A YANG Data Model for OSPF Application-Specific Link Attributes and Flexible Algorithm
draft-ietf-lsr-ospf-flex-algo-yang-16
| Document | Type | Active Internet-Draft (lsr WG) | |
|---|---|---|---|
| Authors | Yingzhen Qu , Acee Lindem | ||
| Last updated | 2026-09-09 (Latest revision 2026-07-21) | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | Proposed Standard | ||
| Formats | |||
| Yang Validation | 0 errors, 0 warnings | ||
| Reviews |
YANGDOCTORS Early review
(of
-00)
by Dhruv Dhody
Almost ready
|
||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | Submitted to IESG for Publication | |
| Associated WG milestone |
|
||
| Document shepherd | Christian Hopps | ||
| Shepherd write-up | Show Last changed 2026-02-03 | ||
| IESG | IESG state | RFC Ed Queue | |
| Action Holders |
(None)
|
||
| Consensus boilerplate | Yes | ||
| Telechat date | (None) | ||
| Responsible AD | Gunter Van de Velde | ||
| Send notices to | chopps@chopps.org | ||
| IANA | IANA review state | Version Changed - Review Needed | |
| IANA action state | RFC-Ed-Ack | ||
| IANA expert review state | Expert Reviews OK | ||
| RFC Editor | RFC Editor status | Awaiting First editor | |
| Details |
draft-ietf-lsr-ospf-flex-algo-yang-16
Internet Y. Qu
Internet-Draft Futurewei Technologies
Updates: 8665, 9350, 9843 (if approved) A. Lindem
Intended status: Standards Track Arrcus, Inc.
Expires: 22 January 2027 21 July 2026
A YANG Data Model for OSPF Application-Specific Link Attributes and
Flexible Algorithm
draft-ietf-lsr-ospf-flex-algo-yang-16
Abstract
This document defines a YANG data model to support OSPF Application-
Specific Link Attributes and Flexible Algorithm. It also creates the
initial version of IANA-maintained YANG modules for IGP Algorithm
Types, IGP Metric-Types, and IGP Link Attribute Applications.
This document updates RFCs 8665, 9350, and 9843.
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 22 January 2027.
Copyright Notice
Copyright (c) 2026 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. YANG Module for OSPF Application-Specific Link Attributes . . 3
3. YANG Module for OSPF Flexible Algorithm . . . . . . . . . . . 12
4. Security Considerations . . . . . . . . . . . . . . . . . . . 32
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 33
5.1. Registering YANG Modules . . . . . . . . . . . . . . . . 33
5.2. Updates to Existing IANA Registries . . . . . . . . . . . 35
5.2.1. IGP Algorithm Types registry . . . . . . . . . . . . 35
5.2.2. IGP Metric-Type registry . . . . . . . . . . . . . . 36
5.3. IANA IGP Algorithm Types Module . . . . . . . . . . . . . 37
5.4. IANA IGP Metric-Type Module . . . . . . . . . . . . . . . 37
5.5. IANA IGP Link Attribute Applications Module . . . . . . . 38
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 39
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 39
7.1. Normative References . . . . . . . . . . . . . . . . . . 39
7.2. Informative References . . . . . . . . . . . . . . . . . 41
Appendix A. Example OSPF Flex-Algo Configuration (XML) . . . . . 42
Appendix B. Example OSPF Flex-Algo Configuration (JSON) . . . . 43
Appendix C. IANA IGP Algorithm Types Module . . . . . . . . . . 44
Appendix D. IANA IGP Metric Types Module . . . . . . . . . . . . 47
Appendix E. IANA IGP Link Attribute Applications Module . . . . 49
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 52
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].
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There are three IANA-maintained YANG modules defined in this document
as well. 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.
This document updates [RFC8665], [RFC9350], and [RFC9843].
The meanings of the symbols in the YANG tree diagrams are defined in
[RFC8340].
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 OSPF Application-Specific Link Attributes
This document defines a YANG module for OSPF Application-Specific
Link Attributes (ASLA) as defined in [RFC9492]. It augments the base
OSPF YANG model defined in [RFC9129] with both configuration and
operational state in OSPFv2 and OSPFv3.
