Network Working Group C. Pignataro, Ed.
Internet-Draft NC State University
Intended status: Informational A. Rezaki
Expires: 17 June 2024 Nokia
S. Krishnan
Cisco
H. ElBakoury
Independent Consultant
A. Clemm
Futurewei
15 December 2023
Sustainability Considerations for Internetworking
draft-cparsk-eimpact-sustainability-considerations-01
Abstract
This document defines a set of sustainability-related terms to be
used while describing and evaluating environmental impacts of
Internet technologies. It also describes several of the design
tradeoffs for trying to optimize for sustainability along with the
other common networking metrics such as performance and availability,
and gives network and protocol designers and implementors
sustainability-related advice and guideance.
Status of This Memo
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Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Definition of Terms . . . . . . . . . . . . . . . . . . . . . 3
3. 'Sustainable X' versus 'X for Sustainability' . . . . . . . . 12
3.1. Sustainable Internetworking . . . . . . . . . . . . . . . 13
3.2. Internetworking for Sustainability . . . . . . . . . . . 14
4. Key Values and Key Value Indicators . . . . . . . . . . . . . 16
4.1. Key Value Enablers . . . . . . . . . . . . . . . . . . . 17
5. Implications to the IETF . . . . . . . . . . . . . . . . . . 18
6. Sustainability Considerations . . . . . . . . . . . . . . . . 18
6.1. Design Tradeoffs . . . . . . . . . . . . . . . . . . . . 18
6.2. Multi-Objective Optimization . . . . . . . . . . . . . . 18
6.3. How Much Resiliency is Really Needed? . . . . . . . . . . 20
6.4. How Much are Performance and Quality of Experience
Compromised? . . . . . . . . . . . . . . . . . . . . . . 20
6.5. Metrics for Sustainability . . . . . . . . . . . . . . . 20
6.6. End-to-End Sustainability . . . . . . . . . . . . . . . . 20
6.7. The Role of Network Management and Orchestration . . . . 21
7. Sustainability Advice and Guidelines for Protocol and Network
Designers and Implementers . . . . . . . . . . . . . . . 22
8. Sustainability Requirements and Phases . . . . . . . . . . . 22
8.1. Phase 1: Visibility . . . . . . . . . . . . . . . . . . . 22
8.2. Phase 2: Insights and Recommendations . . . . . . . . . . 23
8.3. Phase 3: Self-optimization and Automation . . . . . . . . 23
8.3.1. Cycle of Phases . . . . . . . . . . . . . . . . . . . 23
9. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . 24
9.1. Call to Action . . . . . . . . . . . . . . . . . . . . . 24
10. Security Considerations . . . . . . . . . . . . . . . . . . . 24
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 24
12. Informative References . . . . . . . . . . . . . . . . . . . 24
Appendix A. Open Issues and TODOs . . . . . . . . . . . . . . . 26
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27
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1. Introduction
Over the past decade, there has been increased awareness of the
environmental impact produced by the widespread adoption of the
Internet and internetworking technologies. The impact of Internet
technologies has been overwhelmingly positive over the past years
(e.g., providing alternatives to travel, enabling remote and hybrid
work, enabling technology-based endangered species conservation,
etc.), and there is still room for improvement. This document
describes some of the tradeoffs that could be involved while
optimizing for sustainability in addition to or in lieu of
traditional metrics such as performance or availability. It also
proposes some common terminology for discussing environmental impacts
of Internet technologies, and gives network and protocol designers
and implementors sustainability-related advice and guideance.
Finally, it discusses how Internet technologies can be used to help
other fields become more sustainable.
2. Definition of Terms
Given that the term 'considerations' is well known within the IETF
community, it is fair to start by defining 'sustainability'. The
1983 UN Commission on Environment and Development had important
influence on the current use of the term. The commission's 1987
report [UNGA42] defines it as development that "meets the needs of
the present without compromising the ability of future generations to
meet their own needs". This in turn involves balancing economic,
social, and environmental factors.
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, designers, and architects.
