SUSTAIN RG Agenda -- IETF 123 (Madrid and Online)
Datatracker: https://datatracker.ietf.org/rg/sustain/about/
ICS: https://datatracker.ietf.org/meeting/123/session/34419.ics
SUSTAIN RG session: THURSDAY, 24 July, 2025 -- Session IV
When: 17:00 - 19:00 CEST (15:00 - 17:00 UTC)
Room: Tapices -- https://datatracker.ietf.org/meeting/123/floor-plan
Co-chairs: Ali Rezaki (ali.rezaki@nokia.com), Eve Schooler
(eve.schooler@gmail.com), Michael Welzl (michawe@ifi.uio.no)
Materials: https://datatracker.ietf.org/meeting/123/session/sustain
Note taking: https://notes.ietf.org/notes-ietf-123-sustain
Remote participation:
https://meetings.conf.meetecho.com/ietf123/?session=34419
Local onsite tool:
https://meetings.conf.meetecho.com/onsite123/?session=34419
Chat: https://zulip.ietf.org/#narrow/stream/sustain
Recording: https://www.meetecho.com/ietf123/recordings#SUSTAIN
YouTube: https://www.youtube.com/watch?v=FMxu7mT5nZA
REMINDER to Presenters: the duration times include Q&A
Note takers: Marie-José Montpetit
1) 17:00 | 5 min | Title: Co-Chair Intro
Presenters: Ali Rezaki (Nokia), Eve Schooler (U Oxford), & Michael Welzl
(U Oslo)
Charter: https://datatracker.ietf.org/doc/charter-irtf-sustain/
Slides:
https://datatracker.ietf.org/meeting/123/materials/slides-123-sustain-chair-slides-for-sustain-rg-ietf-123-02
Plan ahead: Sustain Workshop in Passau planned for 16-17 July 2026.
2) 17:05 | 20 min | Title: Unlocking Flexibility Potentials of Data Centers and Multi-Use Battery Storages
Presenter: Hermann de Meer (U Passau)
Contributors: Michael Lechl and Alexander Kilian (U Passau)
Slides:
https://datatracker.ietf.org/meeting/123/materials/slides-123-sustain-unlocking-flexibility-potentials-of-data-centers-and-multi-use-battery-storages-02
Abstract:
- Energy and ICT systems are increasingly interdependent, requiring
integrated solutions for sustainable and stable operation. This talk
presents approaches to unlock flexibility potentials from data
centers and multi-use battery storage systems, considering energy
efficiency from a local and grid perspective. For example,
high-performance computing data centers can ship workloads based on
renewable energy availability, reducing curtailment and enabling
lowcarbon operation. It is depicted how wind-powered data centers
and artificial intelligence can support intelligent, sustainable
workload distribution. Multi-use battery storage systems complement
this by providing grid support and balancing volatile renewable
generation. Furthermore, co-locating data centers with battery
storage systems at renewable generation sites allow for a dynamic
level of Quality of Service (QoS) and Quality of Grid Service (QoGS)
by introducing Green Service Level Agreements (GreenSLAs) and Green
Supply Demand Agreements (GreenSDAs), for example. This integrated
strategy supports both market and system needs while offering a
pathway to dependable energy-ICT infrastructures. The presented use
case shows that standards need to be established to realize energy
efficiency and sustainability from a local perspective and a power
grid perspective in decentralized systems consisting of consuming
and generating entities.
Related work:
- A. Berl, E. Gelenbe, M. Di Girolamo, G. Giuliani, H. de Meer, M.
Quan Dang and K. Pentikousis, "Energy-Efficient Cloud Computing",
The Computer journal, vol. 53, no. 7, pp. 1045-1051, Aug. 2009.