The module augments OSPF router configuration with support for the
ASLA operation mode, enabling interoperability during the transition
from legacy advertisements to ASLA. The advertisement mode is
configured per application: by default, RSVP-TE uses "legacy" mode,
while LFA and SR-Policy use "app-specific" mode. These configuration
knobs control whether legacy attributes, application-specific
attributes, or both are advertised for a given application. At
present, only the legacy attributes defined in [RFC9129] are
supported; additional attributes will be included in these TLVs when
the augmentations for the corresponding legacy attributes are added.
The OSPF interfaces are augmented with ASLA configuration.
In addition, both OSPFv2 and OSPFv3 link state database LSAs are
augmented to include the TLVs defined in [RFC9492].
This YANG module references [RFC8349], [RFC9129], [RFC9350],
[RFC9492], and [RFC9587].
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module: ietf-ospf-link-attr
augment /rt:routing/rt:control-plane-protocols
/rt:control-plane-protocol/ospf:ospf:
+--rw ospf-link-attr
+--rw rsvp-te-advertise? attr-advertise-mode
+--rw lfa-advertise? attr-advertise-mode
+--rw sr-policy-advertise? attr-advertise-mode
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
| iana-link-attr-apps:igp-link-attr-app
+--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-tlv* []
+--ro sabm
| +--ro sabm-bit*
| iana-link-attr-apps:igp-link-attr-app
+--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-tlv* []
+--ro sabm
| +--ro sabm-bit*
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| iana-link-attr-apps:igp-link-attr-app
+--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
<CODE BEGINS> file "ietf-ospf-link-attr@2026-07-09.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";
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contact
"WG Web: <https://datatracker.ietf.org/wg/lsr/>
WG List: <mailto:lsr@ietf.org>
Author: Yingzhen Qu
<mailto:yingzhen.ietf@gmail.com>
Author: Acee Lindem
<mailto:acee.ietf@gmail.com>
";
description
"This YANG module defines the configuration and operational
state for OSPF application specific link attributes feature
as defined in RFC 9492.
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 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 2026-07-09 {
description
"Initial version";
reference
"RFC XXXX: A YANG Data Model for OSPF Application-Specific
Link Attributes and Flexible Algorithm";
}
typedef attr-advertise-mode {
type enumeration {
enum legacy {
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value 0;
description
"Only send legacy advertisements, and no ASLA
advertisement. Legacy advertisements will be
used for the application.";
reference
"RFC9492: OSPF Application-Specific Attributes,
Section 12.3.3";
}
enum transition {
value 1;
description
"Send both application-specific and legacy
advertisements. Both application-specific and
legacy attribute advertisements will be used
by the application with advertised legacy attributes
taking precedence.";
reference
"RFC9492: OSPF Application-Specific Attributes,
Section 12.3.3";
}
enum app-specific {
value 2;
description
"Application-specific advertisements are advertised
exclusively except for RSVP-TE in certain situations.
Refer to the reference for the specific rules.";
reference
"RFC9492: OSPF Application-Specific Attributes,
Section 12.3.3 and Section 12.3.4.";
}
}
description
"Link attributes operation mode.";
reference
"RFC 9492 - OSPF Application-Specific Link Attributes,
Section 12.3.";
}
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
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"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-tlv {
container sabm {
leaf-list sabm-bit {
type iana-link-attr-apps:igp-link-attr-app;
description
"Standard Application Identifier Bit Mask bits. This
leaf-list contains enums 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
application, following the same pattern as the
'sabm-bit' leaf-list. Refer to RFC 9492, Section 5
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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 "derived-from-or-self(../rt:type, 'ospf:ospfv2') or "
+ "derived-from-or-self(../rt:type, 'ospf:ospfv3')" {
description
"This augments the OSPF routing protocol when used.";
}
description
"This augments OSPF protocol configuration
with application-specific link attributes.";
reference
"RFC 9492: OSPF Application-Specific Link Attributes,
Section 12.3";
container ospf-link-attr {
