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Framework for Energy Efficiency Management
draft-ietf-green-framework-01

Document Type Active Internet-Draft (green WG)
Authors Benoît Claise , Luis M. Contreras , Jan Lindblad , Marisol Palmero , Emile Stephan , Qin Wu
Last updated 2026-03-25 (Latest revision 2026-03-17)
Replaces draft-belmq-green-framework
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draft-ietf-green-framework-01
GREEN                                                          B. Claise
Internet-Draft                                            Everything OPS
Intended status: Informational                           L. M. Contreras
Expires: 18 September 2026                                    Telefonica
                                                             J. Lindblad
                                                             All For Eco
                                                              M. Palmero
                                                             Independent
                                                              E. Stephan
                                                                  Orange
                                                                   Q. Wu
                                                                  Huawei
                                                           17 March 2026

               Framework for Energy Efficiency Management
                     draft-ietf-green-framework-01

Abstract

   Recognizing the urgent need for energy efficiency, this document
   specifies a management framework focused on networks, devices and
   device components within, or connected to, interconnected systems.
   The framework aims to enable energy usage optimization, based on the
   network condition while achieving the network's functional and
   performance requirements (e.g., improving overall network
   utilization) and also ensure interoperability across diverse systems.
   Leveraging data from existing use cases, it delivers actionable
   metrics to support effective energy management and informed decision-
   making.  Furthermore, the framework defines mechanisms for
   representing and organizing timestamped telemetry data using YANG
   data models and metadata, enabling transparent and reliable
   monitoring.  This structured approach facilitates improved energy
   efficiency through consistent energy management practices.

About This Document

   This note is to be removed before publishing as an RFC.

   The latest revision of this draft can be found at https://github.com/
   ietf-wg-green/draft-ietf-green-framework.html.  Status information
   for this document may be found at https://datatracker.ietf.org/doc/
   draft-ietf-green-framework/.

   Discussion of this document takes place on the Getting Ready for
   Energy-Efficient Networking mailing list (mailto:green@ietf.org),
   which is archived at https://mailarchive.ietf.org/arch/browse/green/.
   Subscribe at https://www.ietf.org/mailman/listinfo/green/.

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   Source for this draft and an issue tracker can be found at
   https://github.com/https://github.com/ietf-wg-green/draft-ietf-green-
   framework.

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 18 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  . . . . . . . . . . . . . . . . . . . . . . . .   4
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   5
   2.  Motivation  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     2.1.  Impact on Energy Metrics  . . . . . . . . . . . . . . . .   7
     2.2.  Device Readiness  . . . . . . . . . . . . . . . . . . . .   8
     2.3.  Why Now?  . . . . . . . . . . . . . . . . . . . . . . . .   8
   3.  Reference Model . . . . . . . . . . . . . . . . . . . . . . .   9
     3.1.  Data Collection Architecture  . . . . . . . . . . . . . .  11
       3.1.1.  Telemetry Push Pattern  . . . . . . . . . . . . . . .  12
       3.1.2.  Controller vs. Device Initiated . . . . . . . . . . .  12
       3.1.3.  UUID-Based Component Identification . . . . . . . . .  13

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       3.1.4.  Measurement Accuracy and Data Source
               Classification  . . . . . . . . . . . . . . . . . . .  13
       3.1.5.  Industry-Standard Certifications  . . . . . . . . . .  14
       3.1.6.  Extensibility Through YANG Identities . . . . . . . .  14
       3.1.7.  Hierarchical Data Model and Default Value
               Inheritance . . . . . . . . . . . . . . . . . . . . .  14
       3.1.8.  Unit Multiplier Consistency . . . . . . . . . . . . .  16
       3.1.9.  Power Factor  . . . . . . . . . . . . . . . . . . . .  16
     3.2.  Typical Power Topologies  . . . . . . . . . . . . . . . .  16
       3.2.1.  Basic Power Supply  . . . . . . . . . . . . . . . . .  17
       3.2.2.  Physical Meter with Legacy Device . . . . . . . . . .  17
       3.2.3.  Physical Meter with New Device  . . . . . . . . . . .  19
       3.2.4.  Power over Ethernet . . . . . . . . . . . . . . . . .  21
       3.2.5.  Single Power Supply with Multiple Devices . . . . . .  22
       3.2.6.  Multiple Power Supplies with Single Device  . . . . .  24
     3.3.  Relationships . . . . . . . . . . . . . . . . . . . . . .  25
     3.4.  Power State Set . . . . . . . . . . . . . . . . . . . . .  26
     3.5.  Power State Set Mapping and Intent  . . . . . . . . . . .  27
       3.5.1.  Capability Discovery  . . . . . . . . . . . . . . . .  27
       3.5.2.  Intent Mapping  . . . . . . . . . . . . . . . . . . .  28
       3.5.3.  SLA Considerations  . . . . . . . . . . . . . . . . .  28
   4.  Interfaces Usage Of the Framework . . . . . . . . . . . . . .  28
     4.1.  Mapping of Use Cases to Framework Interfaces  . . . . . .  28
   5.  Use Case Implementation Requirements: Device vs. Controller
           Centric . . . . . . . . . . . . . . . . . . . . . . . . .  31
     5.1.  Implementation Focus: Where Intelligence Resides  . . . .  31
     5.2.  Key Findings  . . . . . . . . . . . . . . . . . . . . . .  34
       5.2.1.  Device Capabilities Required across Use Cases . . . .  34
       5.2.2.  Controller Capabilities Required across Use Cases . .  34
     5.3.  Implementation Priorities . . . . . . . . . . . . . . . .  34
     5.4.  Next Steps  . . . . . . . . . . . . . . . . . . . . . . .  34
   6.  Conventions and Definitions . . . . . . . . . . . . . . . . .  34
   7.  Operational Considerations  . . . . . . . . . . . . . . . . .  34
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  34
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  35
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  35
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  35
     10.2.  Informative References . . . . . . . . . . . . . . . . .  35
   Appendix A.  TO DO and Open Issues  . . . . . . . . . . . . . . .  36
     A.1.  Discovering Capabilities  . . . . . . . . . . . . . . . .  37
     A.2.  Understanding Device Capabilities . . . . . . . . . . . .  37
     A.3.  Mapping Intents to Device Settings  . . . . . . . . . . .  37
     A.4.  Handling Transitions and Ensuring Safety  . . . . . . . .  37
     A.5.  East-West Traffic/Energy Metrics  . . . . . . . . . . . .  37
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  38
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  38

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1.  Introduction

   [GreenUseCases] analyzes use cases such as "Incremental Application
   of the GREEN Framework" and "Consideration of other domains for end-
   to-end metrics"; these cases demonstrate the need for structured
   network device management that supports energy-efficient operations.
   The framework establishes foundational components for:

   *  Standardization: Ensuring consistent practices across devices and
      network segments to facilitate interoperability

   *  Energy Efficiency Management: Providing guidelines to identify
      inefficiencies, balance energy usage with network/resource/
      component utilization, and implement improvements

   *  Scalability: Approaches that handle increasing network size and
      complexity

   *  Cost Reduction: Optimizing energy usage to lower operational costs
      and extend equipment lifecycles

   *  Competitiveness: Enabling organizations to maintain competitive
      infrastructure through enhanced sustainability

   *  Environmental Impact: Supporting broader energy optimization
      practices and sustainability initiatives by reducing carbon
      footprints

   *  Simplified Implementation: Streamlining deployment of energy-
      efficient measures to minimize service disruptions

   *  Security: Protection of power state and consumption data

   This document specifies an Energy Management framework for devices
   within, or connected to, communication networks, addressing the use
   cases in [GreenUseCases].