Oxford University Press. DOI: 10.1093/comjnl/bxp080
- R. Basmadjian, J. F. Botero, G. Giuliani, X. Hesselbach, S. Klingert
and H. de Meer, "Making Data Centers Fit for Demand Response:
Introducing GreenSDA and GreenSLA Contracts", IEEE Transactions on
Smart Grid, vol. 9, no. 4, pp. 3453-3464, Nov. 2018. DOI:
10.1109/TSG.2016.2632526
- A. Kilian, H. de Meer and G. Schomaker, "Energy-Optimized
Supercomputer Networks Using Wind Energy", Communications of the ACM
(CACM), vol. 68, no. 7, pp. 74-79, Jul. 2025. ACM. DOI:
10.1145/3725981
- M. Lechl, T. Fürmann, H. de Meer and A. Weidlich, "A review of
models for energy system flexibility requirements and potentials
using the new FLEXBLOX taxonomy", Renewable and Sustainable Energy
Reviews, vol. 184, pp. 1-19, Sep. 2023. Elsevier. DOI:
10.1016/j.rser.2023.113570
- M. Lechl, A. Kilian and H. de Meer, "Uncertainty-Aware Scheduling of
Multi-Use Battery Storage Systems" in 16th ACM Int’l. Conf. on
Future and Sustainable Energy Systems (e-Energy '25), June 17-20,
2025, Rotterdam, Netherlands, ACM, Jun. 2025. pp. 243-256. DOI:
10.1145/3679240.3734607
- M. Lechl, H. de Meer and T. Fürmann, "A Stochastic Flexibility
Calculus for Uncertainty-Aware Energy Flexibility Management",
Applied Energy, vol. 379, pp. 1 16, Feb. 2025. Elsevier. DOI:
10.1016/j.apenergy.2024.124907
Question: (Dirk Kutscher) - Would it be useful to create more
flexibility in the pricing?
Answer: Prices could be an incentive but it could also be detrimental.
It depends a bit because the prices for the electricity are set globally
I'm talking about congestion, it's a local thing. The buy/sell locally
can lead to congestion. Need to take the grid into account. Mitigate
between price vs congestion.
Question:(Jesús A. Omaña Iglesias): Are there negative sides? Need more
batteries in certain places?
Answer: Hopefully not - using local batteries saves on transport; the
fees dominate the prices; carbon is reduced by the flexibility.
Question (John Scudder): Using data centers in the turbines - assuming
that the loads are dispatcheable?
Answer: There is no specific assumption on the nature of the load just
localisation and matching the supply and demand.
3) 17:25 | 20 min | Title: Carbon-aware Networking: Challenges and Opportunities
Presenter: Noa Zilberman (U Oxford)
Slides:
https://datatracker.ietf.org/meeting/123/materials/slides-123-sustain-carbon-aware-networking-challenges-and-opportunities-01
Abstract:
- Leveraging the temporal and spatial variability of carbon intensity
presents a significant opportunity to reduce the Internet's carbon
emissions. However, maximizing the impact of carbon awareness
requires addressing specific challenges by the IRTF community. In
this talk, I will explore how carbon awareness can drive the
reduction of operational carbon emissions across the network. I'll
discuss key pain points that can be helped by technological
advancements, but also necessitate community consensus and
standardization. As processing operations increasingly shift from
centralized cloud environments to the distributed edge, I will also
introduce emerging concerns and discuss plans for deploying
carbon-aware network solutions.
Related work:
- Noa Zilberman, Eve M. Schooler, Uri Cummings, Rajit Manohar, Dawn
Nafus, Robert Soulé, and Rick Taylor. Toward Carbon-Aware
Networking. HotCarbon'22, July 2022
- Sawsan El Zahr, Paul Gunning and Noa Zilberman. Exploring the
Benefits of Carbon-Aware Routing. ACM CoNEXT and Proceedings of
the ACM on Networking (PACMNET), December 2023
- Sawsan El-Zahr, William Nathan, Noa Zilberman. Carbon-intelligent
content scheduling in CDNs, ACM/IRTF ANRW, July 2025
- Alexander Clemm, Dirk Kutscher, Michael Welzl, Cedric Westphal, Noa
Zilberman, and Simone Ferlin-Reiter. Greening Networking: Toward a
Net Zero Internet (Dagstuhl Seminar 24402)". Dagstuhl Reports,
Volume 14, Issue 9, 2025
- Yuta Tokusashi, Huynh Tu Dang, Fernando Pedone, Robert Soulé and Noa
Zilberman, The Case For In Network Computing On Demand, Eurosys
2019
- National Engineering Policy Centre (NEPC), Engineering Responsible
AI: foundations for environmentally sustainable AI, Feb 2025
- SmartEdge Project, Innovative Smart Edge Solutions, 2025
Question: (Ali Rezaki) Related to Hermann: if we focus on local
optimizations sometimes we might get it wrong in the end-to-end or
systems view. Have you come across such challenges and how would you see
the challenges in local vs systems level decisions?