description
"Configuration of application attribute advertisement
and usage.";
leaf rsvp-te-advertise {
type attr-advertise-mode;
default "legacy";
description
"Advertisement for RSVP-TE - The default will be
'legacy' and RSVP-TE advertisement (e.g., OSPFv2 Opaque
TE LSAs and OSPFv3 TE LSA will be advertised
independent of configuration if certain attributes are
advertised).";
reference
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"RFC 9492: OSPF Application-Specific Link Attributes,
Section 12.3.4.";
}
leaf lfa-advertise {
type attr-advertise-mode;
default "app-specific";
description
"Advertisement for Link Free Alternates (LFA) - The
default will be 'app-specific'. ASLA advertisements will
be advertised and used by default unless specified
otherwise.";
reference
"RFC 9492: OSPF Application-Specific Link Attributes,
Section 12.3.";
}
leaf sr-policy-advertise {
type attr-advertise-mode;
default "app-specific";
description
"Advertisement for Segment Routing Policy (SR-Policy) -
The default will be 'app-specific'. ASLA advertisements
will be advertised and used by default unless specified
otherwise.";
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-or-self(../../../../../rt:type, "
+ "'ospf:ospfv2') or "
+ "derived-from-or-self(../../../../../rt:type, "
+ "'ospf:ospfv3')" {
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 iana-link-attr-apps:igp-link-attr-app;
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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.";
}
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-or-self("
+ "../../../../../../../../../../../../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-or-self("
+ "../../../../../../../../../../../../rt:type, "
+ "'ospf:ospfv3')" {
description
"This augmentation is only valid for OSPFv3
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E-Router LSAs";
}
description
"Augment OSPFv3 Area scope router-link TLV.";
uses app-specific-link-attr-sub-tlvs;
}
}
<CODE ENDS>
3. YANG Module for OSPF Flexible Algorithm
This document defines a YANG module, ietf-ospf-flex-algo, for OSPF
Flexible Algorithm as defined in [RFC9350]. It is an augmentation of
the OSPF base model as defined in [RFC9129].
The module augments OSPF router configuration with support for
flexible algorithm configuration, including metric types, calculation
types and administrative constraints etc. In addition, both the
OSPFv2 and OSPFv3 link-state databases are augmented to include the
various TLVs defined in [RFC9350].
This YANG module references [RFC8349], [RFC9129], [RFC9350], and
[RFC9587].
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-srlg* te-types:srlg
+--rw calc-type? iana-algo-types:algo-type
+--rw metric-type?
| iana-metric-types:metric-type
+--rw prefix-metric!
+--rw priority? uint8
augment /rt:routing/rt:control-plane-protocols
/rt:control-plane-protocol/ospf:ospf/ospf:areas
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/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?
| iana-metric-types:metric-type
+--ro calc-type? iana-algo-types:algo-type
+--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-flag* identityref
+--ro fa-ex-srlg-sub-tlv
| +--ro srlg* 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?
| iana-metric-types:metric-type
+--ro calc-type? iana-algo-types:algo-type
+--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?
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| 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-flag* identityref
+--ro fa-ex-srlg-sub-tlv
| +--ro srlg* 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:ospfv2
/ospf:ospfv2/ospf:body/ospf:opaque/ospf:ri-opaque:
+--ro fad-tlvs
+--ro fad-tlv* []
+--ro algo-number? uint8
+--ro metric-type?
| iana-metric-types:metric-type
+--ro calc-type? iana-algo-types:algo-type
+--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-flag* identityref
+--ro fa-ex-srlg-sub-tlv
| +--ro srlg* 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
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/ospf:ospfv3/ospf:ospfv3/ospf:body
/ospf:router-information:
+--ro fad-tlvs
+--ro fad-tlv* []
+--ro algo-number? uint8
+--ro metric-type?
| iana-metric-types:metric-type
+--ro calc-type? iana-algo-types:algo-type
+--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-flag* identityref
+--ro fa-ex-srlg-sub-tlv
| +--ro srlg* 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?
| iana-metric-types:metric-type
+--ro calc-type? iana-algo-types:algo-type
+--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?
