



Internet Architecture Board (IAB)                               J. Arkko
Request for Comments: 9547                                 C. S. Perkins
Category: Informational                                      S. Krishnan
ISSN: 2070-1721                                            February 2024


    Report from the IAB Workshop on Environmental Impact of Internet
                     Applications and Systems, 2022

Abstract

   Internet communications and applications have both environmental
   costs and benefits.  The IAB ran an online workshop in December 2022
   to explore and understand these impacts.

   The role of the workshop was to discuss the impacts and the evolving
   industry needs, and to identify areas for improvements and future
   work.  A key goal of the workshop was to call further attention to
   the topic and bring together a diverse stakeholder community to
   discuss these issues.

   Note that this document is a report on the proceedings of the
   workshop.  The views and positions documented in this report are
   those of the workshop participants and do not necessarily reflect IAB
   views and positions.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Architecture Board (IAB)
   and represents information that the IAB has deemed valuable to
   provide for permanent record.  It represents the consensus of the
   Internet Architecture Board (IAB).  Documents approved for
   publication by the IAB are not candidates for any level of Internet
   Standard; see Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc9547.

Copyright Notice

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   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   to this document.

Table of Contents

   1.  Introduction
     1.1.  About the Contents of This Workshop Report
   2.  Scope
     2.1.  Practical Arrangements
   3.  Workshop Topics and Discussion
     3.1.  The Big Picture
     3.2.  Understanding the Impacts
     3.3.  Improvements
     3.4.  Next Steps
       3.4.1.  Overall Strategy
       3.4.2.  Improvements
       3.4.3.  Actions
   4.  Feedback
   5.  Security Considerations
   6.  IANA Considerations
   7.  Position Papers
   8.  Program Committee
   9.  Informative References
   Appendix A.  Workshop Participants
   IAB Members at the Time of Approval
   Acknowledgments
   Authors' Addresses

1.  Introduction

   The IAB ran an online workshop in December 2022 to explore and
   understand the environmental impacts of the Internet.

   The context for the workshop was that Internet communications and
   applications have both environmental costs and benefits.  In the
   positive direction, they can reduce the environmental impact of our
   society, for instance, by allowing virtual interaction to replace
   physical travel.  On the other hand, the Internet can equally well
   act as an enabler for increasing physical goods consumption, for
   instance, by facilitating commerce.

   Beyond the effects associated with its use, Internet applications do
   not come for free either.  The Internet runs on systems that require
   energy and raw materials to manufacture and operate.  While the
   environmental benefits of the Internet may certainly outweigh this
   use of resources in many cases, it is incumbent on the Internet
   industry to ensure that this use of resources is minimized and
   optimized.  In many cases, this is already an economic necessity due
   to operational costs.  And because many consumers, businesses, and
   civil societies care deeply about the environmental impact of the
   services and technologies they use, there is also a clear demand for
   providing Internet services with minimal environmental impact.

   The role of the workshop was to discuss the Internet's environmental
   impact and the evolving industry needs, and to identify areas for
   improvements and future work.  A key goal of the workshop was to call
   further attention to the topic and bring together a diverse
   stakeholder community to discuss these issues.  This report
   summarizes the workshop inputs and discussions.

   The workshop drew many position paper submissions.  Of these, 26 were
   accepted and published to stimulate discussion.  There were active
   discussions both in the meeting and on the workshop mailing list with
   73 participants altogether.

   Perhaps the main overriding observation is how much interest and
   urgency there is on this topic, among engineers, researchers, and
   businesses.

   The workshop discussions and conclusions are covered in Section 3.
   The position papers and links to recordings of workshop sessions can
   be found at <https://www.iab.org/activities/workshops/e-impact/>.
   Presentations and related materials from the workshop are available
   from the IETF Datatracker
   <https://datatracker.ietf.org/group/eimpactws/meetings/>.

   After the workshop, the IETF will continue to discuss general topics
   and specific proposals on a new mailing list, the e-impact list
   (e-impact@ietf.org).  You can subscribe to this list at
   <https://www.ietf.org/mailman/listinfo/e-impact>.

   The IETF is discussing improvements for some specific situations,
   such as the Time-Variant Routing (TVR) proposal, which can help
   optimize connectivity with systems that are periodically on or
   reachable (such as satellites).  We expect more proposals in the
   future.

1.1.  About the Contents of This Workshop Report

   The Internet Architecture Board (IAB) holds occasional workshops
   designed to consider long-term issues and strategies for the
   Internet, and to suggest future directions for the Internet
   architecture.  This long-term planning function of the IAB is
   complementary to the ongoing engineering efforts performed by working
   groups of the Internet Engineering Task Force (IETF).

   Furthermore, the content of this report comes from presentations
   given by workshop participants and notes taken during the
   discussions, without interpretation or validation.  Thus, the content
   of this report follows the flow and dialog of the workshop and
   documents a few next steps and actions, but it does not attempt to
   determine or record consensus on these.

2.  Scope

   Environmental impact assessments and improvements are broad topics,
   ranging from technical questions to economics, business decisions,
   and policies.

   The technical, standards, and research communities can help ensure
   that we have a sufficient understanding of the environmental impact
   of the Internet and its applications.  They can also help to design
   the right tools to continue to build and improve all aspects of the
   Internet, such as addressing new functional needs, easing of
   operations, improving performance and/or efficiency, or reducing
   environmental impacts in other ways.

