



Proposed Sustainability and the Internet Proposed Research GroupA. Gallego Sanchez
Internet-Draft                                                 T-Systems
Intended status: Informational                        A. Rodriguez-Natal
Expires: 23 April 2026                                             Cisco
                                                         L. M. Contreras
                                                              Telefonica
                                                              M. Palmero
                                                                        
                                                             J. Lindblad
                                                             All For Eco
                                                            October 2025


            Path Energy Traffic Ratio API (PETRA) Augmented
                 draft-malja-sustain-petra-augmented-01

Abstract

   This document describes an API to query a network regarding its
   Energy Traffic Ratio and other energy-related metric for a given
   network path.

About This Document

   This note is to be removed before publishing as an RFC.

   The latest revision of this draft can be found at
   https://galledohm.github.io/draft-malja-sustain-petra-augmented/
   draft-malja-sustain-petra-augmented.html.  Status information for
   this document may be found at https://datatracker.ietf.org/doc/draft-
   malja-sustain-petra-augmented/.

   Discussion of this document takes place on the Proposed
   Sustainability and the Internet Proposed Research Group Research
   Group mailing list (mailto:sustain@irtf.org), which is archived at
   https://mailarchive.ietf.org/arch/browse/sustain/.  Subscribe at
   https://www.ietf.org/mailman/listinfo/sustain/.

   Source for this draft and an issue tracker can be found at
   https://github.com/galledohm/draft-malja-sustain-petra-augmented.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.






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   This Internet-Draft will expire on 4 April 2026.

Copyright Notice

   Copyright (c) 2025 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Conventions and Definitions . . . . . . . . . . . . . . . . .   3
   3.  Path Energy Traffic Ratio API (PETRA) . . . . . . . . . . . .   3
     3.1.  Energy Information  . . . . . . . . . . . . . . . . . . .   4
     3.2.  Recursive Usage . . . . . . . . . . . . . . . . . . . . .   5
   4.  YANG Module . . . . . . . . . . . . . . . . . . . . . . . . .   6
     4.1.  Module Structure  . . . . . . . . . . . . . . . . . . . .   6
     4.2.  Module Definition . . . . . . . . . . . . . . . . . . . .   7
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  12
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  13
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  14
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  14
   Appendix A.  Use Cases  . . . . . . . . . . . . . . . . . . . . .  14
     A.1.  SD-WAN  . . . . . . . . . . . . . . . . . . . . . . . . .  14
     A.2.  Multilayer Energy Management  . . . . . . . . . . . . . .  15
     A.3.  SLA Negotiation for Green Services  . . . . . . . . . . .  16
   Appendix B.  Requirements for Energy Efficiency Management  . . .  16
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  18






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1.  Introduction

   Sustainability is becoming one of the major societal goals for the
   next decade, and networks are one of the major consumers of energy
   nowadays.  Sustainability of network services is thus one of the
   forefronts of innovation and action from network service
   stakeholders, involving manufacturers, operators and customers.  In
   this line, there is a shared goal of achieving better energy
   awareness.

   As with any other network metric, the energy traffic ratio could be
   collected from the underlying network infrastructure.  However, there
   is not a common or single definition of energy metrics towards
   network consumers so that they can be uniformly reported,
   particularly in heterogeneous network scenarios.  This document
   introduces an API to query networks about Energy Traffic Ratio.

   Beyond simple efficiency indicators such as watts per gigabit,
   network stakeholders are increasingly interested in richer
   sustainability information, such as carbon intensity, energy, power
   usage effectiveness (PUE), idle energy draw, and transmission losses.
   These additional metrics allow more informed decision-making in
   contexts such as service routing, green SLA negotiations, and
   sustainability reporting.

2.  Conventions and Definitions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

3.  Path Energy Traffic Ratio API (PETRA)

   This document describes an API to query a network about the Energy
   Traffic Ratio for a given path.  It takes as input the source and
   destination of a path along with the traffic throughput between and
   returns energy information related to the traffic on the path.  This
   is energy computed by the infrastructure that is dynamically part of
   the traffic path.  The API is agnostic to the actual hops and
   underlying infrastructure that enables a path, which might change
   transparently to the API.  This document only describes the API, the
   computation of the energy information to return is out of the scope
   of this document.






