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Sustainability Considerations for Internetworking
draft-cparsk-eimpact-sustainability-considerations-00

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This is an older version of an Internet-Draft whose latest revision state is "Replaced".
Authors Carlos Pignataro , Ali Rezaki , Suresh Krishnan
Last updated 2023-11-08
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draft-cparsk-eimpact-sustainability-considerations-00
Network Working Group                                       C. Pignataro
Internet-Draft                                       NC State University
Intended status: Informational                                 A. Rezaki
Expires: 11 May 2024                                               Nokia
                                                             S. Krishnan
                                                                   Cisco
                                                         8 November 2023

           Sustainability Considerations for Internetworking
         draft-cparsk-eimpact-sustainability-considerations-00

Abstract

   Abstract Here...

   By definition, an Internet-Draft is a work in progress.  An impactful
   Abstract and Introduction will be added to this working draft pending
   an initial set of reviews of this -00, and after the main sections
   are stable.

Status of This Memo

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   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on 11 May 2024.

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   Copyright (c) 2023 IETF Trust and the persons identified as the
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   This document is subject to BCP 78 and the IETF Trust's Legal
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   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components

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   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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Definition of Terms . . . . . . . . . . . . . . . . . . . . .   2
   3.  'Sustainable X’ versus 'X for Sustainability’ . . . . . . . .   9
     3.1.  Sustainable Internetworking . . . . . . . . . . . . . . .  10
     3.2.  Internetworking for Sustainability  . . . . . . . . . . .  11
   4.  Key Values and Key Value Indicators . . . . . . . . . . . . .  12
   5.  Sustainability Considerations . . . . . . . . . . . . . . . .  13
     5.1.  Design Tradeoffs  . . . . . . . . . . . . . . . . . . . .  13
     5.2.  Multi-Objective Optimization  . . . . . . . . . . . . . .  13
     5.3.  How Much Resiliency is Really Needed? . . . . . . . . . .  14
     5.4.  How Much is Performance and Quality Compromised?  . . . .  14
   6.  End-to-End Sustainability . . . . . . . . . . . . . . . . . .  15
   7.  Sustainability Requirements and Phases  . . . . . . . . . . .  15
     7.1.  Phase 1: Visibility . . . . . . . . . . . . . . . . . . .  15
     7.2.  Phase 2: Insights and Recommendations . . . . . . . . . .  16
     7.3.  Phase 3: Self-optimization and Automation . . . . . . . .  16
   8.  Conclusion  . . . . . . . . . . . . . . . . . . . . . . . . .  17
     8.1.  Call to Action  . . . . . . . . . . . . . . . . . . . . .  17
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  17
   10. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  17
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  17
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  17
     11.2.  Informative References . . . . . . . . . . . . . . . . .  17
   Appendix A.  Open issues  . . . . . . . . . . . . . . . . . . . .  18
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  18

1.  Introduction

   Introduction Here...

   By definition, an Internet-Draft is a work in progress.  An impactful
   Abstract and Introduction will be added to this working draft pending
   an initial set of reviews of this -00, and after the main sections
   are stable.

2.  Definition of Terms

   This section defines sustainability-specific terms as they are used
   in the document, and as they pertain to environmental impacts.  The
   goal is to provide a common sustainability considerations lexicon for
   network equipment vendors, operators, and designers.  The terms are
   alphabetically organized.

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   Appropriate technology (or intermediate technology):
      refers to technology that is adapted to the local needs of its
      users, that is affordable, sustainable and usually small scale and
      decentralized.  Globally impactful technology is to be adaptable
      to local contexts it is used in.  Regarding internetworking, there
      could be linkages to centralization / decentralization challenges,
      as well as maintainability & deployability aspects.  Considering
      the diversity of local contexts, from developed countries with
      remote/rural coverage/access issues, to developing countries with
      unstable electricity grids as well as literacy and technology
      usability/accessibility issues, internetworking technology needs
      to be designed, developed and operated according to these local
      requirements, also supporting small scale business models to make
      impact.

   Biodiversity loss:
      Biological diversity is a measure of the abundance and variety of
      life on earth.  Biodiversity loss is the depletion of this
      diversity due to human activity, notably through the destruction
      of natural ecosystems and through the cascading effects of climate
      change, materials extraction, waste disposal and pollution, among
      other impacts, on the living world and species.