   The following topics were expected to be discussed at the workshop:

   *  The direct environmental impacts of the Internet, including but
      not limited to energy usage by Internet systems themselves (the
      network equipment along with the associated power and cooling
      infrastructure), energy usage of the relevant end-user devices,
      resources needed for manufacturing the associated devices, or the
      environmental impacts throughout the life cycle of Internet
      systems.  This included discussion about the breakdown of those
      impacts across different system components and operations and
      predictions about the potential future trends for these impacts
      based on changed usage patterns and emerging technologies.

   *  The indirect environmental impacts of the Internet, i.e., its
      effects on society through enabling communications, virtual
      services, or global commerce.

   *  Sharing information about relevant measurement metrics and data
      and identifying the need for additional metrics or measurements.

   *  The need for improvements or new associated functionality.

   *  Sharing information about the societal, business, and regulatory
      situation to help identify areas of opportunity.

   *  Identifying areas where further technical work would be most
      impactful.

   *  Specific improvement proposals.

   *  Past work in the IETF, IRTF, and IAB in this area and the status
      of such work.

   *  Observed user behaviors as they relate to environmental impacts.

   We expected the workshop discussions to connect analysis of the
   issues (e.g., scale of energy consumption or carbon footprint) to
   industry needs (e.g., deployment opportunities) and solutions.

   Business and societal policy questions were in scope only insofar as
   they informed the workshop participants about the context we are in,
   but what those policies should be was not for the workshop to decide
   or even extensively discuss.  The scope also excluded how the
   technical community works and meets, such as the question of in-
   person or hybrid meetings (although it should be noted that the
   workshop itself was run as an online meeting).

2.1.  Practical Arrangements

   The IAB discussed a potential workshop in this area during its May
   2022 retreat.  A call for position papers went out in August 2022.
   Position papers were to be submitted by end of October, a deadline
   that was later extended by one week.

   As noted, the workshop itself was run as an online meeting, with four
   half-day sessions complemented by email discussions and the position
   papers submitted by the participants.

   All in all, 73 people participated in at least one session in the
   workshop.  Participation was by invitation only, based on the
   position paper submissions.

   Every submission was read by at least three members of the program
   committee, and acceptance decisions were communicated back to the
   authors.  Review comments were provided to authors for information,
   and some of the papers were revised before the workshop.

   The program committee decided that due to interest and differing
   areas of expertise, all co-authors were to be invited; most of them
   attended.  The program committee also invited a handful of additional
   participants that were seen as providing valuable input.  Similarly,
   as has been done in previous IAB workshops, the program committee
   members and members of the IAB and IESG were offered an opportunity
   to participate, even in cases where they did not submit a position
   paper.

   The IETF Secretariat and communications staff provided practical
   support during the process, sending announcements, maintaining the
   workshop web page with position papers, setting up mailing lists,
   tracking submissions, helping with blog article submissions, and so
   on.

3.  Workshop Topics and Discussion

   The meeting part of the workshop was divided into four sessions:

   *  The first session was about the big picture and relationships
      between different aspects of sustainability (see Section 3.1).

   *  The second session focused on what we know and do not know and how
      we can measure environmental impacts (see Section 3.2).

   *  The third session was about potential improvements (see
      Section 3.3).

   *  The final fourth session was about conclusions and next steps (see
      Section 3.4).

3.1.  The Big Picture

   This session was about the big picture and how the Internet
   influences the rest of the society.  We also spoke about the goals of
   the workshop.

   The session began with a discussion about what is overall involved in
   this topic.  We also looked at how the IETF has approached this topic
   in the past.

   The discussions also expressed the urgency of action and the
   importance of continuous improvement, i.e., an incremental change
   every year is needed for larger savings at the end of the decade.  We
   continued to talk about the need to recognize how climate change
   impacts different communities in the world, often unfairly.  Finally,
   we focused on the need to be aware of carbon footprint rather than
   pure energy consumption -- carbon intensity of energy sources varies.

   The starting observation from this session was that the issue is much
   bigger than Internet technology alone.  The issue influences all
   parts of society, even matters such as (in)equality, externalized
   costs, and justice.  Another key observation was that improvements
   come in many forms; there is no silver bullet.  The opportunity to
   bring people with different backgrounds together helped us see how we
   approach the topic from different angles -- none of them wrong, but
   also none of them are the sole angle to focus on either.  Only the
   combined effects of complementary efforts can provide the required
   level of changes.

   Some of the useful tools for approaching the issue of course included
   technical solutions but also solidarity, aiming for sufficiency, and
   awareness.  It is important to not stand still waiting for the
   perfect solution.  Renewable energy and carbon awareness were seen as
   a part of the solution but not sufficient by themselves.

