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     Network Working Group                                  B. Claise
     Internet-Draft                                        J. Parello
     Intended Status: Informational               Cisco Systems, Inc.
     Expires: July 12, 2013                              B. Schoening
                                                Independent Consultant
                                                            J. Quittek
                                                       NEC Europe Ltd.
                                                            B. Nordman
                                                     Lawrence Berkeley
                                                   National Laboratory
                                                    February 24, 2013
                        Energy Management Framework
     Status of this Memo
        This Internet-Draft is submitted to IETF in full conformance
        with the provisions of BCP 78 and BCP 79.
        Internet-Drafts are working documents of the Internet
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        This Internet-Draft will expire on July, 2013.
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     Copyright Notice
        Copyright (c) 2012 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
        (http://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.  Code Components
        extracted from this document must include Simplified BSD
        License text as described in Section 4.e of the Trust Legal
        Provisions and are provided without warranty as described in
        the Simplified BSD License.
        This document defines a framework for providing Energy
        Management for devices and device components within or
        connected to communication networks.  The framework defines an
        Energy Management Domain as a set of Energy Objects, for which
        each Energy Object is identified, classified and given
        context.   Energy Objects can be monitored and/or controlled
        with respect to Power, Power State, Energy, Demand, Power
        Attributes, and Battery.  Additionally the framework models
        relationships and capabilities between Energy Objects.
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     Table of Contents
        1. Introduction
                        .......................................... 5
        2. Terminology
                       ........................................... 6
           Device................................................. 6
           Component.............................................. 6
           Energy Management...................................... 6
           Energy Management System (EnMS)........................ 7
           Power.................................................. 8
           Demand................................................. 8
           Power Attributes....................................... 8
           Power Quality.......................................... 9
           Electrical Equipment................................... 9
           Non-Electrical Equipment (Mechanical Equipment)........ 9
           Energy Object......................................... 10
           Electrical Energy Object.............................. 10
           Non-Electrical Energy Object.......................... 10
           Energy Monitoring..................................... 10
           Energy Control........................................ 10
           Provide Energy:....................................... 10
           Receive Energy:....................................... 11
           Power Interface....................................... 11
           Energy Management Domain.............................. 11
           Energy Object Identification.......................... 11
           Energy Object Context................................. 11
           Energy Object Relationship............................ 12
           Aggregation Relationship.............................. 12
           Metering Relationship................................. 12
           Power Source Relationship............................. 12
           Proxy Relationship.................................... 12
           Energy Object Parent.................................. 13
           Energy Object Child................................... 13
           Power State........................................... 13
           Power State Set....................................... 13
           Nameplate Power....................................... 13
        3. Issues Specific to Energy Management ................. 13
           3.1. Power Supply .................................... 15
           3.2. Power and Energy Measurement .................... 20
           3.3. Reporting Sleep and Off States .................. 21
           3.4. Device and Device Components .................... 22
           3.5. Non-Electrical Equipment ........................ 23
        4. 4. Energy Management Abstraction ..................... 23
           4.1. Energy Object and Energy Management Domain ...... 24
           4.2. Power Interface ................................. 25
           4.3. Energy Object Identification and Context ........ 25
           4.4. Energy Object Relationships ..................... 27
           4.5. Energy Monitoring ............................... 33
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           4.6. Control ......................................... 35
           4.7. Energy Management Reference Model................ 39
           4.8 Using Device Relationships to Create Topologies... 40
           4.9 Generalized Relationship Model.................... 47
        5. Energy Management Information Model .................. 50
        6. Example Topologies ................................... 56
           6.1 Example I: Simple Device with one Source.......... 56
           6.2 Example II: Multiple Inlets....................... 57
           6.3 Example III: Multiple Sources..................... 58
        7. Relationship with Other Standards .................... 58
        8. Security Considerations .............................. 59
        9. IANA Considerations .................................. 61
        10. Acknowledgments ..................................... 61
        11. References .......................................... 61
           Normative References.................................. 61
           Informative References................................ 62
        OPEN ISSUES:
        Are Tracked via Issue Tracker. See
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     1. Introduction
        Network management is often divided into the five main areas
        defined in the ISO Telecommunications Management Network
        model: Fault, Configuration, Accounting, Performance, and
        Security Management (FCAPS) [X.700].  Not covered by this
        management model is Energy Management, which is now becoming a
        critical area of concern worldwide as seen in [ISO50001].
