Network Inventory YANG B. Wu, Ed. Internet-Draft Huawei Intended status: Standards Track M. Boucadair Expires: 1 September 2026 Orange C. Zhou China Mobile Q. Wu Huawei 28 February 2026 A YANG Network Data Model for Inventory Topology Mapping draft-ietf-ivy-network-inventory-topology-06 Abstract This document defines a YANG data model to map the network inventory data with the topology data to form a base underlay network. The data model facilitates the correlation between the layer (e.g., Layer 2 or Layer 3) topology information and the inventory data of the underlay network for better service provisioning, network maintenance operations, and other assessment scenarios. Discussion Venues This note is to be removed before publishing as an RFC. Discussion of this document takes place on the Network Inventory YANG Working Group mailing list (inventory-yang@ietf.org), which is archived at https://mailarchive.ietf.org/arch/browse/inventory-yang/. Source for this draft and an issue tracker can be found at https://github.com/ietf-ivy-wg/network-inventory-topology. 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." Wu, et al. Expires 1 September 2026 [Page 1] Internet-Draft Inventory Topology Mapping February 2026 This Internet-Draft will expire on 1 September 2026. Copyright Notice Copyright (c) 2026 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Editorial Note (To be removed by RFC Editor) . . . . . . 3 2. Conventions and Definitions . . . . . . . . . . . . . . . . . 3 3. Sample Use Cases of the Data Model . . . . . . . . . . . . . 4 3.1. Determine Available Resources of Service Attachment Points (SAPs) . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.2. "What-if" Scenarios . . . . . . . . . . . . . . . . . . . 4 4. Module Tree Structure . . . . . . . . . . . . . . . . . . . . 5 4.1. Link Extensions . . . . . . . . . . . . . . . . . . . . . 6 4.2. Port-Breakout Capability . . . . . . . . . . . . . . . . 6 5. Network Inventory Topology YANG Module . . . . . . . . . . . 7 6. Operational Considerations . . . . . . . . . . . . . . . . . 11 7. Security Considerations . . . . . . . . . . . . . . . . . . . 11 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 9.1. Normative References . . . . . . . . . . . . . . . . . . 13 9.2. Informative References . . . . . . . . . . . . . . . . . 13 Appendix A. "link-type" Usage Examples . . . . . . . . . . . . . 15 Appendix B. JSON Example of an MPO Breakout-Channel Port . . . . 17 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 18 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19 Wu, et al. Expires 1 September 2026 [Page 2] Internet-Draft Inventory Topology Mapping February 2026 1. Introduction [I-D.ietf-ivy-network-inventory-yang] defines the base network inventory model to aggregate the inventory data of Network Elements (NEs). This data includes identification of these NEs and their hardware, firmware, and software components. Examples of inventory hardware components could be rack, shelf, slot, board, or physical port. Examples of inventory software components could be platform Operating System (OS), software-modules, bios, or boot-loader [I-D.ietf-ivy-network-inventory-software]. In order to ease navigation from (or to) inventory and network topologies, this document extends the network topology data model [RFC8345] for network inventory mapping: "ietf-network-inventory- topology" (Section 5). This data model provides a mechanism for the correlation with existing network and topology data models, such as "A YANG Network Data Model for Service Attachment Points (SAPs)" [RFC9408], "A YANG Data Model for Layer 2 Network Topologies" [RFC8944], and "A YANG Data Model for Layer 3 Topologies" [RFC8346]. Similar to the base inventory data model [I-D.ietf-ivy-network-inventory-yang], the network inventory topology does not make any assumption about involved NEs and their roles in topologies. As such, the mapping model can be applied independent of the network type (optical local loops, access network, core network, etc.) and application. 