Terminology for Energy Efficiency Network Management
draft-ietf-green-terminology-01

GREEN Working Group                                              G. Chen
Internet-Draft                                                    Huawei
Intended status: Informational                              M. Boucadair
Expires: 17 August 2026                                           Orange
                                                                   Q. Wu
                                                                  Huawei
                                                         L. M. Contreras
                                                              Telefonica
                                                              M. Palmero
                                                              Individual
                                                        13 February 2026

          Terminology for Energy Efficiency Network Management
                  draft-ietf-green-terminology-01

Abstract

   Energy-efficient network management is primarily meant to enhance
   conventional network management with energy-related management
   capabilities that optimize overall network energy consumption.  To
   that aim, specific features and capabilities are required to control
   (and thus optimize) the energy use of involved network elements and
   their components.

   This document defines a set of key terms used within the IETF when
   discussing energy efficiency in network management.  Such reference
   document helps framing discussion and agreeing upon a set of main
   concepts in this area.

Discussion Venues

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

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

   Source for this draft and an issue tracker can be found at
   https://github.com/billwuqin/draft-bclp-green-terminology.

Status of This Memo

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   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on 17 August 2026.

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Table of Contents

   1.  Introduction
   2.  Abbreviations
   3.  Definitions
   4.  Sample Energy Efficiency Metrics and Measurement Methods
     4.1.  Metrics for Access Equipment
     4.2.  Metric for Wireless Access Technologies
     4.3.  Metrics for Routers and Ethernet Switches
     4.4.  Metrics for Small Network Devices
     4.5.  Metric for Power Equipment
     4.6.  Metric for Cooling Equipment
   5.  Operations and Manageability Considerations
   6.  Security Considerations
   7.  Informative References
   Appendix A.  Standards Bodies and Standards
     A.1.  ITU-T SG5
     A.2.  ETSI TCEE
     A.3.  3GPP SA5
   Appendix B.  Changes between Revisions
   Appendix C.  Acknowledgments
   Contributors
   Authors' Addresses

1.  Introduction

   With rising energy costs and increasing awareness of the
   environmental impact of running networks, servers, and various
   equipment, Energy Efficiency is considered by operators as a critical
   component to be integrated in the overall Network Management systems.
   Such integration is ambitioned to feed strategies for achieving
   environmental objectives but also mastering related operational cost.
   Energy Efficiency Management is thus complementing conventional
   network management.

   Section 3 defines a set of terms used within the IETF when discussing
   energy-efficient networks.  The purpose is to (1) ensure consistent
   use of a set of terms in this area, (2) help with the
   characterization of Energy Efficiency (and relevant aspects), (3)
   assist in the development of the YANG data models at the different
   levels in the IETF, and (4) bring clarity to the Energy Efficiency
   related discussions between different groups within the IETF, in
   particular.

   This document does not intend to define a comprehensive list of
   energy-related terms.  Only key terms are defined.  Some of these
   terms are extracted from existing IETF documents and beyond.

   Also, Section 4 provides an inventory of currently used metrics to
   assess/compute energy-related consumption, efficiency ratio, etc.

   Appendix A provides a list of SDOs where relevant energy efficiency
   effort is ongoing.

2.  Abbreviations

   The following abbreviations are used in the document:

   CLEE:  Component Level Energy Efficiency

   DLEE:  Device Level Energy Efficiency

   DSLAM:  Digital Subscriber Line Access Multiplexer

   EER  Energy Efficiency Ratio

   GEPON:  Gigabit Ethernet Passive Optical Network

   GPON:  Gigabit-capable Passive Optical Network

   MSAN:  Multiservice Access Node

   NDR:  None-Drop Rate

   NLEE:  Network Level Energy Efficiency

   PUE:  Power Usage Effectiveness

   SLEE:  Service Level Energy Efficiency

3.  Definitions

   Terms are listed so that terms that are needed to understand other
   terms are listed first.

   Energy:  Is generally a reference to electrical energy and is
      measured in kilowatt-hours (kWh) ([RFC7326]).

   Energy Object:  Represents an 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.

   Power:  Refers to the time rate at which energy is emitted,
      transferred, or received; power is usually expressed in watts
      (joules per second) ([RFC7326]).