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| te-types:extended-admin-group
+--ro fad-flags-sub-tlv
| +--ro fad-flag* identityref
+--ro fa-ex-srlg-sub-tlv
| +--ro srlg* 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
+--ro metric-type?
| iana-metric-types:metric-type
+--ro calc-type? iana-algo-types:algo-type
+--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-flag* identityref
+--ro fa-ex-srlg-sub-tlv
| +--ro srlg* 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
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+--ro fapm-sub-tlv* []
+--ro algo-number? uint8
+--ro fapm-flag* 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-flag* 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
/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-flag* 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-flag* 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* []
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+--ro algo-number? uint8
+--ro fapm-flag* 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
| +--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
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<CODE BEGINS> file "ietf-ospf-flex-algo@2026-07-09.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 {
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,
<https://www.iana.org/assignments/igp-parameters>.";
}
import iana-igp-metric-types {
prefix iana-metric-types;
reference
"IANA IGP Metric-Type registry,
<https://www.iana.org/assignments/igp-parameters>.";
}
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organization
"IETF LSR - Link State Routing Working Group";
contact
"WG Web: <https://datatracker.ietf.org/wg/lsr/>
WG List: <mailto:lsr@ietf.org>
Author: Yingzhen Qu
<mailto:yingzhen.ietf@gmail.com>
Author: Acee Lindem
<mailto:acee.ietf@gmail.com>
";
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).
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 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 2026-07-09 {
description
"Initial Version";
reference
"RFC XXXX: A YANG Data Model for OSPF Application-Specific
Link Attributes and Flexible Algorithm";
}
/* Identities */
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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
"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 {
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type iana-metric-types:metric-type;
description
"Type of metric to be used during the calculation.";
}
leaf calc-type {
type 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.";
}
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-flag {
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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 srlg {
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.";
}
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-flag {
type identityref {
base fapm-flags;
}
description
"Flex-algo prefix metric flags list.";
}
leaf metric {
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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.";
}
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 "derived-from-or-self(../rt:type, 'ospf:ospfv2') or "
+ "derived-from-or-self(../rt:type, 'ospf:ospfv3')" {
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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";
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.";
}
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leaf-list exclude-srlg {
type te-types:srlg;
description
"Shared Risk Link Groups (SRLGs) to be excluded during
the flex-algo path computation.";
}
leaf calc-type {
type iana-algo-types:algo-type;
description
"Calculation-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 iana-metric-types:metric-type;
description
"Type of metric to be used during the calculation.";
}
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/"
+ "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 "derived-from-or-self(../../../../../../../../../../../.."
+ "/../rt:type, 'ospf:ospfv2')" {
description
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"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 "derived-from-or-self(../../../../../../../../../../.."
+ "/rt:type, 'ospf:ospfv2')" {
description
"This augmentation is only valid for OSPFv2.";
}
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 "derived-from-or-self(../../../../../../../../../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 "derived-from-or-self(../../../../../../../../../../../.."
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+ "/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 "derived-from-or-self(../../../../../../../../../../"
+ "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: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 "derived-from-or-self(../../../../../../../../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/"
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+ "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 "derived-from-or-self(../../../../../../../../../../../.."
+ "/../../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/"
+ "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 "derived-from-or-self(../../../../../../../../../../../.."
+ "/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 "derived-from-or-self(../../../../../../../../../.."
+ "/rt:type, 'ospf:ospfv2')" {
description
"This augmentation is only valid for OSPFv2.";
}
description
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"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 "derived-from-or-self(../../../../../../../../../../../.."
+ "/rt:type, 'ospf:ospfv3')" {
description
"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 "derived-from-or-self(../../../../../../../../../.."
+ "/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 */
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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 "derived-from-or-self(../../../../../../../../../.."
+ "/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 {
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 "derived-from-or-self(../../../../../../../../../../../.."
+ "/rt:type, 'ospf:ospfv3')" {
description
"This augmentation is only valid for OSPFv3
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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.";
}
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.";
}
}
<CODE ENDS>
4. Security Considerations
This section is modeled after the template described in Section 3.7.1
of [RFC9907].
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.
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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 - Modification to the application-
specific link attribute advertisement modes (rsvp-te-advertise,
lfa-advertise, sr-policy-advertise) may result in traffic
disruption.
/ospf:ospf/ospf-flex-algo/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 traffic.
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.
5. IANA Considerations
5.1. 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:
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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].