        This document defines a framework for providing Energy
        Management for devices within or connected to communication
        networks.  The framework describes how to identify, classify
        and provide context for such devices.
        The devices, or components of these devices, can then be
        monitored and controlled.  Monitoring includes power, energy,
        demand, and attributes of power.  Control for energy can be
        achieved by setting devices or components power state. If a
        device contains batteries, these can be also be monitored and
        The most basic example of Energy Management is a single device
        reporting information about itself.  However, in many cases,
        energy is not measured by the device itself, but by a meter
        located upstream in the power distribution tree.  An example
        is a power distribution unit (PDU) that measures energy
        supplied to attached devices and reports this to an energy
        management system.  Therefore, devices and their components
        are recognized as having relationships to other devices or
        components in the network from the point of view of energy
        management.  There are further relationships between devices
        and components, respectively, including aggregation
        relationship, metering relationship, power source
        relationship, and proxy relationship.
        Energy Management Documents Overview
        The EMAN standard provides a set of specifications for Energy
        Management.  This document specifies the framework, per the
        Energy Management requirements specified in [EMAN-REQ].
        The applicability statement document [EMAN-AS] provides a list
        of use cases, a cross-reference between existing standards and
        the EMAN standard, and shows how this framework relates to
        other frameworks.
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        The Energy Object Context MIB [EMAN-OBJECT-MIB] specifies
        objects for addressing Energy Object Identification,
        classification, context information, and relationships from
        the point of view of Energy Management.
        The Power and Energy Monitoring MIB [EMAN-MON-MIB] contains
        objects for monitoring of Power, Energy, Demand, Power
        Attributes and Power States.
        Further, the battery monitoring MIB [EMAN-BATTERY-MIB] defines
        managed objects that provide information on the status of
        batteries in managed devices.
     2.    Terminology
        The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
        "OPTIONAL" in this document are to be interpreted as described
        in RFC 2119 [RFC2119].
       Some terms have a NOTE that is not part of the
       definition itself, but is present to take into
       account differences between terminologies of
       different standards organizations or to add a
       comment to help clarify the definition.
          A piece of electrical or non-electrical equipment.
          Reference: Adapted from [IEEE100]
          A part of an electrical or non-electrical equipment
          Reference: Adapted from [ITU-T-M-3400]
       Energy Management
          Energy Management is a set of functions for
          measuring, modeling, planning, and optimizing
          networks to ensure that the network elements and
          attached devices use energy efficiently and is
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          appropriate for the nature of the application and
          the cost constraints of the organization.
          Reference: Adapted from [ITU-T-M-3400]
          1. Energy management refers to the activities,
            methods, procedures and tools that pertain to
            measuring, modeling, planning, controlling and
            optimizing the use of energy in networked
            systems [NMF].
          2. Energy Management is a management domain which
            is congruent to any of FCAPS areas of
            management in the ISO/OSI Network Management
            Model [TMN]. Energy Management for
            communication networks and attached devices is
            a subset or part of an organization's greater
            Energy Management Policies.
       Energy Management System (EnMS)
          An Energy Management System is a combination of
          hardware and software used to administer a
          network with the primary purpose being Energy
          Reference: Adapted from [1037C]
          1. An Energy Management System according to
            [ISO50001] (ISO-EnMS) is a set of systems or
            procedures upon which organizations can develop
            and implement an energy policy, set targets,
            action plans and take into account legal
            requirements related to energy use.  An ISO-
            EnMS allows organizations to improve energy
            performance and demonstrate conformity to
            requirements, standards, and/or legal
          2. Example ISO-EnMS:  Company A defines a set of
            policies and procedures indicating there should
            exist multiple computerized systems that will
            poll energy from their meters and pricing /
            source data from their local utility. Company A
            specifies that their CFO should collect
            information and summarize it quarterly to be
            sent to an accounting firm to produce carbon
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            accounting reporting as required by their local
          3. For the purposes of EMAN, the definition from
            [1037C] is the preferred meaning of an Energy
            Management System (EnMS).  The definition from
            [ISO50001] can be referred to as ISO Energy
            Management System (ISO-EnMS).
          That which does work or is capable of doing work.
          As used by electric utilities, it is generally a
          reference to electrical energy and is measured in
          kilo-watt hours (kWh).