   Energy Management:  Is a set of functions for measuring, modeling,
      planning, and optimizing networks to ensure that the network and
      network-attached devices use energy efficiently and appropriately
      for the nature of the application and the cost constraints of the
      organization ([RFC7326]).

   Energy Monitoring:  Is a part of Energy Management that deals with
      collecting or reading information from devices to aid in Energy
      Management ([RFC7326]).

   Energy Control:  Is a part of Energy Management that deals with
      directing influence over devices ([RFC7326]).

      This control can span a network or a subset of it.

   Energy Saving:  A reduction in total energy consumption, typically
      measured against a baseline or per unit of output, rather than
      just a month-on-month decrease.

   Energy Efficiency:  Refers to optimizing energy usage in network
      components, devices, and across the network to minimize energy use
      as much as possible, thus eliminating energy waste.  Examples to
      improve Energy efficiency include, but are not limited to,
      deactivation of some or all components of network nodes during
      specific periods (e.g., periods with low traffic), adjusting the
      speed of an interface based on network traffic load changes,
      switching to more efficient power supplies and silicon, or
      developing more efficient transmission or signal processing
      algorithms.

   Energy Efficiency Management:  Refers to a set of processes used to
      maintain an inventory of capabilities, use specific metrics to
      measure, report, and assess energy consumption of the network, and
      control the use of available energy in an optimized manner.  The
      overall goal is to ensure that the network and underlying devices
      use energy in a resource-conserving manner and at low cost for the
      nature of the the services it provides and the cost constraints
      while achieving the network’s functional and performance
      requirements (e.g., improving overall network utilization).

   Energy Efficiency Observability:  Is a component of Energy Efficiency
      Management that deals with collecting, reporting, and reading
      metrics information from devices and evaluating the effectiveness
      of energy-aware policies to aid in Energy Efficiency Management.

   Energy Efficiency Control:  Is a component of Energy Efficiency
      Management that deals with directing influence over devices.

   Energy Efficiency Capabilities:  Network Capabilities to optimize
      energy usage in network components, devices, and across the
      network through configurable static attributes (e.g., power saving
      capable attribute which can be applied to both component level and
      device level, or power setting attributes which specify absolute
      power, relative power, who provide power, who consume, who is the
      meter, measurement frequency, or temperature setting, voltage,
      ampere setting).

   Energy Efficiency Metric:  Refers to a metric that is used for the
      assessment of energy consumption of a network, device, or
      component.  One or more metrics can be defined.  These metrics are
      also used for network performance purposes to characterize the
      effectiveness of an Energy Efficiency management strategy.
      Developing energy efficiency metrics for internetworking and
      associated measurement methodologies and conditions as well as
      consistently collecting this data over time are essential to
      demonstrating Energy Efficiency improvements.  An example of a
      common outcome-oriented metric is energy consumption per data
      volume or traffic unit.

   Energy Proportionality  Is the correlation between energy used and
      the associated useful output.  For internetworking this is
      generally interpreted as the proportionality of traffic or traffic
      throughput and energy used.  This concept is broadly applicable to
      networking infrastructure, data center, and other communication
      architectures.  There might not be a one-to-one correlation
      between traffic and energy use, notably due to the materially
      significant idle power use by devices, as well as the overall
      network capacity being allocated to serve at times of highest
      traffic utilization.

   Energy Efficiency/Energy Efficiency Ratio (EER):  The energy
      efficiency is expressed as the ratio between the useful output and
      input of an energy conversion process of a network, device, or
      component.

      For instance, in relation with a networking device, it can be
      stated as the ratio of total throughput (e.g., of a network
      element capacity) to the total power consumed (bits/Joule).

      This ratio (i.e., Energy Efficiency Ratio, EER) is the throughput
      forwarded by 1 watt (e.g., [I-D.ietf-bmwg-powerbench]).

      A higher EER indicates a better energy efficiency.

   Energy-Aware Intent:  A declarative, technology-agnostic expression
      of an energy-related operational objective for the network.
      Unlike imperative configurations that specify exactly how to
      achieve a result, an energy-aware intent focuses on what energy
      behavior is desired (e.g., minimize power consumption or optimize
      energy-to-throughput ratios), leaving the system to determine the
      best enforcement method.