Notwithstanding the most comprehensive set of definition of relevant
terms readers can find at [IPCC], this section contributes the
application and exemplification of the terminology to the
internetworking domain and field. The terms are alphabetically
organized.
Appropriate technology:
formerly referred to as 'intermediate technology', it 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
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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 (CI):
is a measure of the carbon-equivalent emission of consumed
electricity, i.e., grams of carbon-equivalent 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 generation
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:
is a reduction of GHGs from the atmosphere as compensation for
GHGs produced elsewhere and the credit generated and used
respectively. This reduction in GHG emissions can be an increase
in carbon storage through land restauration, or an actual removal
of GHG. For example, certified forestation projects that absorb
carbon dioxide are producing carbon credits that an airline can
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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 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 to higher operating temperatures and other impacts of
climate change, as well as the use of internetworking technology
to increase the resilience of societies and nature itself.
Climate change mitigation:
encompasses all measures to reduce the impact of 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.
CUE:
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Carbon usage effectiveness [CUE] is a metric that helps determine
the amount of greenhouse gas (GHG) emissions produced per unit of
IT energy consumed within a data center. It provides an effective
way to measure operational carbon footprint and thus the
environmental impact of data center operations. The CUE is the
ratio of the total CO2 emissions caused by total data center
energy consumption, divided by the energy consumption of IT
equipment. To calculate CUE when using electricity from the grid,
carbon emissions can be based on published data. See also "PUE".
Doughnut economics:
is a visual framework for sustainable development. It attempts to
find a safe operational space within planetary boundaries and
complementary (yet seemingly opposing) social boundaries, thereby
meeting the needs of human societies without pushing earth
environmental boundaries to their tipping points [Doughnut]. 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:
In physics, energy is defined as the capacity or ability to do
work. For a system to provide an output, the quantitative
property of energy is transferred to it. The energy measurement
unit in the International System of Units (SI) is the joule (J).
Power is energy used per second, measured in the International
System of Units in watts (W), equivalent to the rate of one joule
per second (J/s). In other words, energy is the integration of
power over kime. As such, 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).
Energy efficiency (EE):
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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.
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. While there are various metrics
that can be defined and used to quantify EE, the key to those is
to choose outcome-oriented metrics (e.g., energy consumption per
data volume or traffic unit, in Wh/B [Telefonica].)
Energy equity:
Energy equity aims to minimize the negative impacts of our energy
systems and maximize the benefits for all utility customers.
Historically, these impacts and benefits haven’t been equitably
distributed. Energy equity recognizes that disadvantaged
communities have been historically marginalized and overburdened
by pollution, underinvestment in clean energy infrastructure, and
lack of access to energy efficient housing and transportation.
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. It is not a
given that there is 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 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
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
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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).
GHG Emissions Scopes:
According to the Greenhouse Gas (GHG) Protocol [GHG-Proto],
Chapter 4, the emissions scopes are defined as below:
* Direct GHG emissions are emissions from sources that are owned
or controlled by the company.
* Indirect GHG emissions are emissions that are a consequence of
the activities of the company but occur at sources owned or
controlled by another company.
The GHG protocol [GHG-Proto], Chapter 4, also includes the
following descriptions of emissions scopes for accounting and
reporting purposes:
* Scope 1 Emissions: Direct GHG emissions - Direct GHG emissions
occur from sources that are owned or controlled by the company,
for example, emissions from combustion in owned or controlled
boilers, furnaces, vehicles, etc.; emissions from chemical
production in owned or controlled process equipment.
* Scope 2 Emissions: Electricity indirect GHG emissions - Scope 2
accounts for GHG emissions from the generation of purchased
electricity consumed by the company. Purchased electricity is
defined as electricity that is purchased or otherwise brought
into the organizational boundary of the company. Scope 2
emissions physically occur at the facility where electricity is
generated.
* Companies shall separately account for and report on scopes 1
and 2 at a minimum.