          Reference: [IEEE100]
          1. Energy is the capacity of a system to produce
            external activity or perform work [ISO50001]
          The time rate at which energy is emitted,
          transferred, or received; usually expressed in
          watts (joules per second).
          Reference: [IEEE100]
          The average value of power or a related quantity
          over a specified interval of time. Note: Demand
          is expressed in kilowatts, kilovolt-amperes,
          kilovars, or other suitable units.
          Reference: [IEEE100]
          1.  For EMAN we use kilowatts.
        Power Attributes
          Measurements of the electrical current, voltage, phase and
          frequencies at a given point in an electrical power system.
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          Reference: Adapted from [IEC60050]
          1. Power Characteristics is not intended to be judgmental
          with respect to a reference or technical value and are
          independent of any usage context.
        Power Quality
          Characteristics of the electric current, voltage, phase and
          frequencies at a given point in an electric power system,
          evaluated against a set of reference technical parameters.
          These parameters might, in some cases, relate to the
          compatibility between electricity supplied in an electric
          power system and the loads connected to that electric power
          Reference: [IEC60050]
          1. Electrical characteristics representing power quality
          information are typically required by customer facility
          energy management systems. It is not intended to satisfy the
          detailed requirements of power quality monitoring. Standards
          typically also give ranges of allowed values; the
          information attributes are the raw measurements, not the
          "yes/no" determination by the various standards.
          Reference: [ASHRAE-201]
       Electrical Equipment
          A general term including materials, fittings,
          devices, appliances, fixtures, apparatus,
          machines, etc., used as a part of, or in
          connection with, an electric installation.
          Reference: [IEEE100]
       Non-Electrical Equipment (Mechanical Equipment)
           A general term including materials, fittings,
          devices appliances, fixtures, apparatus,
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          machines, etc., used as a part of, or in
          connection with, non-electrical power
          Reference: Adapted from [IEEE100]
       Energy Object
          An Energy Object (EO) is a piece of equipment
          that is part of or attached to a communications
          network that is monitored, controlled, or aids in
          the management of another device for Energy
       Electrical Energy Object
          An Electrical Energy Object (EEO) is an Energy
          Object that is a piece of Electrical Equipment
       Non-Electrical Energy Object
          A Non-Electrical Energy Object (NEEO) an Energy
          Object that is a piece of Non-Electrical
       Energy Monitoring
          Energy Monitoring is a part of Energy Management
          that deals with collecting or reading information
          from Energy Objects to aid in Energy Management.
       Energy Control
          Energy Control is a part of Energy Management
          that deals with directing influence over Energy
       Provide Energy:
          An Energy Object "provides" energy to another Energy Object
          if there is an energy flow from this Energy Object to the
          other one.
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        Receive Energy:
          An Energy Object "receives" energy from another Energy
          Object if there is an energy flow from the other Energy
          Object to this one.
        Power Interface
           A Power Interface (or simply interface) is an
           interconnection among devices or components where energy
           can be provided, received, or both.
        Power Inlet
           A Power Inlet (or simply inlet) is an interface at which a
           device or component receives energy from another device or
        Power Outlet
          A Power Outlet (or simply outlet) is an interface at which
          a device or component provides energy to another device or
       Energy Management Domain
          An Energy Management Domain is a set of Energy Objects that
          is considered one unit of management.
       Energy Object Identification
          Energy Object Identification is a set of
          attributes that enable an Energy Object to be
          universally unique or linked to other systems.
       Energy Object Context
          Energy Object Context is a set of attributes that
          allow an Energy Management System to classify
          the Energy Object within an organization.
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       Energy Object Relationship
          An Energy Object Relationship is an association among
          Energy Objects
          1. Relationships can be named and could include
          Aggregation, Metering, Power Source, and Proxy.
          Reference: Adapted from [CHEN]
        Aggregation Relationship
          An Aggregation Relationship is an Energy Object
          Relationship where one Energy Object aggregates Energy
          Management information of one or more other Energy Objects.
          The aggregating Energy Object has an Aggregation
          Relationship with each of the other Energy Objects.
        Metering Relationship
          A Metering Relationship is an Energy Object Relationship
          where one Energy Object measures power, energy, demand or
          power attributes of one or more other Energy Objects. The
          measuring Energy Object has a Metering Relationship with
          each of the measured objects.
        Power Source Relationship
          A Power Source Relationship is an Energy Object
          Relationship where one Energy Object provides power to one
          or more Energy Objects. These Energy Objects are referred
          to as having a Power Source Relationship.