      Energy-aware intents ([RFC9315]) are interpreted by network
      management or orchestration systems, which translate them into
      actionable control logic, such as powering down interfaces,
      reducing link speeds.  These intents enable policy-driven,
      automated, and potentially closed-loop energy optimization aligned
      with business goals.

   Power Usage Effectiveness (PUE):  Refers to the metric used to
      measure the energy efficiency of an infrastructure.

      This metric is calculated as the ratio between the total energy
      consumed by an infrastructure and the energy needed for a network
      element/component.

   Network Level Energy Efficiency (NLEE):  Denotes the Energy
      Efficiency of an entire network or a subset part of it (e.g.,
      access network).

   Device Level Energy Efficiency (DLEE):  Denotes the Energy Efficiency
      of a network element.  It can be used, e.g., to compare network
      elements providing the same functionality or a target to optimize
      the configuration of a network element.  Here "Device Level" is
      equivalent to "System Level", which is considered as a "single
      device" or "single entity" from the measurement and reporting
      perspective.

   Component Level Energy Efficiency (CLEE):  Denotes the Energy
      Efficiency of a component of a network element.  It can be used in
      the design, development, and manufacturing of energy efficient
      network elements.  Here "Component Level" is equivalent to "Sub-
      System Level", which is considered as an "abstract " or
      "incomplete specification" of a portion of a system from the
      measurement and reporting perspective.

      CLEE is useful to evaluate the energy efficiency performance of
      individual components of a network element.

      Measuring and understanding the energy efficiency or energy
      consumption of each component within a network element may be used
      to identify key components in a system with regard to energy
      saving.

   Service Level Energy Efficiency (SLEE):  Denotes the total energy
      consumption attributed to delivering a specific service or
      application within a network segment.

      SLEE enables operators to measure and report the per-service
      energy footprint, providing valuable insights for operational
      benchmarking, and capacity planning.

4.  Sample Energy Efficiency Metrics and Measurement Methods

   This section lists some metrics that are adopted by other SDOs.

      DISCUSS: Should we maintain this section?

4.1.  Metrics for Access Equipment

   Access Equipment with line cards working at different profiles/states
   are characterized with different metric values for each specific
   profile/state.

                         Pport = Peq/Nports[W/port]

   Where:

   *  'Peq' is the power (in watts) of a fully equipped wireline network
      equipment with all its line cards working in a specific profile/
      state.

   *  'Nports' is the maximum number of ports served by the broadband
      network equipment under test.

   The formula is defined in [L.1310].

4.2.  Metric for Wireless Access Technologies

   The energy efficiency metric at Radio Frequency (RF) unit level is as
   follows:

                        EErfu = Eoutput/Erfu

   Where:

   *  'Eoutput' is daily RF output energy consumption [Wh] under
      different load.

   *  'Erfu' is daily RF units energy consumption [Wh] under different
      load.

   The formula is defined in [L.1310].

4.3.  Metrics for Routers and Ethernet Switches

   The metric for routers and Ethernet switches is as follows:

                       EER = Ti/Pw [Mbit/s/W]

   Where 'Ti' is NDR throughput, 'Pw' is weighted power (energy
   consumption rate).  The formula is defined in [L.1310].

                       Pw = a*Pu1 + b*Pu2 + c*Pu3

   Where:

   *  'a'/'b'/'c' are the relative weight at different usage percentage
      with a+b+c=1.

   *  'Pu1'/'Pu2'/'Pu3' are the power at different usage percentage.

4.4.  Metrics for Small Network Devices

   A metric for small networking devices intended for home/domestic or
   small office use is as follows:

                      EER = Ti/Pw [Mbit/s/W]

   Where Ti is NDR throughput between wide area network (WAN) and local
   area network (LAN) ports in the ingress direction, Pw is the average
   power during Full load, Idle load and Low power, the formula is
   defined in [L.1310].

                     Ti = 0.35T_idle+0.5T_lowpower+0.15T_maximum
                     Pw = 0.35P_idle+0.5P_lowpower+0.15P_maximum

   where:

   *  (0.35,0.5,0.15) is the relative weight at different usage mode.

