YANG Data Model for IS-IS Application-Specific Link Attributes and Flexible Algorithm
draft-ietf-lsr-isis-flex-algo-yang-04
| Document | Type | Active Internet-Draft (lsr WG) | |
|---|---|---|---|
| Authors | Yingzhen Qu , Acee Lindem , Madhavi Joshi | ||
| Last updated | 2025-10-12 (Latest revision 2025-10-06) | ||
| 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 Michal Vaško
Ready w/issues
|
||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | In WG Last Call | |
| Document shepherd | Christian Hopps | ||
| IESG | IESG state | I-D Exists | |
| Consensus boilerplate | Yes | ||
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | chopps@chopps.org |
draft-ietf-lsr-isis-flex-algo-yang-04
Internet Y. Qu
Internet-Draft Futurewei Technologies
Intended status: Standards Track A. Lindem
Expires: 9 April 2026 M. Joshi
Arrcus, Inc.
6 October 2025
YANG Data Model for IS-IS Application-Specific Link Attributes and
Flexible Algorithm
draft-ietf-lsr-isis-flex-algo-yang-04
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 9 April 2026.
Copyright Notice
Copyright (c) 2025 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
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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 . . . . . . . . . . 13
4. Security Considerations . . . . . . . . . . . . . . . . . . . 24
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 25
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 25
7.1. Normative References . . . . . . . . . . . . . . . . . . 25
7.2. Informative References . . . . . . . . . . . . . . . . . 27
Appendix A. Example IS-IS Flex-Algo Configuration . . . . . . . 27
Appendix B. Example IS-IS Flex-Algo Configuration (JSON) . . . . 28
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 29
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", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
2. YANG Module for IS-IS Application-Specific Link Attributes
This document defined a YANG module for IS-IS Application-Specific
Link Attributes as defined in [RFC9479].
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)
| +--rw transition? empty
+--:(app-specific)
+--rw app-specific? empty
augment /rt:routing/rt:control-plane-protocols
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/rt:control-plane-protocol/isis:isis/isis:interfaces
/isis:interface:
+--rw isis-asla
+--rw interface-asla* [app-id]
+--rw app-id uint16
+--rw unidirectional-link-delay? uint32
+--rw metric-type? uint8
+--rw metric? 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 r-flag? boolean
+--ro udabm-length? uint8
+--ro sabm
| +--ro sabm-bits* identityref
+--ro udabm
+--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 r-flag? boolean
+--ro udabm-length? uint8
+--ro sabm
| +--ro sabm-bits* identityref
+--ro udabm
+--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
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+--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 r-flag? boolean
+--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
+--ro srlg* uint32
<CODE BEGINS> file "ietf-isis-link-attr@2025-09-11.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";
}
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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>
Author: Stephane Litkowski
<mailto:slitkows.ietf@gmail.com>
Author: Madhavi Joshi
<madhavi@arrcus.com>
";
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) 2025 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 2025-09-11 {
description
"Initial version";
reference
"RFC XXXX: YANG Data Model for IS-IS Application-Specific
Link Attributes and Flexible Algorithm";
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}
identity sabm-bit {
description
"Base identity for sabm bits.";
reference
"RFC 8919: IS-IS Application-Specific Link Attributes";
}
identity rsvp-te-bit {
base sabm-bit;
description
"R bit, RSVP-TE.";
}
identity sr-policy-bit {
base sabm-bit;
description
"S bit, Segment Routing Policy.";
}
identity lfa-bit {
base sabm-bit;
description
"F bit, Loop Free Alternate (LFA). Includes all LFA types.";
}
identity flex-algo-bit {
base sabm-bit;
description
"X bit, flexible algorithm.";
reference
"RFC 9350: IGP Flexible Algorithm, Section 12.";
}
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;
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description
"Standard Application Identifier Bit Mask Length in
octets.";
}
leaf r-flag {
type boolean;
default "false";
description
"Reserved.";
}
leaf udabm-length {
type uint8;
description
"User Defined Application Identifier Bit Mask Length
in octets.";
}
container sabm {
leaf-list sabm-bits {
type identityref {
base sabm-bit;
}
description
"SABM bits list. This list will contain
identities for the bits which are set in the
SABA 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.";
}
}
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:unknown-tlvs;
description
"List of application specific link attributes sub-tlvs.";
}
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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 {
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
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"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 {
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 {
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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 ISIS routing protocol when used";
}
description
"This augments ISIS protocol configuration
with application specific link attributes.";
container isis-link-attr {
choice link-attr-op-mode {
mandatory true;
leaf legacy {
type empty;
description
"Only send legacy advertisements.";
}
leaf transition {
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";
}
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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 ISIS routing protocol when used.";
}
description
"This augments ISIS interface configuration
with application specific link attributes.";
container isis-asla {
list interface-asla {
key "app-id";
leaf app-id {
type uint16 {
range "0 .. 1023";
}
description
"Application ID.
0 - RSVP TE. 1 - Segment Routing Policy.
2 - Loop-Free Alternate.";
}
leaf unidirectional-link-delay {
type uint32 {
range "0 .. 16777215";
}
description
"This 24-bit field carries the average link delay in
microseconds.";
}
leaf metric-type {
type uint8;
description
"IGP metric type.";
}
leaf metric {
type uint32 {
range "1 .. 16777215";
}
description
"metric value.";
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}
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 ISIS routing protocol when used";
}
description
"This augments ISIS 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"
+ "/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 ISIS routing protocol when used";
}
description
"This augments ISIS 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" {
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when "/rt:routing/rt:control-plane-protocols/"
+ "rt:control-plane-protocol/rt:type = 'isis:isis'" {
description
"This augment ISIS routing protocol when used";
}
description
"This augments ISIS protocol LSDB.";
uses application-specific-srlg-tlv;
}
}
<CODE ENDS>
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].
