**Session Date/Time:** 24 Jul 2025 15:00

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# sustain

## Summary

This meeting of the sustain working group covered a range of topics related to sustainability in networking, including energy efficiency in data centers, carbon-aware networking, subsea cable impacts, and architectural considerations for sustainable protocols. Discussions focused on challenges in accurately measuring and attributing carbon emissions, balancing local optimization with system-level impact, and potential research areas for improving network sustainability. The meeting also included updates on ongoing projects and initiatives, such as the sustainable subsea networks project and efforts to develop green carbon maps.

## Key Discussion Points

*   **Energy Efficiency in Wind Turbine Data Centers (Hermann):** Discussion around building data centers within wind turbines to use curtailed energy, the importance of system-level perspective (local vs. grid vs. global), and the need for protocols to negotiate energy consumption and service level agreements.
*   **Carbon-Aware Networking Challenges (Noah):** Challenges in quantifying the carbon footprint of network applications, including accounting for static emissions, embodied carbon, and data sharing across domains. Opportunities for carbon reduction through routing optimization, traffic engineering, and content pre-positioning were also discussed.
*   **Subsea Cables and Social Sustainability (Hunter):** Impacts of subsea cables on local ecosystems and communities, emphasizing the importance of social sustainability considerations alongside environmental concerns. Discussion on legacy and vestigial infrastructure connections between colonial infrastructures in the 21st century.
*   **Sustainability Reporting and Network Attribution (Jan):** Problems with current methods used by economists for carbon emission assessment, particularly regarding network traffic. Proposals for better methods to compute network emissions, attribute them to customers, and align with reporting requirements.
*   **RAN Sustainability Measurement (Jesus):** Measurement of the impact of energy-saving policies in a real RAN network, including trade-offs between energy saving and performance. Discussion around the potential for carbon-aware RAN policies.
*   **Green Carbon Maps (Michael):** Proposal to improve carbon intensity estimation by focusing on the European region to build the national carbon intensity to a lower level by using different proxy data.
*   **In-Situ Metrics Aggregation for Path Optimization (Alex):** Presentation on a technical solution using IOM aggregation trace option to obtain green path metrics for sustainable networking paths.
*   **Sustainability and Architecture (Jari):** Update on an IAB architectural document providing design advice for sustainable protocols and network architectures. Identified transport algorithms and encoding as key areas for further research.

## Decisions and Action Items

*   **Action Item:** Presenters to join the sustain mailing list for ongoing communication.
*   **Action Item:** Follow up on question in chat regarding architecture.

## Next Steps

*   Plan a workshop in Passau before IETF Montreal (July 2025).
*   Continue working on quantifying carbon emissions for the networking sector.
*   Explore the proposed research topics, for example new power reduction mechanisms, more accurate attribution.
*   Continue development of Green Carbon Maps.
*   Standardize the aggregation trace options by the community.
*   Continue revising the architectural advice based on feedback.