   CO2e / CO2eq / CO2-eq:
      Carbon dioxide equivalent, is the unit for measuring the climate
      change impact of non-CO2 gases as compared to CO2, which is
      selected as a benchmark.

   Carbon awareness:
      is being mindful of the carbon intensity of the electricity being
      used and prioritizing the use of low carbon intensity electricity
      in network set-up and operations.  As carbon intensity is location
      and time dependent, carbon awareness requires dynamic monitoring
      and response, such as carbon aware routing and networking.  This
      is a form of “demand shaping” which aims to match the use of
      energy with the supply of clean energy.

   Carbon intensity (C.I):
      is a measure of the carbon emission of consumed electricity, i.e.,
      grams of carbon per kilowatt hour (gCO2e/KWh).  When the supplied
      energy mix is purely from renewable sources such as sun and wind,
      carbon intensity is practically 0, when coal and gas-powered
      electricity gets in the mix, carbon intensity increases.  Carbon
      intensity could change instantaneously or predictably based on the
      time and location of electricity use.  Prioritizing electricity
      use when carbon intensity is low is a target.

   Carbon offset and credit:

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      is a removal of GHGs from the atmosphere as compensation for GHGs
      produced elsewhere and the credit generated and used respectively.
      For example, certified forestation projects that absorb carbon
      dioxide are producing carbon credits that an airline can use to
      offset its GHG emissions by using (purchasing) these credits.
      There are accredited carbon trading mechanisms to facilitate this
      exchange.

   Circularity (circular economy):
      is a model or system where material resources and products are
      kept in use for as long as possible through long life cycles,
      reuse, repair, refurbishing and recycling, thereby reducing
      materials use, waste, and pollution as well as biodiversity and
      geodiversity loss.  Keeping internetworking equipment in longer
      use through modularity, serviceability, upgradeability,
      maintainability are strategies to improve circularity.

   Climate change (climate emergency, global warming):
      can be summarized as the increase in the global average
      temperatures and its destructive impact on the interconnected
      systems of the Earth.  The climate emergency refers to the ongoing
      and projected catastrophic impacts of rising global temperatures
      and the narrow time window we have to limit temperature increases
      to a threshold determined by the Paris Climate Agreement (2015) to
      avoid the permanent destabilization of Earth life-support systems.

   Climate change adaptation:
      are the measures we can take to adjust ourselves to the already
      happening and projected future adverse effects of climate change.
      This notably includes raising the resilience of internetworking
      solutions but also the use of internetworking technology to
      increase the resilience of societies and nature itself.

   Climate change mitigation:
      encompasses all measures to reduce climate change.  More
      specifically, any measures that reduce the amount of GHGs in the
      atmosphere can be considered as climate change mitigation through
      reduced inflow of GHGs into the atmosphere (such as burning of
      fossil fuels) or increasing the impact of carbon sinks such as
      forests and oceans.  Reducing the carbon footprint of
      internetworking and increasing its carbon handprint by helping
      other sectors to decarbonize are mitigation efforts.

   Doughnut economics:
      is an effort for finding a safe operational space within planetary
      boundaries and seemingly opposing social boundaries, thereby
      meeting the needs of human societies without pushing earth
      environmental boundaries to their tipping points

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      (https://en.wikipedia.org/wiki/Doughnut_(economic_model)).  The
      significance of this model for interworking is that it
      demonstrates how to conceptualize and position boundaries in our
      designs that are seemingly opposing, to create a balanced
      approach, for example between energy efficiency and performance or
      resiliency and materials efficiency.  It is not one or the other,
      but to find a space where both can be achieved without crossing
      boundaries in respective domains.

   Energy, power, and their measurement:
      Energy is defined as the capacity or ability to do work in
      physics.  For a system to provide an output, it needs energy to be
      transferred to it.  Energy measurement unit is joules (J).  Power
      is energy used per second, measured in watts (W), equivalent to
      the rate of one joule per second (J/s).  Kilowatt-hour (kWh) is
      also a measure of energy, equivalent to 1 kW of power maintained
      for 1 hour, which is equal to 3.6 MJ (million joules).  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 EE
      improvements.