   The framework covers devices and components that can be monitored and
   controlled for energy management purposes:

   *  Power consumers: Routers, switches, servers, storage systems, and
      their components (line cards, fans, disks, processors, GPUs)

   *  Power sources: Uninterruptible power supplies (UPS), Power
      Distribution Units (PDUs), Power over Ethernet (PoE) switches,
      renewable energy systems, and their components (battery cells,
      inverters, photovoltaic panels)

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   *  Monitored entities: Any network-attached device or component with
      a unique identifier (UUID per [RFC8348]) that influences power or
      energy consumption

   This framework defines conceptual requirements and architectural
   patterns for energy efficiency management.  The companion YANG data
   model [PowerAndEnergy] provides the implementable specification,
   including:

   *  Power and energy metric definitions and units

   *  Measurement accuracy representation

   *  Hierarchical default value inheritance

   *  [RFC8348] hardware data model link with energy attributes

   Implementers are expected to refer to both documents: this framework
   for understanding requirements and use cases, the YANG data model for
   implementation details and data structures.

1.1.  Terminology

   The following terms are defined in [GreenTerminology]: Energy, Power,
   Energy Object, Energy Management, Energy Monitoring, and Energy
   Control.

   The following terms are defined in EMAN Framework [RFC7326], athey
   are provided here for convenience:

   Energy Management System (EnMS):  An Energy Management System is a
      combination of hardware and software used to administer a network,
      with the primary purpose of Energy Management.

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      NOTES:

      1. An Energy Management System according to ISO50001 (ISO-EnMS)
         is a set of systems or procedures upon which organizations can
         develop and implement an energy policy, set targets and action
         plans, and take into account legal requirements related to
         energy use.  An ISO-EnMS allows organizations to improve energy
         performance and demonstrate conformity to requirements,
         standards, and/or legal requirements.

      2. Example ISO-EnMS: Company A defines a set of policies and
         procedures indicating that there should exist multiple
         computerized systems that will poll energy measurements from
         their meters and pricing / source data from their local
         utility.  Company A specifies that their CFO (Chief Financial
         Officer) should collect information and summarize it quarterly
         to be sent to an accounting firm to produce carbon accounting
         reporting as required by their local government.

      3. For the purposes of EMAN, the definition herein is the
         preferred meaning of an EnMS.  The definition from ISO50001
         can be referred to as an ISO Energy Management System
         (ISO-EnMS).

   Device:  A device is a piece of electrical or non-electrical
      equipment.  Reference: Adapted from [IEEE100].

   Component:  A component is a part of electrical or non-electrical
      equipment (device).  Reference: Adapted from [TMN].

   Meter (Energy Meter):  A meter is a device intended to measure
      electrical energy by integrating power with respect to time.
      Reference: Adapted from [IEC60050].

   Power Inlet:  A power inlet (or simply "inlet") is an interface at
      which a device or component receives energy from another device or
      component.

   Power Outlet:  A power outlet (or simply "outlet") is an interface at
      which a device or component provides energy to another device or
      component.

   Power Interface:  A Power Interface is a power inlet, outlet, or
      both.

   Power State:  A Power State is a condition or mode of a device (or
      component) that broadly characterizes its capabilities, power, and
      responsiveness to input.  Reference: Adapted from [IEEE1621].

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   Power State Set:  A Power State Set is a collection of Power States
      that comprises a named or logical control grouping.

   Energy Object:  An Energy Object represents a piece of equipment that
      is part of, or attached to, a communications network that is
      monitored or controlled or that aids in the management of another
      device for Energy Management.

   This document uses the terms Power and Energy in accordance with
   [GreenTerminology]:

   *  Power refers to the instantaneous rate at which a device consumes
      or produces electrical energy (typically expressed in Watts).

   *  Energy, by contrast, represents the cumulative amount of work
      performed over time (typically expressed in Joules or Watt-hours).
      Both concepts are required within the YANG modules: Power enables
      real-time monitoring, control, and optimization of device
      operation, while Energy provides a time-integrated view necessary
      for accounting and reporting.  For completeness and alignment with
      existing operational models and use cases, this specification
      includes both Power and Energy attributes.

2.  Motivation

2.1.  Impact on Energy Metrics

   The framework aims to enhance the creation of energy metrics with
   actionable insights by:

   *  Standardizing Metrics: Establishing consistent measurement
      protocols for energy consumption and efficiency.

   *  Enhancing Data Collection: Facilitating comprehensive monitoring
      and data aggregation across devices.

   *  Supporting Real-time Monitoring: Enabling dynamic tracking and
      immediate optimization of energy usage.

   *  Integration Across Devices: Ensuring interoperability for network-
      wide data analysis.

   *  Providing Actionable Insights: Translating raw data into
      meaningful information for decision-making.

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   *  East-West Traffic Impact: Addressing the increasing energy
      footprint of east-west traffic in data centers and distributed
      systems by providing a framework for measuring and optimizing
      energy consumption in these environments.

2.2.  Device Readiness

   While many modern networking devices have basic energy monitoring
   capabilities, these are often proprietary.  The framework defines
   requirements to enhance these capabilities, enabling standardized
   metric production and meaningful data contributions for energy
   management goals.

2.3.  Why Now?

   The motivation of defining a framework for energy management is
   driven by:

   *  Immediate Benefits: Start realizing cost savings, reduced carbon
      footprints, and improved efficiencies.

   *  Rapid Technological Advancements: Aligning the framework with
      current technologies to prevent obsolescence.

   *  Increasing Energy Demands: Mitigating the impact of growing energy
      consumption on costs.

   *  Regulatory Pressure: Preparing for compliance with existing and
      anticipated regulations.

   *  Competitive Advantage: Positioning organizations as leaders in
      innovation.

   *  Foundational Work Ready: Building on the use cases and
      requirements established in Phase I.

   *  Proactive Risk Management: Minimizing risks associated with energy
      costs and environmental factors.

   *  Facilitate Future Innovations: Creating a platform for continuous
      improvements and adaptations.

   *  Stakeholder Engagement: Ensuring diverse perspectives are
      reflected for broader adoption.

   Establishing the framework for energy efficiency management now is
   strategic and timely, leveraging the current momentum of use cases
   and requirements to drive meaningful progress in energy efficiency

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   management.  Delaying its development could result in missed
   opportunities for immediate benefits, increased costs, and challenges
   in adapting to future technological and regulatory landscapes.

3.  Reference Model

   The framework introduces the concept of a Power Interface.  A Power
   Interface is defined as an interconnection among devices where energy
   can be provided, received, or both.  There are someƒ similarities
   between Power Interfaces and network interfaces.  A network interface
   can be set to different states, such as sending or receiving data on
   an attached line.  Similarly, a Power Interface can be receiving or
   providing energy.

   The most basic example of Energy Management is a single device
   reporting information about itself.  In many cases, however, energy
   is not measured by the device itself but is measured upstream in the
   power distribution tree.  For example, a Power Distribution Unit
   (PDU) may measure the energy it supplies to attached devices and
   report this to an Energy Management System.  Therefore, devices often
   have relationships to other devices or components in the power
   network.  An Energy Management System (EnMS) generally requires an
   understanding of the power topology (who provides power to whom), the
   Metering topology (who meters whom), and the potential Aggregation
   (who aggregates values of others).

   The relationships build on the Power Interface concept.  The
   different relationships among device(s)/component(s), as specified in
   this document, include power source, Metering, and Aggregation
   Relationships.