   *  'P_idle'/'P_lowpower'/'P_maximum' is the average power at
      different usage mode.

   *  'T_idle'/'T_lowpower'/'T_maximum' is NDR throughput at different
      usage mode.

4.5.  Metric for Power Equipment

                              δ = Po/Pi

   Where:

   *  'Po' is output power.

   *  'Pi' is input power.

   This energy efficiency value is measured or calculated from the
   testing data over a given time period.  The formula is defined in
   [L.1320].

4.6.  Metric for Cooling Equipment

                             η = Qt/Pi

   Where:

   *  'η' is the energy efficiency of the air conditioner.

   *  'Pi' is the input power.

   *  'Qt' is the sum of the sensible cooling capacity and the latent
      cooling capacity.

   The formula is defined in [L.1320].

5.  Operations and Manageability Considerations

   This document defines terminology intended to ensure consistency
   among various efforts and deployment levels.  No other operations or
   manageability requirements are introduced by this document.

6.  Security Considerations

   Security is not discussed in this document.

7.  Informative References

   [ETSI-ES-203-136]
              "Environmental Engineering (EE); Measurement methods for
              energy efficiency of router and switch equipment", 2017,
              <https://www.etsi.org/deliver/
              etsi_es/203100_203199/203136/01.02.00_50/
              es_203136v010200m.pdf>.

   [I-D.ietf-bmwg-powerbench]
              Pignataro, C., Jacob, R., Fioccola, G., Wu, Q., Chen, G.,
              and S. Prabhu, "Characterization and Benchmarking
              Methodology for Power in Networking Devices", Work in
              Progress, Internet-Draft, draft-ietf-bmwg-powerbench-01,
              12 February 2026, <https://datatracker.ietf.org/doc/html/
              draft-ietf-bmwg-powerbench-01>.

   [L.1310]   "Energy efficiency metrics and measurement methods for
              telecommunication equipment", 2024,
              <https://www.itu.int/rec/T-REC-L.1310-202409-P>.

   [L.1315]   "Standardization terms and trends in energy efficiency",
              2017, <https://www.itu.int/rec/T-REC-L.1315-201705-I>.

   [L.1316]   "Energy efficiency framework", 2019,
              <https://www.itu.int/rec/T-REC-L.1316-201911-I>.

   [L.1320]   "Energy efficiency metrics and measurement for power and
              cooling equipment for telecommunications and data
              centres", 2014,
              <https://www.itu.int/rec/T-REC-L.1320-201403-I>.

   [L.1331]   "Assessment of mobile network energy efficiency", 2020,
              <https://www.itu.int/rec/T-REC-L.1331-202009-S>.

   [L.1333]   "Carbon data intensity for network energy performance
              monitoring", 2022,
              <https://handle.itu.int/11.1002/1000/15028>.

   [L.1410]   "Methodology for environmental life cycle assessments of
              information and communication technology goods, networks
              and services", 2014,
              <https://www.itu.int/rec/T-REC-L.1410-201412-I>.

   [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>.

   [RFC9315]  Clemm, A., Ciavaglia, L., Granville, L. Z., and J.
              Tantsura, "Intent-Based Networking - Concepts and
              Definitions", RFC 9315, DOI 10.17487/RFC9315, October
              2022, <https://www.rfc-editor.org/rfc/rfc9315>.

   [TS28.554] "Management and orchestration; 5G end to end Key
              Performance Indicators (KPI)", 2024,
              <https://www.3gpp.org/ftp/Specs/
              archive/28_series/28.554/28554-i70.zip>.

Appendix A.  Standards Bodies and Standards

   This appendix provides a list of SDOs where relevant energy
   efficiency effort is ongoing.  This appendix does not aim to be
   comprehensive.  The appendix may be removed in future versions of the
   document.

A.1.  ITU-T SG5

   ITU-T Study Group 5 (SG5) has already worked on developing standards
   on energy efficiency.  ITU-T SG5 has many standards in the
   environment efficiency field.  These standards include [L.1310],
   [L.1315], [L.1316], and [L.1320] covering energy efficiency
   terminology, framework, metrics, and measurement methods.

