TEAS V. P. Beeram Internet-Draft HPE Intended status: Standards Track T. Saad Expires: 5 May 2027 R. Gandhi Cisco Systems X. Liu Individual 1 November 2026 YANG Data Model for Topology Filter draft-ietf-teas-yang-topology-filter-04 Abstract This document defines a YANG data model for the management of topology filters/filter-sets on network elements and controllers. 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 5 May 2027. Copyright Notice Copyright (c) 2026 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Beeram, et al. Expires 5 May 2027 [Page 1] Internet-Draft Topology Filter YANG Data Model November 2026 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Use-Cases . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 1.3. Tree Structure . . . . . . . . . . . . . . . . . . . . . 3 2. Topology Filter Data Model . . . . . . . . . . . . . . . . . 4 2.1. Model Structure . . . . . . . . . . . . . . . . . . . . . 4 2.1.1. Topology Filters . . . . . . . . . . . . . . . . . . 4 2.1.2. Topology Filter-Sets . . . . . . . . . . . . . . . . 7 2.2. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 7 3. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 5. Security Considerations . . . . . . . . . . . . . . . . . . . 15 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 16 6.1. Normative References . . . . . . . . . . . . . . . . . . 16 6.2. Informative References . . . . . . . . . . . . . . . . . 17 Appendix A. Usage Examples . . . . . . . . . . . . . . . . . . . 18 A.1. Example 1: ISIS Level-2 Filter with Include-Any . . . . . 18 A.2. Example 2: ISIS Flex-Algo Filter with Exclude . . . . . . 19 A.3. Example 3: NRP Filter with Include-All and Exclude . . . 20 Complete Model Tree Structure . . . . . . . . . . . . . . . . . . 21 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23 1. Introduction A topology filter is a data construct that is used to filter network topologies [RFC8345]. It can be applied on either a native topology or a customized topology [RFC8795] to produce a filtered set of topological elements. A topology filter-set is a union of multiple topology filters that can be applied in tandem on a topology. This document defines a YANG data model for the management of topology filters/filter-sets on network elements and controllers. The authors acknowledge that an implementation may maintain network topologies that are learnt via routing protocols in a Routing Information Base (RIB) [RFC8431] and use routing policies [RFC9067] to filter the entries in the RIB. Such an implementation is not the target of this document. 1.1. Use-Cases * Specification of topology related constraints for TE Path Computation: A few examples of this are - - Compute a path within a specified topology. Beeram, et al. Expires 5 May 2027 [Page 2] Internet-Draft Topology Filter YANG Data Model November 2026 - Compute a path within the topology associated with a specific IGP domain. - Compute a path within the topology learnt from a specific TE Information Source. - Compute a path within the topology defined by the application of one or more topology filters: o Use a topology with elements learnt via ISIS Level-2 and include resource-affinity "RED" o Use a topology with elements associated with ISIS Flexible Algorithm 128 and exclude resource-affinity "BLUE" * Specification of topology associated with a Network Resource Partition (NRP): A few examples of rules for determining the topology associated with the NRP [RFC9543] are: - All the elements in the specified topology are part of the NRP topology. - All the topological elements associated with a specific IGP domain are part of the NRP topology. - All the topological elements that include resource-affinity "RED" and exclude resource-affinity "BLUE" are part of the NRP topology. 1.2. Terminology The terminology for describing YANG data models is found in [RFC7950]. The reader is expected to be familiar with the topology modeling terminology specified in [RFC8345], [RFC8776] and [RFC8795]. The module defined in this document uses the common YANG data types defined in [RFC9911]. 