   As an example demonstration of the diversity of angles and
   improvements relating to environmental issues, the figure below
   classifies the areas that workshop position papers fell on:

             +---- Actors & organizations
             |                                 +---- Avoidance
             +---- Benefits to other fields    |
             |                                 +---- User behavior
             +---- Society, awareness, &       |
             |     justice                     +---- Implementation
             |                                 |
   Workshop -+- Improvements ------------------+
             |                                 |
             |     Understanding &             |       +---- Data plane
             +---- Measurements                |       |
                         |                 Protocols --+---- Routing
                         |                             |
                         +---- Energy                  +---- Edge cloud
                         |                             |
                         +---- Carbon                  +---- Mobile
                                                       |
                                                       +---- Metrics
                                                       |
                                                       +---- Other

                 Figure 1: Position Paper Submission Topics

   Some of the goals for the IETF should include:

   *  Connecting the IETF with others.  Given that the issue is broad,
      it is difficult for one Standards Development Organization (SDO)
      alone to make a significant impact or even have the full picture.
      Working in collaboration with others is necessary, and
      understanding the situation beyond technology will be needed.

   *  Continuous improvement.  It is important that the IETF (among
      others) set itself on a continuous improvement cycle.  No single
      improvement will change the overall situation sufficiently, but
      over a longer period of time, even smaller changes every year will
      result in larger improvements.

   *  Finding the right targets for improvements in the Internet.  These
      should perhaps not be solely defined by larger speeds or bigger
      capacity but rather increased usefulness to society and declining
      emissions from the Information and Communications Technology (ICT)
      sector.

   *  Specifying what research needs to be done, i.e., where additional
      knowledge would allow us to find better improvements.  For
      instance, not enough is known about environmental impacts beyond
      energy, such as natural resources used for manufacturing or the
      use of water.  Carbon awareness and measurements across domains
      are also poorly understood today.  And business model impacts --
      such as the role of advertising on the Internet's carbon footprint
      -- deserve more study.

3.2.  Understanding the Impacts

   The second session focused on what we know and do not know and how we
   can measure environmental impacts.

   The initial presentation focused on narrowing down the lower and
   upper limits of the energy use of the Internet and putting some
   common but erroneous claims into context.  There was also discussion
   regarding the energy consumption of the ICT sector and how it
   compares to some other selected industries, such as aviation.

   Dwelling deeper into the energy consumption and the carbon footprint
   of the ICT sector, there was discussion regarding how the impact was
   split amongst the networks, data centers, and user devices (with the
   user devices appearing to contribute to the largest fraction of
   impact).  Also, while a lot of the energy-consumption-related studies
   and discussions have been focused on data centers, some studies
   suggested that data center energy usage is still a small fraction of
   energy use as compared to residential and commercial buildings.

   There were also further discussions during both the presentations and
   in the hallway chats regarding the press and media coverage of the
   potential environment technologies.  The overall sense of the
   participants seemed to be that there was a lot of sensational
   headlines, but they were not really backed by measurements done by
   the industry and academia and were fraught with errors.  Some of
   these media reports were off by quite a bit, sometimes even by an
   order of magnitude (e.g., confusing MBps vs. Mbps in calculations).
   The potential harm of having widely circulating misinformation was
   noted; it can hinder realistic efforts to reduce carbon emissions.

   In the rest of the session, we looked at both additional data
   collected from the operators as well as factors that -- depending on
   circumstances -- may drive energy consumption.  For instance, these
   include peak capacity and energy proportionality.

   If energy consumption is minimally affected by an offered load, the
   ratio of peak capacity to typical usage becomes a critical factor in
   energy consumption.  On the other hand, systems with energy
   proportionality scale their resource and energy consumption more
   dynamically based on the offered load.  The lack of energy
   proportionality in many parts of the network infrastructure was
   noted, along with the potential gains if it can be improved.

   There were also observations that showed that the energy consumption
   grew as a step function when the peak capacity was reached (even
   instantaneously), and additional capacity was built up by performing
   network upgrades to handle these new peaks.  This resulted in an
   overall higher baseline energy consumption, even when the average
   demand did not change that much.  Thus, the ability to shift load to
   reduce peak demand was highlighted as a potential way to delay
   increases in consumption when energy proportionality is lacking.

3.3.  Improvements

   The third session was about potential improvements.

   As noted earlier, there are many different types of improvements.  In
   the discussion, we focused mostly on protocol aspects and looked at
   metrics, telemetry, routing, multicast, and data encoding formats.

   The two initial presentations focused on metrics and telemetry with
   the premise that visibility is a very important first step
   (paraphrasing Peter Drucker's mantra of "You cannot improve what you
   don't measure").  There was a discussion of the scopes of emissions,
   and it seemed that, from a networking vendor perspective, while
   directly controlled emissions and emissions from purchased energy are
   easily measurable, emissions from across the entire value chain can
   be much larger.  Thus, it seemed important that networking vendors
   put effort into helping their customers measure and mitigate their
   environmental impact as well.  The need for standardized metrics was
   very clear, as it helps avoid proprietary, redundant, and even
   contradictory metrics across vendors.

   The initial and the near-term focus was related to metrics and
   techniques related to energy consumption of the networking devices
   themselves, while the longer term focus can go into topics much
   further removed from the IETF circular design, such as packaging, in
   order to form a more holistic picture.  The overall feeling was that
   the topics of metrics, telemetry, and management are quite specific
   and could be targets to be worked on in the IETF in the near term.