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* Scope 3 Emissions: Other indirect GHG emissions - Scope 3 is an
optional reporting category that allows for the treatment of
all other indirect emissions. Scope 3 emissions are a
consequence of the activities of the company, but occur from
sources not owned or controlled by the company. Some examples
of scope 3 activities are extraction and production of
purchased materials; transportation of purchased fuels; and use
of sold products and services.
In telecommunications networks, Scope 3 emissions include the use
phase of the sold products in operations, and is currently the
largest part by far, of the whole GHG emissions (Scopes 1, 2 and
3), depending on the carbon intensity of the energy supply in use.
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
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):
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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. The PUE is defined by dividing the total amount of power
entering a data center by the power used solely to run the IT
equipment within it. PUE is expressed as a ratio, with the
overall power usage effectiveneess improving as the quotient
decreases towards one. See also "CUE".
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
[Planet-B]. 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
by volume) and others are biodiversity loss, land use, fresh
water, ocean acidification, chemical pollution, ozone depletion
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(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. Another descriptive source for this
phenomenon can be found at [Frontiers].
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 [UN-SDG].
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 [ITU-ICT-SDG]. Notably, most UN SDGs
provide guidance for the handprint impact of internetworking
technologies, while some are also related to potential action for
footprint reduction. The 17 SDGs are:
Goal 1 No poverty
Goal 2 Zero hunger
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Goal 3 Good health and well-being
Goal 4 Quality education
Goal 5 Gender equality
Goal 6 Clean water and sanitation
Goal 7 Affordable and clean energy
Goal 8 Decent work and economic growth
Goal 9 Industry, innovation and infrastructure
Goal 10 Reduced inequalities
Goal 11 Sustainable cities and communities
Goal 12 Responsible consumption and production
Goal 13 Climate action
Goal 14 Life below water
Goal 15 Life on land
Goal 16 Peace, justice and strong institutions
Goal 17 Partnerships for the Goals
The SDG Academy [SDG-Acad] also provides useful information on the
topic, as well as progress to date.
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 "Definition of Terms"
section. 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
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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 material acquisition, components
and services used, to downstream for wherever the technology is used
and then decommissioned. Further, this includes transportation of
materials or products, and the carbon-friendliness of the means and
routes chosen. What this implies is that we are responsible for the
direct and indirect impacts of our activity, both on demand and
supply directions.
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.
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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
economic ones as well. There are very practical considerations, for
example: are there partial or total barriers to accessing the
Internet or its services? what is the impact of biases in artificial
intelligence (AI), as it pertains gender biases, when those AI models
are used in job selection? 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; thinking in terms of profit, people, and planet, as
well as the KV/KVI approach described below bring 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, equity in
access, to name a few.
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Climate change mitigation and climate change adaptation, as defined
in the "Definition of Terms" section, 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, the 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 Section 4.
The following are some examples of internetworking for
sustainability. This is not a comprehensive list; many more such
examples can be found. Leveraging internetworking for sustainability
usually involves special requirements, which are listed along with
the examples.
* Smart Grid: The Smart Grid [RFC6272] generally refers to
enhancements to traditional electrical grids that offer additional
features such as two-way flows of electricity (e.g., accommodating
solar panels, electrical batteries) and granular control of the
grid (e.g., allowing to selectively turn off certain consumers
such as Heating, Ventilation, and Air Conditioning (HVAC) units
during certain times.) The Smart Grid aims to improve
sustainability by facilitating concepts such as peak shaving
(i.e., lowering peak usage to reduce the amount of excess
generation of electricity that is not needed during non-peak
periods), and encouraging residential homes and business to invest
in renewable energy sources such as solar, for example offering
credit for feeding surplus energy being generated back into the
grid. For this to work, the Smart Grid requires support by
networking technology that enables the required control loops as
well as visibility into grid telemetry. This, in turn, requires
the support of new requirements, including aspects of security
(since a critical infrastructure is at stake), adherence to high
precision service levels and ultra-low latency communication
(e.g., to mitigate sudden spikes in voltage), and special
provisions to ensure data privacy (given that data from private
households, electrical vehicles, and personal devices is
involved.)