   Energy efficiency (EE):
      can be summarized as doing the same task with less energy use,
      that is, providing a useful output/impact with as little energy as
      possible, eliminating energy waste.  Switching to more efficient
      power supplies and silicon or developing more efficient
      transmission or signal processing algorithms improve EE.

   Energy proportionality:
      is the correlation between energy used and the associated useful
      output.  For internetworking this is generally interpreted as the
      proportionality of traffic and energy used.  It is not a given
      that there is a 1-to-1 correlation between traffic and energy use,
      notably due to the significant idle power use by networking
      devices and the network capacity being allocated w.r.t. peak load.

   Energy savings / conservation (ES):
      is the avoidance of energy use, by eliminating a task altogether,
      when possible.  Shutting down unused ports on a networking
      equipment is energy savings/conservation.

   Footprint (environmental/ecological):
      in general terms is the impact we have on the planet.  It can be
      divided into subcategories as carbon footprint, water footprint,
      land footprint, biodiversity footprint, etc.  Related to the
      climate emergency, we are mostly focused on our carbon footprint,
      however, it has been shown that sub-categories of footprint are

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      not entirely independent of each other.  For example, our carbon
      footprint has a proven impact on the climate emergency through
      rising global temperatures, cascading significant impact on forest
      cover in warming areas since tree species adapted to certain
      climates vanish, thereby reducing biodiversity in that region, in-
      return impacting the carbon sink properties of the environment and
      exacerbating climate change.  A holistic approach to our
      environmental footprint would therefore provide the best
      opportunity to create impact.

   GHGs:
      Greenhouse gases, are types of gases that trap heat from the sun
      in earth’s atmosphere, thereby increasing average global
      temperatures and creating the climate emergency.  Carbon dioxide
      (CO2) is one of the most common (and reference) greenhouse gases.
      There are others such as methane (CH4 – a much more potent GHG
      than CO2) and sulfur hexafluoride (SF6 – an artificial electrical
      insulator with tens of thousands of times more warming effect than
      CO2.

   GWP:
      Global warming potential, is the potential impact of GHGs on
      climate change, measured in CO2e.

   Geodiversity:
      is the variety of the nonliving parts of nature, that is, the
      materials constituting Earth, including soils, water (rivers,
      lakes, oceans), minerals, landforms and the associated processes
      that form and change them.  The materials used in the production
      of internetworking equipment as well as their manufacturing and
      operational processes themselves, have impact (footprint) on
      geodiversity.  Materials efficiency as well as circularity
      improvements help mitigate this impact.

   Handprint (environmental/ecological):
      is a concept developed in contrast to footprint, to quantify and
      demonstrate the positive environmental/ecological impact of
      technologies, products or organizations.  Through a LCA (life
      cycle assessment) approach, the use of a technology or the
      products and services of an organization would have both a
      footprint and handprint usually denoted by the terms “X for
      sustainability” (handprint) and “Sustainable X” (footprint).  What
      is important is that handprint impact does not compensate for
      footprint impact.  They are to be calculated and reported
      independently; footprint to be minimized as much as possible, and
      handprint maximized as much as possible, which are by definition
      different activities anyway.  Otherwise, this might be construed
      as “greenwashing”. A popular seesaw figure in common

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      sustainability literature depicting handprint and footprint
      sitting on opposite ends of a seesaw, one going up while the other
      is going down is a misguided representation.

   LCA (Life Cycle Assessment):
      is a comprehensive methodology to measure the environmental impact
      of a product, service, or process over its complete lifecycle,
      from the extraction and procurement of materials, through design,
      manufacturing, distribution, deployment, operations (use),
      maintenance/repair, decommissioning, refurbishment/reuse,
      recycling and disposal (waste), considering the full upstream and
      downstream supply chains as well.  It is an extremely complicated
      process and there are multiple methods used worldwide, which might
      not produce same/similar results.  LCA covers full footprint
      aspects, not only covering carbon, but also materials and
      biodiversity.

   Materials efficiency and reuse:
      is the concept of using less primary and (more) recycled materials
      to provide the same output.  A networking equipment that provides
      the same function with less aluminium used is more materials
      efficient.  Reuse of materials in manufacturing, thereby reducing
      primary materials extraction is a cornerstone of circularity,
      reducing environmental footprint and promoting geodiversity.