Answer: I discussed with Hermann; network traffic is very much periodic
so you can predict what would be the amount of traffic at certain times
of day and what will be the demand; we can work together with energy
providers. Moreover, carbon intensity is a property of the grid. Many of
the discussed challenges (like how to account for static emissions) are
unrelated to the grid.
4) 17:45 | 20 min | Title: Making Infrastructural Waves: Subsea Cables and the Socio-environmental Ramifications of Invisible Digital Growth
Presenter: Hunter Vaughan (Emerson College)
Paper: Report on Best Practices in Subsea Telecommunications
Sustainability
Publications Archive: Sustainable Subsea Networks
Slides:
https://datatracker.ietf.org/meeting/123/materials/slides-123-sustain-hunter-vaughan-making-waves-subsea-cables-and-the-socio-environmental-ramifications-of-invisible-digital-growth-01
Abstract:
- In this talk, I will discuss the challenges to environmental and
social sustainability presented by digital infrastructure growth in
an era of accelerated climate crisis. This will include a summary of
our two-stage four-year grant work on the Sustainable Subsea
Networks project; my own specific reflections on attempting to lead
boundary-spanning collaborative research with industry, local
communities, and experts from marine ecology to renewable energy;
and expansive consideration on the future costs and consequences of
infrastructural growth to cater to the heavy data needs of smart
cities and high computational machine learning (eg. "AI", large
language models such as Chat GPT, etc).
Question: (Eve Schooler) I have been fascinated for quite a while with
the subsea cable community and how it dovetails into the work on media
and film. What is the interaction of Sustain with an organization like
the Internet Society and the Internet Society Foundation for grants? Can
you tell us about how the subsea cable community catalyzed all the
stakeholders? How might we assemble the statkeholders - here at the IRTF
- as wired/core networking technology people?
Answer: The Internet Society Foundation were your first cohort in 2021
to 2022. They launched a greening the internet funding grant scheme.
Nicole Starosielski wrote a book called the Undersea Network that rocked
the world of media film and media studies with a large understanding of
the infrastructures. It improved the relationship with the TV industry
and it also helped with the ICT infrastructure. There was also work with
Ireland that included outreach. ICT industries are welcoming and would
like to be better environmentally.
5) 18:05 | 15 min | Title: Assessment, Attribution, Reporting and Reduction: Quick Survey of Proposed Internet Research Topics
Presenter: Jan Lindblad (All for Eco AB)
Slides:
https://datatracker.ietf.org/meeting/123/materials/slides-123-sustain-jan-lindblad-assessment-attribution-reporting-and-reduction-quick-survey-of-proposed-internet-research-topics-01
Abstract:
- This presentation proposes four areas of internet research related
to energy management and GHG reporting. Due to the lack of
standards, organizations invent their own methods for assessing
their networking footprint. Often, this does not end well.
Attribution of scope 3 emissions is done ad-hoc. While addressing
these questions, the reporting stacks of governments around the
world need to be considered. Finally, a device-type neutral and
vendor agnostic language for expressing power saving is needed.
Comment (in chat): (Carlos Bernardos) The paper mentioned: "Submission
received: 31 May 2018 / Revised: 11 July 2018 / Accepted: 11 July 2018 /
Published: 17 July 2018"
I find this a bit odd, without reading the paper, my first reaction
would be to take a careful look at it.