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   The API can return a variety of energy-related parameters to provide
   a complete view of path sustainability.  These include: base energy
   efficiency indicators, energy mix, renewable energy contributions,
   and standby or idle consumption.

   Furthermore, the PETRA's energy parameters complement ongoing work on
   green service intents [I-D.irtf-nmrg-ibn-usecases], enabling
   customers to express sustainability objectives such as energy
   consumption thresholds, renewable energy usage, and carbon intensity
   limits.  PETRA provides the underlying energy measurement interface
   necessary for providers to fulfill, assure, and report on these green
   intents.  Moreover, by exposing detailed energy and carbon-related
   parameters, PETRA can allow intent translation components to map
   green service objectives into network resource allocation and path
   selection decisions.

3.1.  Energy Information

   This API allows to return a number of energy attributes associated
   with the path and the traffic.  Currently the parameters that could
   be returned as energy information as part of the query are:

   *  *Watts per Gigabit:* How many Watts are consumed per Gigabit of
      traffic traversing the path.

   *  *Carbon Intensity:* How much carbon emissions are generated as a
      consequence of the energy consumed.

   *  *Energy Mix (%):* Percentage of energy used in the path that comes
      from different energy sources (e.g., solar, wind, biomass,
      nuclear, fossil fuel).

   *  *Greenness Degree (%):* The aggregated percentage of energy
      consumed on the path that comes from renewable sources.  Useful to
      rank and select paths based on renewable energy usage.

   *  *Sustainability Score (0–1):* Composite metric combining greenness
      degree and energy efficiency (Watts per Gigabit), calculated as
      (Greenness/100) × 1/(1 + Watts per Gigabit).  Higher values
      indicate more sustainable, efficient paths.

   *  *Power Usage Effectiveness (PUE):* The ratio of total facility
      power consumption to the power consumption of networking/IT
      equipment.

   *  *Transmission Loss (%):* The percentage of energy lost along the
      path due to transmission inefficiencies.




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   *  *Idle Energy Draw (Watts):* The amount of energy consumed by the
      path infrastructure when idle or under negligible load.

   These metrics are OPTIONAL, and an implementation MAY support a
   subset depending on available measurement capabilities.

3.2.  Recursive Usage

   The API is envisioned in such a way that could be used recursively.
   That means, subpaths could report their energy consumption using
   PETRA and such energy consumption could be aggregated and reported
   for the overall path also using PETRA.

   Similarly, this API could be (recursively) used to provide energy
   information according to the definition of Service Models in an SDN
   context as described in [RFC8309].  In that case, using Figure 3 in
   [RFC8309] as reference, PETRA could be used between the Controller(s)
   and the Network Orchestrator(s), between the Network Orchestrator(s)
   and the Service Orchestrator, and between the Service Orchestrator
   and the Customer(s).

   While considering recursive usage, the aspect of double-counting
   shall also be taken into consideration.  Double counting refers to
   the fact of counting more than once the same energy consumed.
   Organizations using PETRA in a recursive manner need to take
   appropriate measures to ensure no double-counting occurs across
   recursive calls to the API.
























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                                                    Customer
                               ------------------   Service  ----------
                              |                  |  Model   |          |
   PETRA as                   |     Service      |<-------->| Customer |
   Customer Service           |   Orchestrator   |    (a)   |          |
   related API                |                  |           ----------
                               ------------------
                                  .          .
   ##########################    .            .        (b)   -----------
                                . (b)          .      ......|Application|
                               .                .     :     |  BSS/OSS  |
   PETRA as                   .                  .    :      -----------
   Service related API       .  Service Delivery  .   :
                            .       Model          .  :
                    ------------------    ------------------
                   |                  |  |                  |
   #############   |     Network      |  |     Network      |
                   |   Orchestrator   |  |   Orchestrator   |
                   |                  |  |                  |
                   .------------------    ------------------.
   PETRA as               .         :                       :        .
   Network API   .         : Network Configuration :         .
               .            :        Model          :         .
         ------------     ------------     ------------    ------------
        |            |   |            |   |            |  |            |
   ###  | Controller |   | Controller |   | Controller |  | Controller |
        |            |   |            |   |            |  |            |
         ------------     ------------     ------------    ------------
            :              .       .                 :            :
            :             .         .      Device    :            :
            :            .           . Configuration :            :
            :            .           .     Model     :            :
        ---------     ---------   ---------     ---------      ---------
       | Network |   | Network | | Network |   | Network |    | Network |
       | Element |   | Element | | Element |   | Element |    | Element |
        ---------     ---------   ---------     ---------      ---------

4.  YANG Module

   This is a posible definition of PETRA as a module following the YANG
   specification [RFC6020].