   Net-zero:
      in general, is to bring down GHGs as close to zero as possible.
      It is generally recognized that it may not be possible to get GHGs
      to 0 in many contexts and the balance is said to be covered by
      carbon offset.  For example, many organizations and countries have
      net-zero targets by certain dates and typically what they mean is
      that they will reduce their GHGs by more than 90% and the
      remaining up to 10% will be offset.

   PUE:
      Power usage effectiveness, is a data centre energy efficiency
      metric.

   Planetary boundaries:
      is a concept that defines 9 environmental boundaries, if not
      crossed, provides a safe space for humanity to live.  This was
      developed and tracked by the Stockholm Resilience Centre (https:">
      //www.stockholmresilience.org/research/planetary-boundaries.html
      ).  Unfortunately, their latest report indicates that 6 out of the
      9 boundaries have already been crossed.  This translates to the
      increased risk of irreversible environmental change, the so-called
      tipping points.  Climate change is one of these boundaries,
      represented as carbon dioxide concentration in the atmosphere (ppm

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      by volume) and others are biodiversity loss, land use, fresh
      water, ocean acidification, chemical pollution, ozone depletion
      (one boundary that has been successfully mitigated), atmospheric
      aerosols and biogeochemical (nitrogen in the atmosphere and
      phosphorus in oceans).

   Rebound effect:
      is the reduction in the potential benefits of more efficient
      technologies and solutions to reduce resource use, due to the
      increased demand they might trigger as costs might decrease, in
      return even increasing the overall resource use.  This is known as
      Jevons paradox: efficiency leading to increased demand.  In
      internetworking, this can manifest itself when more energy and
      resource efficient systems reduce the cost for infrastructure
      build and operations and when this is reflected to customers as
      reduced cost, customers respond by increased use of
      telecommunications services which pushes infrastructure build and
      operations upwards, thereby negating the projected gains from
      efficiency measures.

   Tipping points:
      are critical environmental thresholds, which when crossed likely
      lead to irreversible state changes in climate systems that might
      push the overall earth system out of its stable state that
      supports life on Earth.  For example, there are tipping points
      defined for the Antarctic and Greenland ice sheets disappearing,
      the Arctic sea-ice loss, Siberian permafrost loss or the dieback
      of the Amazon and Boreal forests.  As planetary boundaries are
      crossed, the likelihood of the tipping points being reached also
      increases.  When the tipping points are hit, notably
      simultaneously, the overall impact to the global Earth system
      might be catastrophic, as another stable state which no longer
      supports life could be reached.

   UN SDGs:
      United Nations Sustainable Development Goals are 17 global
      objectives that collectively define a framework for a sustainable
      global system where people and the planet collectively thrive and
      live in peace, prosperity and equity.  They were adopted in 2015
      and most of them have a target achievement date of 2030 (https:">
      //sdgs.un.org/goals).  They are part of the so-called UN 2030
      Agenda.  The International Telecommunications Union (ITU) has
      published on how our technology could help meet the UN SDGs:">
      https:">
      //www.itu.int/en/mediacentre/backgrounders/Pages/icts-to-achieve-
      the-united-nations-sustainable-development-goals.aspx . Notably,
      most UN SDGs provide guidance for the handprint impact of
      internetworking technologies, while some are also related to

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      potential action for footprint reduction.  The 17 SDGs are:">
      SDG 1 - No poverty, SDG2 - Zero hunger, SDG3 - Good health and
      well-being, SDG 4 - Quality education, SDG 5 - Gender equality,
      SDG 6 - Clean water and sanitation, SDG 7 - Affordable and clean
      energy, SDG 8 - Decent work and economic growth, SDG 9 - Industry,
      innovation and infrastructure, SDG 10 - Reduced inequalities, SDG
      11 - Sustainable cities and communities, SDG 12 - Responsible
      consumption and production, SDG 13 - Climate action, SDG 14 - Life
      below water, SDG 15 - Life on land, SDG 16 - Peace, justice, and
      strong institutions, SDG 17 - Partnerships for the goals.

3.  'Sustainable X’ versus 'X for Sustainability’

   Every technology solution, system or process has sustainability
   impacts, as it uses energy and resources and operates in a given
   context to provide a [perceived] useful output.  These impacts could
   be both negative and positive w.r.t sustainability outcomes.  With a
   simplistic view, the negative impact is termed as footprint and the
   positive impact is handprint, as defined in the terms section above.
   Again, generally speaking, footprint considerations of a technology
   are grouped under “Sustainable X” and the handprint considerations
   are covered under “X for Sustainability”.