1.1. Editorial Note (To be removed by RFC Editor) Note to the RFC Editor: This section is to be removed prior to publication. This document contains placeholder values that need to be replaced with finalized values at the time of publication. This note summarizes all of the substitutions that are needed. Please apply the following replacements: * XXXX --> the assigned RFC number for this I-D * AAAA --> the assigned RFC number for [I-D.ietf-ivy-network-inventory-yang] 2. Conventions and Definitions The meanings of the symbols in the YANG tree diagrams are defined in [RFC8340]. Wu, et al. Expires 1 September 2026 [Page 3] Internet-Draft Inventory Topology Mapping February 2026 This document uses terms defined in [I-D.ietf-ivy-network-inventory-yang]. 3. Sample Use Cases of the Data Model 3.1. Determine Available Resources of Service Attachment Points (SAPs) The inventory topology data model can be used as a basis for correlating underlay information, such as physical port components. Figure 1 exemplifies this usage. During service provisioning, to check available physical port resources, the SAPs information can be associated with the underlay inventory information and interface information associated with the inventory topology, e.g., "parent-termination-point" of SAP Model can be associated with the "port-component-ref" of the inventory topology data model, which can be used to check the availability and capacity of physical ports. +-----------------+ | Customer | +--------+--------+ Customer Service Models | (e.g., L3SM, L2SM) | +--------+--------+ | Service | | Orchestration | +------+---+------+ | | SAP Network Model | | Inventory Topology Model +------+---+------+ | Network | | Controller | +--------+--------+ | +---------------------+---------------------+ | Network | +-------------------------------------------+ Figure 1: An Example Usage of Network Inventory Topology 3.2. "What-if" Scenarios [I-D.irtf-nmrg-network-digital-twin-arch] defines Network Digital Twin (NDT) as a virtual representation of the physical network. Such representation is meant to be used to analyze, diagnose, emulate, and then manage the physical network based on data, models, and interfaces. Wu, et al. Expires 1 September 2026 [Page 4] Internet-Draft Inventory Topology Mapping February 2026 [I-D.ietf-nmop-simap-concept] defines Service and Infrastructure Maps (SIMAP) as an abstraction model that provides a unified view of both service and infrastructure information, enabling correlation between service requirements and underlying resource capabilities. Both architectures require accurate mapping between logical network topology and physical inventory as a foundational data layer. This model provides the essential physical resource information to such systems, enabling them to perform accurate "what-if" analysis (e.g., impact prediction of hardware EOL, path re-optimization under resource constraints, service availability assessment). 4. Module Tree Structure An overview of the structure of the "ietf-network-inventory-topology" module is shown in Figure 2. module: ietf-network-inventory-topology augment /nw:networks/nw:network/nw:node: +--rw inventory-mapping-attributes +--rw ne-ref? nwi:ne-ref augment /nw:networks/nw:network/nt:link: +--rw inventory-mapping-attributes +--rw link-type? string augment /nw:networks/nw:network/nw:node/nt:termination-point: +--rw inventory-mapping-attributes +--rw ne-ref? nwi:ne-ref +--rw port-ref? leafref +--ro port-breakout! +--ro breakout-channel* [channel-id] +--ro channel-id uint16 Figure 2: The Structure of the Network Inventory Mapping Data Model The module defines two features "inventory-to-topology-navigate" and "topology-to-inventory-navigate" to control the navigation direction (from topology to inventory and vice versa). The module augments the "ietf-network-topology" module as follows: * Inventory mapping attributes for nodes, links, and termination points: The corresponding containers augments the topology module with the references to the base network inventory The inventory topology model associates inventory data with overlay topologies. It can be used as the "supporting-networks" of SAP, Layer 2, or Layer 3 topologies. Wu, et al. Expires 1 September 2026 [Page 5] Internet-Draft Inventory Topology Mapping February 2026 4.1. Link Extensions This document adds a lightweight "link-type" leaf to the topology link mapping to enable basic physical media classification. * "link-type" – A string indicating the link media type, such as "copper", "fiber", or "coax". For wireless media, values such as "microwave", or "wifi" may be used The "link-type" serves as a lightweight discriminator that guides to the appropriate specialized inventory model for detailed resource information. For example, wired media (fiber, copper) typically reference a passive network inventory model, such as the one defined in [I-D.ygb-ivy-passive-network-inventory]. 