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-apps
Maintained by IANA? Y
namespace: urn:ietf:params:xml:ns:yang:iana-igp-link-attr-apps
prefix: iana-link-attr-apps
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
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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
5.2. Updates to Existing IANA Registries
5.2.1. IGP Algorithm Types registry
IANA is requested to add a "Name" column to the "IGP Algorithm Types"
registry [IANA-IGP-ALGO-Types] under the "Interior Gateway Protocol
(IGP) Parameters" registry group. The values for the "Name" column
for existing Algorithm Types are:
+=======+========+====================================+===========+
| Value | Name | Description | Reference |
+=======+========+====================================+===========+
| 0 | SPF | Shortest Path First (SPF) | [RFC8665] |
| | | algorithm based on link metric. | |
| | | This is the standard shortest path | |
| | | algorithm as computed by the IGP | |
| | | protocol. Consistent with the | |
| | | deployed practice for link-state | |
| | | protocols, Algorithm 0 permits any | |
| | | node to overwrite the SPF path | |
| | | with a different path based on its | |
| | | local policy. | |
+-------+--------+------------------------------------+-----------+
| 1 | Strict | Strict Shortest Path First (SPF) | [RFC8665] |
| | SPF | algorithm based on link metric. | |
| | | The algorithm is identical to | |
| | | Algorithm 0 but Algorithm 1 | |
| | | requires that all nodes along the | |
| | | path will honor the SPF routing | |
| | | decision. Local policy at the | |
| | | node claiming support for | |
| | | Algorithm 1 MUST NOT alter the SPF | |
| | | paths computed by Algorithm 1. | |
+-------+--------+------------------------------------+-----------+
Table 1
Also, IANA is requested to add this document to the "Reference" of
the "IGP Algorithm Types" registry.
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5.2.2. IGP Metric-Type registry
IANA is requested to add a "Name" column to the "IGP Metric-Type"
registry [IANA-IGP-Metric-Types] under the "Interior Gateway Protocol
(IGP) Parameters" registry group. The values for the "Name" column
for existing Metric Types are:
+=======+==============+==============+==========+================+
|Type |Name |Description |Reference | Allowed in |
| | | | | Generic-Metric |
+=======+==============+==============+==========+================+
|0 |IGP Metric |IGP Metric |[RFC9350],| No |
| | | |Section | |
| | | |5.1 | |
+-------+--------------+--------------+----------+----------------+
|1 |Min |Min |[RFC9350],| No |
| |Unidirectional|Unidirectional|Section | |
| |Link Delay |Link Delay as |5.1 | |
| | |defined in | | |
| | |[RFC8570], | | |
| | |Section 4.2 | | |
| | |and [RFC7471],| | |
| | |Section 4.2 | | |
+-------+--------------+--------------+----------+----------------+
|2 |TE Default |Traffic |[RFC9350],| No |
| |Metric |Engineering |Section | |
| | |Default Metric|5.1 | |
| | |as defined in | | |
| | |[RFC5305], | | |
| | |Section 3.7 | | |
| | |and Traffic | | |
| | |Engineering | | |
| | |Metric as | | |
| | |defined in | | |
| | |[RFC3630], | | |
| | |Section 2.5.5 | | |
+-------+--------------+--------------+----------+----------------+
|3 |Bandwidth |Bandwidth |[RFC9843],| Yes |
| |Metric |Metric |Section | |
| | | |5.1 | |
+-------+--------------+--------------+----------+----------------+
|128-255|Reserved |Reserved for |[RFC9843],| Yes |
| | |User-Defined |Section | |
| | |Metric |5.1 | |
+-------+--------------+--------------+----------+----------------+
Table 2
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Also, IANA is requested to add this document to the "Reference" of
the "IGP Metric-Type" registry.
5.3. IANA IGP Algorithm Types Module
This document creates the initial version of the IANA-maintained
"iana-igp-algo-types" YANG module. 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-algo-types"
| YANG module. They must instead be added to the "IGP Algorithm
| Types" registry in the "Interior Gateway Protocol (IGP)
| Parameters" registry group.
IANA is requested to add this note to [IANA-IGP-ALGO-Types]:
| When this registry is modified, the YANG module "iana-igp-algo-
| types" [IANA-YANG-Parameters] must be updated as defined in RFC
| XXXX.
When a value is added to the "IGP Algorithm Types" registry, a new
"enum" statement needs to be added to the "iana-igp-algo-types" YANG
module. The name of the "enum" is a lowercase version of the name as
provided in the registry with spaces replaced with hyphens, i.e.,
"-"s, and beginning with "algo-". The "enum" statement should have
the following sub-statements defined:
"value": Contains the decimal value of the IANA-assigned
value.
"description": Replicates the description from the registry.
"reference": Replicates the reference(s) from the registry
with the title of the document(s) added.