1.3. Tree Structure A simplified graphical representation of the data model is presented in the appendix of this document. The tree format defined in [RFC8340] is used for the YANG data model tree representation. Beeram, et al. Expires 5 May 2027 [Page 3] Internet-Draft Topology Filter YANG Data Model November 2026 2. Topology Filter Data Model 2.1. Model Structure The high-level model structure defined by this document is as shown below: module: ietf-topology-filter augment /nw:networks: +--rw topology-filters! | +--rw topology-filter* [name] | +--rw name string | +--rw topology-ref | | .......... | +--rw include-any | | .......... | +--rw include-all | | .......... | +--rw exclude | .......... +--rw topology-filter-sets! +--rw topology-filter-set* [name] +--rw name string + .......... The top-level 'networks' container [RFC8345] is augmented with a set of topology filters and a set of topology filter-sets. 2.1.1. Topology Filters The 'topology-filters' container carries a list of topology filters. Each topology-filter entry specifies a set of include-any, include- all and exclude filtering rules that can be applied on either the native topology or a user specified topology. 2.1.1.1. Topology Reference The 'topology-ref' container indicates the topology on which the filtering rules need to be applied. The referenced topology could be a predefined TE topology and/or a specific IGP domain. The absence of the 'topology-ref' indicates that the filtering rules are to be applied on the native topology. The 'igp-domain-identifier' container identifies a specific IGP domain using the following attributes: Beeram, et al. Expires 5 May 2027 [Page 4] Internet-Draft Topology Filter YANG Data Model November 2026 * 'protocol-id': The IGP protocol type: OSPFv2, OSPFv3, or IS-IS. The values are those of the 'te-info-source' type defined in [RFC8795], restricted to 'ospfv2', 'ospfv3', and 'isis'. * 'instance-id': The identifier of the IGP protocol instance. Multiple instances of the same IGP protocol can coexist on a network element. * 'division-id': The identifier of a division within the IGP instance. The semantics of this field depend on the IGP protocol type: for OSPF, this is the Area ID; for IS-IS, this is the Level. * 'algo-number': The algorithm number associated with the topology (e.g., the IGP Flexible Algorithm number). * 'mt-id': The Multi-Topology Identifier as defined in [RFC4915] for OSPF and [RFC5120] for IS-IS. When any of these leaves are absent from the 'igp-domain-identifier' container, they are treated as wildcards and match any value. Similarly, when any of the leaves in the 'te-topology-identifier' container are absent, they are treated as wildcards and match any value. +--rw topology-ref +--rw igp-domain-identifier | +--rw protocol-id? tet:te-info-source | +--rw instance-id? uint32 | +--rw division-id? uint32 | +--rw algo-number? uint8 | +--rw mt-id? uint16 +--rw te-topology-identifier +--rw provider-id? te-global-id +--rw client-id? te-global-id +--rw topology-id? te-topology-id 2.1.1.2. Filters The 'include-any', 'include-all' and 'exclude' containers carry a varied set of attributes that can be used as rules to filter the topology. If the topology-filter entry carries no filtering rules and only references a specific topology, then the set of filtered topological elements produced is the same as the one defined by the referenced topology. When a filter attribute (leaf-list or list) is absent or empty in a given container, it is treated as a wildcard and does not constrain the filter results for that attribute type. Beeram, et al. Expires 5 May 2027 [Page 5] Internet-Draft Topology Filter YANG Data Model November 2026 The filtering semantics are as follows: * 'include-any': A topological element matches the 'include-any' container if, for each populated attribute list, it matches at least one attribute in that list (OR within each attribute list, AND across attribute lists). * 'include-all': A topological element matches the 'include-all' container if, for each populated attribute list, it matches all attributes in that list (AND within each attribute list, AND across attribute lists). * 'exclude': A topological element matches the 'exclude' container if, for each populated attribute list, it matches at least one attribute in that list (OR within each attribute list, AND across attribute lists). A topological element is included in the resulting filtered topology if and only if it satisfies all of the following conditions (AND operation across containers): 1. It matches the 'include-any' container (if populated). 2. It matches the 'include-all' container (if populated). 