4.2. Port-Breakout Capability High-density Ethernet ports (e.g., 400 Gb/s DR4) can be split into multiple independent lower-speed channels. The breakout channels represent the intrinsic capability of the port to be partitioned, regardless of whether the port is currently configured as a trunk or as a breakout port. A trunk port is associated with exactly one physical interface. A breakout port is a port that is decomposed into two or more physical interfaces; those interfaces may run at the same or different speeds and may consume the same or a different number of breakout channels. The container "port-breakout" is added under the termination-point augmentation. It lists the logical channels into which the single physical port can be divided. Only termination-points whose parent port is breakout-capable need to instantiate the container; otherwise the container is omitted, keeping the topology model minimal for the common non-breakout case. Breakout channel is an atomic resource element obtained by partitioning a breakout port. One physical interface may be associated with one or more breakout channels, but one breakout channel MUST NOT be associated with more than one physical interface. Appendix B provides example configurations. It is assumed that a port which supports breakout can be configured either as a trunk port or as a breakout port. Interface channelisation (e.g., VLAN sub-interfaces) is outside the scope of this document and is addressed by the Layer 2 network topology model [RFC8944]. Wu, et al. Expires 1 September 2026 [Page 6] Internet-Draft Inventory Topology Mapping February 2026 5. Network Inventory Topology YANG Module This module augments the Network Topology [RFC8345]. This module imports the base network inventory [I-D.ietf-ivy-network-inventory-yang]. file "ietf-network-inventory-topology@2026-02-28.yang" module ietf-network-inventory-topology { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-network-inventory-topology"; prefix nwit; import ietf-network { prefix nw; reference "RFC 8345: A YANG Data Model for Network Topologies, Section 4.1"; } import ietf-network-topology { prefix nt; reference "RFC 8345: A YANG Data Model for Network Topologies, Section 4.2"; } import ietf-network-inventory { prefix nwi; reference "RFC AAAA: A YANG Data Model for Network Inventory"; } organization "IETF Network Inventory YANG (ivy) Working Group"; contact "WG Web: WG List: IVY Editor: Bo Wu Editor: Mohamed Boucadair Author: Cheng Zhou Author: Qin Wu "; description "This YANG module defines a YANG module for network Wu, et al. Expires 1 September 2026 [Page 7] Internet-Draft Inventory Topology Mapping February 2026 topology and inventory mapping. 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."; revision 2026-02-28 { description "Initial revision."; reference "RFC XXXX: A Network Data Model for Inventory Topology Mapping"; } // Groupings // Node Grouping with 1:1 mapping to NE grouping node-inventory-mapping-attributes { description "Attributes for mapping a topology node to a Network Element (NE) in the physical inventory."; container inventory-mapping-attributes { description "Container for inventory mapping attributes of a node."; leaf ne-ref { type nwi:ne-ref; description "Reference to the NE in the inventory that corresponds to this topology node. This reference establishes a 1:1 mapping between the logical node and its physical NE."; } } } Wu, et al. Expires 1 September 2026 [Page 8] Internet-Draft Inventory Topology Mapping February 2026 // TP Grouping with 1:1 mapping to physical port grouping