstract This document defines a YANG data model to support IS-IS Application- Specific Link Attributes and Flexible Algorithm. 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 November 2026. Copyright Notice Copyright (c) 2026 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Qu, et al. Expires 1 November 2026 [Page 1] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 Table of Contents 1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2 2. YANG Module for IS-IS Application-Specific Link Attributes . 2 3. YANG Module for IS-IS Flexible Algorithm . . . . . . . . . . 15 4. Security Considerations . . . . . . . . . . . . . . . . . . . 27 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 28 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 28 7.1. Normative References . . . . . . . . . . . . . . . . . . 28 7.2. Informative References . . . . . . . . . . . . . . . . . 30 Appendix A. Example IS-IS Flex-Algo Configuration . . . . . . . 30 Appendix B. Example IS-IS Flex-Algo Configuration (JSON) . . . . 31 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 32 1. Overview This document defines two YANG [RFC7950] data modules. The first module is to provide support for configuration and operational state for IS-IS Application-Specific Link Attributes as defined in [RFC9479], and the second module is to support IS-IS Flexible Algorithm as defined in [RFC9350]. Both modules are augmenting the IETF IS-IS YANG model [RFC9130]. 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. YANG Module for IS-IS Application-Specific Link Attributes This document defines a YANG module for IS-IS Application-Specific Link Attributes as defined in [RFC9479]. This YANG module references [RFC6991], [RFC8349], [RFC9130], and [RFC9350]. module: ietf-isis-link-attr augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/isis:isis: +--rw isis-link-attr +--rw (link-attr-op-mode)? +--:(legacy) | +--rw legacy? empty +--:(transition) Qu, et al. Expires 1 November 2026 [Page 2] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 | +--rw transition? empty +--:(app-specific) +--rw app-specific? empty augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/isis:isis/isis:interfaces /isis:interface: +--rw isis-asla +--rw interface-asla* [link-attr-app] +--rw link-attr-app identityref +--rw te-metric? uint32 +--rw admin-group? uint32 +--rw srlgs +--rw srlg* uint32 augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/isis:isis/isis:database /isis:levels/isis:lsp/isis:extended-is-neighbor /isis:neighbor/isis:instances/isis:instance: +--ro asla-sub-tlvs +--ro asla-sub-tlv* [] +--ro l-flag? boolean +--ro sabm-length? uint8 +--ro udabm-length? uint8 +--ro sabm | +--ro sabm-bits* identityref +--ro udabm +--ro te-metric? uint32 +--ro admin-group? uint32 +--ro max-bandwidth? | rt-types:bandwidth-ieee-float32 +--ro max-reservable-bandwidth? | rt-types:bandwidth-ieee-float32 +--ro unreserved-bandwidths | +--ro unreserved-bandwidth* [] | +--ro priority? uint8 | +--ro unreserved-bandwidth? | rt-types:bandwidth-ieee-float32 +--ro unidirectional-link-delay | +--ro flags | | +--ro unidirectional-link-delay-subtlv-flags* | | identityref | +--ro value? uint32 +--ro min-max-unidirectional-link-delay | +--ro flags | | +--ro min-max-unidirectional-link-delay-subtlv-flags* | | identityref | +--ro min-value? uint32 | +--ro max-value? uint32 +--ro unidirectional-link-delay-variation Qu, et al. Expires 1 November 2026 [Page 3] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 | +--ro value? uint32 +--ro unidirectional-link-loss | +--ro flags | | +--ro unidirectional-link-loss-subtlv-flags* | | identityref | +--ro value? uint32 +--ro unidirectional-link-residual-bandwidth | +--ro value? rt-types:bandwidth-ieee-float32 +--ro unidirectional-link-available-bandwidth | +--ro value? rt-types:bandwidth-ieee-float32 +--ro unidirectional-link-utilized-bandwidth | +--ro value? rt-types:bandwidth-ieee-float32 +--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/isis:isis/isis:database /isis:levels/isis:lsp/isis:mt-is-neighbor /isis:neighbor/isis:instances/isis:instance: +--ro asla-sub-tlvs +--ro asla-sub-tlv* [] +--ro l-flag? boolean +--ro sabm-length? uint8 +--ro udabm-length? uint8 +--ro sabm | +--ro sabm-bits* identityref +--ro udabm +--ro te-metric? uint32 +--ro admin-group? uint32 +--ro max-bandwidth? | rt-types:bandwidth-ieee-float32 +--ro max-reservable-bandwidth? | rt-types:bandwidth-ieee-float32 +--ro unreserved-bandwidths | +--ro unreserved-bandwidth* [] | +--ro priority? uint8 | +--ro unreserved-bandwidth? | rt-types:bandwidth-ieee-float32 +--ro unidirectional-link-delay | +--ro flags | | +--ro unidirectional-link-delay-subtlv-flags* | | identityref | +--ro value? uint32 +--ro min-max-unidirectional-link-delay | +--ro flags | | +--ro min-max-unidirectional-link-delay-subtlv-flags* Qu, et al. Expires 1 November 2026 [Page 4] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 | | identityref | +--ro min-value? uint32 | +--ro max-value? uint32 +--ro unidirectional-link-delay-variation | +--ro value? uint32 +--ro unidirectional-link-loss | +--ro flags | | +--ro unidirectional-link-loss-subtlv-flags* | | identityref | +--ro value? uint32 +--ro unidirectional-link-residual-bandwidth | +--ro value? rt-types:bandwidth-ieee-float32 +--ro unidirectional-link-available-bandwidth | +--ro value? rt-types:bandwidth-ieee-float32 +--ro unidirectional-link-utilized-bandwidth | +--ro value? rt-types:bandwidth-ieee-float32 +--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/isis:isis/isis:database /isis:levels/isis:lsp: +--ro application-specific-srlg-tlv +--ro as-srlg-tlv* [] +--ro neighbor-system-id? isis:system-id +--ro pseudo-node-id? uint8 +--ro l-flag? boolean +--ro sabm-length? uint8 +--ro udabm-length? uint8 +--ro sabm | +--ro sabm-bits* identityref +--ro udabm +--ro length-of-sub-tlvs? uint8 +--ro link-id-sub-tlvs | +--ro link-local-remote-ids | | +--ro link-local-id? union | | +--ro link-remote-id? union | +--ro ipv4-interface-addr | | +--ro ipv4-int-addr? inet:ipv4-address | +--ro ipv4-neighbor-addr | | +--ro ipv4-neighbor-addr? inet:ipv4-address | +--ro ipv6-interface-addr | | +--ro ipv6-int-addr? inet:ipv6-address | +--ro ipv6-neighbor-addr | +--ro ipv6-neighbor-addr? inet:ipv6-address +--ro srlgs Qu, et al. Expires 1 November 2026 [Page 5] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 +--ro srlg* uint32 file "ietf-isis-link-attr@2026-04-30.yang" module ietf-isis-link-attr { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-isis-link-attr"; prefix isis-link-attr; import ietf-inet-types { prefix inet; reference "RFC 6991: Common YANG Data Types"; } import ietf-routing { prefix rt; reference "RFC 8349: A YANG Data Model for Routing Management (NMDA Version)"; } import ietf-isis { prefix isis; reference "RFC 9130: YANG Data Model for the IS-IS Protocol"; } import ietf-routing-types { prefix rt-types; reference "RFC 8294: Common YANG Data Types for the Routing Area"; } 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 Author: Acee Lindem Author: Madhavi Joshi Qu, et al. Expires 1 November 2026 [Page 6] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 "; description "This YANG module defines the configuration and operational state for IS-IS application specific link attributes feature as defined in RFC 9479. 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 (http://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 2026-04-30 { description "Initial version"; reference "RFC XXXX: YANG Data Model for IS-IS Application-Specific Link Attributes and Flexible Algorithm"; } grouping isis-te-link-attrs { description "IS-IS Application-Specific Link Attributes (ASLA) inherited from the base IS-IS TE attributes"; leaf te-metric { type uint32; description "TE default metric."; reference "RFC 5305: IS-IS Extensions for Traffic Engineering, Section 3.7"; Qu, et al. Expires 1 November 2026 [Page 7] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 } leaf admin-group { type uint32; description "Administrative Group / Resource Class/Color."; reference "RFC 5305: IS-IS Extensions for Traffic Engineering, Section 3.1"; } leaf max-bandwidth { type rt-types:bandwidth-ieee-float32; description "Maximum bandwidth."; reference "RFC 5305: IS-IS Extensions for Traffic Engineering, Section 3.4"; } leaf max-reservable-bandwidth { type rt-types:bandwidth-ieee-float32; description "Maximum reservable bandwidth."; reference "RFC 5305: IS-IS Extensions for Traffic Engineering, Section 3.5"; } container unreserved-bandwidths { description "All unreserved bandwidths."; list unreserved-bandwidth { leaf priority { type uint8 { range "0 .. 