   The GREEN Framework Reference Model is represented in Figure 1.

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 +------------------------------------------------------------------+
 |                                                                  |
 |                  (3) Network Domain Level                        |-+
 |                                                                  | |
 +------------------------------------------------------------------+ |
                                                                      |
 (a)              (b)          (c)                                    v
 Inventory        Monitor        DataSheets/DataBase and/or          (g)
 Of identity      Energy        | via API,                           API
 and Capability   Efficiency    | Metadata and other             Service
      ^               ^         | device/component/network     Interface
      |               |         | related information to be:          ^
      |               |         |                                     |
      |               |         |  .Power/Energy related metrics      |
      |               |         |  .Origin of Energy Mix              |
      |               |         |  .Carbon aware based on location    |
      |               |         |                                     |
      |               |         |                                     |
      |               |         v                                     |
 +------------------------------------------------------------------+ |
 |                                                                  | |
 |       (2) controller (collection, compute and aggregate?)        |-+
 |                                                                  |
 +------------------------------------------------------------------+
                 ^                      ^                      ^ |
      (d)        |     (e)              |   (f)                | |
      Inventory  |     Monitor power    |   Control            | |
      Capability |     Proportion       |   (Energy saving     | |
                 |     Energy efficiency|   Functionality      | |
                 |     ratio, power     |   Localized mgmt/    | |
                 |     consumption,     |   network wide mgmt) | |
                 |     etc)             |                      | |
                 |                      |                      | v
 +--------------------------------------------------------------------+
 |                                                                    |
 |                       (1) Device/Component                         |
 |                                                                    |
 | +---------+  +-----------+  +----------------+  +----------------+ |
 | | (I)     |  | (II)      |  | (III)          |  | (IV)           | |
 | |         |  |           |  | Legacy         |  | 'Attached'(PoE | |
 | | Device  |  | Component |  | Device         |  | end Point)     | |
 | |         |  |           |  |                |  |                | |
 | +---------+  +-----------+  +----------------+  +----------------+ |
 +--------------------------------------------------------------------+

               Figure 1: GREEN Framework Reference Model

   The main elements in the framework are as follows:

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   *  (a), (d) Discovery and Inventory

   *  (b), (c) GREEN Metrics

   *  (b), (e) Monitor energy efficiency

   *  (f) Control Energy Saving

   *  (g) API Service Interface: enables access for service consumption,
      enabling data retrieval , control, and integration through API,
      e.g., [PetraApi].

   The monitoring interface (e) monitors more aspects than just power
   and energy, (for example traffic monitoring) but this is not covered
   in the framework.

   Note that the GREEN framework specifies logical blocks, however, the
   Energy Efficiency Management function might be implemented inside the
   device, based in [RFC8348], in the controller, or a combination of
   both.

   Even if the reference model implicitly assumes a hierarchical network
   structure, this assumption acknowledges that conventional networks
   have flatter and anticipate more distributed topologies.

   The reference model covers every network device and component that
   have a Unique Identifiable ID (UUID) and can represent or influence
   power or energy consumption.  If the component can be uniquely
   identified, it can be modeled.

   In scope:

   *  Devices

   *  Chassis,

   *  Line cards, modules, ports

   *  Power supply units (PSUs), fans, thermal units

   *  Accelerators, GPUs, NPUs

   *  Virtualized components where applicable

   *  Any element providing power, energy

3.1.  Data Collection Architecture

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3.1.1.  Telemetry Push Pattern

   The framework recommends a push-based telemetry model for energy
   efficiency data collection, where network devices stream power and
   energy measurements to management systems rather than waiting for
   poll requests.

   For energy monitoring specifically, push-based telemetry offers:

   *  Temporal accuracy: Energy consumption varies over time; push
      models capture variations that polling might miss.

   *  Reduced latency: Anomalies (power spikes, efficiency degradation)
      are detected immediately.

   *  Network and data collection efficiency: Eliminates repetitive
      poll/response cycles.

   *  Scalability: Controllers can subscribe once rather than poll
      continuously.

   Following the YANG-Push approach, several parameters from EMAN
   [RFC7460] are not needed in this framework:

   *  eoEnergyCollectionStartTime: Collection timing is managed by YANG-
      Push subscriptions.

   *  eoEnergyMaxConsumed/eoEnergyMaxProduced: Devices do not store
      energy time series; controllers handle historical data.

   *  Energy collection parameters table: Replaced by YANG-Push
      subscription configuration.

3.1.2.  Controller vs. Device Initiated

   The framework supports both initiation models:

   *  Controller-Initiated:

      -  Controller subscribes to Energy Objects streaming.

      -  Provides centralized control over monitoring scope and
         frequency

      -  Enables dynamic adjustment of monitoring based on operational
         needs

   *  Device-Initiated:

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      -  Devices can autonomously report critical energy events

      -  Useful for threshold violations or hardware failures

      -  Complements controller-initiated subscriptions

3.1.3.  UUID-Based Component Identification

   Energy metrics are anchored to hardware components using UUIDs from
   the "ietf-hardware" YANG module [RFC8348]:

   *  Each physical component (chassis, power supply, line card, etc.)
      has a stable UUID

   *  Energy metrics reference these UUIDs, enabling correlation with:

      -  Component lifecycle (installation, replacement,
         decommissioning)

      -  Inventory management systems

      -  Warranty and support tracking

      -  Asset management databases

   To enable stable component identification across systems, the GREEN
   Framework supports dual identifiers based on [RFC8348]: controllers
   will need to assign their own ID during onboarding, query the
   device's "ietf-hardware" UUID, and maintain a mapping between both
   for cross-system correlation.

3.1.4.  Measurement Accuracy and Data Source Classification

   Power and energy data reported by network elements differ
   significantly in origin and reliability.  Some values are derived
   from calibrated sensors, while others are based on manufacturer
   specifications, historical observations, or analytical models.  To
   ensure meaningful comparison, aggregation, and interpretation, the
   framework requires all reported energy-related metrics to include an
   explicit indication of measurement accuracy.

   The framework defines a common classification of data accuracy
   covering unknown, estimated, and directly measured values.  Measured
   data is further differentiated by precision levels.  This
   classification enables consumers of the data to assess reliability,
   prioritize upgrades, support regulatory compliance, and avoid
   incorrect aggregation or double counting across measurement domains.

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   Detailed accuracy categories, and extensibility mechanisms are
   specified in the GREEN YANG data model [PowerAndEnergy].

3.1.5.  Industry-Standard Certifications

   In addition to measurement accuracy, the framework supports the
   reporting of industry-standard energy efficiency certifications, per
   Energy Object, when available (for example a PSU).  These
   certifications provide vendor- or laboratory-validated benchmarks
   that characterize the designed efficiency of equipment and
   components.

   Certification information complements measurement accuracy by
   providing a stable, device-level reference for procurement,
   compliance, and lifecycle management, while accuracy indicators
   describe the reliability of operational measurements.  Together,
   these mechanisms enable informed assessment of both expected and
   observed energy performance.

   The purpose of this framework and YANG module is not to identify all
   certifications, but to establish a foundation for future extensions.
   Detailed certification models and encoding rules are defined in the
   companion GREEN YANG data model.

3.1.6.  Extensibility Through YANG Identities

   The accuracy hierarchy uses YANG identityref to allow vendor-specific
   extensions:

   identity accuracy-measured-vendor-calibrated {
     base accuracy-measured;
     description
       "Vendor-specific calibrated sensor with certificate ID XYZ";
   }

   This maintains interoperability (base accuracy-measured
   classification) while supporting proprietary accuracy metadata.