tp-inventory-mapping-attributes { description "Attributes for mapping a topology termination point (TP) to a physical port in the network inventory."; container inventory-mapping-attributes { description "Container for inventory mapping attributes of a TP."; uses nwi:port-ref { refine "port-ref" { description "Reference to the physical port component in the network inventory. This reference establishes a 1:1 mapping between the logical TP and its physical port component."; } } // breakout channels (lightweight, per physical port) container port-breakout { presence "Indicates the port supports channel breakout."; config false; description "Breakout capability of the physical port represented by this TP. One TP maps to one physical port; channels are listed here. This container is present only when the underlying hardware supports partitioning the port into multiple independent channels (e.g., 400G to 4x100G)."; list breakout-channel { key "channel-id"; description "List of breakout channels available on this port. Each entry represents an independent lane or sub-port that can be used for channelized interfaces."; leaf channel-id { type uint16; description "Unique identifier for the breakout channel within the scope of the parent port."; } } // breakout-channel } // port-breakout } } // Link Grouping with placeholder for future augumentation grouping link-inventory-mapping-attributes { Wu, et al. Expires 1 September 2026 [Page 9] Internet-Draft Inventory Topology Mapping February 2026 description "Attributes for classifying link media type. Detailed inventory reference is intentionally omitted from this model; implementations should use the appropriate specialized inventory modules based on the indicated link-type."; container inventory-mapping-attributes { description "Container for inventory-related attributes of a link. This container provides lightweight media classification. The link-type indicates which specialized inventory model contains detailed resource information: - Wired media (fiber, copper): passive network inventory - Wireless media (microwave, Wi-Fi): wireless-specific inventory Detailed inventory references may be added in future modules."; leaf link-type { type string; description "Classification of the link media type at the topology layer. Example values include 'copper', 'fiber', 'microwave', or 'wifi'."; } } } // Main blocks augment "/nw:networks/nw:network/nw:node" { description "Augments the network topology node with inventory mapping attributes. This enables correlation between the logical node and its physical network element."; uses node-inventory-mapping-attributes; } augment "/nw:networks/nw:network/nt:link" { description "Augments the network topology link with inventory-related attributes."; uses link-inventory-mapping-attributes; } augment "/nw:networks/nw:network/nw:node/nt:termination-point" { Wu, et al. Expires 1 September 2026 [Page 10] Internet-Draft Inventory Topology Mapping February 2026 description "Augments the TP with inventory mapping attributes for physical port correlation and breakout capability reporting."; uses tp-inventory-mapping-attributes; } } 6. Operational Considerations This model enables a network controller to report discovered network topology and inventory information. Automatic discovery serves as the primary mechanism, with selective configuration capabilities provided for scenarios where discovery is not feasible. For typical operations such as service provisioning and network planning, the model offers read-only query access to authoritative mappings between logical topology and physical inventory. The inventory-mapping-attributes containers are defined as read-write (config true) to accommodate cases where automatic discovery is not possible, including: * Customer-premises equipment (CPE) outside the operator's management domain * Leased lines and third-party transport resources * Planned or hypothetical resources for future deployment In these cases, the operator manually configures the mapping to maintain accurate topology-to-inventory correlation. The following nodes are read-only (config false) as they represent hardware-determined state: port-breakout: Hardware capability