4.1.  Module Structure








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   module: irtf-petra
     +--rw energy
        +---x query
           +---w input
           |  +---w src-ip        ietf-inet-types:ip-address
           |  +---w dst-ip        ietf-inet-types:ip-address
           |  +---w throughput    uint32
           +--ro output
              +--ro (result)?
                 +--:(success)
                 |  +--ro success
                 |     +--ro watts-per-gigabit?   decimal64
                 |     +--ro carbon-intensity?    uint32
                 |     +--ro energy-mix*          -> list of sources and percentages
                 |     +--ro greenness-degree?    decimal64
                 |     +--ro sustainability-score? decimal64
                 |     +--ro pue?                 decimal64
                 |     +--ro transmission-loss?   decimal64
                 |     +--ro idle-watts?          decimal64
                 +--:(invalid-address)
                    +--ro invalid-address

4.2.  Module Definition

   module irtf-petra {
     yang-version 1.1;
     namespace "urn:irtf:params:xml:ns:yang:irtf-petra";
     prefix irtf-petra;

     import ietf-inet-types {
       prefix ietf-inet-types;
     }

     organization
       "";
     contact
       "";
     description
       "Initial YANG rendition of the PETRA Energy API, v1.0.1

       Copyright (c) 2025 IETF Trust and the persons identified as
       authors of the code. All rights reserved.

       Redistribution and use in source and binary forms, with or
       without modification, is permitted pursuant to, and subject to
       the license terms contained in, the Revised BSD License set
       forth in Section 4.c of the IETF Trust's Legal Provisions
       Relating to IETF Documents



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       (https://trustee.ietf.org/license-info).

       This version of this YANG module is part of RFC XXXX
       (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
       for full legal notices.

       The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL',
       'SHALL NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED',
       'NOT RECOMMENDED', 'MAY', and 'OPTIONAL' in this document
       are to be interpreted as described in BCP 14 (RFC 2119)
       (RFC 8174) when, and only when, they appear in all
       capitals, as shown here.
       ";

   /*
       If you have an implementation of this YANG module, you could
       access it like something this over RESTCONF:

       $ curl --location --request POST \
         'https://localhost:8008/restconf/operations/energy/query' \
         --header 'Content-Type: application/yang-data+json' \
         --user 'admin:admin' \
         --data-raw '{
             'input' : {
                 'src-ip': '10.10.10.10',
                 'dst-ip': '10.20.20.20',
                 'throughput': '40'
             }
           }'

       And if all goes well, you might receive (besides all the
       HTTP headers) a reply body with something like this:

       {
         'output': {
           'success': {
             'watts-per-gigabit': '191.855',
             'carbon-intensity': '108'
           }
         }
       }
   */

     revision 2025-10-06 {
       description
         "Extended PETRA YANG module with richer input parameters
          and additional energy/sustainability metrics.";
       reference



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         "RFC XXXX: ...";
     }

     // ===== Groupings =====

     grouping query-parameters-g {
       description
         "Common input parameters for energy path queries.";

       leaf src {
         type inet:ip-address;
         mandatory true;
         description
           "Source IP address for the path.";
       }

       leaf dst {
         type inet:ip-address;
         mandatory true;
         description
           "Destination IP address for the path.";
       }

       leaf throughput {
         type decimal64 {
           fraction-digits 2;
         }
         units "Gbps";
         description
           "Throughput of the traffic for which the path energy ratio is calculated.";
       }

       leaf measurement-interval {
         type uint32;
         units "seconds";
         description
           "Optional measurement interval (duration) for the query.
            If omitted, defaults to instantaneous or most recent data.";
       }

       leaf recursive {
         type boolean;
         default "false";
         description
           "Whether the query should be expanded recursively across
            multiple administrative domains (if supported).";
       }
     }