   Implementation details are in [PowerAndEnergy].

3.1.7.  Hierarchical Data Model and Default Value Inheritance

   The framework leverages the hierarchical structure of the "ietf-
   hardware" YANG module [RFC8348] to minimize redundant data reporting
   and simplify device implementation.  The framework refers as parent-
   child relationships.

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   Energy objects inherit their hierarchical containment relationships
   from the hardware component tree.  For example:

   *  A chassis(parent) contains line cards(children).

   *  Each line card(parent) contains ports(children).

   *  Each chassis(parent) is powered by power supply units(children).

   Energy metrics and metadata follow these same hierarchical
   relationships, enabling:

   *  Child components inherit measurement accuracy from their parent
      unless explicitly overridden.

   *  Reduced reporting overhead: Devices only transmit accuracy
      metadata for components that differ from their parent.

   *  Hierarchical validation: Controllers leverage the device
      containment tree (per [RFC8348]) to verify parent measurements by
      aggregating child values.

   The YANG data model [PowerAndEnergy] implements hierarchical defaults
   for key attributes.  For example:

   The data-source-accuracy leaf has a default value of accuracy-like-
   parent, meaning:

   *  If a chassis reports accuracy-measured-gold (±5%)

   *  All child components(line cards, ports, fans) automatically
      inherit accuracy-measured-gold

   *  Only components with different accuracy need to explicitly report
      their value

   Example:

Chassis (accuracy: gold ±5%)
├── Line Card 1 (inherits: gold ±5%)  ← No need to report
├── Line Card 2 (inherits: gold ±5%)  ← No need to report
└── PSU 1 (explicit: silver ±10%)     ← Must report (differs from parent)

   This reduces YANG-Push telemetry volume while maintaining accuracy
   transparency.

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3.1.8.  Unit Multiplier Consistency

   While unit-multiplier does not inherit, the framework recommends:

   *  Mandatory unit-multiplier specification OR

   *  Default to multiplier-units (10^0 = 1) for simplicity

   *Rationale from WG Discussion:* > "Either mandatory or default to 1,
   not inheritance.  Leave it open to authors to discuss further."  The
   final YANG model can choose either approach, but must not use
   inheritance to avoid client code complexity.

3.1.9.  Power Factor

   The YANG data model [PowerAndEnergy] introduces a power-factor leaf
   to capture Power Factor (PF), enabling controller engines to
   accurately compute real power.  PF is essential for accurately
   estimating real power consumption in AC-powered components,
   especially Power Supply Units (PSUs).

   The power-factor leaf defaults to 100 (unity power factor), meaning:
   - Devices with typical resistive loads don't need to report power
   factor - Only devices with significant reactive power (motors, large
   PSUs) need explicit values - Simplifies data for most networking
   equipment

3.2.  Typical Power Topologies

   The following reference model describes physical power topologies
   that exist in parallel with a communication topology.  While many
   more topologies can be created with a combination of devices, the
   following are some basic ones that show how Energy Management
   topologies differ from Network Management topologies.  Only the
   controller, devices and components, are depicted here, as the Network
   Domain Level remains identical.

   NOTE:

   *  "###" is used to denote a transfer of energy using Power
      Interface.

   *  "- >" is used to denote a transfer of information using Network
      Interface.

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3.2.1.  Basic Power Supply

   This covers the basic example of router connected to Power Outlet in
   the wall.

  +--------------------------------------------------------------------+
  |                                                                    |
  |                  (3) Network Domain Level                          |
  |                                                                    |
  +--------------------------------------------------------------------+

  (a)              (b)              (c)
  Inventory        Monitor       +- DataSheets/DataBase and/or via API
  Of identity      Energy        |  Metadata and other device/component
  and Capability   Efficiency    |  /network related information:
       ^               ^         |
       |               |         |  .Power/Energy related metrics
       |               |         |   information
       |               |         |  .Origin of Energy Mix
       |               |         |  .Carbon aware based on location
       |               |         |
       |               |         |
       |               |         |
       |               |         v
  +--------------------------------------------------------------------+
  |                                                                    |
  |       (2) controller (collection, compute and aggregate?)          |
  |                                                                    |
  +--------------------------------------------------------------------+
                                               ^   ^   ^
                                               |   |   |
                                              (d) (e) (f)
                                               |   |   |
                                               |   |   v
              +--------------+            +------------------+
              |              |            |                  |
              | Power Supply |############| Device/Component |
              |              |            |                  |
              +--------------+            +------------------+

          Figure 2: Reference Model Example: Basic Power Supply

3.2.2.  Physical Meter with Legacy Device

   This covers the basic example of device connected to wall Power
   Outlet, with a Physical Meter placed in the wall Power Outlet,
   because the device can not monitor its power, energy, demand.

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  +--------------------------------------------------------------------+
  |                                                                    |
  |                  (3) Network Domain Level                          |
  |                                                                    |
  +--------------------------------------------------------------------+

  (a)              (b)              (c)
  Inventory        Monitor       +- DataSheets/DataBase and/or via API
  Of identity      Energy        |  Metadata and other device/component
  and Capability   Efficiency    |  /network related information:
       ^               ^         |
       |               |         |  .Power/Energy related metrics
       |               |         |   information
       |               |         |  .Origin of Energy Mix
       |               |         |  .Carbon aware based on location
       |               |         |
       |               |         |
       |               |         |
       |               |         v
  +--------------------------------------------------------------------+
  |                                                                    |
  |       (2) controller (collection, compute and aggregate?)          |
  |                                                                    |
  +--------------------------------------------------------------------+
                                ^
                                |
                               (e)
                                |
                                |
      +--------------+   +----------------+   +---------------+
      |              |   |                |   |               |
      | Power Supply |###| Physical Meter |###| Legacy Device |
      |              |   |                |   |               |
      +--------------+   +----------------+   +---------------+

            Figure 3: Reference Model Example: Physical Meter

   When the EnMS discovers the physical meter, it must know for which
   Energy Object(s) it measures power or energy.  This is the Metering
   Relatonship.

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   A Metering Relationship is a relationship where one Energy Object
   measures power, energy, demand, or Power Attributes of one or more
   other Energy Objects.  The Metering Relationship gives the view of
   the Metering topology.  Physical meters can be placed anywhere in a
   power distribution tree.  For example, utility meters monitor and
   report accumulated power consumption of the entire building.
   Logically, the Metering topology overlaps with the wiring topology,
   as meters are connected to the wiring topology.  A typical example is
   meters that clamp onto the existing wiring.

3.2.3.  Physical Meter with New Device

   This covers the example of device connected to wall Power Outlet,
   with a Physical Meter placed in the wall Power Outlet, because the
   previous device was not able to monitor its power, energy, demand.