7"; } description "Priority from 0 to 7."; } leaf unreserved-bandwidth { type rt-types:bandwidth-ieee-float32; description "Unreserved bandwidth."; } description "List of unreserved bandwidths for different priorities."; } reference "RFC 5305: IS-IS Extensions for Traffic Engineering, Section 3.6"; Qu, et al. Expires 1 November 2026 [Page 8] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 } reference "RFC 5305: IS-IS Extensions for Traffic Engineering"; } grouping application-identifier-bit-mask { description "Identification of the set of applications associated with link attribute advertisements"; leaf l-flag { type boolean; description "Legacy Flag. When set, all of the applications specified in the bit mask MUST use the legacy advertisements."; } leaf sabm-length { type uint8; description "Standard Application Identifier Bit Mask Length in octets."; } leaf udabm-length { type uint8; description "User Defined Application Identifier Bit Mask Length in octets."; } container sabm { leaf-list sabm-bits { type identityref { base iana-link-attr-apps:igp-link-attr-app; } description "SABM bits list. This list will contain identities for the bits which are set in the SABM bits."; } description "Standard Application Identifier Bit Mask."; } container udabm { description "User Defined Application Identifier Bit Mask. This container is to be augmented by user defined applications."; } } Qu, et al. Expires 1 November 2026 [Page 9] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 grouping application-specific-link-attributes-sub-tlv { description "Grouping for specification of the applications and application-specific attribute values."; container asla-sub-tlvs { list asla-sub-tlv { uses application-identifier-bit-mask; uses isis-te-link-attrs; uses isis:neighbor-extended-te-extensions; uses isis:unknown-tlvs; description "List of application specific link attributes sub-tlvs."; } description "Application specific link attributes sub-tlv."; } } grouping application-specific-srlg-tlv { description "Grouping of a TLV to advertise application-specific SRLGs for a given link."; container application-specific-srlg-tlv { list as-srlg-tlv { leaf neighbor-system-id { type isis:system-id; description "Neighbor System-ID."; } leaf pseudo-node-id { type uint8; description "Pseudo-node ID."; } uses application-identifier-bit-mask; leaf length-of-sub-tlvs { type uint8; description "Length of sub-tlvs."; } container link-id-sub-tlvs { description "Link Identifier sub-TLVs."; container link-local-remote-ids { description "Link local/remote identifier sub-tlv."; leaf link-local-id { type union { Qu, et al. Expires 1 November 2026 [Page 10] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 type inet:ipv4-address; type uint32; } description "Local identifier of the link. It could be an IPv4 address or a local identifier."; } leaf link-remote-id { type union { type inet:ipv4-address; type uint32; } description "Remote identifier of the link. It could be an IPv4 address or a remotely learned identifier."; } } container ipv4-interface-addr { leaf ipv4-int-addr { type inet:ipv4-address; description "IPv4 address for the interface."; } description "IPv4 interface address sub-tlv."; } container ipv4-neighbor-addr { leaf ipv4-neighbor-addr { type inet:ipv4-address; description "IPv4 address for a neighboring router on this link."; } description "IPv4 neighbor address sub-tlv."; } container ipv6-interface-addr { leaf ipv6-int-addr { type inet:ipv6-address; description "IPv6 address for the interface."; } description "IPv6 interface address sub-tlv."; } container ipv6-neighbor-addr { leaf ipv6-neighbor-addr { Qu, et al. Expires 1 November 2026 [Page 11] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 type inet:ipv6-address; description "IPv6 address for a neighboring router on this link."; } description "IPv6 neighbor address sub-tlv."; } } container srlgs { description "List of SRLGs."; leaf-list srlg { type uint32; description "SRLG value of the link."; } } description "List of application specific SRLG tlvs."; } description "Application specific SRLG tlv."; } } /* Configuration */ augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol" + "/isis:isis" { when "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/rt:type = 'isis:isis'" { description "This augment IS-IS routing protocol when used"; } description "This augments IS-IS protocol configuration with application specific link attributes."; container isis-link-attr { choice link-attr-op-mode { default "legacy"; leaf legacy { type empty; description "Only send legacy advertisements."; } leaf transition { Qu, et al. Expires 1 November 2026 [Page 12] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 type empty; description "Send both application-specific and legacy advertisements."; } leaf app-specific { type empty; description "Only send application-specific advertisements."; } description "Link attributes mode. Default to legacy mode for backward compatibility."; } description "Link attributes operation mode."; } } augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol" + "/isis:isis/isis:interfaces/isis:interface" { when "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/" + "rt:type = 'isis:isis'" { description "This augment IS-IS routing protocol when used."; } description "This augments IS-IS interface configuration with application specific link attributes."; container isis-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."; } leaf te-metric { type uint32; description "TE metric."; reference Qu, et al. Expires 1 November 2026 [Page 13] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 "RFC 5305: IS-IS Extensions for Traffic Engineering"; } leaf admin-group { type uint32; description "Administrative Group / Resource Class/Color."; reference "RFC 5305: IS-IS Extensions for Traffic Engineering"; } container srlgs { description "List of SRLGs."; leaf-list srlg { type uint32; description "SRLG value of the link."; } } description "ASLA interface configuration."; } description "Application specific link attributes configuration."; } } /* TLV 22 */ augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol" + "/isis:isis/isis:database/isis:levels/isis:lsp" + "/isis:extended-is-neighbor/isis:neighbor" + "/isis:instances/isis:instance" { when "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/rt:type = 'isis:isis'" { description "This augment IS-IS routing protocol when used"; } description "This augments IS-IS protocol LSDB TLV22."; uses application-specific-link-attributes-sub-tlv; } /* TLV 223 */ augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol" + "/isis:isis/isis:database/isis:levels/isis:lsp" Qu, et al. Expires 1 November 2026 [Page 14] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 + "/isis:mt-is-neighbor/isis:neighbor" + "/isis:instances/isis:instance" { when "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/rt:type = 'isis:isis'" { description "This augment IS-IS routing protocol when used"; } description "This augments IS-IS protocol LSDB TLV223."; uses application-specific-link-attributes-sub-tlv; } /* Application-specific SRLG TLV 238 */ augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol" + "/isis:isis/isis:database/isis:levels/isis:lsp" { when "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/rt:type = 'isis:isis'" { description "This augment IS-IS routing protocol when used"; } description "This augments IS-IS protocol LSDB."; uses application-specific-srlg-tlv; } } 3. YANG Module for IS-IS Flexible Algorithm This section defines the YANG module for IS-IS Flexible Algorithm. The module uses the identities defined in the IANA-maintained YANG modules for IGP Algorithm Types [IANA-IGP-ALGO-Types] and