   ITU-T SG5 is also responsible for other standards that might be of
   interest to protocol developers and network operators.  For example:

   *  [L.1331] specifies assessment of mobile network energy efficiency.

   *  [L.1333] specifies the correlation between the carbon intensity
      indicator and energy efficiency metric.  The carbon KPI defined in
      [L.1333] refers to the energy efficiency metric defined in ITU-T
      L.1331.

   *  [L.1410] focuses on the assessment of the environmental impact of
      information and communication technology (ICT) goods, networks and
      services.  It provides specific guidance on energy and greenhouse
      gas (GHG) impacts.

A.2.  ETSI TCEE

   ETSI Technical Committee (TC) Environment Engineering (EE) is
   collaborating with ITU-T SG5 to develop technically aligned standards
   on energy efficiency and environment aspect.  These standards include
   energy efficiency, power feeding solution, circular economy and
   network efficiency KPI and eco-design requirement for ICT, with the
   aim to build an international eco-environmental standardization.

   [ETSI-ES-203-136] defines the energy consumption metrics and
   measurement methods for router and Ethernet switch equipment.  It
   specifies a methodology and the test conditions to measure the power
   consumption of router and switch equipment and is also applicable to
   Core, edge, and access routers.

A.3.  3GPP SA5

   3GPP SA5 has, in Release 17, extended its scope from RAN only to the
   whole 5G System (5GS) and worked on Energy Efficiency (EE) and Energy
   Saving (ES) of mobile networks.  EE Key Performance Indicators (KPI)
   have been defined for the 5G Core network and Network Slices.

   The 3GPP Energy Efficiency in the RAN is defined by the performance
   divided by the Energy Consumption (EC), where the definition of the
   performance depends on the type of network entity it applies to.
   From this, SA5 work aimed at defining the best metrics for each of
   them, and their measurement method.

   In Rel-18, WG SA5 works with ETSI NFV to explore more accurate
   virtual CPU usage measurements from ETSI NFV MANO, Introduce
   additional metrics when estimating the Energy Consumption of Virtual
   Machines, e.g., their virtual disk or link usage.  In addition new
   use cases for Energy Saving, applied to NG-RAN, 5GC, and Network
   Slicing, AI/ML assisted energy saving scenarios are also being
   investigated.

   Specifically, [TS28.554] defines a number of energy efficiency KPIs,
   including a generic Network Slice Energy Efficiency KPI, defined as
   the ratio between the performance of the network slice and its energy
   consumption.

Appendix B.  Changes between Revisions

   v00 - v01

   *  Add two terms including Energy Object and energy saving.

   *  Update powerbench reference into WG draft.

   *  Generalized DSLAM, MSAM GPON GEPON equipment into Access
      equipment.

   v03 - v04

   *  Add Shailesh Prabhu as contributor.

   *  Add one new definition on Service Level Energy Efficiency (SLEE).

   *  Add one new definition on Energy-Aware Intent.

   *  Update Device Level Energy Efficiency definition and Component
      Level Energy Efficiency, clarify their relation with system level
      and sub-system level.

   *  Other Editorial changes.

   v02 - v03

   *  Update Energy Efficiency Capability Definition.

   *  Change Marisol's affiliation.

   v01 - v02

   *  Add one new section on Operations and Manageability
      Considerations;

   *  Add three new energy efficiency related terms based on comments
      raised during the interim meeting;

   *  Update 4 existing terms such as energy efficiency definition,
      energy efficiency metric, energy efficiency capabilities energy
      proportionality based on comments raised on the list.

Appendix C.  Acknowledgments

   This work has benefited from the discussions that occurred during
   GREEN interim meeting and on GREEN mailing list.  Thanks Benoit
   Claise, Gen Chen, Emile Stephan, Rob Wilton for valuable review and
   comments.  Thanks Peter Liu for helping provide input to initial
   version of the draft.

Contributors

   Shailesh Prabhu
   Nokia
   Email: shailesh.prabhu@nokia.com

Authors' Addresses

   Gen Chen
   Huawei
   Email: chengen@huawei.com

   Mohamed Boucadair
   Orange
   Email: mohamed.boucadair@orange.com

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

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

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