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   +-------------------------------------------------------------+
   |                                                             |
   |                  (3) Network Domain Level                   |
   |                                                             |
   +-------------------------------------------------------------+

   (a)             (b)           (c)
   Inventory      Monitor    +- DataSheets/DataBase and/or via API
   of identity    Energy     |  Metadata and other device/
   & capability  Efficiency  |  component/network related
        ^               ^    |  information:
        |               |    |  .Power/Energy related metrics
        |               |    |   Information
        |               |    |  .Origin of Energy Mix
        |               |    |  .Carbon aware based on location
        |               |    |
        |               |    |
        |               |    |
        |               |    v
   +--------------------------------------------------------------+
   |                                                              |
   |    (2) controller (collection, compute and aggregate?)       |
   |                                                              |
   +--------------------------------------------------------------+
                                 ^                 ^   ^   ^
                                 |                 |   |   |
                                (e)               (d) (e) (f)
                                 |                 |   |   |
                                 |                 |   |   v
    +--------------+   +----------------+   +------------------+
    |              |   |                |   |                  |
    | Power Supply |###| Physical Meter |###| Device/Component |
    |              |   |                |   |                  |
    +--------------+   +----------------+   +------------------+

     Figure 4: Reference Model Example: Physical Meter with New Device

   The most important issue in such a topology is to avoid the double
   counting in the Energy Management System (EnMS).  The physical meter
   reports the Energy transmitted, while the connected Device/Component
   might also report its consumed Energy.  Those two values are
   identical.  Without the knowledge of this specific topology, that is
   the Metering Relationship between the two Energy Objects, the EnMS
   will double count the Energy consumed in the network.

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3.2.4.  Power over Ethernet

   This covers the example of a switch port (Power Outlet) the provides
   energy with Power over Ethernet (PoE) to a PoE end points (camera,
   access port, etc.).

  +--------------------------------------------------------------------+
  |                                                                    |
  |                  (3) Network Domain Level                          |
  |                                                                    |
  +--------------------------------------------------------------------+

  (a)              (b)              (c)
  Inventory        Monitor       +- DataSheets/DataBase and/or via API
  Of identity      Energy        |  Metadata and other device/component
  and Capability   Efficiency    |  /network related information:
       ^               ^         |
       |               |         |  .Power/Energy related metrics
       |               |         |   information
       |               |         |  .Origin of Energy Mix
       |               |         |  .Carbon aware based on location
       |               |         |
       |               |         |
       |               |         |
       |               |         v
  +--------------------------------------------------------------------+
  |                                                                    |
  |       (2) controller (collection, compute and aggregate?)          |
  |                                                                    |
  +--------------------------------------------------------------------+
                ^   ^   ^                    ^   ^   ^
                |   |   |                    |   |   |
               (d) (e) (f)                  (d) (e) (f)
                |   |   |                    |   |   |
                |   |   v                    |   |   v
              +--------------+            +----------------+
              |              |            |                |
              | Device       |############| PoE End Point  |
              | (switch)     |            |                |
              |              |            |                |
              +--------------+            +----------------+

          Figure 5: Reference Model Example: Power over Ethernet

   Double counting is also an issue in such an example.  The switch
   port, via its Power Outlet, reports the Energy transmitted, while the
   PoE End Point, via its Power Inlet, reports its Energy consumed.

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   A second issue in such an example is the control topology.  The
   controller must have the knowledge that, if it shuts down the switch
   port, it will also switch off the connected PoE End Point, as a
   consequence.  This is the Power Source Relationship.

   A Power Source Relationship is a relationship where one Energy Object
   provides power to one or more Energy Objects.  The Power Source
   Relationship gives a view of the physical wiring topology -- for
   example, a PoE End Point receiving power from a switch port over PoE
   or a data center server receiving power from two specific Power
   Interfaces from two different PDUs.

   On top of that, there might be two control points for the PoE End
   Point.  First the connected switch port but also the controller
   direct connection to the PoE End Point (f).  Via this interface, the
   controller might for example put the PoE End Point to a lower Power
   State.

3.2.5.  Single Power Supply with Multiple Devices

   This covers the example of a smart PDU that provides energy to a
   series of routers in a rack.

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  +--------------------------------------------------------------------+
  |                                                                    |
  |                  (3) Network Domain Level                          |
  |                                                                    |
  +--------------------------------------------------------------------+

  (a)              (b)              (c)
  Inventory        Monitor       +- DataSheets/DataBase and/or via API
  Of identity      Energy        |  Metadata and other device/component
  and Capability   Efficiency    |  /network related information:
       ^               ^         |
       |               |         |  .Power/Energy related metrics
       |               |         |   information
       |               |         |  .Origin of Energy Mix
       |               |         |  .Carbon aware based on location
       |               |         |
       |               |         |
       |               |         |
       |               |         v
  +--------------------------------------------------------------------+
  |                                                                    |
  |       (2) controller (collection, compute and aggregate?)          |
  |                                                                    |
  +--------------------------------------------------------------------+
                ^   ^   ^                     ^   ^   ^
                |   |   |                     |   |   |
               (d) (e) (f)                   (d) (e) (f) ... N
                |   |   |                     |   |   |
                |   |   v                     |   |   v
              +--------------+            +--------------------+
              |              |            |                    |
              | Power Supply |############| Device/Component 1 |
              | (Smart PDU)  |  #         |                    |
              |              |  #         +--------------------+
              +--------------+  #
                                #
                                #         +--------------------+
                                #         |                    |
                                ##########| Device/Component 2 |
                                   #      |                    |
                                   #      +--------------------+
                                   #
                                   #      +--------------------+
                                   #      |                    |
                                   #######| Device/Component N |
                                          |                    |
                                          +--------------------+

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       Figure 6: Reference Model Example: Single Power Supply with
                             Multiple Devices

3.2.6.  Multiple Power Supplies with Single Device

 +--------------------------------------------------------------------+
 |                                                                    |
 |                  (3) Network Domain Level                          |
 |                                                                    |
 +--------------------------------------------------------------------+

 (a)              (b)              (c)
 Inventory        Monitor       +- DataSheets/DataBase and/or via API
 Of identity      Energy        |  Metadata and other device/component
 and Capability   Efficiency    |  /network related information:
      ^               ^         |
      |               |         |  .Power/Energy related metrics
      |               |         |   information
      |               |         |  .Origin of Energy Mix
      |               |         |  .Carbon aware based on location
      |               |         |
      |               |         |
      |               |         |
      |               |         v
 +--------------------------------------------------------------------+
 |                                                                    |
 |       (2) controller (collection, compute and aggregate?)          |
 |                                                                    |
 +--------------------------------------------------------------------+
       ^   ^   ^                ^   ^   ^                 ^   ^   ^
       |   |   |                |   |   |                 |   |   |
      (d) (e) (f)              (d) (e) (f)               (d) (e) (f)
       |   |   |                |   |   |                 |   |   |
       |   |   v                |   |   v                 |   |   v
    +----------------+      +------------------+      +----------------+
    |                |      |                  |      |                |
    | Power Supply 1 |######| Device/Component |######| Power Supply 2 |
    |                |      |                  |      |                |
    +----------------+      +------------------+      +----------------+

    Figure 7: Reference Model Example: Multiple Power Supplies with
                             Single Device

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3.3.  Relationships

   The framework for Energy Management needs to describe a means to
   monitor and control devices and components, and it needs to describe
   the relationships among, and connections between, devices and
   components.

   Two Energy Objects can establish an Energy Object Relationship to
   model the deployment topology with respect to Energy Management.

   Relationships are modeled with a Relationship that contains the UUID
   of the other participant in the relationship, along with a
   Relationship type.

   There are three types of relationships are Power Source, Metering,
   and Aggregations.

   *  A Power Source Relationship is a relationship where one Energy
      Object provides power to one or more Energy Objects.  The Power
      Source Relationship gives a view of the physical wiring topology
      -- for example, a data center server receiving power from two
      specific Power Interfaces from two different PDUs.

      Note: A Power Source Relationship may or may not change as the
      direction of power changes between two Energy Objects.  The
      relationship may remain to indicate that the change of power
      direction was unintended or an error condition.

