]> Huawei

lana.wubo@huawei.com

Orange

mohamed.boucadair@orange.com

China Mobile

zhouchengyjy@chinamobile.com

Huawei

bill.wu@huawei.com

Operations and Management Network Inventory YANG Automation Network Digital Map Network Inventory Network Operation Network Topology This document specifies a YANG data model that extends the network topology data model (RFC 8345) to map network topologies with inventories. The data model introduces the "inventory-topology" network type and augmentations for physical entity mappings and capabilities, which may be used by any overlay network topology for service provisioning validation, network maintenance, and capacity planning. Discussion Venues Discussion of this document takes place on the Network Inventory YANG Working Group mailing list (ivy@ietf.org), which is archived at . Source for this draft and an issue tracker can be found at .

Introduction 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 . In order to ease navigation between inventory and network topologies, this document extends the network topology data model for network inventory mapping: "ietf-network-inventory-topology" (). The YANG data model in this document conforms to the YANG data modeling language . Similar to the base inventory data model , the network inventory topology data model does not make any assumption about involved NEs and their roles in topologies. As such, the mapping data model can be applied independent of the network type (optical local loops, access network, core network, etc.) and application. Therefore, this YANG data model can be used to represent a physical network instance at the lowest underlay abstraction level, as shown in . Alternatively, it can be used in conjunction with existing network topology models, such as , , , , and , when they contain nodes, links, or termination points belonging to the lowest underlay level.

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
• 2026-09-11 --> the actual date of the publication of this document

Conventions and Definitions

Requirements Notations 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 when, and only when, they appear in all capitals, as shown here. The following terms are defined in and are not redefined here:

• augment
• data model
• data node

The meanings of the symbols in the YANG tree diagrams are defined in . This document uses terms defined in . The document adheres to the folding conventions in .

Sample Use Cases of the Data Model

Determine Available Resources of Service Attachment Points (SAPs) The inventory topology data model provides a physical port reference (port-ref) that enables correlation between logical topology entities and physical inventory components. During service provisioning, the SAP's parent-termination-point can be associated with the inventory topology's port-ref to locate the underlying physical resource. illustrates the query interactions. During service provisioning, the orchestrator can issue a query using the SAP data model (e.g., obtaining a list of SAPs across multiple PEs as shown in ), and then uses the inventory topology data model to identify the physical port underlying each candidate SAP. Specifically, the "parent-termination-point" of a SAP is mapped to the corresponding "port-ref" in the inventory topology, allowing the orchestrator to locate the physical resource. The orchestrator can then consult other relevant topology models (e.g., ) to verify whether the identified port has adequate capacity for the requested service. If the physical port underlying a candidate SAP has insufficient resources (e.g., port speed fully utilized), the orchestrator can select an alternate SAP that maps to a different port with adequate capacity. If no alternative SAP is available, the orchestrator flags the request for manual intervention, providing the operator with precise inventory information about the bottleneck (e.g., "Port GE0/6/1 on NE-PE1 is at 95% utilization"). The resource constraint can also feed into a "what-if" analysis (see ) to evaluate hardware upgrades or alternative underlay paths.

An Example Usage of Network Inventory Topology

Multi-layer Network Navigation A multi-layer network encompasses multiple layers (e.g., Layer 2 and Layer 3, or Optical Transport Network (OTN) and Wavelength Division Multiplexing (WDM) layers). A multi-layer network topology comprises nodes, links, and termination points that can belong to different layers. A multi-layer network can contain multiple types of topological elements: physical elements (associated with an inventory element) or logical elements (associated with topology elements in the underlay layer). The topology models support navigation across the different layers, down to the physical layer, as defined in . The navigation between the physical layer and the network inventory is outside the scope of the topology models and is addressed in this document. This document augments both "ietf-network" (for nodes and network- types) and "ietf-network-topology" (for links and termination points), following the standard extension pattern described in . This augmentation associates inventory data nodes with topology data nodes to support multi-layer navigation across physical and logical resources. To make this navigation operationally explicit, this module provides concrete YANG data nodes in the "inventory-mapping-attributes" container, where the leaf "ne-ref" links topology nodes to their corresponding network elements, and the leaf "port-ref" links termination points to their physical port components, thereby enabling direct correlation between the topology and the underlying inventory.

"What-if" Scenarios 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. 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 End-of-Life, path re-optimization under resource constraints, service availability assessment).

Module Tree Structure An overview of the structure of the "ietf-network-inventory-topology" module is shown in .

The Structure of the Network Inventory Mapping Data Model

The module augments the "ietf-network-topology" module as follows:

Inventory mapping attributes for nodes, and termination points:

The corresponding containers augments the topology module with the references to the base network inventory

Link Extensions This document adds a lightweight "link-type" leaf to the topology link mapping to enable basic physical media classification.