IGP Metric Type [IANA-IGP-Metric-Types] in [I-D.ietf-lsr-ospf-flex-algo-yang]. This YANG module references [RFC8349], [RFC8776], and [RFC9130]. module: ietf-isis-flex-algo augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/isis:isis: +--rw isis-flex-algo +--rw flex-algo* [algo-number] +--rw algo-number uint8 +--rw advertise-definition? boolean +--rw admin-groups | {te-types:extended-admin-groups, | te-types:named-extended-admin-groups}? Qu, et al. Expires 1 November 2026 [Page 15] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 | +--rw exclude-admin-groups* leafref | +--rw include-any-admin-groups* leafref | +--rw include-all-admin-groups* leafref +--rw exclude-srlgs* | -> /te:te/globals/named-srlgs/named-srlg/name | {te-types:named-srlg-groups}? +--rw metric-type? identityref +--rw calc-type? identityref +--rw prefix-metric! +--rw priority? uint8 augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/isis:isis/isis:database /isis:levels/isis:lsp/isis:router-capabilities: +--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-groups* uint64 +--ro fa-in-any-ag-sub-tlv | +--ro extended-admin-groups* uint64 +--ro fa-in-all-ag-sub-tlv | +--ro extended-admin-groups* uint64 +--ro fad-flags-sub-tlv | +--ro fad-flags* identityref +--ro fa-ex-srlg-sub-tlv | +--ro srlgs* uint32 +--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/isis:isis/isis:database /isis:levels/isis:lsp/isis:extended-ipv4-reachability /isis:prefixes: +--ro fapm-sub-tlvs +--ro fapm-sub-tlv* [] +--ro algo-number? uint8 +--ro metric? uint32 augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/isis:isis/isis:database /isis:levels/isis:lsp /isis:mt-extended-ipv4-reachability/isis:prefixes: +--ro fapm-sub-tlvs +--ro fapm-sub-tlv* [] Qu, et al. Expires 1 November 2026 [Page 16] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 +--ro algo-number? uint8 +--ro metric? uint32 augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/isis:isis/isis:database /isis:levels/isis:lsp/isis:ipv6-reachability /isis:prefixes: +--ro fapm-sub-tlvs +--ro fapm-sub-tlv* [] +--ro algo-number? uint8 +--ro metric? uint32 augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/isis:isis/isis:database /isis:levels/isis:lsp/isis:mt-ipv6-reachability /isis:prefixes: +--ro fapm-sub-tlvs +--ro fapm-sub-tlv* [] +--ro algo-number? uint8 +--ro metric? uint32 notifications: +---n flex-algo-not-supported +--ro routing-protocol-name? leafref +--ro isis-level? level +--ro algo-number? uint8 file "ietf-isis-flex-algo@2026-04-30.yang" module ietf-isis-flex-algo { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-isis-flex-algo"; prefix isis-flex-algo; 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 "RFC8776: Common YANG Data Types for Traffic Engineering."; } import ietf-isis { prefix isis; reference "RFC 9130: YANG Data Model for the IS-IS Protocol"; } import ietf-te { Qu, et al. Expires 1 November 2026 [Page 17] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 prefix te; reference "RFC XXXX: A YANG Data Model for Traffic Engineering Tunnels, Label Switched Paths, and Interfaces"; } import iana-igp-algo-types { prefix iana-algo-types; reference "RFC XXXX: YANG Data Model for OSPF Application-Specific Link Attributes and Flexible Algorithm"; } import iana-igp-metric-types { prefix iana-metric-type; 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 Author: Acee Lindem Author: Madhavi Joshi "; description "The YANG module defines the configuration and operational state for IS-IS Flexible Algorithm as defined in RFC 9350. 