**Session Date/Time:** 17 Mar 2026 06:00

# [SUSTAIN](../wg/sustain.html)

## Summary
The SUSTAIN research group met at IETF 125 to discuss multidisciplinary research into the sustainability and resilience of the internet. The session covered five main technical areas: high-resolution sub-national carbon mapping, server lifecycle and traffic testbed measurements, the impact of generative AI on web protocols and storage, service-level sustainability accounting in multi-domain networks, and the development of a holistic API for evaluating path energy.

## Key Discussion Points

### Towards a Sub-National Carbon Map
**Presenter: Wen Cai**
[Slides](https://datatracker.ietf.org/meeting/125/materials/slides-125-sustain-wen-cai-towards-a-sub-national-carbon-map-00)

*   **Methodology:** The research proposes moving beyond national-level carbon intensity data (like Electricity Maps) to NUTS-3 and LAU (Local Administrative Units) levels. It uses OpenInfraMap, ENTSO-E, and TSO data to calculate local carbon intensity based on local production and imports from parent regions.
*   **Findings:** National averages often mask significant local variations. For example, in mainland Spain, solar production in specific municipalities creates hourly carbon intensity profiles that differ drastically from the national average.
*   **Networking Implications:** This data is critical for carbon-aware routing. A path to a "greener" country may not actually be lower-carbon if the specific path traverses carbon-intensive sub-regions.
*   **Discussion:** **Diego Lopez** inquired whether the maps focus on production or consumption; **Wen Cai** clarified it is a combination of both per hour. **Sebastian** asked about applications in other industries, which **Wen Cai** noted could include infrastructure site selection.

### Traffic testbed and Carbon topography representation
**Presenter: Sebastian**
[Slides](https://datatracker.ietf.org/meeting/125/materials/slides-125-sustain-traffic-testbed-and-carbon-topography-representation-tools-to-better-measure-understand-and-analyse-server-lifecycle-impacts-01)

*   **Testbed (TRAFFIC):** The study measured various hardware (Dell servers to Raspberry Pis) at the power plug under modular loads. 
*   **Key Finding:** CPU usage is a poor proxy for power consumption, with deviations up to 25% depending on the service (e.g., AI inference vs. counting).
*   **Carbon Topography:** A visualization tool to determine whether fabrication (embodied carbon), static power, or dynamic power dominates a server's footprint based on regional carbon intensity and load.
*   **Optimization Strategies:** 
    1. Use low-carbon energy.
    2. Maximize server load (efficiency increases with load).
    3. Extend equipment lifespan (amortizing embodied carbon over 10 years instead of 4).
*   **Discussion:** **Michael Welzl** asked about scaling testbeds; **Sebastian** emphasized the need for internal hardware measurements (RAM, fans) rather than just software proxies.

### Small World Web of AI
**Presenter: Noa Zilberman**
[Slides](https://datatracker.ietf.org/meeting/125/materials/slides-125-sustain-noa-zilberman-small-world-web-of-ai-00)

*   **Concept:** Proposes a shift where servers send prompts/metadata instead of raw content (images/video), and the client generates the content locally via GenAI.
*   **Protocol Changes:** Suggests a "gen-ability" indicator in HTTP/2 SETTINGS frames (value 0x07) and a new HTML class for generated content.
*   **Sustainability Trade-offs:** While it significantly reduces network traffic and CDN storage (reducing embodied carbon of disks), current generation energy on end-user devices is much higher than transmission energy.
*   **Discussion:** **Jen-Hsuan** noted similarities to agent-to-agent scenarios. **Dirk Trossen** questioned the latency and energy efficiency of generating at multiple locations versus caching. **Jari Arkko** raised concerns about brand consistency and "hallucinations" in critical contexts like surveillance. **Noa Zilberman** emphasized that standards must evolve now to steer future AI integration sustainably.

### EXIGENCE View on Sustainability of ICT
**Presenter: Artur Hecker**
[Slides](https://datatracker.ietf.org/meeting/125/materials/slides-125-sustain-artur-hecker-exigence-view-on-sustainability-of-ict-01)

*   **Problem:** ICT services are increasingly disaggregated across domains, making end-to-end measurement difficult.
*   **EXIGENCE Approach:** A three-pillar methodology: Measurement, Optimization, and Incentivization.
*   **Service-Level Accounting:** Proposes an "energy overlay" where "ecodata" (Joules, CO2) is reported along the Service Function Chain (SFC). 
*   **Incentives:** Suggests providers can incentivize users to accept lower SLAs (e.g., lower video resolution) to achieve energy savings beyond what is possible through hardware efficiency alone.
*   **Discussion:** **Jen-Hsuan** asked if this requires underlay protocol modifications; **Artur Hecker** replied that while rough models can work over existing protocols, precise attribution requires more complex mapping within domains.

### Sustainability Holistic API for Path Energy Evaluation (SHAPE)
**Presenter: Luis Contreras**
[Slides](https://datatracker.ietf.org/meeting/125/materials/slides-125-sustain-sustainability-holistic-api-for-path-energy-evaluation-shape-00)

*   **Overview:** SHAPE is an evolution of the PETRA API (originally discussed in the GREEN WG as `draft-petra-green-api`).
*   **Scope:** Focuses on sustainability metrics for network paths, including energy mix, greenness degree, sleep mode availability, and anomaly factors.
*   **Architecture:** Positioned to interface between network controllers and service orchestrators to allow customers to request "Decarbonization Level Agreements."
*   **Use Cases:** SD-WAN reporting, multilayer energy management (IP+Optical), and 5G edge selection.
*   **Discussion:** **Jen-Hsuan** asked about the generic nature of the API; **Luis Contreras** confirmed the intent is to keep parameters generic while implementation remains technology-specific.

## Decisions and Action Items
*   **Data Sharing:** Wen Cai to share GitHub repository links for the sub-national carbon map data for RG review.
*   **Cross-WG Coordination:** Presenters (Artur Hecker, Luis Contreras) to coordinate with the GREEN working group regarding overlapping API and architectural models.

## Next Steps
*   **One-Year Review:** The SUSTAIN-RG is due for its one-year review. The chairs will solicit formal feedback on the mailing list.
*   **IETF 126:** The group plans to meet in person in Vienna. Participants are encouraged to review the SHAPE API draft and provide feedback on the proposed sustainability parameters.