5.4. IANA IGP Metric-Type Module
This document creates the initial version of the IANA-maintained
"iana-igp-metric-types" YANG module. 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:
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| 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.
IANA is requested to add this note to [IANA-IGP-Metric-Types]:
| When this registry is modified, the YANG module "iana-igp-metric-
| types" [IANA-YANG-Parameters] must be updated as defined in RFC
| XXXX.
When a value is added to the "IGP Metric-Type" registry, a new "enum"
statement needs to be added to the "iana-igp-metric-types" YANG
module. The name of the "enum" is a lowercase version of the name as
provided in the registry with the spaces replaced with hyphens, i.e.,
"-"s. The "enum" statement should have the following sub-statements
defined:
"value": Contains the decimal value of the IANA-assigned
value.
"description": Replicates the description from the registry.
"reference": Replicates the reference(s) from the registry
with the title of the document(s) added.
5.5. IANA IGP Link Attribute Applications Module
This document creates the initial version of the IANA-maintained
"iana-igp-link-attr-apps" YANG module. 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 Identifiers" registry in the "Interior
| Gateway Protocol (IGP) Parameters" registry group.
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" [IANA-YANG-Parameters] must be updated as defined in
| RFC XXXX.
When a value is added to the "Link Attribute Application Identifiers"
registry, a new "enum" statement needs to be added to the "iana-igp-
link-attr-apps" YANG module. The name of the "enum" is a lowercase
version of the Name field as provided in the registry with spaces
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replaced with hyphens, i.e., "-"s and ending with "-app". In order
to form the YANG "enum", the name of the application is taken from
the beginning the name listed in the registry, not including text in
parenthesis. The "enum" statement should have the following sub-
statements defined:
"value": Contains the decimal value of the IANA-assigned
value.
"description": Replicates the Name text when a new value
is added.
"reference": Replicates the reference(s) from the registry
with the title of the document(s) added.
6. 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.
Thanks to Med Boucadair, Ketan Talaulikar, Les Ginsberg, and Mahesh
Jethanandani for extensive review and comments.
7. References
7.1. Normative References
[IANA-IGP-ALGO-Types]
IANA, "IGP Algorithm Types",
<https://www.iana.org/assignments/igp-parameters>.
[IANA-IGP-Metric-Types]
IANA, "IGP Metric-Type",
<https://www.iana.org/assignments/igp-parameters>.
[IANA-Link-Attr-Apps]
IANA, "Link Attribute Application Identifiers",
<https://www.iana.org/assignments/igp-parameters>.
[IANA-YANG-Parameters]
IANA, "YANG Module Names",
<https://www.iana.org/assignments/yang-parameters>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
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[RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
(TE) Extensions to OSPF Version 2", RFC 3630,
DOI 10.17487/RFC3630, October 2003,
<https://www.rfc-editor.org/info/rfc3630>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/info/rfc3688>.
[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, DOI 10.17487/RFC5305, October
2008, <https://www.rfc-editor.org/info/rfc5305>.
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
<https://www.rfc-editor.org/info/rfc6020>.
[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,
<https://www.rfc-editor.org/info/rfc7471>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
<https://www.rfc-editor.org/info/rfc7950>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration
Access Control Model", STD 91, RFC 8341,
DOI 10.17487/RFC8341, March 2018,
<https://www.rfc-editor.org/info/rfc8341>.
[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,
<https://www.rfc-editor.org/info/rfc8349>.
[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, <https://www.rfc-editor.org/info/rfc8570>.
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[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,
<https://www.rfc-editor.org/info/rfc8665>.
[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,
<https://www.rfc-editor.org/info/rfc9129>.
[RFC9350] Psenak, P., Ed., Hegde, S., Filsfils, C., Talaulikar, K.,
and A. Gulko, "IGP Flexible Algorithm", RFC 9350,
DOI 10.17487/RFC9350, February 2023,
<https://www.rfc-editor.org/info/rfc9350>.
[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,
<https://www.rfc-editor.org/info/rfc9492>.
[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,
<https://www.rfc-editor.org/info/rfc9587>.
[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, <https://www.rfc-editor.org/info/rfc9843>.
7.2. 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,
<https://datatracker.ietf.org/doc/html/draft-ietf-tls-
rfc8446bis-14>.