"link-type":

An identityref indicating the link media type.

Examples of wired link types are "copper", "fiber", or "coax". For wireless media, values such as "microwave", or "wlan" may be used. See also for more detailed microwave radio attributes.

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" or "copper") typically references a passive network inventory model such as the one defined in .

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 a JSON instance example for a port with breakout capabilities. It is assumed that a port which supports breakout can be configured either as a trunk port or as a breakout port. The "port-breakout" container serves as a capability advertisement for the termination-point of the parent physical port. It does not provide direct references or pointers to the resulting lower-speed termination-points or interfaces. The correlation between a specific "channel-id" and its corresponding lower-speed termination-point is outside the scope of this document and is expected to be provided by a future companion module. Interface channelisation (e.g., VLAN sub-interfaces) is also outside the scope of this document and is addressed by the Layer 2 network topology model .

Network Inventory Topology YANG Module This module augments the Network Topology module defined in . This module imports the base network inventory . Editor: Bo Wu Editor: Mohamed Boucadair Author: Cheng Zhou Author: Qin Wu "; description "This module defines a YANG module for network 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 2026-09-11 { description "Initial revision."; reference "RFC XXXX: A Network Data Model for Inventory Topology Mapping"; } identity link-type { description "Base identity for classifying the physical media type of a link at the inventory topology layer. Additional identities may be defined to cover other media types."; } identity copper { base link-type; description "Copper-based physical link."; } identity fiber { base link-type; description "Fiber-based physical link."; } identity coax { base link-type; description "Coaxial cable-based physical link."; } identity microwave { base link-type; description "Microwave-based wireless link. Detailed microwave radio attributes are defined in the microwave topology data model."; reference "RFC 9656: A YANG Data Model for Microwave Topology"; } identity wlan { base link-type; description "IEEE 802.11 wireless link."; } identity unknown { base link-type; description "The link media type is unknown or could not be determined. This identity is used as a fallback when the physical medium cannot be classified into any of the other defined types. When a discovery system is unable to determine the media type, it should use this identity rather than leaving the leaf unset. An unset leaf indicates that the link type has not been assessed, whereas unknown explicitly records that the medium could not be classified."; } identity leased-fiber { base fiber; description "Leased fiber link. The physical medium is fiber, but the link is provided by a third-party operator. Detailed physical attributes are typically not visible to the lessee."; } augment "/nw:networks/nw:network/nw:network-types" { description "Introduces a new network type for inventory topology mapping."; container inventory-topology { presence "Indicates a physical network topology, containing physical-layer attributes including inventory mapping, port breakout capabilities, and link media types."; description "Container for the inventory-topology network type. When present, it signals that the network contains physical-layer augmentations as defined in this module. This network type is typically discovered by the network controller to identify a physical underlay network; it may be configured manually when discovery is not available. This network type is intended to serve as the underlay for logical network topologies (Layer 2, Layer 3, Traffic Engineering (TE), etc.)."; } } augment "/nw:networks/nw:network/nw:node" { when '../nw:network-types/nwit:inventory-topology'; description "Augments the network topology node with inventory mapping attributes. This enables correlation between the logical node and its physical network element."; container inventory-mapping-attributes { presence "If present, it indicates this is a physical node, which maps to a network element. If not present, it indicates it is an abstract node."; 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."; } } } augment "/nw:networks/nw:network/nt:link" { when '../nw:network-types/nwit:inventory-topology'; description "Augments the network topology link with inventory-related attributes."; container inventory-mapping-attributes { presence "Indicates a physical link, at the lowest underlay abstraction level."; 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, wlan): wireless-specific inventory Detailed inventory references may be added in future modules."; leaf link-type { type identityref { base link-type; } description "Classification of the link media type at the topology layer. The base identity 'link-type' is extensible. Examples of derived identities include 'copper', 'fiber', 'coax', 'microwave', and 'wlan'. This leaf serves as a lightweight discriminator. When the value is 'microwave', detailed microwave link attributes are defined in the microwave topology data model. Wired media (e.g., fiber, copper, or coax) may be detailed in a passive network inventory data model."; } } } augment "/nw:networks/nw:network/nw:node/nt:termination-point" { when '../../nw:network-types/nwit:inventory-topology'; description "Augments the termination point (TP) with inventory mapping and port breakout."; container inventory-mapping-attributes { presence "If present, it indicates this is a physical TP, which maps to a port component. If not present, it indicates it is a logical TP."; 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."; } } } 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 "Indicates the 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 "Records a unique identifier for the breakout channel within the scope of the parent port."; } } } } } ]]>

Operational Considerations The "ietf-network-inventory-topology" YANG module 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

Therefore, in typical deployments, "ne-ref", "port-ref", and "link-type" SHOULD be populated through automatic discovery but MAY only be overridden manually in exceptional cases (e.g., CPE, leased lines, or planned resources). The "port-breakout" container MUST always reflect hardware-determined state and therefore MUST NOT be manually configured. The "inventory-topology" presence container under "network-types" is typically set by the network controller when it discovers or provisions network instance representing the physical layer. It MAY be configured manually to declare a network as an inventory topology when discovery is not available.