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). Qu, et al. Expires 1 November 2026 [Page 18] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 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 2026-04-30 { description "Initial Version"; reference "RFC XXXX: YANG Data Model for IS-IS Application-Specific Link Attributes and Flexible Algorithm"; } /* Identities */ identity fad-flags { description "Base identity for IS-IS FAD flags."; } identity m-bit { base fad-flags; description "M bit, when set, the flex-algo specific prefix and ASBR metric MUST be used for inter-area and external prefix calculation."; } /* Groupings */ grouping fa-ex-ag-sub-tlv { container fa-ex-ag-sub-tlv { leaf-list extended-admin-groups { type uint64; description "Extended administrative group as defined in RFC 7308."; } description "The flex-algo exclude admin group sub-tlv."; } description "The flex-algo exclude admin group sub-tlv."; } Qu, et al. Expires 1 November 2026 [Page 19] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 grouping fa-in-any-ag-sub-tlv { container fa-in-any-ag-sub-tlv { leaf-list extended-admin-groups { type uint64; description "Extended administrative group as defined in RFC 7308."; } description "The flex-algo include-any admin group sub-tlv."; } description "The flex-algo include-any admin group sub-tlv."; } grouping fa-in-all-ag-sub-tlv { container fa-in-all-ag-sub-tlv { leaf-list extended-admin-groups { type uint64; description "Extended administrative group as defined in RFC 7308."; } description "The flex-algo include-all admin group sub-tlv."; } description "The flex-algo include-all admin group sub-tlv."; } grouping fad-flags-sub-tlv { container fad-flags-sub-tlv { leaf-list fad-flags { type identityref { base fad-flags; } description "Flex-algo definition flags list."; } description "IS-IS flex-algo definition flags."; } description "The flex-algo definition flags sub-tlv."; } grouping fa-ex-srlg-sub-tlv { container fa-ex-srlg-sub-tlv { leaf-list srlgs { type uint32; Qu, et al. Expires 1 November 2026 [Page 20] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 description "SRLG value as defined in RFC 4203."; } description "The flex-algo exclude SRLG sub-tlv."; } description "The flex-algo exclude SRLG sub-tlv."; } 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."; } 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."; } uses fa-ex-ag-sub-tlv; uses fa-in-any-ag-sub-tlv; uses fa-in-all-ag-sub-tlv; uses fad-flags-sub-tlv; uses fa-ex-srlg-sub-tlv; uses isis:unknown-tlvs; description "List of flex-algo definition TLVs."; Qu, et al. Expires 1 November 2026 [Page 21] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 } description "IS-IS Flexible Algorithm Definition TLV."; } description "IS-IS Flexible Algorithm Definition (FAD) TLV."; } 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 FAPM sub-TLV specification."; } 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."; } /* Configurations */ augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol" + "/isis:isis" { when "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/rt:type = 'isis:isis'" { description "This augment IS-IS routing protocol when used"; } description "This augments IS-IS protocol configuration with flexible algorithm."; container isis-flex-algo { list flex-algo { key "algo-number"; Qu, et al. Expires 1 November 2026 [Page 22] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 leaf algo-number { type uint8 { range "128..255"; } description "Flex-algo number - must in in the inclusive range of 128-255."; } leaf advertise-definition { type boolean; default "true"; description "Enable to advertise the flex-algo definition."; } container admin-groups { if-feature "te-types:extended-admin-groups"; if-feature "te-types:named-extended-admin-groups"; leaf-list exclude-admin-groups { type leafref { path "/te:te/te:globals/te:named-admin-groups/" + "te:named-admin-group/te:name"; } description "Exclude rule used during the flex-algo path computation."; } leaf-list include-any-admin-groups { type leafref { path "/te:te/te:globals/te:named-admin-groups/" + "te:named-admin-group/te:name"; } description "Include-any rule used during the flex-algo path computation."; } leaf-list include-all-admin-groups { type leafref { path "/te:te/te:globals/te:named-admin-groups/" + "te:named-admin-group/te:name"; } description "Include-all rule used during the flex-algo path computation."; } description "Specify links for the flex-algo path computation."; } leaf-list exclude-srlgs { Qu, et al. Expires 1 November 2026 [Page 23] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 