3. It does not match the 'exclude' container (if populated). If an OR operation across attribute lists is desired for 'include- any', this can be achieved by defining multiple topology filters (each with its own 'include-any' container) and combining them using a topology-filter-set, which produces a union of the individual filter results. The 'link-affinity' attribute carries resource affinity names that have a consistent meaning across the domain in which the filter is applied. How a name maps to the affinity values (e.g., administrative-group bits) of a link is outside the scope of this document. Beeram, et al. Expires 5 May 2027 [Page 6] Internet-Draft Topology Filter YANG Data Model November 2026 +--rw include-any | +--rw link-affinity* string | +--rw link-name* string | +--rw node-prefix* inet:ip-prefix | +--rw as* inet:as-number | +--rw info-source* [source-id instance-id division-id] | +--rw source-id tet:te-info-source | +--rw instance-id uint32 | +--rw division-id uint32 +--rw include-all | +--rw link-affinity* string | +--rw link-name* string | +--rw node-prefix* inet:ip-prefix | +--rw as* inet:as-number | +--rw info-source* [source-id instance-id division-id] | +--rw source-id tet:te-info-source | +--rw instance-id uint32 | +--rw division-id uint32 +--rw exclude +--rw link-affinity* string +--rw link-name* string +--rw node-prefix* inet:ip-prefix +--rw as* inet:as-number +--rw info-source* [source-id instance-id division-id] +--rw source-id tet:te-info-source +--rw instance-id uint32 +--rw division-id uint32 2.1.2. Topology Filter-Sets The 'topology-filter-sets' container carries a list of topology filter-sets. Each topology-filter-set entry constitutes a list of topology-filter references. This is used when there is a need to create a union of multiple topology filters. +--rw topology-filter-sets! +--rw topology-filter-set* [name] +--rw name string +--rw topology-filter* -> ../../../topology-filters/topology-filter/name 2.2. YANG Module Beeram, et al. Expires 5 May 2027 [Page 7] Internet-Draft Topology Filter YANG Data Model November 2026 file "ietf-topology-filter@2026-11-01.yang" module ietf-topology-filter { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-topology-filter"; prefix topo-filt; import ietf-inet-types { prefix inet; reference "RFC 9911: Common YANG Data Types"; } import ietf-network { prefix nw; reference "RFC 8345: A YANG Data Model for Network Topologies"; } import ietf-te-types { prefix te-types; reference "RFC 8776: Common YANG Data Types for Traffic Engineering"; } import ietf-te-topology { prefix tet; reference "RFC 8795: YANG Data Model for Traffic Engineering Topologies"; } organization "IETF Traffic Engineering Architecture and Signaling (TEAS) Working Group."; contact "WG Web: WG List: Editor: Vishnu Pavan Beeram Editor: Tarek Saad Editor: Rakesh Gandhi Editor: Xufeng Liu "; description "This YANG module defines data definitions for managing topology filters. Beeram, et al. Expires 5 May 2027 [Page 8] Internet-Draft Topology Filter YANG Data Model November 2026 Copyright (c) 2026 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Revised BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX; see the RFC itself for full legal notices."; revision 2026-11-01 { description "Initial revision."; reference "RFC XXXX: YANG Data Model for Topology Filters."; } /* * G R O U P I N G S */ /* * Grouping - Topology Information Source. */ grouping igp-topology-info-source { description "Grouping for igp topology information source."; leaf protocol-id { type tet:te-info-source { enum ospfv2 { description "OSPFv2."; } enum ospfv3 { description "OSPFv3."; } enum isis { description "IS-IS."; } } description "IGP Protocol Type. Only the 'ospfv2', 'ospfv3', and 'isis' values of 'te-info-source' are applicable."; Beeram, et al. Expires 5 May 2027 [Page 9] Internet-Draft Topology Filter YANG Data Model November 2026 reference "RFC 8795: YANG Data Model for Traffic Engineering (TE) Topologies"; } leaf instance-id { type uint32; description "The identifier of the IGP protocol instance."; } leaf division-id { type uint32; description "The identifier of a division within the IGP instance. The semantics of this field depend on the IGP protocol type: for OSPF, this is the Area ID; for IS-IS, this is the Level."; } } /* * Grouping - IGP Domain Identifier. */ grouping igp-domain-identifier { description "Grouping for igp domain identifier."; container igp-domain-identifier { description "Container for igp domain identifier."; uses igp-topology-info-source; leaf algo-number { type uint8; description "The algorithm number associated with the topology (e.g., the IGP Flexible Algorithm number)."; } leaf mt-id { type uint16; description "The Multi-Topology Identifier."; reference "RFC 4915: Multi-Topology (MT) Routing in OSPF RFC 5120: M-ISIS: Multi Topology (MT) Routing in Intermediate System to Intermediate Systems (IS-ISs)"; Beeram, et al. Expires 5 May 2027 [Page 10] Internet-Draft Topology Filter YANG Data Model November 2026 } } } /* * Grouping - Topology Reference */ grouping topology-reference { description "Grouping for topology reference."; container topology-ref { description "Container for topology reference."; uses igp-domain-identifier; uses te-types:te-topology-identifier; } } /* * Grouping - Topology