Security Considerations This section is modeled after the template described in . The "ietf-network-inventory-topology" YANG module defines a data model that is designed to be accessed via YANG-based management protocols, such as Network Configuration (NETCONF) and RESTCONF . These YANG-based management (1) have to use a secure transport layer and (2) have to use mutual authentication (e.g., Secure Shell (SSH) , TLS , and QUIC ). The Network Configuration Access Control Model (NACM) 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', and 'link-type':

  These nodes are sensitive as they establish the mapping between logical topology and physical inventory. Incorrect inventory mapping (e.g., stale or manually misconfigured 'ne-ref' or 'port-ref' values) may lead to mis-provisioning of services or misinterpretation of physical resource availability, which can result in failed service activation, unexpected traffic paths, or inaccurate capacity planning.

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', 'port-ref', and 'link-type':

  These nodes are sensitive as they reveal network infrastructure details. 'ne-ref' may be used to track the set of network elements; 'port-ref' discloses internal port and component naming; 'link-type' can reveal infrastructure ownership (e.g., the 'leased-fiber' identity distinguishes third-party transport from owned infrastructure).

• 'port-breakout':

  This node exposes hardware capabilities.

There are no particularly sensitive RPC or action operations defined in this module. As this module augments the network topology model defined in , the module also inherits the security considerations discussed in for the underlying network topology data model.

IANA Considerations IANA is requested to register the following URI in the "ns" subregistry within the "IETF XML Registry" : IANA is requested to register the following YANG module in the "YANG Module Names" registry within the "YANG Parameters" registry group:

