**Session Date/Time:** 16 Jun 2025 14:00

# [GREEN](../wg/green.html)

## Summary

The GREEN Working Group held an interim meeting to discuss updates on existing drafts, primarily focusing on the framework for energy-efficient management and proposed Yang data models. A significant portion of the meeting was dedicated to an in-depth discussion of challenges and open questions related to data model design, including power control granularity, aggregation, and the relationship between models and the framework. The chairs proposed forming a data model design team to accelerate progress, and this proposal received strong support from those present. An upcoming hackathon focused on green networking use cases was also announced.

## Key Discussion Points

*   **Framework for Energy-Efficient Management (`draft-bell-green-framework`)**:
    *   The framework proposes three levels (Network Domain, Controller, Device/Component) and three key interfaces (Inventory Capability, Monitoring, Control).
    *   Core concepts include **Energy Objects**, **Metering Relationships** (X meters for Y), and **Power Source Relationships** (X powers Y), with a brief mention of **Aggregation Relationships**. These relationships are crucial for understanding energy flows and avoiding double-counting in measurements.
    *   An open question was raised regarding the granularity of **Power State Sets** (e.g., simple on/off vs. more complex states like hibernate, sleep, or minimum efficiency). Standardizing these states across diverse devices and vendors presents a challenge, particularly when linking them to performance SLAs (e.g., recovery time, throughput, latency).
    *   Discussion highlighted the need for data models to support both hiding complexity for mainline cases while retaining auditable detail for scenarios like customer/use case assignment.

*   **Yang Data Models for Energy Efficiency**:
    *   The presentation outlined a proposed model architecture with Network Inventory, Network Level Energy Efficiency Management, and Device Level models.
    *   Existing work (e.g., `draft-cwb-green-energy-saving-management` and `draft-li-green-power`) was referenced, with a proposal to consolidate common definitions into an `energy-efficiency-common` module.
    *   This common module would define features, identities (energy saving modes, methods, power states), types, and groupings for energy consumption data and power parameters.
    *   **Open issues in data model design**:
        *   **Framework Dependence**: Whether data models should be tightly coupled with the framework or remain largely independent, with a consensus that core Yang keys (like UUIDs for devices/components) should be aligned.
        *   **Model Layering**: The need for device/component level, network level (inventory/topology), and potentially higher-level service models to allocate energy consumption to specific services or customers.
        *   **Power Control Granularity**: Whether control states should be generic (e.g., EMAN's work) or specific to component types (e.g., line cards, optics), and how to align configurable states with operational states.
        *   **Control Intent**: Whether control actions relate to desired operational intent (e.g., "sleep capable mode") allowing the device to optimize, or direct, granular power usage control.
        *   **Aggregation**: How to model aggregation at device and network levels, report aggregate and fine-grained data without double-counting.
        *   **Reporting Accuracy/Granularity**: Whether measurement accuracy should be statically defined in the model or dynamically reported by devices.
        *   **Time Intervals**: How to standardize or manage time intervals for aggregated power usage reporting.

*   **Use Cases and Terminology Documents**:
    *   No updates were presented for the use cases document, with a goal for adoption by the next meeting.
    *   A request for Working Group adoption of a terminology document was noted, with discussion deferred to IETF 123.

*   **Hackathon Announcement (IETF 123 Madrid)**:
    *   An upcoming hackathon will exercise green networking use cases, including applying the green framework, collecting energy information from cloud-native functions, end-to-end metrics, video streaming energy consumption, and addressing double-counting with smart PDUs.
    *   The setup will involve an Exigence streaming environment, wireless access points, physical meters, and access to smart PDUs in Telefonica labs. Data collection and visualization will be key.

## Decisions and Action Items

*   The request for a Working Group adoption call on the `common-energy-efficiency-model` module was deferred. The chairs indicated that more alignment on design direction is needed first.
*   Discussion on the Working Group adoption of the terminology document was deferred to IETF 123. Participants were encouraged to review the document in the meantime.
*   A poll of the room indicated **strong support** for forming a **Data Model Design Team** (12 votes for, 2 against). The chairs will discuss how to proceed based on this feedback.
*   A poll of the room indicated **strong support** for arranging **more frequent interim meetings** (12 votes for, 1 against).
*   The chairs will discuss the feedback received on the design team and more frequent interim meetings to determine the best approach for progressing the data model work.
*   Luis will send an email to the GREEN WG mailing list advertising the upcoming hackathon and inviting participation.

## Next Steps

*   The chairs will evaluate the feedback on a Data Model Design Team and increased interim meeting frequency, and communicate a plan for accelerating progress on the Yang data models.
*   Working Group members are encouraged to review the terminology documents in preparation for discussion at IETF 123.
*   Participants interested in contributing to the hackathon at IETF 123 should reach out to Luis and monitor the mailing list for updates.
*   A call for presentations for the GREEN sessions at IETF 123 will be announced.