Information Sources */ grouping topology-info-sources { description "Grouping for topology information sources."; list info-source { key "source-id instance-id division-id"; description "List of information-sources."; leaf source-id { type tet:te-info-source; description "Information Source."; } leaf instance-id { type uint32; description "The identifier of the information source routing protocol instance."; } leaf division-id { type uint32; description "The identifier of a division within the information source instance. For OSPF, this is the Area ID; for IS-IS, this is the Level."; Beeram, et al. Expires 5 May 2027 [Page 11] Internet-Draft Topology Filter YANG Data Model November 2026 } } } /* * Grouping - Custom Topology Filters */ grouping custom-topology-filters { description "Grouping for custom topology filters."; leaf-list link-affinity { type string; description "List of resource affinity names. The names are consistently defined across the domain in which the filter is applied."; } leaf-list link-name { type string; description "List of link names."; } leaf-list node-prefix { type inet:ip-prefix; description "List of IP prefixes that identify nodes."; } leaf-list as { type inet:as-number; description "List of AS numbers."; } uses topology-info-sources; } /* * Grouping - Topology Filters */ grouping topology-filters { description "Grouping for topology filters."; container topology-filters { presence "Enable Topology Filters."; description "Container for topology filters."; list topology-filter { Beeram, et al. Expires 5 May 2027 [Page 12] Internet-Draft Topology Filter YANG Data Model November 2026 key "name"; description "List of topology filters."; leaf name { type string; description "A string that uniquely identifies the topology filter."; } uses topology-reference; container include-any { description "A topological element matches this container if, for each populated attribute list, it matches at least one attribute in that list (OR within each list, AND across lists)."; uses custom-topology-filters; } container include-all { description "A topological element matches this container if, for each populated attribute list, it matches all attributes in that list (AND within each list, AND across lists)."; uses custom-topology-filters; } container exclude { description "A topological element matches this container if, for each populated attribute list, it matches at least one attribute in that list (OR within each list, AND across lists). Matched elements are excluded from the filtered topology."; uses custom-topology-filters; } } } } /* * Grouping - Topology Filter Sets */ grouping topology-filter-sets { description "Grouping for topology filter sets."; container topology-filter-sets { presence "Enable Topology Filter-Sets."; Beeram, et al. Expires 5 May 2027 [Page 13] Internet-Draft Topology Filter YANG Data Model November 2026 description "Container for topology filter sets."; list topology-filter-set { key "name"; description "List of topology filter sets."; leaf name { type string; description "A string that uniquely identifies the topology filter-set."; } leaf-list topology-filter { type leafref { path "../../../topo-filt:topology-filters/" + "topo-filt:topology-filter/topo-filt:name"; } description "Reference to a specific topology filter from the list of topology filters."; } } } } /* * Augment - Topology Filters / Topology Filter-Sets */ augment "/nw:networks" { description "Augment networks with topology-filters and topology-filter-sets."; uses topology-filters; uses topology-filter-sets; } } 3. Acknowledgements The authors would like to thank Sudharsana Venkatraman for her input from discussions. 4. IANA Considerations IANA is requested to register the following URI in the "ns" registry within the "IETF XML Registry" group [RFC3688]: Beeram, et al. Expires 5 May 2027 [Page 14] Internet-Draft Topology Filter YANG Data Model November 2026 URI: urn:ietf:params:xml:ns:yang:ietf-topology-filter Registrant Contact: The IESG XML: N/A; the requested URI is an XML namespace. IANA is requested to register the following YANG module in the "YANG Module Names" registry [RFC6020] within the "YANG Parameters" registry group. Name: ietf-topology-filter Maintained by IANA?: N Namespace: urn:ietf:params:xml:ns:yang:ietf-topology-filter Prefix: topo-filt Reference: RFC XXXX 5. Security Considerations This section is modeled after the template described in Section 3.7.1 of [RFC9907]. The "ietf-topology-filter" YANG module defines a data model that is designed to be accessed via YANG-based management protocols, such as the Network Configuration Protocol (NETCONF) [RFC6241] and RESTCONF [RFC8040]. These YANG-based