   The next part of the discussion highlighted the need to understand
   the trade-offs involved in changing forwarding decisions -- such as
   increased jitter and stretch.  Jitter is about delay fluctuation
   between packets in a stream [RFC4689].  Stretch is defined as the
   difference between the absolute shortest path traffic could take
   through the network and the path the traffic actually takes
   [RFC7980].  Impacts on jitter and stretch point to the need for
   careful design and analysis of improvements from a system perspective
   to ensure that the intended effect is indeed reached across the
   entire system and is not only a local optimum.

   We also talked about the potentially significant impact, provided the
   network exhibits energy proportionality, of using efficient binary
   formats instead of textual representations when carrying data in
   protocols.  This is something that can be adopted relatively easily
   in new protocols as they are developed.  Indeed, some recently
   finished protocols, such as HTTP/2, have already chosen to use this
   technique [RFC9113].  General-purpose binary formats, such as Concise
   Binary Object Representation (CBOR) [RFC8949], are also available for
   use.

   There were also some interesting discussions regarding the use of
   multicast and whether it would help or hurt on the energy efficiency
   of communications.  There were some studies and simulations that
   showed the potential gains to be had, but they were to be balanced
   against some of the well-known barriers to deployment of multicast.
   We also heard from a leading Content Delivery Network (CDN) operator
   regarding their views on multicast and how it relates to media usage
   and consumption models.  The potential negative effects of multicast
   in wireless and constrained networks were also discussed in hallway
   conversations.  Overall, the conclusion was that the use of multicast
   can potentially provide some savings but only in some specific
   scenarios.

   For all improvements, the importance of metrics was frequently
   highlighted to ensure changes lead to a meaningful reduction in the
   overall carbon footprint of systems.

3.4.  Next Steps

   The fourth and final session was about conclusions and next steps.
   This section highlights some of these conclusions.

3.4.1.  Overall Strategy

   While only a few things are easy, the road ahead for making
   improvements seems clear: we need to continue to improve our
   understanding of the environmental impact and have a continuous cycle
   of improvements that lead not just to better energy efficiency but to
   reduced overall carbon emissions.  The IETF can play an important
   part in this process, but of course there are other aspects beyond
   protocols.

   On understanding our environmental impact, the first step is better
   awareness of sustainability issues in general, which helps us better
   understand where our issues are.  The second step is willingness to
   understand in detail what the causes and relationships are within our
   issues.  What parts, components, or behaviors in the network cause
   what kinds of impacts?  An overall drive in the society to report and
   improve environmental impacts can be helpful in creating a
   willingness to get to this information.

   On establishing a continuous cycle of improvements, the ability to
   understand where we are, making improvements, and then seeing the
   impact of those improvements is of course central.  But obviously the
   key questions are what are the potential improvements and how can we
   accelerate them?  It should be noted that quick, large changes are
   not likely.  But a continuous stream of smaller changes can create a
   large impact over a longer period of time.

   One of the key realizations from this workshop was that the problem
   to be solved is very large and complex; therefore, there is no single
   solution that fixes everything.  There are some solutions that could
   help in the near term and others that would only show benefits over
   longer periods, but they are both necessary.

   One further challenge is that due to the size and complexity of the
   problem, there are likely varying opinions on what Key Performance
   Indicators (KPIs) need to be measured and improved.

3.4.2.  Improvements

   In looking at potential improvements, it is essential that any
   associated trade-offs be understood (note that not all improvements
   do indeed entail a trade-off).

   Importantly, the role of the Internet in improving other areas of
   society must not be diminished.  Understanding the costs and benefits
   requires taking a holistic view of energy consumption, focusing not
   just on the carbon footprint of the Internet but of the broader
   systems in which it is used.  For instance, discussion in session
   three revealed how some changes might impact latency and jitter.
   Given that these characteristics are important factors in how virtual
   meetings are perceived by potential participants, it is important
   that the performance of networks satisfy these participants at a
   level such that they are willing to use them over other potentially
   more environmentally harmful methods, such as travel.  Focusing
   solely on the carbon footprint of the Internet, or solely on the
   carbon footprint of travel, risks missing the bigger picture
   potential savings.

   Note that, while shifting to virtual meetings is a common example of
   how the carbon footprint could be decreased, it is important to
   consider different use cases, some of which may not be as obvious to
   us human users as meetings are.  Improvements may bring different or
   even larger impacts in other situations, e.g., Internet-connected
   electronics might benefit from different characteristics than human
   users, e.g., with regards to support for intermittent connectivity.

   The relationships between different system components and the impact
   of various detailed design choices in networks are not always
   apparent.  A local change in one node may have an impact in other
   nodes.  When considering environmental sustainability, in most cases,
   the overall system impact is what counts more than local impacts.  Of
   course, other factors, such as device battery life and availability
   of power, may result in other preferences, such as optimizing for
   low-power usage of end-user devices, even at the cost of increases
   elsewhere.

   In terms of useful tools for building improvements, the following
   were highlighted in discussions:

   *  Measures beyond protocol design, such as implementations or
      renewable energy use.  Not everything is about protocols.

   *  Metrics, measurements, and data are very beneficial.  Carbon-aware
      metrics in particular would be very useful.  All additional
      information makes us more aware of what the environmental impacts
      are, and it also enables optimization, adjustments based on
      Artificial Intelligence (AI), carbon-directed computing and
      networking tools, and so on.

   *  It would be beneficial to be able to provide various systems a
      more dynamic ability to slow down and sleep.  Awareness of energy
      availability and type would also allow us to employ time and place
      shifting for reducing carbon impacts.