   *  A Metering Relationship is a relationship where one Energy Object
      measures power, energy, demand, or Power Attributes of one or more
      other Energy Objects.  The Metering Relationship gives the view of
      the Metering topology.  Physical meters can be placed anywhere in
      a power distribution tree.  For example, utility meters monitor
      and report accumulated power consumption of the entire building.
      Logically, the Metering topology overlaps with the wiring
      topology, as meters are connected to the wiring topology.  A
      typical example is meters that clamp onto the existing wiring.

   *  An Aggregation Relationship is a relationship where one Energy
      Object aggregates Energy Management information of one or more
      other Energy Objects.  The Aggregation Relationship gives a model
      of devices that may aggregate (sum, average, etc.) values for
      other devices.  The Aggregation Relationship is slightly different
      compared to the other relationships, as this refers more to a
      management function.

   To prevent double counting in scenarios where one Energy Object
   provides power to another (e.g., PoE switch port to PoE endpoint):

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   Convention: Report both consumed and delivered energy separately: -
   The providing Energy Object reports total-energy-consumed (self) AND
   total-energy-delivered (to downstream) - The receiving Energy Object
   reports total-energy-consumed

   Example: A PoE switch port consuming 1W and providing 9W to an
   endpoint: - Port reports: total-energy-consumed=1W, total-energy-
   produced=9W - Endpoint reports: total-energy-consumed=9W

   Controllers must use Metering Relationships to identify and avoid
   aggregating both values.

   In some situations, it is not possible to discover the Energy Object
   Relationships, and an EnMS or administrator must manually set them.
   Given that relationships can be assigned manually, the following
   sections describe guidelines for use.

3.4.  Power State Set

   The Energy Object contains a Power State Set attribute that
   represents a set of Power States a device or component supports.

   A Power State describes a condition or mode of a device or component.
   While Power States are typically used for control, they may be used
   for monitoring only.

   A device or component is expected to support at least one set of
   Power States consisting of at least two states: an on state and an
   off state.

   The semantics of a Power State are specified by:

   *  The functionality provided by an Energy Object in this state.

   *  A limitation of the power that an Energy Object uses in this
      state.

   *  A combination of the first two.

   The semantics of a Power State should be clearly defined.  Limitation
   (curtailment) of the power used by an Energy Object in a state may be
   specified by:

   *  An absolute power value.

   *  A percentage value of power relative to the Energy Object's
      Nameplate Power.

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   *  An indication of power relative to another Power State.  For
      example, specify that power in state A is less than in state B.

   *  For supporting Power State management, an Energy Object provides
      statistics on Power States, including the time an Energy Object
      spent in a certain Power State and the number of times an Energy
      Object entered a Power State.

   There are many existing standards describing device and component
   Power States.  TO BE COMPLETED

3.5.  Power State Set Mapping and Intent

   Defining and enforcing power states can be challenging, because each
   Energy Object's technical capabilities must be mapped to high-level
   operational intents for energy-efficient operation.  The following
   examples illustrate how an Energy Object's power-saving capabilities
   can be aligned with typical intents:

   *  running at reduced capacity during predictable low-demand periods;

   *  lowering energy use while maintaining required performance levels;

   *  operating at a reduced service level when the site is on a backup
      power source during a grid outage.

   By expressing such intents, a controller can decide which power state
   an Energy Object should enter at any given time and under what
   conditions.

3.5.1.  Capability Discovery

   Identifying what power states an Energy Object supports is crucial
   for onboarding and integration, especially for legacy systems.  Key
   discovery elements include:

   *  Whether the energy object supports multiple Power State Sets.

   *  Semantics and limitations of each state (e.g., absolute power,
      relative power).

   *  Transition characteristics, such as the time required to move
      between states.

   *  Energy Object-specific state transition constraints like
      frequency, which may limit energy-saving measures to avoid
      damaging the device/components.

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   *  Impacts on measurement accuracy.

3.5.2.  Intent Mapping

   The goal of intent mapping is to translate Energy-Aware intent into
   specific device/component configurations.  For example:

   *  An intent like "reduce power consumption at low utilization" might
      map to a predefined low-power state.

   *  Controllers may interpret intents variably, e.g., "run at half
      capacity but be ready to scale up if needed."

   This is comparable to intent mapping in YANG-based systems, from
   high-level Customer-Facing Services (CFS) to Resource-Facing Services
   (RFS) and ultimately to device-specific configurations.

3.5.3.  SLA Considerations

   Meanwhile saving energy, the device or component shouldn't drop below
   a certain performance threshold or allow a certain service reduction
   or degradation.  Based on this, there are two kinds of service level
   expectations (SLAs) are associated with Power State behavior:

   *  Transition SLAs - e.g., the maximum time allowed to transition
      between states.

   *  Operational SLAs - e.g., device frequency or operational cycle
      limits that ensure long-term hardware health.

4.  Interfaces Usage Of the Framework

   This section provides an overview of how the GREEN use cases
   described in [GreenUseCases] interact with the framework interfaces
   defined in this document.

   Each use case is characterized by the sequence of framework
   interfaces it invokes to achieve energy-efficiency objectives.

4.1.  Mapping of Use Cases to Framework Interfaces

   The table Table 1 maps each GREEN use case to the framework
   interfaces and summarizes how these are used:

   *  The first line shows the interface sequences.

   *  The second line briefly describes the functional purpose of that
      flow.

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   The notation a->b->c represents the flow between framework components
   as described in the Figure 1, where:

   *  (a) Discovery interface

   *  (b) Monitoring interface

   *  (c) Metrics interface

      +====+========================+==============================+
      | UC | Use Case               | Interfaces Usages            |
      +====+========================+==============================+
      | 1  | Incremental deployment | c; c->b; a->d->b->e          |
      +----+------------------------+------------------------------+
      |    | of the GREEN Framework | 1,2: legacy; 3: GREEN WG     |
      |    |                        | support (i)                  |
      +----+------------------------+------------------------------+
      | 2  | Selective Reduction of | e->b->c->f                   |
      +----+------------------------+------------------------------+
      |    | Energy Consumption     | monitor->metrics->control    |
      +----+------------------------+------------------------------+
      | 3  | Reporting on Lifecycle | c->g                         |
      +----+------------------------+------------------------------+
      |    | Management             | metrics / metadata->API or   |
      |    |                        | report                       |
      +----+------------------------+------------------------------+
      | 4  | Real-time Energy       | b->c                         |
      |    | Metering               |                              |
      +----+------------------------+------------------------------+
      |    | of Virtualised NFs     | monitor->metrics             |
      +----+------------------------+------------------------------+
      | 5  | Indirect Energy        | b->f                         |
      |    | Monitoring             |                              |
      +----+------------------------+------------------------------+
      |    | & Control              | monitor aggregate->control   |
      +----+------------------------+------------------------------+
      | 6  | Consideration of Other | c->g->b                      |
      +----+------------------------+------------------------------+
      |    | Domains for End-to-End | metrics->cross-domain API->  |
      +----+------------------------+------------------------------+
      |    | Metrics                | monitoring                   |
      +----+------------------------+------------------------------+
      | 7  | Dynamic Adjustment via | b->f->c                      |
      +----+------------------------+------------------------------+
      |    | Traffic Levels         | observe->control->update     |
      |    |                        | metrics                      |
      +----+------------------------+------------------------------+
      | 8  | Video Streaming Use    | b->c->f                      |