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     grouping energy-metrics-g {
       description
         "Grouping for query result metrics.";
       leaf watts-per-gigabit {
         type decimal64 { fraction-digits 3; }
         units "W/Gb";
         description "Watts consumed per Gigabit transmitted";
       }
       leaf carbon-intensity {
         type uint32;
         units "gCO2e/kWh";
         description "Grams of CO2 equivalent per kilowatt-hour consumed";
       }
       list energy-mix {
         key "source";
         description
           "Percentage contribution of each energy source to the total energy used on the path.";
         leaf source {
           type enumeration {
             enum solar;
             enum wind;
             enum hydro;
             enum nuclear;
             enum coal;
             enum gas;
             enum biomass;
             enum other;
           }
           description "Type of energy source.";
         }
         leaf percentage {
           type decimal64 { fraction-digits 2; }
           units "%";
           description "Percentage of path energy from this source.";
         }
       }
       leaf greenness-degree {
         type decimal64 { fraction-digits 2; }
         units "%";
         description
           "Aggregated percentage of energy from renewable sources.";
       }
       leaf sustainability-score {
         type decimal64 { fraction-digits 3; }
         description
           "Composite metric combining greenness degree and efficiency.
            Suggested formula: (Greenness/100) × 1/(1 + Watts per Gigabit).";
       }



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       leaf pue {
         type decimal64 { fraction-digits 2; }
         description
           "Power Usage Effectiveness: ratio of total facility energy to IT/networking energy.";
       }
       leaf transmission-loss {
         type decimal64 { fraction-digits 2; }
         units "%";
         description
           "Energy lost in transmission as percentage of total energy input.";
       }
       leaf idle-watts {
         type decimal64 { fraction-digits 3; }
         units W;
         description
           "Energy consumed by the path infrastructure when idle.";
       }
     }

     // ===== PETRA Container =====

     container energy {
       description
         "PETRA API top-level container for energy queries.";

       action query {
         description
           "Query the network for energy consumption and
            sustainability metrics along a given path.";

         input {
           uses query-parameters-g;
         }

         output {
           choice result {
             description
               "Result of the PETRA query.";

             container success {
               description
                 "Successful query returning energy metrics.";
               leaf timestamp {
                 type yang:date-and-time;
                 description
                   "Time when the energy data was measured or aggregated.";
               }
               leaf aggregation-level {



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                 type enumeration {
                   enum path;
                   enum subpath;
                   enum site;
                   enum facility;
                 }
                 description
                   "Level of aggregation of reported data.";
               }
               container metrics {
                 uses energy-metrics-g;
                 description
                   "Collection of energy and sustainability metrics.";
               }
             }

             container invalid-address {
               description
                 "Invalid source or destination IP address supplied.";
             }

             container unsupported-metric {
               description
                 "The requested metric is not supported by this implementation.";
             }

             container insufficient-data {
               description
                 "The system could not collect sufficient data for the query.";
             }
           }
         }
       }
     }
   }

5.  Security Considerations

   In order to mitigate security risks, the PETRA API should implement
   the necessary mechanisms for authentication, secure data transfer and
   privacy preservation.  On the other hand, in order to prevent denial
   of service attacks, new subsequent similar requests could be silently
   ignored during periods or time, or even requests from the same client
   could be filtered to prevent system (i.e., controller or
   orchestrator) affection.






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6.  IANA Considerations

   This document has no IANA actions.

7.  References

7.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/rfc/rfc2119>.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <https://www.rfc-editor.org/rfc/rfc3688>.

   [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)", RFC 6020,
              DOI 10.17487/RFC6020, October 2010,
              <https://www.rfc-editor.org/rfc/rfc6020>.

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
              <https://www.rfc-editor.org/rfc/rfc6241>.

   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
              Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
              <https://www.rfc-editor.org/rfc/rfc6242>.

   [RFC6991]  Schoenwaelder, J., Ed., "Common YANG Data Types",
              RFC 6991, DOI 10.17487/RFC6991, July 2013,
              <https://www.rfc-editor.org/rfc/rfc6991>.

   [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
              <https://www.rfc-editor.org/rfc/rfc8040>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.