   *  When we design systems, paying attention to the used data formats
      may pay off significantly, as argued in [Moran].

   *  There's a new possible opportunity for deploying multicast as well
      [Navarre].

   *  Designing systems for energy-constrained situations may actually
      make the resulting systems work well in several environments.

3.4.3.  Actions

   The workshop discussed a number of possible actions.  These actions
   are not about how to take specific technical solutions forward but
   rather about how to discuss the topic going forward or what technical
   areas to focus on:

   *  We need to continue the discussion -- not all questions are
      answered.  Additional discussion within the IETF will be needed.
      Continuing to connect the IETF with others in society and other
      SDOs around this topic is also useful.

   *  It is useful to find a role and a scope for IETF work in this
      area.  The IETF will not develop alternative energy sources, work
      on social issues, or have detailed discussions about
      implementation strategies or electronics design.  However, the
      IETF has a role in measurement mechanisms, protocol design, and
      standards -- but of course, activities in this role need to be
      aware of other aspects, such as implementation strategies.

   *  Increase our understanding of the environmental impacts of
      Internet technologies.  One discussion topic that arose during the
      workshop was whether each new RFC should dedicate a section to
      discuss these impacts.  No conclusion was drawn about the way to
      document these in RFCs, but it is clear that the IETF community
      will need to understand the environmental issues better.  (Perhaps
      in addition to learning about the actual issues, guidelines for
      analyzing protocols with regards to their impacts could be
      useful.)

   *  IETF activities on specific technologies are already ongoing or
      starting; for example, metrics are being discussed in the Network
      Management Research Group [NMRG], the Operations and Management
      Area Working Group [OPSAWG], and the new Time-Variant Routing
      Working Group [TVRWG].  It may also be useful to start with the
      low-hanging fruits, such as:

      -  Focusing on improving energy proportionality and the consequent
         use of efficient data formats.

      -  Avoiding crypto assets -- such as Non-Fungible Tokens (NFTs)
         and cryptocurrencies.

      -  Being able to carry information that needs to be shared for the
         purposes of enabling load and time shifting.

   *  Help initiate research activities that address some of the issues,
      such as broader gathering and sharing of measurement data,
      analysis of this data, and examination of business-related issues,
      such as how peering or advertising impacts sustainability.  In
      addition, there may be a need to look at research for specific
      areas of improvements that are promising but not ready for
      standards discussion.

   In summary, the goals that the IETF should have include:

   *  Full understanding of the Internet's environmental impact.

   *  Continuous improvement of our technology.

   *  Launching research-relevant activities.

   To support these goals, the IAB has created the e-impact program
   [E-IMPACT] as a venue for further discussions concerning
   environmental impacts and sustainability of Internet technology.

4.  Feedback

   The organizers received generally positive feedback about the
   workshop.

   One practical issue from the organizer's point of view was that, due
   to the extension of the deadline, the final submissions and paper
   reviews collided in part with the IETF 115 meeting.  This led to it
   being very difficult for the program committee and practical
   organization staff to find time for the activity.  We recommend
   avoiding such collisions in the future.

5.  Security Considerations

   The workshop itself did not address specific security topics.  Of
   course, individual changes in Internet technology or operations that
   influence environmental impacts may also influence security aspects.
   These need to be looked at for every proposed change.

   Such influence on security may come in different forms.  For
   instance:

   *  A mechanism that makes energy consumption information available
      may be susceptible to tampering or providing false information.
      For example, in [McDaniel], the author argues that economics and
      history show that different players will attempt to cheat if a
      benefit can be accrued by doing so, e.g., by misreporting.  As a
      result, sustainability measures and systems must be modeled as
      systems under threat.

   *  A mechanism that allows control of network elements for
      optimization purposes may be misused to cause denial-of-service or
      other types of attacks.

   *  Avoiding the use of crypto assets where other mechanisms suffice.

   *  Streamlining what data is sent may improve privacy if less
      information is shared.

6.  IANA Considerations

   This document has no IANA actions.

7.  Position Papers

   The following position papers were submitted to the workshop:

   *  Chris Adams, Stefano Salsano, Hesham ElBakoury: "Extending IPv6 to
      support Carbon Aware Networking" [Adams]

   *  Per Anderson, Suresh Krishnan, Jan Lindblad, Snezana Mitrovic,
      Marisol Palmero, Esther Roure, Gonzalo Salgueiro: "Sustainability
      Telemetry" [Anderson]

   *  Jari Arkko, Nina Lövehagen, Pernilla Bergmark: "Environmental
      Impacts of the Internet: Scope, Improvements, and Challenges"
      [Arkko]

   *  R. Bolla, R. Bruschi, F. Davoli, C. Lombardo, Beatrice Siccardi:
      "6Green: Green Technologies for 5/6G Service-Based Architectures"
      [Bolla]

   *  Alexander Clemm, Lijun Dong, Greg Mirsky, Laurent Ciavaglia, Jeff
      Tantsura, Marie-Paule Odini: "Green Networking Metrics" [ClemmA]

   *  Alexander Clemm, Cedric Westphal, Jeff Tantsura, Laurent
      Ciavaglia, Marie-Paule Odini, Michael Welzl: "Challenges and
      Opportunities in Green Networking" [ClemmB]