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      |    | Case                   |                              |
      +----+------------------------+------------------------------+
      |    |                        | monitor->metrics->control    |
      +----+------------------------+------------------------------+
      | 9  | WLAN Network Energy    | b->f                         |
      |    | Saving                 |                              |
      +----+------------------------+------------------------------+
      |    |                        | monitor->control             |
      +----+------------------------+------------------------------+
      | 10 | Fixed Network Energy   | b->f                         |
      +----+------------------------+------------------------------+
      |    | Saving                 | monitor->control             |
      +----+------------------------+------------------------------+
      | 11 | Energy Efficiency      | a->b->c->f->g                |
      |    | Network                |                              |
      +----+------------------------+------------------------------+
      |    | Management             | discover->monitor->metrics-> |
      +----+------------------------+------------------------------+
      |    |                        | control->API                 |
      +----+------------------------+------------------------------+
      | 12 | ISAC-enabled Energy-   | ---                          |
      |    | Aware                  |                              |
      +----+------------------------+------------------------------+
      |    | Smart City Traffic     | not clearly specified        |
      |    | Mgmt                   |                              |
      +----+------------------------+------------------------------+
      | 13 | Double Accounting Open | c->g                         |
      +----+------------------------+------------------------------+
      |    | Issue                  | metrics / metadata->API      |
      +----+------------------------+------------------------------+
      | 14 | Energy Efficiency      | b->f                         |
      |    | Under                  |                              |
      +----+------------------------+------------------------------+
      |    | Power Shortage         | monitor->control             |
      +----+------------------------+------------------------------+
      | 15 | Energy-Efficient Mgmt  | b->c->f                      |
      |    | of                     |                              |
      +----+------------------------+------------------------------+
      |    | AI Training Workloads  | monitor->metrics->control    |
      +----+------------------------+------------------------------+

                   Table 1: Use Cases Interfaces Usage

   Use Case 1 (Incremental Deployment) illustrates how the usage of the
   framework interfaces evolves during the lifecycle of a network or
   device group, starting with legacy reporting, which is represented by
   1=(c) and 2=(c -> b) and progressively incorporating GREEN-specific
   components 3=(a -> d -> b -> e).

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5.  Use Case Implementation Requirements: Device vs. Controller Centric

   This section analyzes the [GreenUseCases] to identify which
   capabilities require device-level implementation versus controller
   orchestration.  This guides implementers on device feature priorities
   and operators on controller capabilities needed for effective energy
   management.

   The framework distinguishes between two orthogonal concepts:

5.1.  Implementation Focus: Where Intelligence Resides

   Device-Centric Use Cases require autonomous on-device decision-
   making: - Example: UC 14 (Power Shortage) - Device must independently
   manage backup power transitions when network connectivity is lost. -
   It might require local algorithms, minimal controller dependency,
   autonomous operation, etc.

   Controller-Centric Use Cases require centralized orchestration and
   network-wide visibility: - Example: UC 10 (Fixed Network Saving) -
   Controller predicts traffic patterns across devices and coordinates
   state changes. - It requires cross-device coordination, centralized
   intelligence

   Use Cases need both device capabilities and controller coordination:
   - Example: UC 9 (WLAN Energy Saving) - Devices support power modes;
   controller coordinates AP groups to maintain coverage.

   Who triggers telemetry is independent of implementation focus and
   follows YANG-Push [RFC8641] patterns:

   Controller-Initiated, or Dynamic subscription: - Controller
   establishes YANG-Push subscriptions to energy objects - Device
   streams telemetry at specified intervals (periodic) or on change
   (event-driven) - Centralized monitoring policy management

   Device-Initiated, or Static Subscription: - Device autonomously
   pushes alerts without prior subscription - Used for threshold
   violations, hardware failures, certification degradation -
   Complements controller-initiated monitoring

   Even device-centric use cases(autonomous operation) typically use
   controller-initiated telemetry (controller subscribes to observe
   device behavior).  These concepts are independent.

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    +======================+==============+===========================+
    | UC#                  | Use Case     | Critical Capabilities     |
    +======================+==============+===========================+
    | *Device-Centric*     |              |                           |
    +----------------------+--------------+---------------------------+
    | 14                   | Power        | Backup power awareness,   |
    |                      | Shortage     | autonomous operation      |
    |                      | Management   |                           |
    +----------------------+--------------+---------------------------+
    | 1                    | Incremental  | Baseline metrics,         |
    |                      | Deployment   | certification reporting,  |
    |                      |              | capability discovery      |
    +----------------------+--------------+---------------------------+
    +----------------------+--------------+---------------------------+
    | *Device +            |              |                           |
    | Controller*          |              |                           |
    +----------------------+--------------+---------------------------+
    | 4                    | Virtualized  | HW-layer metering, VM     |
    |                      | NF Metering  | correlation, real-time    |
    |                      |              | telemetry push            |
    +----------------------+--------------+---------------------------+
    | 9                    | WLAN Energy  | PoE power modes, double   |
    |                      | Saving       | counting, coordinated     |
    |                      |              | state transitions         |
    +----------------------+--------------+---------------------------+
    +----------------------+--------------+---------------------------+
    | *Controller-Centric* |              |                           |
    +----------------------+--------------+---------------------------+
    | 2                    | Selective    | Traffic pattern analysis, |
    |                      | Energy       | coordinated sleep modes,  |
    |                      | Reduction    | global optimization       |
    +----------------------+--------------+---------------------------+
    | 3                    | Lifecycle    | External database         |
    |                      | Reporting    | integration, carbon       |
    |                      |              | factor correlation,       |
    |                      |              | metadata aggregation      |
    +----------------------+--------------+---------------------------+
    | 5                    | Indirect     | PDU/meter integration,    |
    |                      | Monitoring   | topology-aware            |
    |                      |              | aggregation, proxy        |
    |                      |              | measurement               |
    +----------------------+--------------+---------------------------+
    | 6                    | Cross-Domain | Multi-domain API          |
    |                      | Metrics      | integration, double-      |
    |                      |              | accounting prevention,    |
    |                      |              | metric mapping            |
    +----------------------+--------------+---------------------------+
    | 7                    | Wireless     | *Traffic-aware power      |

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    |                      | Transport    | adjustment, dynamic link  |
    |                      | Optimization | control, pattern          |
    |                      |              | recognition               |
    +----------------------+--------------+---------------------------+
    | 8                    | Video        | Multicast optimization,   |
    |                      | Streaming    | cache placement, traffic  |
    |                      |              | engineering               |
    +----------------------+--------------+---------------------------+
    | 10                   | Fixed        | pattern prediction,       |
    |                      | Network      | coordinated               |
    |                      | Saving       | reconfiguration, AI/ML    |
    |                      |              | integration               |
    +----------------------+--------------+---------------------------+
    | 11                   | Network-Wide | Centralized visibility,   |
    |                      | Management   | topology mapping, vendor- |
    |                      |              | neutral aggregation       |
    +----------------------+--------------+---------------------------+
    | 12                   | ISAC Smart   | Context-aware activation, |
    |                      | City         | city-wide coordination,   |
    |                      |              | sensing prioritization    |
    +----------------------+--------------+---------------------------+
    | 13                   | Double       | Metering topology         |
    |                      | Accounting   | awareness, relationship   |
    |                      | Prevention   | modeling, intelligent     |
    |                      |              | aggregation               |
    +----------------------+--------------+---------------------------+
    | 15                   | AI Training  | Energy-aware scheduling,  |
    |                      | Workloads    | data placement, East-West |
    |                      |              | traffic optimization      |
    +----------------------+--------------+---------------------------+
    | 16                   | Cross-Layer  | Multi-layer coordination  |
    |                      | Saving       | (L0-L3), cross-layer      |
    |                      |              | state synchronization     |
    +----------------------+--------------+---------------------------+

                   Table 2: Use Case Implementation Focus

   <<TODO - consider to include>>

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5.2.  Key Findings

5.2.1.  Device Capabilities Required across Use Cases

5.2.2.  Controller Capabilities Required across Use Cases

5.3.  Implementation Priorities

5.4.  Next Steps

   <<TODO - ends here>>

6.  Conventions and Definitions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

7.  Operational Considerations

8.  Security Considerations

   Resiliency is an implicit use case of energy efficiency management
   which comes with numerous security considerations :

   Controlling Power State and power supply of entities are considered
   highly sensitive actions, since they can significantly affect the
   operation of directly and indirectly connected devices.  Therefore,
   all control actions must be sufficiently protected through
   authentication, authorization, and integrity protection mechanisms.