determined by physical port characteristics 7. Security Considerations This section is modeled after the template described in Section 3.7 of [I-D.ietf-netmod-rfc8407bis]. Wu, et al. Expires 1 September 2026 [Page 11] Internet-Draft Inventory Topology Mapping February 2026 The "ietf-network-inventory-topology" YANG module defines a data model that is designed to be accessed via YANG-based management protocols, such as NETCONF [RFC6241] and RESTCONF [RFC8040]. These YANG-based management (1) have to use a secure transport layer (e.g., SSH [RFC4252], TLS [RFC8446], 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: 'ne-ref', 'port-ref', 'link-type': These nodes are sensitive as they establish the mapping between logical topology and physical inventory. Unauthorized modification could lead to incorrect resource allocation or service disruption. 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: 'ne-ref': The references may be used to track the set of network elements. While read-only, they may reveal network infrastructure details. 'port-breakout': This node exposes hardware capabilities. 8. IANA Considerations IANA is requested to register the following URI in the "ns" subregistry within the "IETF XML Registry" [RFC3688]: URI: urn:ietf:params:xml:ns:yang:ietf-network-inventory-topology Registrant Contact: The IESG. XML: N/A; the requested URI is an XML namespace. Wu, et al. Expires 1 September 2026 [Page 12] Internet-Draft Inventory Topology Mapping February 2026 IANA is requested to register the following YANG module in the "YANG Module Names" registry [RFC6020] within the "YANG Parameters" registry group: Name: ietf-network-inventory-topology Namespace: urn:ietf:params:xml:ns:yang:ietf-network-inventory-topology Prefix: nwit Maintained by IANA? N Reference: RFC XXXX 9. References 9.1. Normative References [I-D.ietf-ivy-network-inventory-yang] Yu, C., Belotti, S., Bouquier, J., Peruzzini, F., and P. Bedard, "A Base YANG Data Model for Network Inventory", Work in Progress, Internet-Draft, draft-ietf-ivy-network- inventory-yang-14, 5 February 2026, . [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004, . [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010, . [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, . [RFC9408] Boucadair, M., Ed., Gonzalez de Dios, O., Barguil, S., Wu, Q., and V. Lopez, "A YANG Network Data Model for Service Attachment Points (SAPs)", RFC 9408, DOI 10.17487/RFC9408, June 2023, . 9.2. Informative References Wu, et al. Expires 1 September 2026 [Page 13] Internet-Draft Inventory Topology Mapping February 2026 [I-D.ietf-ivy-network-inventory-software] Wu, B., Zhou, C., Wu, Q., and M. Boucadair, "A YANG Network Data Model of Network Inventory Software Extensions", Work in Progress, Internet-Draft, draft-ietf- ivy-network-inventory-software-02, 20 October 2025, . [I-D.ietf-netmod-rfc8407bis] Bierman, A., Boucadair, M., and Q. Wu, "Guidelines for Authors and Reviewers of Documents Containing YANG Data Models", Work in Progress, Internet-Draft, draft-ietf- netmod-rfc8407bis-28, 5 June 2025, . [I-D.ietf-nmop-simap-concept] Havel, O., Claise, B., de Dios, O. G., and T. Graf, "SIMAP: Concept, Requirements, and Use Cases", Work in Progress, Internet-Draft, draft-ietf-nmop-simap-concept- 08, 23 February 2026, . [I-D.irtf-nmrg-network-digital-twin-arch] Zhou, C., Yang, H., Duan, X., Lopez, D., Pastor, A., Wu, Q., Boucadair, M., and C. Jacquenet, "Network Digital Twin: Concepts and Reference Architecture", Work in Progress, Internet-Draft, draft-irtf-nmrg-network-digital- twin-arch-12, 27 February 2026, . [I-D.ygb-ivy-passive-network-inventory] Yu, C., Guo, A., Busi, I., Boroon, M., Belotti, S., van caenegem, T., S., S. 1., B., S., Davis, N., Tilocca, M., Peters, B., Yoon, B. Y., LIUYUCONG, Zhao, Y., and A. Sakalabhaktula, "A YANG Data Model for Passive Network Inventory", Work in Progress, Internet-Draft, draft-ygb- ivy-passive-network-inventory-03, 7 January 2026, . [RFC4252] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH) Authentication Protocol", RFC 4252, DOI 10.17487/RFC4252, January 2006, . Wu, et al. Expires 1 September 2026 [Page 14] Internet-Draft Inventory Topology Mapping