   *  Toerless Eckert, Mohamed Boucadair, Pascal Thubert, Jeff Tantsura:
      "IETF and Energy - An Overview" [Eckert]

   *  Greening of Streaming: "Tune In.  Turn On.  Cut Back.  Finding the
      optimal streaming 'default' mode to increase energy efficiency,
      shift consumer expectations, and safeguard choice" [GOS]

   *  Romain Jacob: "Towards a power-proportional Internet" [Jacob]

   *  Fieke Jansen and Maya Richman: "Environment, internet
      infrastructure, and digital rights" [Jansen]

   *  Michael King, Suresh Krishnan, Carlos Pignataro, Pascal Thubert,
      Eric Voit: "On Principles for a Sustainability Stack" [King]

   *  Suresh Krishnan, Carlos Pignataro: "Sustainability considerations
      for networking equipment" [Krishnan]

   *  Jukka Manner: "Sustainability Considerations" [Manner]

   *  Vesna Manojlovic: "Internet Infrastructure and Climate Justice"
      [Manojlovic]

   *  Mike Mattera: "Understanding the Full Emissions Impact from
      Internet Traffic" [Mattera]

   *  John Preuß Mattsson: "Environmental Impact of Crypto-Assets"
      [Mattsson]

   *  Brendan Moran, Henk Birkholz, Carsten Bormann: "CBOR is Greener
      than JSON" [Moran]

   *  Louis Navarre, Franoçis Michel, Olivier Bonaventure: "It Is Time
      to Reconsider Multicast" [Navarre]

   *  Bruce Nordman: "Applying Internet Architecture to Energy Systems"
      [Nordman]

   *  Alvaro Retana, Russ White, Manuel Paul: "A Framework and
      Requirements for Energy Aware Control Planes" [Retana]

   *  Shayna Robinson, Remy Hellstern, Mariana Diaz: "Sea Change:
      Prioritizing the Environment in Internet Architecture" [Robinson]

   *  Daniel Schien, Paul Shabajee, Chris Preist: "Rethinking Allocation
      in High-Baseload Systems: A Demand-Proportional Network
      Electricity Intensity Metric" [Schien]

   *  Eve M.  Schooler, Rick Taylor, Noa Zilberman, Robert Soulé, Dawn
      Nafus, Rajit Manohar, Uri Cummings: "A Perspective on Carbon-aware
      Networking" [Schooler]

   *  Selome Kostentinos Tesfatsion, Xuejun Cai, Arif Ahmed: "End-to-end
      Energy Efficiency at Service-level in Edge Cloud" [Kostentinos]

   *  Pascal Thubert: "Digital Twin and Automation" [Thubert]

   *  Wim Vanderbauwhede: "Frugal Computing" [Vanderbauwhede]

   *  Michael Welzl, Ozgu Alay, Peyman Teymoori, Safiqul Islam:
      "Reducing Green House Gas Emissions With Congestion Control"
      [Welzl]

8.  Program Committee

   The program committee members were:

   *  Jari Arkko, Ericsson (program committee co-chair)

   *  Lars Eggert, Netapp (program committee co-chair)

   *  Luis M. Contreras, Telefónica

   *  Toerless Eckert, Futurewei

   *  Martin Flack, Akamai

   *  Mike Mattera, Akamai

   *  Colin Perkins, University of Glasgow

   *  Barath Raghavan, USC

   *  Daniel Schien, University of Bristol

   *  Eve M. Schooler, Intel

   *  Rick Taylor, Ori Industries

   *  Jiankang Yao, CNNIC

9.  Informative References

   [Adams]    Adams, C., Salsano, S., and H. ElBakoury, "Extending IPv6
              to support Carbon Aware Networking", Position paper in the
              IAB Workshop on Environmental Impacts of Internet
              Applications and Systems, December 2022.

   [Anderson] Anderson, P., Krishnan, S., Lindblad, J., Mitrovic, S.,
              Palmero, M., Roure, E., and G. Salgueiro, "Sustainability
              Telemetry", Position paper in the IAB Workshop on
              Environmental Impacts of Internet Applications and
              Systems, December 2022.

   [Arkko]    Arkko, J., Lövehagen, N., and P. Bergmark, "Environmental
              Impacts of the Internet: Scope, Improvements, and
              Challenges", Position paper in the IAB Workshop on
              Environmental Impacts of Internet Applications and
              Systems, December 2022.

   [Bolla]    Bolla, R., Bruschi, R., Davoli, F., Lombardo, C., and B.
              Siccardi, "6Green: Green Technologies for 5/6G Service-
              Based Architectures", Position paper in the IAB Workshop
              on Environmental Impacts of Internet Applications and
              Systems, December 2022.

   [ClemmA]   Clemm, A., Dong, L., Mirsky, G., Ciavaglia, L., Tantsura,
              J., and M. Odini, "Green Networking Metrics", Position
              paper in the IAB Workshop on Environmental Impacts of
              Internet Applications and Systems, December 2022.

   [ClemmB]   Clemm, A., Westphal, C., Tantsura, J., Ciavaglia, L.,
              Odini, M., and M. Welzl, "Challenges and Opportunities in
              Green Networking", Position paper in the IAB Workshop on
              Environmental Impacts of Internet Applications and
              Systems, December 2022.