   Entities that are not sufficiently secure to operate directly on the
   public Internet do exist and can be a significant cause of risk, for
   example, if the remote control functions can be exercised on those
   devices from anywhere on the Internet.

   The monitoring of energy-related quantities of an entity as addressed
   can be used to derive more information than just the received and
   provided energy; therefore, monitored data requires protection.  This
   protection includes authentication and authorization of entities
   requesting access to monitored data as well as confidentiality
   protection during transmission of monitored data.  Privacy of stored
   data in an entity must be taken into account.  Monitored data may be
   used as input to control, accounting, and other actions, so integrity
   of transmitted information and authentication of the origin may be
   needed.

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9.  IANA Considerations

   This document has no IANA actions.

10.  References

10.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/rfc/rfc2119>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.

   [RFC8348]  "A YANG Data Model for Hardware Management", March 2018,
              <https://www.rfc-editor.org/info/rfc8348>.

10.2.  Informative References

   [GreenTerminology]
              Chen, G., Boucadair, M., Wu, Q., Contreras, L. M., and M.
              P. Palmero, "Terminology for Energy Efficiency Network
              Management", Work in Progress, Internet-Draft, draft-ietf-
              green-terminology-01, 13 February 2026,
              <https://datatracker.ietf.org/doc/html/draft-ietf-green-
              terminology-01>.

   [GreenUseCases]
              Stephan, E., Palmero, M. P., Claise, B., Wu, Q.,
              Contreras, L. M., Bernardos, C. J., and X. Chen, "Use
              Cases for Energy Efficiency Management", Work in Progress,
              Internet-Draft, draft-ietf-green-use-cases-01, 22 January
              2026, <https://datatracker.ietf.org/doc/html/draft-ietf-
              green-use-cases-01>.

   [I-D.li-green-power]
              Li, T. and R. Bonica, "A YANG model for Power Management",
              Work in Progress, Internet-Draft, draft-li-green-power-00,
              17 October 2024, <https://datatracker.ietf.org/doc/html/
              draft-li-green-power-00>.

   [IEC60050] IEC, "Power Utility Automation", 11 December 2000,
              <http://www.iec.ch/smartgrid/standards/>.

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   [IEEE100]  IEEE, "The Authoritative Dictionary of IEEE Standards
              Terms", 11 December 2000, <http://ieeexplore.ieee.org/xpl/
              mostRecentIssue.jsp?punumber=4116785>.

   [IEEE1621] IEEE, "Standard for User Interface Elements in Power
              Control of Electronic Devices Employed in Office/Consumer
              Environments, IEEE 1621", December 2004.

   [PetraApi] Rodriguez-Natal, A., Contreras, L. M., Palmero, M. P.,
              Lindblad, J., and A. G. Sánchez, "Path Energy Traffic
              Ratio API (PETRA)", Work in Progress, Internet-Draft,
              draft-petra-green-api-03, 2 March 2026,
              <https://datatracker.ietf.org/doc/html/draft-petra-green-
              api-03>.

   [PowerAndEnergy]
              Claise, B., Chen, G., Palmero, M. P., and J. Lindblad,
              "Power and Energy YANG Module", Work in Progress,
              Internet-Draft, draft-bcmj-green-power-and-energy-yang-04,
              2 March 2026, <https://datatracker.ietf.org/doc/html/
              draft-bcmj-green-power-and-energy-yang-04>.

   [RFC7326]  Parello, J., Claise, B., Schoening, B., and J. Quittek,
              "Energy Management Framework", RFC 7326,
              DOI 10.17487/RFC7326, September 2014,
              <https://www.rfc-editor.org/rfc/rfc7326>.

   [RFC7460]  Chandramouli, M., Claise, B., Schoening, B., Quittek, J.,
              and T. Dietz, "Monitoring and Control MIB for Power and
              Energy", RFC 7460, DOI 10.17487/RFC7460, March 2015,
              <https://www.rfc-editor.org/rfc/rfc7460>.

   [RFC8641]  Clemm, A. and E. Voit, "Subscription to YANG Notifications
              for Datastore Updates", RFC 8641, DOI 10.17487/RFC8641,
              September 2019, <https://www.rfc-editor.org/rfc/rfc8641>.

   [TMN]      "International Telecommunication Union, "TMN management
              functions"", February 2000, <ITU-T Recommendation M.3400>.

Appendix A.  TO DO and Open Issues

   *  IEC60050 reference needs a new URL

   The following topics remain open for further discussion points:

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A.1.  Discovering Capabilities

   *  Enable automatic detection of power-saving features.

   *  Allow controllers to easily discover device-specific limits like
      transition time and duty cycle.

A.2.  Understanding Device Capabilities

   *  Explore if Energy Objects can support multiple sets of power
      states.

   *  Make power states clearly described and understandable.

   *  Represent these capabilities in a machine-readable format.

A.3.  Mapping Intents to Device Settings

   *  Develop ways to translate high-level energy goals (like "save
      energy at low utilization") into actual device configurations.

   *  Create a standard method to describe this mapping across systems.

A.4.  Handling Transitions and Ensuring Safety

   *  Capability to power off individual components, as described in
      [I-D.li-green-power], should be explicitly modeled in the Power
      State Set. Also to review recovery procedures and impact on
      dependent Energy Objects.

   *  Consider how long it takes for an Energy Object to switch power
      states.

   *  Recommendation to standardize a data model for safe limits on
      frequency or speed of transitions to prevent device/component's
      damage.

   *  Model SLAs that include both performance (e.g., transition time)
      and device safety (e.g., cycle limitations).

A.5.  East-West Traffic/Energy Metrics

   *  Recommendation to standardize a data model for new equipment
      interconnected East-West with optimized energy consumption.

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Acknowledgments

   This framework takes into account concepts from the Energy MANagement
   (EMAN) Framework [RFC7326], authors by John Parello, Benoit Claise,
   Brad Schoening, and Juergen Quittek.  The contribution of Luis M.
   Contreras to this document has been supported by the Smart Networks
   and Services Joint Undertaking (SNS JU) under the European Union's
   Horizon Europe research and innovation projects 6Green (Grant
   Agreement no. 101096925) and Exigence (Grant Agreement no.
   101139120).

Authors' Addresses

   Benoit Claise
   Everything OPS
   Email: benoit@everything-ops.net

   Luis M. Contreras
   Telefonica
   Email: luismiguel.contrerasmurillo@telefonica.com

   Jan Lindblad
   All For Eco
   Email: jan.lindblad+ietf@for.eco

   Marisol Palmero
   Independent
   Email: marisol.ietf@gmail.com

   Emile Stephan
   Orange
   Email: emile.stephan@orange.com

   Qin Wu
   Huawei
   Email: bill.wu@huawei.com

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