References Normative References Huawei Technologies Nokia Vodafone FiberCop Cisco This document defines a base YANG data model for reporting network inventory. The scope of this base model is set to be application- and technology-agnostic. The base data model can be augmented with application- and technology-specific details. This document defines an abstract (generic, or base) YANG data model for network/service topologies and inventories. The data model serves as a base model that is augmented with technology-specific details in other, more specific topology and inventory data models. YANG is a data modeling language used to model configuration data, state data, Remote Procedure Calls, and notifications for network management protocols. This document describes the syntax and semantics of version 1.1 of the YANG language. YANG version 1.1 is a maintenance release of the YANG language, addressing ambiguities and defects in the original specification. There are a small number of backward incompatibilities from YANG version 1. This document also specifies the YANG mappings to the Network Configuration Protocol (NETCONF). In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. The standardization of network configuration interfaces for use with the Network Configuration Protocol (NETCONF) or the RESTCONF protocol requires a structured and secure operating environment that promotes human usability and multi-vendor interoperability. There is a need for standard mechanisms to restrict NETCONF or RESTCONF protocol access for particular users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and content. This document defines such an access control model. This document obsoletes RFC 6536. This document describes an IANA maintained registry for IETF standards which use Extensible Markup Language (XML) related items such as Namespaces, Document Type Declarations (DTDs), Schemas, and Resource Description Framework (RDF) Schemas. YANG is a data modeling language used to model configuration and state data manipulated by the Network Configuration Protocol (NETCONF), NETCONF remote procedure calls, and NETCONF notifications. [STANDARDS-TRACK] Informative References Huawei China Mobile Huawei Orange This document extends the base Network Inventory YANG model to support non-physical network elements (NEs), such as controllers, virtual routers, and virtual firewalls, as well as software components like platform operating systems and software modules. In addition to the software revisions and patches already defined in the base model, this extension introduces software status and time stamp information. This document defines a YANG data model for representing an abstract view of the provider network topology that contains the points from which its services can be attached (e.g., basic connectivity, VPN, network slices). Also, the model can be used to retrieve the points where the services are actually being delivered to customers (including peer networks). This document augments the 'ietf-network' data model defined in RFC 8345 by adding the concept of Service Attachment Points (SAPs). The SAPs are the network reference points to which network services, such as Layer 3 Virtual Private Network (L3VPN) or Layer 2 Virtual Private Network (L2VPN), can be attached. One or multiple services can be bound to the same SAP. Both User-to-Network Interface (UNI) and Network-to-Network Interface (NNI) are supported in the SAP data model. This document defines a YANG data model for Layer 2 network topologies. In particular, this data model augments the generic network and network topology data models with topology attributes that are specific to Layer 2. This document defines a YANG data model for Layer 3 network topologies. This document defines a YANG data model for representing, retrieving, and manipulating Traffic Engineering (TE) Topologies. The model serves as a base model that other technology-specific TE topology models can augment. Huawei Technologies Huawei Technologies Individual Nokia Telefonica This document defines a YANG data model for representing, retrieving, and manipulating Optical Transport Network (OTN) topologies. It is independent of control plane protocols and captures topological and resource-related information pertaining to OTN. This document captures the current syntax used in YANG module tree diagrams. The purpose of this document is to provide a single location for this definition. This syntax may be updated from time to time based on the evolution of the YANG language. This document defines two strategies for handling long lines in width-bounded text content. One strategy, called the "single backslash" strategy, is based on the historical use of a single backslash ('\') character to indicate where line-folding has occurred, with the continuation occurring with the first character that is not a space character (' ') on the next line. The second strategy, called the "double backslash" strategy, extends the first strategy by adding a second backslash character to identify where the continuation begins and is thereby able to handle cases not supported by the first strategy. Both strategies use a self-describing header enabling automated reconstitution of the original content. China Mobile China Mobile China Mobile Huawei Orange Orange The application of Digital Twin technology in the networking field is meant to develop various rich network applications, realize efficient and cost-effective data-driven network management, and accelerate network innovation. This document presents an overview of the concept of Network Digital Twin (NDT), provides the basic definitions and a reference architecture, lists a set of application scenarios, and discusses such technology's benefits and key challenges. This document is a product of the Network Management Research Group (NMRG) of the Internet Research Task Force (IRTF). This document reflects the consensus of the research group. It is not a candidate for any level of Internet Standard and is published for informational purposes. Huawei Everything OPS Telefonica Swisscom This document defines the concept of Service & Infrastructure Maps (SIMAP) and identifies a set of SIMAP requirements and use cases. The SIMAP was previously known as Digital Map. SIMAP evolves the earlier 'Digital Map' concept by making explicit the ties between service and infrastructure layers, clarifying expected outcomes for operations and automation, and addressing ambiguity associated with the term 'digital.' The document intends to be used as a reference for the assessment of the various topology modules to meet SIMAP requirements. This document defines a YANG data model to describe microwave and millimeter-wave radio links in a network topology. Futurewei Nokia Ciena FiberCop NBN This document presents a YANG data model for tracking and managing passive network inventory. The model augments the base network inventory model. This document defines encoding rules for representing configuration data, state data, parameters of Remote Procedure Call (RPC) operations or actions, and notifications defined using YANG as JavaScript Object Notation (JSON) text. This document provides guidelines for authors and reviewers of specifications containing YANG data models, including IANA-maintained YANG modules. Recommendations and procedures are defined, which are intended to increase interoperability and usability of Network Configuration Protocol (NETCONF) and RESTCONF protocol implementations that utilize YANG modules. This document obsoletes RFC 8407; it also updates RFC 8126 by providing additional guidelines for writing the IANA considerations for RFCs that specify IANA-maintained YANG modules. The Network Configuration Protocol (NETCONF) defined in this document provides mechanisms to install, manipulate, and delete the configuration of network devices. It uses an Extensible Markup Language (XML)-based data encoding for the configuration data as well as the protocol messages. The NETCONF protocol operations are realized as remote procedure calls (RPCs). This document obsoletes RFC 4741. [STANDARDS-TRACK] This document describes an HTTP-based protocol that provides a programmatic interface for accessing data defined in YANG, using the datastore concepts defined in the Network Configuration Protocol (NETCONF). The Secure Shell Protocol (SSH) is a protocol for secure remote login and other secure network services over an insecure network. This document describes the SSH authentication protocol framework and public key, password, and host-based client authentication methods. Additional authentication methods are described in separate documents. The SSH authentication protocol runs on top of the SSH transport layer protocol and provides a single authenticated tunnel for the SSH connection protocol. [STANDARDS-TRACK] This document specifies version 1.3 of the Transport Layer Security (TLS) protocol. TLS allows client/server applications to communicate over the Internet in a way that is designed to prevent eavesdropping, tampering, and message forgery. This document obsoletes RFC 8446, which specified TLS 1.3. This document obsoletes RFC 5246 (specifying TLS 1.2) and RFCs 5077, 6961, 7627, and 8422, all of which pertain to TLS 1.2 or earlier, and updates RFCs 5705 and 6066. This document also specifies new requirements for TLS 1.2 implementations. This document defines the core of the QUIC transport protocol. QUIC provides applications with flow-controlled streams for structured communication, low-latency connection establishment, and network path migration. QUIC includes security measures that ensure confidentiality, integrity, and availability in a range of deployment circumstances. Accompanying documents describe the integration of TLS for key negotiation, loss detection, and an exemplary congestion control algorithm.

'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: Key parts of the JSON example are as follows:

JSON Example of an Multi-fibre Push On (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 of the "port-breakout" container for this port.

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. Thanks to Olga Havel for the detailed shepherd review.

Contributors Huawei

yuchaode@huawei.com