   [E-IMPACT] IAB, "Environmental Impacts of Internet Technology", IAB
              Program, <https://datatracker.ietf.org/group/eimpact>.

   [Eckert]   Eckert, T., Ed., Boucadair, M., Ed., Thubert, P.,
              Tantsura, J., and C. Pignataro, "An Overview of Energy-
              related Effort within the IETF", Work in Progress,
              Internet-Draft, draft-eckert-ietf-and-energy-overview-06,
              6 January 2024, <https://datatracker.ietf.org/doc/html/
              draft-eckert-ietf-and-energy-overview-06>.

   [GOS]      Greening of Streaming, "Tune In. Turn On. Cut Back.
              Finding the optimal streaming 'default' mode to increase
              energy efficiency, shift consumer expectations, and
              safeguard choice", Position paper in the IAB Workshop on
              Environmental Impacts of Internet Applications and
              Systems, December 2022.

   [Jacob]    Jacob, R., "Towards a power-proportional Internet",
              Position paper in the IAB Workshop on Environmental
              Impacts of Internet Applications and Systems, December
              2022.

   [Jansen]   Jansen, F. and M. Richman, "Environment, internet
              infrastructure, and digital rights", Position paper in the
              IAB Workshop on Environmental Impacts of Internet
              Applications and Systems, December 2022.

   [King]     King, M., Krishnan, S., Pignataro, C., Thubert, P., and E.
              Voit, "On Principles for a Sustainability Stack", Position
              paper in the IAB Workshop on Environmental Impacts of
              Internet Applications and Systems, October 2022.

   [Kostentinos]
              Tesfatsion, S., Cai, X., and A. Ahmed, "End-to-end Energy
              Efficiency at Service-level in Edge Cloud", Position paper
              in the IAB Workshop on Environmental Impacts of Internet
              Applications and Systems, December 2022.

   [Krishnan] Krishnan, S. and C. Pignataro, "Sustainability
              considerations for networking equipment", Position paper
              in the IAB Workshop on Environmental Impacts of Internet
              Applications and Systems, December 2022.

   [Manner]   Manner, J., "Sustainability Considerations", Position
              paper in the IAB Workshop on Environmental Impacts of
              Internet Applications and Systems, December 2022.

   [Manojlovic]
              Manojlovic, V., "Internet Infrastructure and Climate
              Justice", Position paper in the IAB Workshop on
              Environmental Impacts of Internet Applications and
              Systems, October 2022.

   [Mattera]  Mattera, M., "Understanding the Full Emissions Impact from
              Internet Traffic", Position paper in the IAB Workshop on
              Environmental Impacts of Internet Applications and
              Systems, October 2022.

   [Mattsson] Preuß Mattsson, J., "Environmental Impact of Crypto-
              Assets", Position paper in the IAB Workshop on
              Environmental Impacts of Internet Applications and
              Systems, December 2022.

   [McDaniel] McDaniel, P., "Sustainability is a Security Problem", ACM
              SIGSAC Conference on Computer and Communications Security
              (CCS), November 2022.

   [Moran]    Moran, B., Birkholz, H., and C. Bormann, "CBOR is Greener
              than JSON", Position paper in the IAB Workshop on
              Environmental Impacts of Internet Applications and
              Systems, October 2022.

   [Navarre]  Navarre, L., Michel, F., and O. Bonaventure, "It Is Time
              to Reconsider Multicast", Position paper in the IAB
              Workshop on Environmental Impacts of Internet Applications
              and Systems, December 2022.

   [NMRG]     IRTF, "Network Management Research Group NMRG", IRTF
              Research Group, March 1999,
              <https://www.irtf.org/nmrg.html>.

   [Nordman]  Nordman, B., "Applying Internet Architecture to Energy
              Systems", Position paper in the IAB Workshop on
              Environmental Impacts of Internet Applications and
              Systems, December 2022.

   [OPSAWG]   IETF, "Operations and Management Area Working Group
              (opsawg)", IETF Working Group,
              <https://datatracker.ietf.org/wg/opsawg/about/>.

   [Retana]   Retana, A., White, R., and M. Paul, "A Framework for
              Energy Aware Control Planes", Work in Progress, Internet-
              Draft, draft-retana-rtgwg-eacp-07, 24 August 2023,
              <https://datatracker.ietf.org/doc/html/draft-retana-rtgwg-
              eacp-07>.

   [RFC4689]  Poretsky, S., Perser, J., Erramilli, S., and S. Khurana,
              "Terminology for Benchmarking Network-layer Traffic
              Control Mechanisms", RFC 4689, DOI 10.17487/RFC4689,
              October 2006, <https://www.rfc-editor.org/info/rfc4689>.

   [RFC7980]  Behringer, M., Retana, A., White, R., and G. Huston, "A
              Framework for Defining Network Complexity", RFC 7980,
              DOI 10.17487/RFC7980, October 2016,
              <https://www.rfc-editor.org/info/rfc7980>.

   [RFC8949]  Bormann, C. and P. Hoffman, "Concise Binary Object
              Representation (CBOR)", STD 94, RFC 8949,
              DOI 10.17487/RFC8949, December 2020,
              <https://www.rfc-editor.org/info/rfc8949>.