[RFC4252] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH)
Authentication Protocol", RFC 4252, DOI 10.17487/RFC4252,
January 2006, <https://www.rfc-editor.org/info/rfc4252>.
[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,
<https://www.rfc-editor.org/info/rfc6241>.
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[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<https://www.rfc-editor.org/info/rfc8040>.
[RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
<https://www.rfc-editor.org/info/rfc8340>.
[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,
<https://www.rfc-editor.org/info/rfc8792>.
[RFC9000] Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based
Multiplexed and Secure Transport", RFC 9000,
DOI 10.17487/RFC9000, May 2021,
<https://www.rfc-editor.org/info/rfc9000>.
[RFC9907] Bierman, A., Boucadair, M., Ed., and Q. Wu, "Guidelines
for Authors and Reviewers of Documents Containing YANG
Data Models", BCP 216, RFC 9907, DOI 10.17487/RFC9907,
March 2026, <https://www.rfc-editor.org/info/rfc9907>.
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].
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<?xml version='1.0' encoding='UTF-8'?>
<routing xmlns="urn:ietf:params:xml:ns:yang:ietf-routing">
<router-id>1.1.1.1</router-id>
<control-plane-protocols>
<control-plane-protocol>
<type xmlns:ospf="urn:ietf:params:xml:ns:yang:ietf-ospf">\
ospf:ospfv2</type>
<name>OSPFv2</name>
<ospf xmlns="urn:ietf:params:xml:ns:yang:ietf-ospf">
<areas>
<area>
<area-id>0.0.0.0</area-id>
</area>
</areas>
<ospf-flex-algo xmlns="urn:ietf:params:xml:ns:yang:\
ietf-ospf-flex-algo">
<flex-algo>
<algo-number>200</algo-number>
<admin-groups>
<exclude-admin-group>AA:BB</exclude-admin-group>
</admin-groups>
<calc-type xmlns:iana-algo-types="urn:ietf:params:\
xml:ns:yang:iana-igp-algo-types">algo-spf</calc-type>
<metric-type xmlns:iana-metric-types="urn:ietf:params:\
xml:ns:yang:iana-igp-metric-types">igp-metric\
</metric-type>
<prefix-metric/>
<priority>100</priority>
</flex-algo>
</ospf-flex-algo>
</ospf>
</control-plane-protocol>
</control-plane-protocols>
</routing>
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.
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{
"ietf-routing:routing": {
"router-id": "1.1.1.1",
"control-plane-protocols": {
"control-plane-protocol": [
{
"type": "ietf-ospf:ospfv2",
"name": "OSPFv2",
"ietf-ospf:ospf": {
"areas": {
"area": [
{
"area-id": "0.0.0.0"
}
]
},
"ietf-ospf-flex-algo:ospf-flex-algo": {
"flex-algo": [
{
"algo-number": 200,
"admin-groups": {
"exclude-admin-group": "AA:BB"
},
"calc-type": "algo-spf",
"metric-type": "igp-metric",
"prefix-metric": {},
"priority": 100
}
]
}
}
}
]
}
}
}
Appendix C. IANA IGP Algorithm Types Module
//RFC Editor: please remove the Appendix C before publication and
replace XXXX with the RFC number that is assigned to the document.
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.
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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].
<CODE BEGINS> file "iana-igp-algo-types@2026-07-09.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
<mailto:iana@iana.org>";
description
"The YANG module defines the YANG data types for IANA-registered
Interior Gateway Protocol (IGP) Algorithm Types.
This YANG module is maintained by IANA and reflects the 'IGP
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.
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//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.
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.";
reference
"Interior Gateway Protocol (IGP) Parameters, IGP Algorithm Types
(https://www.iana.org/assignments/igp-parameters/
igp-parameters.xhtml#igp-algorithm-types)";
revision 2026-07-09 {
description
"Initial Version";
reference
"RFC XXXX: YANG Data Model for OSPF Application-Specific
Link Attributes and Flexible Algorithm";
}
typedef algo-type {
type enumeration {
enum algo-spf {
value 0;
description
"Shortest Path First (SPF) algorithm based on link metric.