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}?
| +--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
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+--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* []
+--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
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notifications:
+---n flex-algo-not-supported
+--ro routing-protocol-name? leafref
+--ro isis-level? level
+--ro algo-number? uint8
<CODE BEGINS> file "ietf-isis-flex-algo@2025-10-06.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 {
prefix te;
}
import iana-igp-algo-types {
prefix iana-algo-types;
}
import iana-igp-metric-types {
prefix iana-metric-type;
}
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
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<mailto:acee.ietf@gmail.com>
Author: Stephane Litkowski
<mailto:slitkows.ietf@gmail.com>
Author: Madhavi Joshi
<madhavi@arrcus.com>
";
description
"The YANG module defines the configuration and operational
state for ISIS 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) 2025 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject to
the license terms contained in, the Revised BSD License set
forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX;
see the RFC itself for full legal notices.
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL
NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED',
'MAY', and 'OPTIONAL' in this document are to be interpreted as
described in BCP 14 (RFC 2119) (RFC 8174) when, and only when,
they appear in all capitals, as shown here.";
revision 2025-10-06 {
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 ISIS FAD flags.";
}
identity m-bit {
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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.";
}
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
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"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
"ISIS 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;
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, value between 128 and 255 inclusive.";
}
leaf metric-type {
type identityref {
base iana-metric-type:metric-type;
}
description
"Type of metric to be used during the calculation.";
}
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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.";
}
description
"ISIS Flexible Algorithm Definition TLV.";
}
description
"ISIS 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, value between 128 and 255
inclusive.";
}
leaf metric {
type uint32;
description
"Prefix metric.";
}
description
"List of flex-algo prefix sub-tlvs.";
}
description
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"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 ISIS routing protocol when used";
}
description
"This augments ISIS protocol configuration
with flexible algorithm.";
container isis-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: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.";
}
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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 {
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
"Calcuation-type. Value from 0-127 inclusive from the
IANA 'IGP Algorithm Types' registry defined under the
'Interior Gateway Protocol (IGP) Parameters' registry.";
}
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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"
+ "/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 ISIS routing protocol when used";
}
description
"This augments ISIS 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 ISIS routing protocol when used";
}
description
"This augments ISIS protocol LSDB prefix.";
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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 ISIS routing protocol when used";
}
description
"This augments ISIS 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" {
when "/rt:routing/rt:control-plane-protocols/"
+ "rt:control-plane-protocol/"
+ "rt:type = 'isis:isis'" {
description
"This augment ISIS routing protocol when used";
}
description
"This augments ISIS 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 ISIS routing protocol when used";
}
description
"This augments ISIS protocol LSDB prefix.";
uses fapm-sub-tlvs;
}
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/* notification */
notification flex-algo-not-supported {
uses isis:notification-instance-hdr;
leaf algo-number {
type uint8 {
range "128..255";
}
description
"Flex-algo identifier which is not supported by the IS-IS
instance.";
}
description
"This notification is sent when an IS-IS instance does not
support this flex-algo.";
}
}
<CODE ENDS>
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.
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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.
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.
The YANG model was developed using the suite of YANG tools written
and maintained by numerous authors.
7. References
7.1. Normative References
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[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-02, 12 September 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-lsr-
ospf-flex-algo-yang-02>.
[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>.
[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>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/info/rfc3688>.
[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>.
[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>.
[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>.
[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>.
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[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
[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>.
[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,
<https://www.rfc-editor.org/info/rfc9130>.
[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>.
[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,
<https://www.rfc-editor.org/info/rfc9479>.
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,
<https://www.rfc-editor.org/info/rfc8792>.
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].
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<?xml version='1.0' encoding='UTF-8'?>
<te xmlns="urn:ietf:params:xml:ns:yang:ietf-te">
<enable>true</enable>
<globals>
<named-admin-groups>
<named-admin-group>
<name>blue</name>
</named-admin-group>
</named-admin-groups>
</globals>
</te>
<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:isis="urn:ietf:params:xml:ns:yang:ietf-isis">\
isis:isis</type>
<name>isis</name>
<isis xmlns="urn:ietf:params:xml:ns:yang:ietf-isis">
<system-id>1111.2222.3333</system-id>
<area-address>49.0001.0000.0000.0001</area-address>
<isis-flex-algo xmlns="urn:ietf:params:xml:ns:yang:\
ietf-isis-flex-algo">
<flex-algo>
<algo-number>200</algo-number>
<admin-groups>
<exclude-admin-groups>blue</exclude-admin-groups>
</admin-groups>
<metric-type xmlns:iana-metric-types=\
"urn:ietf:params:xml:ns:yang:iana-igp-metric-types">\
iana-metric-types:igp-metric</metric-type>
<calc-type xmlns:iana-algo-types=\
"urn:ietf:params:xml:ns:yang:iana-igp-algo-types">\
iana-algo-types:algo-spf</calc-type>
<prefix-metric/>
<priority>100</priority>
</flex-algo>
</isis-flex-algo>
</isis>
</control-plane-protocol>
</control-plane-protocols>
</routing>
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.
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{
"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
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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
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