   [RFC8309]  Wu, Q., Liu, W., and A. Farrel, "Service Models
              Explained", RFC 8309, DOI 10.17487/RFC8309, January 2018,
              <https://www.rfc-editor.org/rfc/rfc8309>.





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   [RFC8340]  Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
              BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
              <https://www.rfc-editor.org/rfc/rfc8340>.

7.2.  Informative References

   [I-D.belmq-green-framework]
              Claise, B., Contreras, L. M., Lindblad, J., Palmero, M.
              P., Stephan, E., and Q. Wu, "Framework for Energy
              Efficiency Management", Work in Progress, Internet-Draft,
              draft-belmq-green-framework-05, 6 October 2025,
              <https://datatracker.ietf.org/doc/html/draft-belmq-green-
              framework-05>.

Acknowledgments

   Kudos to Elis Lulja for his help with the OpenAPI specification in
   early versions of this draft.  Thanks to Fernando Sanz Garcia and
   Lori Jakab for their help and support on this work.

   The contribution of A.  Gallego Sánchez to this document has been
   partially supported by the Smart Networks and Services Joint
   Undertaking (SNS JU) under the European Union's Horizon Europe
   research and innovation project Sustain6G (Grant Agreement no.
   101191936).

   The contribution of L.M.  Contreras to this document has been
   partially supported by the Smart Networks and Services Joint
   Undertaking (SNS JU) under the European Union's Horizon Europe
   research and innovation projects 6Green (Grant Agreement no.
   101096925) and Exigence (Grant Agreement no. 101139120).

Appendix A.  Use Cases

   This section describes some use-cases where this specification might
   be useful.

A.1.  SD-WAN

   Software-Defined Wide-Area Networks (SD-WAN) have become a common way
   for enterprises to provide cost-effective connectivity across their
   different geographically distributed sites.  Typically, SD-WAN
   deployments operate as an overlay network that is established on top
   of an existing underlay connectivity network.  One aspect to consider
   is that in many SD-WAN production deployments the operator of the
   overlay network and the operator of the underlay network are
   different organizations.




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   This poses an additional challenge when trying to derive
   sustainability metrics.  Even if the underlay network is instrumented
   to collect energy data, this data is opaque to the operator of the
   overlay network which has no access to underlay information.  While
   operators of underlay networks offer certain general network metrics
   to overlay operators, no interface has been defined to allow the
   overlay operator to query the underlay network for energy
   information.

   In this context, the PETRA specification presented in this document
   enables the operator of the SD-WAN network to coordinate with the
   underlay operator to capture sustainability data.  This in turns
   opens further use-cases, from observability and reporting to
   potentially overlay policies based on underlay energy data, further
   enabling an overall more sustainable operation of the network.

   In addition to energy considerations in SD-WAN deployments, PETRA can
   also be leveraged for broader energy-aware service routing.  In this
   context, network controllers and service orchestrators—such as SD-WAN
   controllers, transport SDN controllers, 5G slice orchestrators, or
   multi-domain service orchestrators—can use PETRA metrics not only to
   balance latency, throughput, or load, but also to optimize path
   selection according to sustainability objectives.  For example, paths
   with the lowest carbon intensity or the highest share of renewable
   energy in their energy mix could be preferred, enabling service
   differentiation where “green paths” are explicitly prioritized.  This
   brings a paradigm where routing decisions are jointly driven by
   network performance and environmental impact.

A.2.  Multilayer Energy Management

   The concept of multilayer L3-L1 collection involves integrating data
   from different network layers to provide a comprehensive view of
   network operations.  The use case of multilayer involves collecting
   and correlating data from Layer 3 (network layer) down to Layer 1
   (physical layer).  This multilayer approach allows for better network
   performance, optimization, and troubleshooting by providing end-to-
   end visibility.

   Leveraging PETRA API for multilayer L3-L1 collection use case
   enhances energy management by providing comprehensive visibility,
   enabling optimization, and supporting proactive management.  This
   makes PETRA a useful tool for more accurate, efficient and effective
   energy management in modern networks.