This is the standard shortest path algorithm as computed by
the IGP protocol. Consistent with the deployed practice for
link-state protocols, Algorithm 0 permits any node to
overwrite the SPF path with a different path based on its
local policy.";
reference
"RFC 8665: OSPF Extensions for Segment Routing";
}
enum algo-strict-spf {
value 1;
description
"Strict Shortest Path First (SPF) algorithm based on
link metric. The algorithm is identical to Algorithm 0 but
Algorithm 1 requires that all nodes along the path will
honor the SPF routing decision. Local policy at the node
claiming support for Algorithm 1 MUST NOT alter the SPF
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paths computed by Algorithm 1.";
reference
"RFC 8665: OSPF Extensions for Segment Routing";
}
}
default "algo-spf";
description
"IGP Algorithm Type. The algorithm types are defined in IANA
IGP Algorithm Types registry";
}
}
<CODE ENDS>
Appendix D. IANA IGP Metric Types Module
//RFC Editor: please remove the Appendix D before publication and
replace XXXX with the RFC number that is assigned to the document.
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 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].
<CODE BEGINS> file "iana-igp-metric-types@2026-07-09.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
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Tel: +1 310 301 5800
<mailto:iana@iana.org>";
description
"The YANG module defines the YANG data types for IANA-registered
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.";
reference
"Interior Gateway Protocol (IGP) Parameters, IGP Metric-Type
(https://www.iana.org/assignments/igp-parameters/
igp-parameters.xhtml#igp-metric-type)";
revision 2026-07-09 {
description
"Initial Version";
reference
"RFC XXXX: A YANG Data Model for OSPF Application-Specific
Link Attributes and Flexible Algorithm";
}
typedef metric-type {
type enumeration {
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enum igp-metric {
value 0;
description
"IGP Metric.";
reference
"RFC9350: IGP Flexible Algorithm, Section 5.1";
}
enum min-unidirectional-link-delay {
value 1;
description
"Min Unidirectional Link Delay as defined in RFC 8570
and RFC 7471 Section 4.2.";
reference
"RFC 9350: IGP Flexible Algorithm, Section 5.1";
}
enum te-default-metric {
value 2;
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 9350: IGP Flexible Algorithm, Section 5.1";
}
enum bandwidth-metric {
value 3;
description
"Bandwidth metric.";
reference
"RFC 9843: IGP Flexible Algorithms: Bandwidth, Delay,
Metrics, and Constraints";
}
}
default "igp-metric";
description
"IGP Metric-Type. The metric types
are defined in IANA IGP Metric-Type registry.";
}
}
<CODE ENDS>
Appendix E. IANA IGP Link Attribute Applications Module
//RFC Editor: please remove the Appendix E before publication and
replace XXXX with the RFC number that is assigned to the document.
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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.
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].
<CODE BEGINS> file "iana-igp-link-attr-apps@2026-07-09.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-apps;
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
<mailto:iana@iana.org>";
description
"The YANG module defines the YANG data types for IANA-registered
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
Qu & Lindem Expires 22 January 2027 [Page 50]
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(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.";
reference
"Interior Gateway Protocol (IGP) Parameters, IGP Algorithm Types
(https://www.iana.org/assignments/igp-parameters/
igp-parameters.xhtml#link-attribute-application-identifiers)";
revision 2026-07-09 {
description
"Initial Version";
reference
"RFC XXXX: YANG Data Model for OSPF Application-Specific
Link Attributes and Flexible Algorithm";
}
typedef igp-link-attr-app {
type enumeration {
enum rsvp-te-app {
value 0;
description
"RSVP-TE (R-bit).";
reference
"RFC 9479: IS-IS Application-Specific Link Attributes";
}
enum segment-routing-policy-app {
value 1;
description
"Segment Routing Policy (S-bit).";
reference
"RFC 9479: IS-IS Application-Specific Link Attributes";
}
enum loop-free-alternate-app {
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value 2;
description
"Loop-Free Alternate (F-bit).";
reference
"RFC 9479: IS-IS Application-Specific Link Attributes";
}
enum flexible-algorithm-app {
value 3;
description
"Flexible Algorithm (X-bit).";
reference
"RFC 9350: IGP Flexible Algorithm, Section 12.";
}
}
description
"Application IDs used for Link Attributes, which are defined
in the IANA Link Attribute Application Identifiers registry.";
reference
"RFC 9479: IS-IS Application-Specific Link Attributes";
}
}
<CODE ENDS>
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
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