   [RFC9113]  Thomson, M., Ed. and C. Benfield, Ed., "HTTP/2", RFC 9113,
              DOI 10.17487/RFC9113, June 2022,
              <https://www.rfc-editor.org/info/rfc9113>.

   [Robinson] Robinson, S., Hellstern, R., and M. Diaz, "Sea Change:
              Prioritizing the Environment in Internet Architecture",
              Position paper in the IAB Workshop on Environmental
              Impacts of Internet Applications and Systems, December
              2022.

   [Schien]   Schien, D., Shabajee, P., and C. Preist, "Rethinking
              Allocation in High-Baseload Systems: A Demand-Proportional
              Network Electricity Intensity Metric", Position paper in
              the IAB Workshop on Environmental Impacts of Internet
              Applications and Systems, December 2022.

   [Schooler] Schooler, E., Taylor, R., Zilberman, N., Soulé, R., Nafus,
              D., Manohar, R., and U. Cummings, "A Perspective on
              Carbon-aware Networking", Position paper in the IAB
              Workshop on Environmental Impacts of Internet Applications
              and Systems, October 2022.

   [Thubert]  Thubert, P., "Digital Twin and Automation", Position paper
              in the IAB Workshop on Environmental Impacts of Internet
              Applications and Systems, December 2022.

   [TVRWG]    IESG, "Time-Variant Routing (tvr)", IETF Working Group,
              <https://datatracker.ietf.org/group/tvr/about/>.

   [Vanderbauwhede]
              Vanderbauwhede, W., "Frugal Computing", Position paper in
              the IAB Workshop on Environmental Impacts of Internet
              Applications and Systems, December 2022.

   [Welzl]    Welzl, M., Alay, O., Teymoori, P., and S. Islam, "Reducing
              Green House Gas Emissions With Congestion Control",
              Position paper in the IAB Workshop on Environmental
              Impacts of Internet Applications and Systems, October
              2022.

Appendix A.  Workshop Participants

   The participants who attended at least one of the four sessions were:

   *  Alex Clemm

   *  Ali Rezaki

   *  Arif Ahmed

   *  Beatrice Siccardi

   *  Brendan Moran

   *  Bruce Nordman

   *  Carlos Pignataro

   *  Carsten Bormann

   *  Cedric Westphal

   *  Chiara Lombardo

   *  Chris Adams

   *  Colin Perkins

   *  Daniel Schien

   *  Dawn Nafus

   *  Dom Robinson

   *  Eric Voit

   *  Éric Vyncke

   *  Esther Roure Vila

   *  Eve M. Schooler

   *  Fieke Jansen

   *  Franco Davoli

   *  Gonzalo Salgueiro

   *  Greg Mirsky

   *  Henk Birkholz

   *  Hesham ElBakoury

   *  Hosein Badran

   *  Iankang Yao

   *  Jan Lindblad

   *  Jari Arkko

   *  Jens Malmodin

   *  Jiankang Yao

   *  John Preuß Mattsson

   *  Jukka Manner

   *  Julien Maisonneuve

   *  Kristin Moyer

   *  Lars Eggert

   *  Laurent Ciavaglia

   *  Lijun Dong

   *  Louis Navarre

   *  Louise Krug

   *  Luis M. Contreras

   *  Marisol Palmero Amador

   *  Martin Flack

   *  Maya Richman

   *  Michael Welzl

   *  Mike Mattera

   *  Mohamed Boucadair

   *  Nina Lövehagen

   *  Noa Zilberman

   *  Olivier Bonaventure

   *  Pascal Thubert

   *  Paul Shabajee

   *  Per Andersson

   *  Pernilla Bergmark

   *  Peyman Teymoori

   *  Qin Wu

   *  Remy Hellstern

   *  Rick Taylor

   *  Rob WIlton

   *  Rob Wilton

   *  Romain Jacob

   *  Russ White

   *  Safiqul Islam

   *  Selome Kostentinos Tesfatsion

   *  Shayna Robinson

   *  Snezana Mitrovic

   *  Stefano Salsano

   *  Suresh Krishnan

   *  Tirumaleswar Reddy.K

   *  Toerless Eckert

   *  Uri Cummings

   *  Vesna Manojlovic

   *  Wim Vanderbauwhede

IAB Members at the Time of Approval

   Internet Architecture Board members at the time this document was
   approved for publication were:

      Dhruv Dhody
      Lars Eggert
      Wes Hardaker
      Cullen Jennings
      Mallory Knodel
      Suresh Krishnan
      Mirja Kühlewind
      Tommy Pauly
      Alvaro Retana
      David Schinazi
      Christopher Wood
      Qin Wu
      Jiankang Yao

Acknowledgments

   Naturally, most of the credit goes to the workshop participants.

   The organizers wish to thank Cindy Morgan and Greg Wood for their
   work on the practical arrangements and communications relating to the
   workshop.  This report was greatly enhanced by the feedback provided
   on it.  Thanks to Michael Welzl in particular for his detailed
   review.

Authors' Addresses

   Jari Arkko
   Ericsson
   Email: jari.arkko@ericsson.com


   Colin S. Perkins
   University of Glasgow
   Email: csp@csperkins.org


   Suresh Krishnan
   Cisco
   Email: suresh.krishnan@gmail.com