   Additionally, when sustainability impacts are considered, not only
   environmental but also societal and economic perspectives need to be
   taken into account, both for footprint and handprint domains.  A
   systems perspective ensures that the interactions and feedback loops
   are not forgotten among different sub-areas of sustainability.

   Another fundamental sustainability impact assessment requirement is
   to cover the complete impact of a product, service or process over
   its full lifetime.  Life Cycle Assessment (LCA) starts from the raw
   materials extraction & acquisition phases, and continues with design,
   manufacturing, distribution, deployment, use, maintenance,
   decommissioning, refurbishment/reuse, and ends with end-of-life
   treatment (recycling & waste).  It is imperative that we consider not
   only the design and build stages of our technologies but also its use
   and end-of-life phases.  An equally essential way of ensuring a
   holistic perspective is the supply-chain dimension.  When we consider
   the footprint impact of a technology we are building, we need to
   consider the full supply chain that the technology is part of, both
   upstream, what it inherits from the materials, components and
   services used, to downstream for wherever the technology is used and
   then decommissioned.  What this implies is that we are responsible
   for the direct and indirect impacts of our activity, both on demand
   and supply directions.

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   Below, we cover the “Sustainable Internetworking” and
   “Internetworking for Sustainability” perspectives in more detail.

3.1.  Sustainable Internetworking

   Sustainable internetworking is about ensuring that the negative
   impacts of internetworking are minimized as much as possible.

   In the environmental / ecological sustainability domain, the sub-
   areas to be considered are:

   *  Climate change,

   *  materials efficiency, circularity, preservation of geodiversity,
      and

   *  biodiversity preservation.

   Climate change considerations in internetworking by and large
   translate to energy sourcing, consumption, savings and efficiency as
   this impacts the GHGs of the internetworking systems directly, when
   mostly non-renewable energy sources are used for the operations of
   the networks.  When the carbon intensity of the energy supply used in
   operations decreases (more renewable energy in the supply mix), then
   the use phase GHGs also proportionally decrease.  This might put the
   GHG emissions of the manufacturing and materials extraction and
   acquisition phases ahead of the use phase.  These are called the
   embodied emissions.

   However, energy is not the only aspect to consider: materials
   efficiency and circularity are key actions to limit the resource use
   of our technologies, thereby reducing the scarcity of materials but
   also the destruction of many ecosystems during their extraction and
   manufacturing, polluting water and land with waste, which might also
   impact directly or indirectly the abundance and health of the species
   on the planet, namely biodiversity.  While it is significantly more
   difficult to quantify and measure the impact of our technologies in
   these domains, the planetary boundaries framework provides helpful
   guidance.

   For the societal and economic footprint of our technologies, we need
   to be mindful about the potential negative effects of our
   technologies w.r.t. the social boundaries, as depicted in the so-
   called doughnut economics model, that includes education, health,
   incomes, housing, gender equality, social equity, inclusiveness,
   justice and more.  What we need to realize is that our technology has
   direct and indirect impacts in these aspects and the challenge is not
   only to meet environmental sustainability targets but social and

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   economic ones as well.  There are very practical considerations for
   example: does centralization/concentration in internetworking affect
   empowerment and inclusion, or the relationship of automation and AI
   use with bias or job creation.  More technology doesn’t always mean
   better outcomes for all and can we mitigate this impact?  Admittedly,
   a quantitative approach to the societal and economical aspects is
   more challenging but the KV/KVI approach described below brings some
   relief.

3.2.  Internetworking for Sustainability

   When it comes to the positive impact of internetworking in tackling
   the sustainability challenges faced, we are in the “internetworking
   for sustainability” realm.  This is a very diverse topic covering
   innumerable industrial and societal verticals and use cases.
   Essentially, we are asking how our technology can help other sectors
   and users to decarbonize, and to reduce their own footprints and to
   increase their handprints in environmental, societal and economic
   dimensions.  These are induced or enablement effects.  Examples are
   how internetworking is being used in smart energy grids or smart
   cities, transport, health care, education, agriculture, manufacturing
   and other verticals.  While efficiency gains are usually a basis,
   there are also other impacts through ubiquitous network coverage,
   sensing, affordability, ease of maintenance and operation,
   decentralization, to name a few.