* Smart Cities: Many applications for smart cities involve
optimizations to make cities more sustainable. Examples include
smart garbage disposals that reduce the number of truck rolls (and
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associated emissions) to collect garbage only when needed, and
guidance systems for smart parking that reduce the amount of
vehicle traffic used to find parking spots. These applications
are enabled by networking. Again, special requirements need to be
supported for networks to support those applications, such as the
ability to deploy equipment in harsh urban environments, or
monitoring for vandalism.
* Smart Agriculture: Smart agriculture involves minimizing usage of
resources such as fertilizer and water in the production of
agricultural output. This also helps minimize the area set aside
for farming and reclaim land for other purposes including
biodiversity. Similarly, networking is an enabler for
environmental sustainability. Special requirements for
applications in this space include aspects such as the ability to
support networking equipment without the need to run power lines
(e.g., using battery or solar), and support for intermittent
communications.
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. The main idea is shifting
from measuring performance to measuring value.
While key values could be universal, like for example the United
Nations Sustainable Development Goals (UN SDGs) [UN-SDG], how they
are measured, or perceived (KVIs) could be context dependent and 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
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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-SOCIETAL-KV-KVI] [M6G-VALUE-PERF] [Hexa-X_D1.2].
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.
4.1. Key Value Enablers
Between the design and creation of a technology, and realization of
the value generated by its deployment and use, there are a number of
enablers and blockers of its usage. We generally refer to them as KV
Enablers. These are the key factors that would scale and spread use
cases or block their deployment.
Technical enablers are the features needed for the technical
capabilities and feasibility of the use cases, like the network
features being deployed to support the use case. Beyond the
technical aspects, there are also criteria at the system level which
determine the context in which the technology will be used as well as
the actions of the use case stakeholders. These might affect the
level of adaptation to a particular society or ecosystem, such as
cost of connectivity and Internet service access, availability of
services, security, and privacy. While technical enablers are in
more direct control of protocol and network designers, system-level
enablers might in second-order, indirect, or beyond control,
depending on the actions of other stakeholders and the existing
environment.
An important corollary is that KV enablers can be used to derive
technological requirements, KPIs and advancements to maximize key
value.
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5. Implications to the IETF
This section describes the implications of sustainability to the
IETF. Specifically, the high-level relevant areas on which the IETF
can act upon, and a rough prioritization. These potentially include
use cases, protocols, metrics, etc.
A key area to understand the relevance and implication is regarding
IETF Protocols.
6. Sustainability Considerations
6.1. 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, 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
only network availability (e.g., by having excess capacity and backup
paths) or optimizing only performance (e.g., by increasing speeds
selecting paths based on delays only) can be in opposition to
optimizing sustainability objectives. For a given application, use-
case, or vertical realization of technology, a Pareto-efficient
choise is potentially presented on a win-win of improving
sustainability without sacrificing availability or performance beyond
the application tolerance.
Consequently, 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 "Definition of
Terms" section.
6.2. Multi-Objective Optimization
To understand this new model, we can analyze a simplified example.
Assume the following topology, passing traffic from A to B:
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A
|
+----------+
| Router 1 |------------+
+----------+ |
| | | | | +----------+
| | | | | | Router 3 |
| | | | | +----------+
+----------+ |
| Router 2 |------------+
+----------+
|
B
Figure 1: Simplified Network for Multi-Objective Optimization
Router 1 is directly connected to Router 2 through five parallel
links, of 10 Gbps each. Router 1 can also reach Router 2 through
Router 3 with 40 Gbps links between Router 1 and Router 3, and
between Router 3 and Router 2. 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.
Another option is to use flexible Ethernet, where the five links
combined are aggregated into one active virtual link which has 15
Gbps, and another inactive link of 35 Gbps of capacity -- although a
physical link cannot be half-active and half-inactive as far as PHY
and optics are concerned.
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6.3. How Much Resiliency is Really Needed?
When we add sustainability considerations, resiliency is not the
single objective to optimize. We can represent a computer network as
a mathematics graph, in which different nodes and links are selected
depending on the network and path optimization. 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 ratio of overall network capacity (in
bandwidth, compute power, etc.) over the used network 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.