if-feature "te-types:named-srlg-groups"; type leafref { path "/te:te/te:globals/te:named-srlgs/te:named-srlg/" + "te:name"; } description "Shared Risk Link Groups (SRLGs) to be excluded during the flex-algo path computation."; } 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; } default "iana-algo-types:algo-spf"; description "Calculation-type. Value from 0-127 inclusive from the IANA 'IGP Algorithm Types' registry defined under the 'Interior Gateway Protocol (IGP) Parameters' registry."; } container prefix-metric { 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" Qu, et al. Expires 1 November 2026 [Page 24] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 + "/isis:isis/isis:database/isis:levels/isis:lsp" + "/isis:router-capabilities" { when "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/" + "rt:type = 'isis:isis'" { description "This augment IS-IS routing protocol when used"; } description "This augments IS-IS protocol LSDB router capability."; uses fad-tlvs; } augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol" + "/isis:isis/isis:database/isis:levels/isis:lsp" + "/isis:extended-ipv4-reachability/" + "isis:prefixes" { when "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/" + "rt:type = 'isis:isis'" { description "This augment IS-IS routing protocol when used"; } description "This augments IS-IS protocol LSDB prefix."; uses fapm-sub-tlvs; } augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol" + "/isis:isis/isis:database/isis:levels/isis:lsp" + "/isis:mt-extended-ipv4-reachability/isis:prefixes" { when "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/" + "rt:type = 'isis:isis'" { description "This augment IS-IS routing protocol when used"; } description "This augments IS-IS protocol LSDB prefix."; uses fapm-sub-tlvs; } augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol" + "/isis:isis/isis:database/isis:levels/isis:lsp" + "/isis:ipv6-reachability/isis:prefixes" { Qu, et al. Expires 1 November 2026 [Page 25] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 when "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/" + "rt:type = 'isis:isis'" { description "This augment IS-IS routing protocol when used"; } description "This augments IS-IS protocol LSDB prefix."; uses fapm-sub-tlvs; } augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol" + "/isis:isis/isis:database/isis:levels/isis:lsp" + "/isis:mt-ipv6-reachability/isis:prefixes" { when "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/" + "rt:type = 'isis:isis'" { description "This augment IS-IS routing protocol when used"; } description "This augments IS-IS protocol LSDB prefix."; uses fapm-sub-tlvs; } /* Notification */ notification flex-algo-not-supported { uses isis:notification-instance-hdr; leaf algo-number { type uint8; description "Flex-algo identifier which is not supported by the IS-IS 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 IS-IS instance does not support this flex-algo."; } } Qu, et al. Expires 1 November 2026 [Page 26] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 4. 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 [RFC8446], 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: /isis:isis/isis-link-attr/link-attr-op-mode - Modification to the protocol operation mode may result in traffic disruption. /isis:isis/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. Some of the readable data nodes in the modules 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. The exposure of the Link State Database (LSDB) will expose the detailed topology of the network. This may be undesirable since both due to the fact that exposure may facilitate other attacks. Additionally, network operators may consider their topologies to be sensitive confidential data. 5. IANA Considerations This document registers a URI in the IETF XML registry [RFC3688]. Following the format in [RFC3688], the following registrations are requested: URI: urn:ietf:params:xml:ns:yang:ietf-isis-link-attr Registrant Contact: The IESG. XML: N/A, the requested URI is an XML namespace. Qu, et al. Expires 1 November 