   Climate change mitigation and climate change adaptation, as defined
   in the terms section above, are particular focus areas where
   internetworking could help create more resilience in our societies
   and economies along with sustainability.

   Essentially, handprint considerations are asking us to think about
   how our technology could be used to tackle sustainability challenges
   at first, and second, to generate feedback on how to create enablers
   and improvements in our technology for it to be more impactful.  The
   usual KPIs related to technical system parameters would be largely
   insufficient for this purpose.  Supporting this effort, Key Values
   (KV) and Key Value Indicators (KVIs) concepts have been developed, to
   be used in conjunction with use cases to develop impactful solutions.
   KV and KVIs are the subject of the nxt section below.

   TBC.

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4.  Key Values and Key Value Indicators

   In the context of sustainability, key values are what matters to
   societies and to people when it comes to direct and indirect outcomes
   of the use of our technology.  While KPIs help us to build, monitor
   and improve the design and implementation of our technologies, key
   values and their qualitative and quantitative indicators tell us
   about their usefulness and value to society and people.  As we want
   our technology to help tackle the grand challenges of our planet,
   their likelihood of usefulness and impact is a paramount
   consideration.  KVs and KVIs help set our bearings right and also
   demonstrate the impact we could create.

   While key values could be universal, like for example the United
   Nations Sustainable Development Goals (UN SDGs), how they are
   measured, or perceived (KVIs) could be context dependent, that is,
   use case specific.  To give a simplified example, UN SDG 3, “good
   health and well-being” is a key value for any society and individual.
   Then, when we consider the use case of providing health care and
   wellness services in a remote, rural community which doesn’t have any
   hospitals or specialist doctors, a key value indicator could be how
   fast a patient could access health care services without having to
   travel out of town, or the successful medical interventions that
   could be carried out remotely.  Then the next step is to identify
   which parts of our technology could help enable this and design our
   technology to create impact for the KVs as per KVIs.  In this case,
   universal network coverage, capacity and features to integrate
   multitude of sensors, low-latency and jitter communication services
   could all be enablers with their own design targets and KPIs defined.
   Subsequently, we would track the KVIs and the KPIs together for
   successful outcomes.

   Admittedly, this might not be a straightforward task to carry out for
   each protocol design.  Yet, such analyses could be included in design
   processes along with use case development, covering a group of
   technology design activities (protocols) together.  There are ongoing
   efforts in mobile networking research to use KVs/KVIs efficiently
   [M6G-KVI] [M6G-VP].

   While we find ourselves trying to optimize seemingly contradicting
   parameters or aspects such as reducing latency and jitter and
   increasing bandwidth and reach targets with sustainability ones like
   reduced energy consumption and increased energy efficiency, key
   values and key value indicators would help keep our eyes on the
   targets that matter for the end users and communities and societies.
   Considerations for such potential design trade-offs, which are at the
   heart of our engineering innovations, is the topic of the next
   section.

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5.  Sustainability Considerations

5.1.  Design Tradeoffs

   Traditionally, digital communication networks are optimized for a
   specific set of criteria that proxies for business metrics.  A
   network operator providing services to their customers intends to
   maximize profits, by increasing top-line revenue and decreasing
   bottom-line associated costs.  This directly translates to goals of
   optimizing performance and availability, while reducing various
   costs.

   Most recently, as explained above, various forces elevate the need
   for sustainability in networking technologies and architectures, to
   quantify and minimize negative environmental impact.

   A first approximation to this conundrum indicates that optimizing
   network availability (e.g., by having excess capacity and backup
   paths) or optimizing performance (e.g., by increasing speeds
   selecting paths based on delays only) can be in opposition to
   optimizing sustainability objectives.  As such, network architects
   and designers are presented with a set of new design tradeoffs: a
   multi-objective optimization that satisfies border requirements and
   global optima for availability, performance, and sustainability
   simultaneously.  This is not unlike the doughnut economics model
   concept introduced in the Terms above.

