]> Huawei

liuchunchi@huawei.com

Orange

mohamed.boucadair@orange.com

Huawei

bill.wu@huawei.com

Telefonica

luismiguel.contrerasmurillo@telefonica.com

Cisco

mpalmero@cisco.com

Operations and Management GREEN Working Group Energy Efficient Energy Saving Energy Management Energy-efficient network management is primary meant to enhance conventional network management with energy-related management capabilities to optimize the overall energy consumption at the level of a network. To that aim, specific features and capabilities are required to control (and thus optimize) the energy use of involved network element and their components. This document is 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 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 . Source for this draft and an issue tracker can be found at .

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 committing environmental objectives but also mastering related operational cost. Energy Efficiency management is thus complementing conventional network management. defines a set of terms used within the IETF when discussing Energy-efficiency 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 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, provides an inventory of currently used metrics to assess/compute energy-related consumption, efficiency ratio, etc. provides a list of SDOs where relevant energy efficiency effort is ongoing.

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

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) ().

Power:

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

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 ().

Energy Monitoring:

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

Energy Control:

Is a part of Energy Management that deals with directing influence over devices ().

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

Energy Efficiency Network Management:

Refers to the ability to control the use of available energy in an optimized manner (e.g., in a resource conserved manner and at low cost) in a network.

Energy Efficiency Metric:

Refers to a metric that is used for the evaluation and 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.

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., ).

A higher EER indicates a better energy efficiency.

Power Usage Effectiveness (PUE):

Refer 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 optiize the configuration of a a network element.

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 a network elements.

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.

Sample Energy Efficiency Metrics and Measurement Methods This section lists some metrics that are adopted by other SDOs.

• DISCUSS: Should we maintian this section?

Metrics for DSLAM, MSAN, GPON, and GEPON Equipment Equipment with line cards working at different profiles/states are characterized with different metric values for each specific profile/state. 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. The formula is defined in .

Metric for Wireless Access Technologies The energy efficiency metric at Radio Frequency (RF) unit level is as follows: 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 .

Metrics for Routers and Ethernet Switches The metric for routers and Ethernet switches is as follows: Where 'Ti' is NDR throughput, 'Pw' is weighted power (energy consumption rate). The formula is defined in . 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.

Metrics for Small Network Devices A metric for small networking devices intended for home/domestic or small office use is as follows: 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 . 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.

Metric for Power Equipment 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 .

Metric for Cooling Equipment 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 .

Security Considerations Security is not discussed in this document.

Informative References This document defines a framework for Energy Management (EMAN) for devices and device components within, or connected to, communication networks. The framework presents a physical reference model and information model. The information model consists of an Energy Management Domain as a set of Energy Objects. Each Energy Object can be attributed with identity, classification, and context. Energy Objects can be monitored and controlled with respect to power, Power State, energy, demand, Power Attributes, and battery. Additionally, the framework models relationships and capabilities between Energy Objects. North Carolina State University ETH Zürich Huawei Huawei This document defines a standard mechanism to measure, report, and compare power usage of different networking devices and under different network configurations and conditions.

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.

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 , , , and 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:

• specifies assessment of mobile network energy efficiency.
• specifies the correlation between the carbon intensity indicator and energy efficiency metric. The carbon KPI defined in refers to the energy efficiency metric defined in ITU-T L.1331.
• 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.

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. 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.

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, 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.

Acknowledgments TODO acknowledge.