2026 [Page 27] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 URI: urn:ietf:params:xml:ns:yang:ietf-isis-flex-algo Registrant Contact: The IESG. XML: N/A, the requested URI is an XML namespace. This document registers the YANG module in the YANG Module Names registry [RFC7950]. name: ietf-isis-link-attr Maintained by IANA? N namespace: urn:ietf:params:xml:ns:yang:ietf-isis-link-attr prefix: isis-link-attr reference: RFC XXXX name: ietf-isis-flex-algo Maintained by IANA? N namespace: urn:ietf:params:xml:ns:yang:ietf-isis-flex-algo prefix: isis-flex-algo reference: RFC XXXX 6. Acknowledgements Thanks to Michal Vasko for his YANG doctors review. Thanks to Adrian Farrel for his OPS directorate review. Thanks to Renato Westphal for review and comments. 7. References 7.1. Normative References [I-D.ietf-lsr-ospf-flex-algo-yang] Qu, Y. and A. Lindem, "YANG Data Model for OSPF Application-Specific Link Attributes and Flexible Algorithm", Work in Progress, Internet-Draft, draft-ietf- lsr-ospf-flex-algo-yang-07, 30 March 2026, . [IANA-IGP-ALGO-Types] IANA, "IGP Algorithm Types", . [IANA-IGP-Metric-Types] IANA, "IGP Metric-Type", . Qu, et al. Expires 1 November 2026 [Page 28] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004, . [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, . [RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, July 2013, . [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016, . [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, . [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, . [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, . Qu, et al. Expires 1 November 2026 [Page 29] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 [RFC8776] Saad, T., Gandhi, R., Liu, X., Beeram, V., and I. Bryskin, "Common YANG Data Types for Traffic Engineering", RFC 8776, DOI 10.17487/RFC8776, 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, . [RFC9130] Litkowski, S., Ed., Yeung, D., Lindem, A., Zhang, J., and L. Lhotka, "YANG Data Model for the IS-IS Protocol", RFC 9130, DOI 10.17487/RFC9130, 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, . [RFC9479] Ginsberg, L., Psenak, P., Previdi, S., Henderickx, W., and J. Drake, "IS-IS Application-Specific Link Attributes", RFC 9479, DOI 10.17487/RFC9479, October 2023, . 7.2. Informative References [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, . Appendix A. Example IS-IS Flex-Algo Configuration The following is an example configuration for IS-IS Flexible Algorithm using the YANG model defined in this document. Note: '\' line wrapping per [RFC8792]. Qu, et al. Expires 1 November 2026 [Page 30] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 true blue 1.1.1.1 \ isis:isis isis 1111.2222.3333 49.0001.0000.0000.0001 200 blue \ iana-metric-types:igp-metric \ iana-algo-types:algo-spf 100 Appendix B. Example IS-IS Flex-Algo Configuration (JSON) The following is an example configuration for IS-IS Flexible Algorithm in JSON format using the YANG model defined in this document. Qu, et al. Expires 1 November 2026 [Page 31] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 { "te": { "enable": true, "globals": { "named-admin-groups": { "named-admin-group": { "name": "blue" } } } }, "routing": { "router-id": "1.1.1.1", "control-plane-protocols": { "control-plane-protocol": { "type": "isis:isis", "name": "isis", "isis": { "system-id": "1111.2222.3333", "area-address": "49.0001.0000.0000.0001", "isis-flex-algo": { "flex-algo": { "algo-number": 200, "admin-groups": { "exclude-admin-groups": "blue" }, "metric-type": "iana-metric-types:igp-metric", "calc-type": "iana-algo-types:algo-spf", "prefix-metric": "", "priority": 100 } } } } } } } Authors' Addresses Yingzhen Qu Futurewei Technologies United States of America Email: yingzhen.ietf@gmail.com Qu, et al. Expires 1 November 2026 [Page 32] Internet-Draft IS-IS ASLA and Flex-Algo YANG April 2026 Acee Lindem Arrcus, Inc. United States of America Email: acee.ietf@gmail.com Madhavi Joshi Arrcus, Inc. United States of America Email: madhavi@arrcus.com Qu, et al. Expires 1 November 2026 [Page 33]