5.2.  Multi-Objective Optimization

   To understand this new model, we can analyze a simplified example.
   Assume the following topology, passing traffic from A to B:

                           A
                           |
                      +----------+
                      | Router 1 |------------+
                      +----------+            |
                       | | | | |         +----------+
                       | | | | |         | Router 3 |
                       | | | | |         +----------+
                      +----------+            |
                      | Router 2 |------------+
                      +----------+
                           |
                           B

       Figure 1: Simplified Network for Multi-Objective Optimization

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   Router 1 is connected to Router 2 with five parallel links, of 10
   Gbps each.  Router 1 can also reach Router 2 through Router 3 with 40
   Gbps links.  Let’s assume that the capacity-planned traffic between A
   and B equals 15 Gbps.

   In this scenario, a topology optimized for performance and
   availability/resiliency would have all links and routers on, and
   would likely forward traffic using two of the parallel links.
   Utilizing the path through Router 3 might lower performance, but it
   serves as a backup path.

   On the other hand, when we add sustainability as a consideration,
   different options are presented.  One of them is to remove from the
   topology Router 3 and associated links, and shutdown links and optics
   in two or three of the parallel links.  Another option is to
   completely shutdown all the parallel links and route traffic through
   Router 3 (i.e., not maximizing performance alone, but maximizing at
   the time performance, availability and resiliency, and
   sustainability.)  The choice between these two options will depend on
   the aggregate sustainability metrics of network elements in each of
   the two topologies.

5.3.  How Much Resiliency is Really Needed?

   When we add sustainability considerations, resiliency is not the
   single objective to optimize.  And while the graphs of resiliency and
   sustainability might be impractical to approximate with formulas,
   there are ratios that can give a sense of border conditions.

   For example, consider the overall network capacity over the used
   capacity, and let’s call it “Resiliency Index”. If this number is
   one, there’s no resiliency; and as the ratio grows, so potentially
   unused capacity that could be utilized in a failure event.
   Similarly, consider the values os sustainability metrics for when the
   Resiliency Index is one and for when it is two.  These borders points
   might give an indication of the slope for each objective.

5.4.  How Much is Performance and Quality Compromised?

   The fields of performance and quality of experience have the benefit
   of significant study and standardization of metrics.  In a similar
   way than with resiliency, a degradation of performance and Quality of
   Service parameters, such as bandwidth, latency, jitter, etc., can
   very well be observed and measured, as a variation of sustainability
   metrics.  The relative slopes of improvement of each goal would hint
   as to where the balance lies.

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6.  End-to-End Sustainability

   The networking industry is in the starting phases of addressing this
   objective.  We are seeing a sprinkling of sustainability features
   across the networking stack and components of devices, whether it is
   on forwarding chips, power supplies, optics, or compute.  Many of
   those optimizations and features are typically local in nature, and
   widely scattered across different elements of a network architecture.
   An opportunity for maximizing the positive environmental impact of
   these technologies calls for a more cohesive and complementary view
   that spans the complete product lifecycle for hardware and software,
   as well as how some of these features work in unison.

   For example, features that provide energy saving modes for devices
   can be dynamically utilized when the network utilization is such that
   performance would not significantly suffer.  Or consider a core
   router of today that becomes more usable as an edge/access router of
   the future due to the need for higher throughput in the core.  This
   section explores the benefits of macro-optimizations by clustering in
   specific phases, versus micro-optimizing locally without awareness of
   the network context.

7.  Sustainability Requirements and Phases

   The sustainability considerations described above and the associated
   goals cannot always be achieved at the same time and we expect the
   following high level phases:

   1.  Visibility: In this phase we focus on the measurement and
       collection of metrics.

   2.  Insights and Recommendations: In this phase we focus on deriving
       insights and providing recommendations that can be acted upon
       manually over large time scales.

   3.  Self-Optimization via Automation: In this phase we build
       awareness into the systems to automatically recognize
       opportunities for improvement and implement them.

7.1.  Phase 1: Visibility

   Visibility represents collecting and organizing data in a standard
   vendor agnostic manner.  The first step in improving our
   environmental impact is to actually measure it in a clear and
   consistent manner.  The IETF, IRTF and the IAB have a long history of
   work in this field, and this has greatly helped with the
   instrumentation of network equipment in collecting metrics for
   network management, performance, and troubleshooting.  On the

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   environmental-impact side though, there has been a proliferation of a
   wide variety of vendor extensions based on these standards.  Without
   a common definition of metrics across the industry and widespread
   adoption we will be left with ill-defined, potentially redundant,
   proprietary, or even contradicting metrics.  Similarly, we also need
   to work on standard telemetry for collecting these metrics so that
   interoperability can be achieved in multi-vendor networks.