February 2026 [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, . [RFC7951] Lhotka, L., "JSON Encoding of Data Modeled with YANG", RFC 7951, DOI 10.17487/RFC7951, August 2016, . [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, . [RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, . [RFC8346] Clemm, A., Medved, J., Varga, R., Liu, X., Ananthakrishnan, H., and N. Bahadur, "A YANG Data Model for Layer 3 Topologies", RFC 8346, DOI 10.17487/RFC8346, March 2018, . [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, . [RFC8944] Dong, J., Wei, X., Wu, Q., Boucadair, M., and A. Liu, "A YANG Data Model for Layer 2 Network Topologies", RFC 8944, DOI 10.17487/RFC8944, November 2020, . Appendix A. "link-type" Usage Examples This appendix provides examples illustrating the usage of the link- type data node. Scenario: Device SW-1 and device SW-2 are directly connected by a fiber. Physical topology: +--------+ +--------+ | | | | | [SW-1] +========= fiber link ===============+ [SW-2] | | | | | +--------+ +--------+ Key parts of the JSON example is as follows: Wu, et al. Expires 1 September 2026 [Page 15] Internet-Draft Inventory Topology Mapping February 2026 { "ietf-network:networks": { "network": [ { "network-id": "campus-topology", "node": [ { "node-id": "SW-1", "ietf-network-inventory-topology:inventory-mapping-attributes": { "ne-ref": "NE-SW1" }, "ietf-network-topology:termination-point": [ { "tp-id": "TP-SW1-P1", "ietf-network-inventory-topology:inventory-mapping-attributes": { "ne-ref": "NE-SW1", "port-ref": "/nwi:network-inventory/nwi:network-elements/nwi:network-element[ne-id='NE-SW1']/nwi:components/nwi:component[component-id='eth-port-1']" } } ] }, { "node-id": "SW-2", "ietf-network-inventory-topology:inventory-mapping-attributes": { "ne-ref": "NE-SW2" }, "ietf-network-topology:termination-point": [ { "tp-id": "TP-SW2-P1", "ietf-network-inventory-topology:inventory-mapping-attributes": { "ne-ref": "NE-SW2", "port-ref": "/nwi:network-inventory/nwi:network-elements/nwi:network-element[ne-id='NE-SW2']/nwi:components/nwi:component[component-id='eth-port-1']" } } ] } ], "ietf-network-topology:link": [ { "link-id": "Link-SW1-SW2", "source": { "source-node": "SW-1", "source-tp": "TP-SW1-P1" }, "destination": { "dest-node": "SW-2", "dest-tp": "TP-SW2-P1" }, Wu, et al. Expires 1 September 2026 [Page 16] Internet-Draft Inventory Topology Mapping February 2026 "ietf-network-inventory-topology:inventory-mapping-attributes": { "link-type": "fiber" } } ] } ] } } Appendix B. JSON Example of an MPO Breakout-Channel Port This appendix provides an example of a 400 Gb/s DR4 port that is physically implemented as four independent 100 Gb/s lanes (an MPO breakout). The lanes are exposed as breakout-channel entries so that the port can later be configured as either a single 400G trunk or four 100G breakout interfaces. The instance data below shows the minimal JSON encoding [RFC7951] of the "port-breakout" container for this port. Wu, et al. Expires 1 September 2026 [Page 17] Internet-Draft Inventory Topology Mapping February 2026 =============== NOTE: '\' line wrapping per RFC 8792 ================ { "ietf-network-topology:networks": { "network": [ { "network-id": "example:underlay-topology-400g", "node": [ { "node-id": "example:n1", "termination-point": [ { "tp-id": "example:400g-1/0/1", "ietf-network-inventory-topology:inventory-mapping-\ attributes": { "ne-ref": "example:NE-1", "port-ref": "example:port-1", "port-breakout": { "breakout-channel": [ { "channel-id": 1 }, { "channel-id": 2 }, { "channel-id": 3 }, { "channel-id": 4 } ] } } } ] } ] } ] } } Acknowledgments The authors wish to thank Italo Busi, Olga Havel, Aihua Guo, Oscar Gonzalez de Dios, and many others for their helpful comments and suggestions. Contributors Chaode Yu Huawei Email: yuchaode@huawei.com Wu, et al. Expires 1 September 2026 [Page 18] Internet-Draft Inventory Topology Mapping February 2026 Authors' Addresses Bo Wu (editor) Huawei Email: lana.wubo@huawei.com Mohamed Boucadair Orange Email: mohamed.boucadair@orange.com Cheng Zhou China Mobile Email: zhouchengyjy@chinamobile.com Qin Wu Huawei Email: bill.wu@huawei.com Wu, et al. Expires 1 September 2026 [Page 19]