Comment (in the chat): (Poonam Yadav) Would be certainly interested in
organising a session in carbon accounting conference.
Comment in the chat (Jan Lindblad): @poonam, great to hear. Please
connect with me at jan.lindblad@for.eco or on LinkedIn
Comment in the chat (Marisol Palmero): @poonam I will also be interested
to be part of the discussion, marisol.ietf@gmail.com
Comment in the chat (Ali Rezaki): Poonam, please copy sustain@irtf.org
in your e-mail so colleagues who are not here could be aware. Many
thanks.
Question: (Dave Oran) Asking the inverse question: how much power would
be saved if a customer would leave?
Answer: I think it's quite strongly related to question number two I
proposed there, but yes, it's perhaps a different perspective.
Question: (Marisol Palmero) In the GHE: from the engineering perspective
the CO2 is often double booked.
Answer: Its the protocol we have and that is being followed by the
companies.
Question: (Adrian Gallego) How can this create more strategy in the
future?
Answer: We have to get started with defining the theoretical foundations
and maybe policy languages.
6) 18:20 | 15 min | Title: An Evaluation of RAN Sustainability Strategies in Production Networks
Presenter: Jesus Alberto Omaña Iglesias (Telefonica)
Contributors: Andra Lutu (Telefonica)
Slides:
https://datatracker.ietf.org/meeting/123/materials/slides-123-sustain-an-evaluation-of-ran-sustainability-strategies-in-production-networks-01
Abstract:
- Reducing energy consumption is a primary goal for the mobile
telecommunication industry, with strong environmental and economic
implications. The main target for savings is the Radio Access
Network (RAN), which is responsible for more than 70% of the total
energy costs incurred by operators. Lowering energy costs at the RAN
is possible by reducing the number of active carriers at off-peak
locations and times where the demand can be served with a lower
capacity than deployed. While the scientific community has been
proposing a plethora of complex solutions to switch off
underutilized carriers, production networks largely rely nowadays on
threshold-based strategies that run at individual RAN equipment and
are typically enabled only overnight. Moreover, there are no
real-world evaluations of the effectiveness of carrier switch-off
approaches in reducing energy consumption or their impact on the end
users. In this talk, we present the results of benchmarking five
fixed-threshold-based cell sleep policies deployed in a production
network serving large geographical regions. The study provides
unprecedented insights on industry-grade RAN sustainability at
scale, in terms of actual energy savings and trade-offs with user
experience. Our insights suggest that the capability of the tested
policies in reducing the energy costs hits a clear barrier if no
degradation is admissible for any user, and provides a strong
empirical basis in support of more flexible approaches to save
energy at the RAN.
Related Work:
- O. E. Martínez-Durive, J. Suárez-Varela, J. O. Iglesias, A. Lutu,
and M. Fiore, An Evaluation of RAN Sustainability Strategies in
Production Networks, IEEE INFOCOM 2025
- M. Kalntis, A. Lutu, J. O. Iglesias, F. A. Kuipers, and G.
Iosifidis, Smooth Handovers via Smoothed Online Learning, IEEE
INFOCOM 2025
- M. Kalntis, J. Suárez-Varela, J. O. Iglesias, A. K. Bhattacharjee,
G. Iosifidis, F. A. Kuipers, and A. Lutu, Through the Telco Lens: A
Countrywide Empirical Study of Cellular Handovers, ACM IMC ’24
Question: (Eve Schooler) How about linking to carbon awareness or carbon
intensity?
Answer: We are trying to do that but it is different. We are trying to
to do that but considering the carbon awareness but i mean in general
the different between being energy efficient and carbon aware is with
energy efficient, you'll directly affect cost. So far there are no
incentives, at least monetary to be carbon aware. While the UK is a
particular case north vs. south with different levels vs. centralized
approaches like in Spain you could optimize much more carbon in certain
regions than others.
Question: (Ali Rezaki) Any plan to include other contributors?