7.2.  Phase 2: Insights and Recommendations

   Once the metrics have been collected, categorized, and aggregated in
   a common format, it would be straightforward to visualize these
   metrics and allow consumers to draw insights into their GHG and
   energy impact.  The visualizations would take the form of high-level
   dashboards that provide aggregate metrics and potentially some form
   of maturity continuum.  We think this can be accomplished using
   reference implementations of the standards developed in phase 1.  We
   do expect vendors and other open projects to customize this and
   incorporate specific features.  This will allow identifying sources
   of environmental impact and address any potential issues through
   operational changes, creation of best-practices, and changes towards
   a greener, more environmentally friendly equipment, software,
   platforms, applications, and protocols.

7.3.  Phase 3: Self-optimization and Automation

   Manually making changes as mentioned in Phase 2 works for changes
   needed on large timescales but does not scale to improvements on
   smaller scales (i.e., it is impractical in many levels for an
   operator to be looking at a dashboard monitoring usage and making
   changes in real-time 24x7).  There is a need to provision some amount
   of self-awareness into the network itself, at various layers, so that
   it can recognize opportunities for improvement and make those changes
   and measure the effects by closing the loop.  The goals of the
   consumers can be stated in a declarative fashion, and the networks
   can continually use mechanisms such as ML/DL/AI with an additional
   goal to optimize for improvements in the environmental impact.  These
   include, for example:

   *  Discovery and advertisement of networking characteristics that
      have either direct or indirect environmental impact,

   *  greener networking protocols that can move traffic on to more
      energy efficient paths, directing topological graphs to optimize
      environmental impacts, and

   *  protocols that can instruct equipment to move under-utilized links
      and devices into low-energy modes.

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8.  Conclusion

   The pre-eminent message in this document is to elevate the need and
   sense of urgency of including sustainability considerations in our
   protocol and system design, and to provide editors with
   sustainability lexicon, definitions, and priorities to carry out that
   task.  As an added benefit, by including sustainability
   considerations, it will be possible to optimize for not only
   performance parameters but also sustainability ones, through
   respective trade-offs in our protocols and systems.

   We also envision that on top of minimizing the environmental impact
   of our technologies and helping consumers identify and reduce the
   environmental impact of their use, we can also make a positive impact
   on other less-traditionally and non-Internet technologies as well as
   non-technologies.  E.g., use our technologies to choose greener and
   more efficient sources of power, control HVAC systems efficiently,
   etc.  We are looking forward to our efforts that will positively
   impact the environment using Internet technologies and protocols.

8.1.  Call to Action

   INSERT specific call to action here.

9.  Security Considerations

   TBC.

10.  Acknowledgements

   TBC.

11.  References

11.1.  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/info/rfc2119>.

11.2.  Informative References

   [M6G-KVI]  Wikström, G., Schuler Scott, A., Mesogiti, I., Stoica, R.,
              Georgiev, G., Barmpounakis, S., Gavras, A., Demestichas,
              P., Hamon, M., Hallingby, H., and D. Lund, "What societal
              values will 6G address?", 17 May 2022,
              <https://doi.org/10.5281/zenodo.6557534>.

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   [M6G-VP]   Ziegler, V. and S. Yrjola, "6G Indicators of Value and
              Performance", 4 May 2020,
              <https://doi.org/10.1109/6GSUMMIT49458.2020.9083885>.

Appendix A.  Open issues

   [ISSUE 1]  Complete "Abstract"

   [ISSUE 2]  Shall the 'Definition of Terms' be moved into its own
              document to be cited by all e-impact-related documents?

   [ISSUE 3]  Complete "Introduction"

   [ISSUE 4]  Finalize Call-to-Action in the Conclusion

   [ISSUE 5]  Pending input from Jukka Manner

Authors' Addresses

   Carlos Pignataro
   North Carolina State University
   United States of America
   Email: cpignata@gmail.com, cmpignat@ncsu.edu

   Ali Rezaki
   Nokia
   Germany
   Email: ali.rezaki@nokia.com

   Suresh Krishnan
   Cisco Systems, Inc.
   United States of America
   Email: sureshk@cisco.com

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