management protocols (1) have to use a secure transport layer (e.g., Secure Shell (SSH) [RFC4252], TLS [RFC9846], and QUIC [RFC9000]) and (2) 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 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: * "/networks/topology-filters/": This subtree specifies the configurations for topology filters. By manipulating these data nodes, a malicious attacker may cause unauthorized and improper behavior to any service that is making use of the filtered set of topological elements produced by the application of the compromised topology filter. Beeram, et al. Expires 5 May 2027 [Page 15] Internet-Draft Topology Filter YANG Data Model November 2026 * "/networks/topology-filter-sets": This subtree specifies the configurations for topology filter-sets. By manipulating these data nodes, a malicious attacker may cause unauthorized and improper behavior to any service that is making use of the filtered set of topological elements produced by the application of the compromised topology filter-set. 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. These are the subtrees and data nodes and their sensitivity/vulnerability: * "/networks/topology-filters": Unauthorized access to this subtree can disclose the topology filters used in the network. * "/networks/topology-filter-sets": Unauthorized access to this subtree can disclose the topology filter-sets used in the network. 6. References 6.1. Normative References [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004, . [RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P. Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF", RFC 4915, DOI 10.17487/RFC4915, June 2007, . [RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi Topology (MT) Routing in Intermediate System to Intermediate Systems (IS-ISs)", RFC 5120, DOI 10.17487/RFC5120, February 2008, . [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010, . [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, . Beeram, et al. Expires 5 May 2027 [Page 16] Internet-Draft Topology Filter YANG Data Model November 2026 [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016, . [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, . [RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, March 2018, . [RFC8345] Clemm, A., Medved, J., Varga, R., Bahadur, N., Ananthakrishnan, H., and X. Liu, "A YANG Data Model for Network Topologies", RFC 8345, DOI 10.17487/RFC8345, March 2018, . [RFC8776] Saad, T., Gandhi, R., Liu, X., Beeram, V., and I. Bryskin, "Common YANG Data Types for Traffic Engineering", RFC 8776, DOI 10.17487/RFC8776, June 2020, . [RFC8795] Liu, X., Bryskin, I., Beeram, V., Saad, T., Shah, H., and O. Gonzalez de Dios, "YANG Data Model for Traffic Engineering (TE) Topologies", RFC 8795, DOI 10.17487/RFC8795, August 2020, . [RFC9846] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 9846, DOI 10.17487/RFC9846, July 2026, . [RFC9911] Schönwälder, J., Ed., "Common YANG Data Types", RFC 9911, DOI 10.17487/RFC9911, December 2025, . 6.2. Informative References [RFC4252] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH) Authentication Protocol", RFC 4252, DOI 10.17487/RFC4252, January 2006, . [RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, . Beeram, et al. Expires 5 May 2027 [Page 17] Internet-Draft Topology Filter YANG Data Model November 2026 [RFC8431] Wang, L., Chen, M., Dass, A., Ananthakrishnan, H., Kini, S., and N. Bahadur, "A YANG Data Model for the Routing Information Base (RIB)", RFC 8431, DOI 10.17487/RFC8431, September 2018, . [RFC9000] Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based Multiplexed and Secure Transport", RFC 9000, DOI 10.17487/RFC9000, May 2021, . [RFC9067] Qu, Y., Tantsura, J., Lindem, A., and X. Liu, "A YANG Data Model for Routing Policy", RFC 9067, DOI 10.17487/RFC9067, October 2021, . [RFC9543] Farrel, A., Ed., Drake, J., Ed., Rokui, R., Homma, S., Makhijani, K., Contreras, L., and J. Tantsura, "A Framework for Network Slices in Networks Built from IETF Technologies", RFC 9543, DOI 10.17487/RFC9543, March 2024, . [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, . Appendix A. Usage Examples This appendix provides JSON encoding examples of the topology filter configuration as defined in this document. The examples use JSON encoding per [RFC7950] and [RFC8040]. A.1. Example 1: ISIS Level-2 Filter with Include-Any This example creates a topology filter named "isis-level2-red" that operates on the IS-IS Level-2 topology and includes topological elements that have link-affinity "RED". Since only one attribute list is populated in 'include-any', an element is included if it matches at least one value in that