6.4. How Much are Performance and Quality of Experience 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.
6.5. Metrics for Sustainability
A sustainability quantification framework is paramount for
understanding the sustainability posture of a system, as well as its
potential for aid in sustainability outcomes.
6.6. 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.
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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.
6.7. The Role of Network Management and Orchestration
Deployment and operational aspects play a critical role in making
networks more sustainable. A detailed explanation of that role, the
associated challenges, as well as an outline of solution approaches
is provided in [I-D.irtf-nmrg-green-ps]. Here are some areas in
which network management can help make networks more sustainable; for
a more extensive treatment, please refer to that document.
* Dimensioning: Networks should be deployed and configured with
sufficient capacity to serve their intended purpose. At the same
time, overprovisioning and providing too many resources should be
avoided, as this results in waste and unnecessary environmental
impact. Network management can faciliate proper dimensioning of
networks by providing the methods and tools that allow to assess
network usage, determine required capacities, identify trends to
allow to proactively accommodate traffic growth and new services.
* Network optimization: Network management applications can help
solve difficult network optimization problems involving multiple
parameters, multiple and sometimes conflicting objectives, and
mitigation of tradeoffs. Network optimization examples include
maximization of utilization or of aggregate QoE scores,
minimization of the possibility of SLA violations with a given
amount of network resources, or optimization of the cost of
configured paths. Network metrics related to sustainability are
another set of parameters that can be optimized.
* Rapid Discovery and Provisioning Schemes: One of the biggest
potential opportunities in reducing environmental impact of
networks concerns the ability to power resources such as equipment
or line cards down when they are momentarily not needed due to
swings in traffic demands. In general, this involves fully
automated management control loops with very short time scales.
Network management can enable such schemes, involving algorithms
that determine and control the rapid de- and re-commissioning of
networking resources, as well as the necessary control protocols
that facilitate aspects such as rapid resource discovery,
reprovisioning, or reconvergence of management state.
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7. Sustainability Advice and Guidelines for Protocol and Network
Designers and Implementers
This section renders the sustainability considerations into specific
guidelines and advice for the design and development of networking
technologies.
WIP
8. Sustainability Requirements and Phases
The considerations and advice for sustainability described in the
"Sustainability Considerations" and "Sustainability Advice and
Guidelines for Protocol and Network Designers and Implementers"
sections and their 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.
8.1. 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
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.
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8.2. 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 could 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:
Visibility". 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.
8.3. Phase 3: Self-optimization and Automation
Manually making changes as mentioned in "Phase 2: Insights and
Recommendations" 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.
8.3.1. Cycle of Phases
The three phases run in an iterative fashion, such that after phases
1, 2, and 3 are completed for an interation, there will be an added
awareness of what (else) to collect back to phase 1.
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Further, sustainability-aware self-optimization is something to
explore in Autonomic Networking.
9. 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.
9.1. Call to Action
INSERT specific call to action here.
10. Security Considerations
TBC.
11. Acknowledgements
TBC.
12. Informative References
[CUE] Belady, C., Azevedo, D., Patterson, M., Pouchet, J., and
R. Tipley, "Carbon Usage Effectiveness (CUE): A Green Grid
Data Center Sustainability Metric", 2 December 2010,
<https://www.thegreengrid.org/en/resources/library-and-
tools/241-Carbon-Usage-Effectiveness-%28CUE%29%3A-A-Green-
Grid-Data-Center-Sustainability-Metric>.
[Doughnut] Wikipedia, "Doughnut (economic model)", 13 October 2023,
<https://en.wikipedia.org/wiki/Doughnut_(economic_model)>.
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[Frontiers]
Frontiers, "The Rebound Effect and the Jevons' Paradox:
Beyond the Conventional Wisdom", 2023,
<https://www.frontiersin.org/research-topics/6598/the-
rebound-effect-and-the-jevons-paradox-beyond-the-
conventional-wisdom#overview>.