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A.3.  SLA Negotiation for Green Services

   Another use case for PETRA could be the negotiation of green Service
   Level Agreements (gSLAs) between operators and enterprise customers.
   By exposing PETRA-derived metrics such as renewable energy
   percentage, carbon intensity, or sustainability scores, providers can
   offer differentiated SLAs that explicitly include environmental
   targets.  This enables customers to select network services not only
   based on performance guarantees, but also on their environmental
   footprint, for example requesting that at least 60% of traffic be
   carried over renewable-powered infrastructure.  Such gSLAs empower
   customers to align their digital services with corporate
   sustainability goals and reporting requirements, while operators can
   use PETRA as the trusted source of verifiable energy data.

   gSLAs can be negotiated using customer-expressed green intents that
   specify objectives such as maximum energy consumption, minimum energy
   efficiency, carbon emission limits, and renewable energy usage [I-
   D.irtf-nmrg-ibn-usecases].  PETRA's metrics, including watts per
   gigabit, carbon intensity, and energy mix, provide essential
   measurements to translate these intents into network configurations
   and to monitor compliance during service operation.  The lifecycle of
   green intents, encompassing fulfillment and assurance phases
   [RFC9315], can be supported by PETRA through its capability to
   deliver real-time energy metrics for translation into network
   policies and subsequent monitoring and validation.

Appendix B.  Requirements for Energy Efficiency Management

   The document Framework for Energy Efficiency Management
   [I-D.belmq-green-framework] describes a framework that comprises a
   controller element.  In that document, the tasks of the controller
   are defined as "collection, compute and aggregate".  In the context
   of that framework, the controller could also expose PETRA to offer
   path-related energy information.  The figure below updates the one
   present in [I-D.belmq-green-framework] to add an additional interface
   (interface 'g') to the controller to represent the Path Traffic Ratio
   API.













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   +--------------------------------------------------------------------+
   |                                                                    |
   |                  (3) Network Domain Level                          |
   |                                                                    |
   +--------------------------------------------------------------------+

   (a)             (b)             (c)
   Inventory       Monitor      +- DataSheets/DataBase
   Of identity     Energy       |  and/or via API
   and Capability  Efficiency   |  Metadata and other
         ^              ^       | device/component/network
         |              |       | related information:                  (g)
         |              |       |                                      PETRA
         |              |       |  .Power/Energy related metrics         API
         |              |       |  .information                           ^
         |              |       |  .origin of Energy Mix                  |
         |              |       |  .carbon aware based on location        |
         |              |       |                                         |
         |              |       v                                         |
   +--------------------------------------------------------------------+ |
   |                                                                    | |
   |       (2) controller (collection, compute and aggregate?)          +-+
   |                                                                    |
   +--------------------------------------------------------------------+
                   ^                      ^                      ^ |
         (d)        |     (e)              |   (f)                | |
         Inventory  |     Monitor power    |   Control            | |
         Capability |     Proportion       |   (Energy saving     | |
                    |     Energy efficiency|   Functionality      | |
                    |     ratio, power     |   Localized mgmt/    | |
                    |     consumption,     |   network wide mgmt) | |
                    |     etc)             |                      | |
                    |                      |                      | v
   +--------------------------------------------------------------------+
   |                                                                    |
   |                       (1) Device/Component                         |
   |                                                                    |
   | +---------+  +-----------+  +----------------+  +----------------+ |
   | | (I)     |  | (II)      |  | (III)          |  | (IV)           | |
   | |         |  |           |  | Legacy         |  | 'Attached'(PoE | |
   | | Device  |  | Component |  | Device         |  | end Point)     | |
   | |         |  |           |  |                |  |                | |
   | +---------+  +-----------+  +----------------+  +----------------+ |
   +--------------------------------------------------------------------+

         Figure 1: PETRA Integration in Energy Management Framework





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Authors' Addresses

   Adrian Gallego Sanchez
   T-Systems
   Guadalajara
   Spain
   Email: ADRIAN.GALLEGO-SANCHEZ@t-systems.com


   Alberto Rodriguez-Natal
   Cisco
   Madrid
   Spain
   Email: natal@cisco.com


   Luis M. Contreras
   Telefonica
   Madrid
   Spain
   Email: luismiguel.contrerasmurillo@telefonica.com


   Marisol Palmero
   Toledo
   Spain
   Email: marisol.ietf@gmail.com


   Jan Lindblad
   All For Eco
   Email: jan.lindblad+ietf@for.eco



















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