list. This corresponds to the use-case: "Use a topology with elements learnt via ISIS Level-2 and include resource-affinity RED". Beeram, et al. Expires 5 May 2027 [Page 18] Internet-Draft Topology Filter YANG Data Model November 2026 { "ietf-network:networks": { "ietf-topology-filter:topology-filters": { "topology-filter": [ { "name": "isis-level2-red", "topology-ref": { "igp-domain-identifier": { "protocol-id": "isis", "division-id": 2 } }, "include-any": { "link-affinity": [ "RED" ] } } ] } } } A.2. Example 2: ISIS Flex-Algo Filter with Exclude This example creates a topology filter named "isis-flexalgo128-no- blue" that operates on the IS-IS topology associated with Flexible Algorithm 128 and excludes topological elements with link-affinity "BLUE". This corresponds to the use-case: "Use a topology with elements associated with ISIS Flexible Algorithm 128 and exclude resource-affinity BLUE". Beeram, et al. Expires 5 May 2027 [Page 19] Internet-Draft Topology Filter YANG Data Model November 2026 { "ietf-network:networks": { "ietf-topology-filter:topology-filters": { "topology-filter": [ { "name": "isis-flexalgo128-no-blue", "topology-ref": { "igp-domain-identifier": { "protocol-id": "isis", "algo-number": 128 } }, "exclude": { "link-affinity": [ "BLUE" ] } } ] } } } A.3. Example 3: NRP Filter with Include-All and Exclude This example creates a topology filter named "nrp-filter" for defining a Network Resource Partition (NRP) topology. It uses 'include-all' to require that topological elements match all values in each populated attribute list (AND within each list) and satisfy all populated attribute lists (AND across lists). In this case, elements must have link-affinity "RED" AND belong to AS 64496. It also excludes any element with link-affinity "BLUE". Additionally, a topology-filter-set named "nrp-filter-set" is created that references both "isis-level2-red" (from Example 1) and "nrp-filter" to form a union of the two filters. Beeram, et al. Expires 5 May 2027 [Page 20] Internet-Draft Topology Filter YANG Data Model November 2026 { "ietf-network:networks": { "ietf-topology-filter:topology-filters": { "topology-filter": [ { "name": "nrp-filter", "include-all": { "link-affinity": [ "RED" ], "as": [ 64496 ] }, "exclude": { "link-affinity": [ "BLUE" ] } } ] }, "ietf-topology-filter:topology-filter-sets": { "topology-filter-set": [ { "name": "nrp-filter-set", "topology-filter": [ "isis-level2-red", "nrp-filter" ] } ] } } } Complete Model Tree Structure module: ietf-topology-filter augment /nw:networks: +--rw topology-filters! | +--rw topology-filter* [name] | +--rw name string | +--rw topology-ref | | +--rw igp-domain-identifier | | | +--rw protocol-id? tet:te-info-source | | | +--rw instance-id? uint32 Beeram, et al. Expires 5 May 2027 [Page 21] Internet-Draft Topology Filter YANG Data Model November 2026 | | | +--rw division-id? uint32 | | | +--rw algo-number? uint8 | | | +--rw mt-id? uint16 | | +--rw te-topology-identifier | | +--rw provider-id? te-global-id | | +--rw client-id? te-global-id | | +--rw topology-id? te-topology-id | +--rw include-any | | +--rw link-affinity* string | | +--rw link-name* string | | +--rw node-prefix* inet:ip-prefix | | +--rw as* inet:as-number | | +--rw info-source* [source-id instance-id division-id] | | +--rw source-id tet:te-info-source | | +--rw instance-id uint32 | | +--rw division-id uint32 | +--rw include-all | | +--rw link-affinity* string | | +--rw link-name* string | | +--rw node-prefix* inet:ip-prefix | | +--rw as* inet:as-number | | +--rw info-source* [source-id instance-id division-id] | | +--rw source-id tet:te-info-source | | +--rw instance-id uint32 | | +--rw division-id uint32 | +--rw exclude | +--rw link-affinity* string | +--rw link-name* string | +--rw node-prefix* inet:ip-prefix | +--rw as* inet:as-number | +--rw info-source* [source-id instance-id division-id] | +--rw source-id tet:te-info-source | +--rw instance-id uint32 | +--rw division-id uint32 +--rw topology-filter-sets! +--rw topology-filter-set* [name] +--rw name string +--rw topology-filter* -> ../../../topology-filters/topology-filter/name Contributors Colby Barth HPE Email: jonathan.barth@hpe.com Beeram, et al. Expires 5 May 2027 [Page 22] Internet-Draft Topology Filter YANG Data Model November 2026 Srihari R. Sangli HPE Email: srihari.sangli@hpe.com Chandrasekar Ramachandran HPE Email: chandrasekar.ramachandran@hpe.com Authors' Addresses Vishnu Pavan Beeram HPE Email: vishnupavan.ietf@gmail.com Tarek Saad Cisco Systems Email: tsaad.net@gmail.com Rakesh Gandhi Cisco Systems Email: rgandhi@cisco.com Xufeng Liu Individual Email: xufeng.liu.ietf@gmail.com Beeram, et al. Expires 5 May 2027 [Page 23]