Answer: We want to, and from a technology perspective it's possible but
not easy. And we are looking at other models to encourage this.
7) 18:35 | 10 min | Title: Towards a Free Finer-grain Carbon Map
Presenter: Wen Cai (U Oslo)
Slides:
https://datatracker.ietf.org/meeting/123/materials/slides-123-sustain-wen-cai-towards-a-free-finer-grain-carbon-map-01
Abstract
- Energy-efficient computing requires access to carbon intensity
information, which forms the basis for carbon-aware routing, load
shifting, network optimization, and the selection of locations for
processing and storage. Existing APIs and databases — such as
ElectricityMap — divide the world into large areas like “Bidding
Zones” (European regions defined by ENTSO-E), offering only coarse
granularity in regional carbon intensity.
However, corporations and organizations need more than a regional
carbon-intensity map. We therefore propose a freely available carbon
map with finer granularity: a much more detailed, dynamic database
at the city level for each country.
Our methodology estimates carbon intensity by taking into account
city-level population, local energy consumption, and energy
production, using publicly available data to generate a
high-resolution global carbon intensity map.
Question: (Jan Lindblad) Do we need to improve on the contracts, that
are not based solely on averages, and incentives that are are key.
Answer: Yes we need to include inputs from different providers to the
consumer; we should discuss off line.
Question: (Poonam Yadav) Do you have the final architecture and
topology?
Answer: Question moved to email with the mailing list to be included.
8) 18:45 | 10 min | Title: Aggregation Trace Option for In-situ Operations, Administration, and Maintenance (IOAM)
Presenter: Alex Clemm
Paper: Towards Sustainable Networking: Unveiling Energy Efficiency
Through Hop and Path Efficiency Indicators in Computer Networks
Internet-Draft: draft-cxx-ippm-ioamaggr-03
Slides:
https://datatracker.ietf.org/meeting/123/materials/slides-123-sustain-alex-clemm-green-path-metrics-01
Abstract:
- Observability of metrics relating to energy use is a key enabler for
applications that aim to improve the sustainability of networks
being operated. While the main focus is typically on metrics
provided by individual devices and their components, some metrics
can also be applied to paths in a network to allow, for example, for
smarter path selection decisions. However, the collection of such
data is not trivial today as it requires correlation of multiple
data points collected individually across devices.
This presentation motivates the introduction and provides an
overview of Green Path Metrics related to the energy use and
efficiency of network traffic traversing multiple devices. It
provides an overview of a recently proposed Aggregation Trace
Option, an extension of iOAM technology that allows to aggregate
path metrics in a network without needing to contend with issues
such as the need to correlate and postprocess raw data or packet
sizes that grow with path lengths. A PoC that uses this new protocol
to obtain sustainability path metrics is briefly presented.
Question: (Eve Schooler) I have been thinking for a long time that
path-related metrics of aggregated values would be very useful and so I
want to understand if it is your intent to make your aggregation option
extensible?
Answer: Yes the intent is to make it basically extensible in multiple
ways: in terms of the actual aggregation function that is being used as
well as for the data items that are being referenced.
Comment: (Ike Kunze) Interested in collaborating and will reach out.
9) 18:55 | 5 min | Title: Sustainable Network Architecture
Presenter: Jari Arkko (Ericsson)
Internet-Draft: draft-various-eimpact-arch-considerations-01
Slides:
https://datatracker.ietf.org/meeting/123/materials/slides-123-sustain-update-on-network-architecture-considerations-for-sustainability-03
Abstract:
- The question of how architecture can influence sustainability has
been the topic for a design team in the IETF from the beginning of
the year. The early results were reported at length in the SUSTAIN
RG meeting in March. This talk reports briefly the most recent
updates, and calls for review and action. In particular, we want to
highlight the call for research on some aspects of this, such as
understanding the interaction between transport protocol behavior
and network node sleep modes.
Question: (Michel Welzl) What is the status of the draft?
Answer(Suresh Krishnan) We plan to work on it.
19:00 END