[GHG-Proto]
"The Greenhouse Gas Protocol - A Corporate Accounting and
Reporting Standard, revised version", Geneva: World
Business Council for Sustainable Development, Washington,
DC: World Resources Institute, 2004,
<https://ghgprotocol.org/sites/default/files/standards/
ghg-protocol-revised.pdf>.
[Hexa-X_D1.2]
"Expanded 6G vision, use cases and societal values -
including aspects of sustainability, security and
spectrum", Deliverable D1.2, 30 April 2021, <https://hexa-
x.eu/wp-content/uploads/2021/05/Hexa-X_D1.2.pdf>.
[I-D.irtf-nmrg-green-ps]
Clemm, A., Westphal, C., Tantsura, J., Ciavaglia, L., and
M. Odini, "Challenges and Opportunities in Management for
Green Networking", Work in Progress, Internet-Draft,
draft-irtf-nmrg-green-ps-01, 23 October 2023,
<https://datatracker.ietf.org/doc/html/draft-irtf-nmrg-
green-ps-01>.
[IPCC] "Intergovernmental Panel on Climate Change (IPCC). (2022).
Annex I: Glossary. In Global Warming of 1.5°C: IPCC
Special Report on Impacts of Global Warming of 1.5°C above
Pre-industrial Levels in Context of Strengthening Response
to Climate Change, Sustainable Development, and Efforts to
Eradicate Poverty (pp. 541-562)", Cambridge University
Press, doi 10.1017/9781009157940.008, 2022,
<https://www.ipcc.ch/sr15/chapter/glossary/>.
[ITU-ICT-SDG]
ITU, "Digital technologies to achieve the UN SDGs", 2023,
<https://www.itu.int/en/mediacentre/backgrounders/Pages/
icts-to-achieve-the-united-nations-sustainable-
development-goals.aspx>.
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[M6G-SOCIETAL-KV-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>.
[M6G-VALUE-PERF]
Ziegler, V. and S. Yrjola, "6G Indicators of Value and
Performance", 4 May 2020,
<https://doi.org/10.1109/6GSUMMIT49458.2020.9083885>.
[Planet-B] Azote for Stockholm Resilience Centre, based on analysis
in Richardson et al 2023, "Planetary boundaries", 2023,
<https://www.stockholmresilience.org/research/planetary-
boundaries.html>.
[RFC6272] Baker, F. and D. Meyer, "Internet Protocols for the Smart
Grid", RFC 6272, DOI 10.17487/RFC6272, June 2011,
<https://www.rfc-editor.org/info/rfc6272>.
[SDG-Acad] "SDG Academy", 2023, <https://sdgacademy.org>.
[Telefonica]
Telefonica, "Consolidated Annual Report 2021", 2021,
<https://statics.telefonica.com/en/financial-reports/2021/
Consolidated-Annual-
Report/#i7111116644124bd299d124820baf28f7_394>.
[UN-SDG] "Sustainable Development, the 17 Goals", 2023,
<https://sdgs.un.org/goals>.
[UNGA42] UN, "Report of the World Commission on Environment and
Development : "Our common future"", 4 August 1987,
<http://digitallibrary.un.org/record/139811>.
Appendix A. Open Issues and TODOs
[ISSUE 1] Complete "Abstract"
[ISSUE 2] Complete "Introduction"
[ISSUE 3] Complete and strengthen the "Implications to the IETF"
section
[ISSUE 4] Strengthen "Metrics for Sustainability"
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[ISSUE 5] Align on Main Section, "Concrete Advice/Requirements for
Designers and Developers"
[ISSUE 6] What can the IETF do for "Phase 2: Insights and
Recommendations"
[ISSUE 7] Finalize Call-to-Action in the Conclusion
Authors' Addresses
Carlos Pignataro (editor)
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
Hesham ElBakoury
Independent Consultant
Email: helbakoury@gmail.com
Alexander Clemm
Futurewei
2220 Central Expressway
Santa Clara, CA 95050
United States of America
Email: ludwig@clemm.org
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