        Proxy Relationship
          A Proxy Relationship is an Energy Object Relationship where
          one Energy Object provides the Energy Management
          capabilities on behalf of one or more other Energy Objects.
          These Energy Objects are referred to as having a Proxy
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       Energy Object Parent
          An Energy Object Parent is an Energy Object that
          participates in an Energy Object Relationship and
          is considered as providing the capabilities in
          the relationship.
       Energy Object Child
          An Energy Object Child is an Energy Object that
          participates in an Energy Object Relationships
          and is considered as receiving the capabilities
          in the relationship.
       Power State
          A Power State is a condition or mode of a device
          that broadly characterizes its capabilities,
          power consumption, and responsiveness to input.
          Reference: Adapted from [IEEE1621]
       Power State Set
          A collection of Power States that comprise a
          named or logical grouping of control is a Power
          State Set.
       Nameplate Power
          The Nameplate Power is the nominal Power of a
          device as specified by the device manufacturer.
     3.    Issues Specific to Energy Management
        With Energy Management, there exists a wide variety of devices
        that may be contained in the same deployments as a
        communication network but comprise a separate facility, home,
        or power distribution network.
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        Target devices for Energy Management are all Energy Objects
        that can directly or indirectly be monitored or controlled by
        an Energy Management System (EnMS) using the Internet
        protocol, for example:
            - Simple electrical appliances / fixtures
            - Hosts, such as a PC, a server, or a printer
            - switches, routers, base stations, and other network
        equipment and middleboxes
            - A component within devices, such as a battery inside a
        PC, a line card inside a switch, etc...
            - Power over Ethernet (PoE) endpoints
            - Power Distribution Units (PDU)
            - Protocol gateway devices for Building Management Systems
            - Electrical meters
            - Sensor controllers with subtended sensors
        There may also exist varying protocols deployed among these
        power distributions and communication networks.
        An Energy Management framework should also apply to these
        types of separate networks as they connect and interact with a
        communications network.
        This section explains special issues of Energy Management
        particularly concerning power supply, Power, and Energy
        metering, and the reporting of Power States.
        Energy Management has particular challenges in that a power
        distribution network is used for the supply of energy to
        various devices and components, while a separate communication
        network is typically used to monitor and control the power
        distribution network.
        To illustrate the issues we start with a simple and basic
        scenario where a single powered device receives Energy and
        reports energy-related information about itself to an Energy
        Management System (EnMS), see Figure 1
                               | Energy Management System |
                                           ^  ^
                                monitoring |  | control
                                           v  v
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                                    | powered device  |
                  Figure 1: Basic energy management scenario
        The powered device may have local energy control mechanisms,
        for example putting itself into a sleep mode when appropriate,
        and it may receive energy control commands for similar
        purposes from the EnMS.  Information reported from a powered
        device to the EnMS includes at least the Power State of the
        powered device (on, sleep, off, etc.).
        This and similar cases are well understood and likely to
        become very common for Energy Management.  They can be handled
        with well established and standardized management procedures.
        The only missing components today are standardized information
        and data models for reporting and configuration, such as, for
        example, energy-specific MIB modules [RFC2578] and YANG
        modules [RFC6020].
        However, the nature of energy supply and use introduces some
        issues that are special to Energy Management.  The following
        subsections address these issues and illustrate them by
        extending the basic scenario in Figure 1.
        WRT to Energy management there nothing new for faults, config,
        performance or security management. We can re-use those
        aspects of network management for an EnMS. But when there are
        aspects specific to EM then this framework adds them. For
        example with faults we can re-use rmon or snmp traps. For
        security existing means like SNMPv3 security can be used.
       3.1.  Power Supply
        A powered device may supply itself with power.  Sensors, for
        example, commonly have batteries or harvest Energy.  However,
        most powered devices that are managed by an EnMS receive
        external power.
        While many devices receive Power from unmanaged supply
        systems, the number of manageable power supply devices is
        In datacenters, for example, many Power Distribution Units
        (PDUs) allow the EnMS to switch power individually for each
        socket and also to measure the provided Power.  This is an
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        action much different from many other network management
        tasks: In such and similar cases, switching power supply for a
        powered device or monitoring its power is not done by
        communicating with the actual powered device itself, but with
        an external device (in this case, the PDU
        Consequently, a standard for Energy Management must not just
        cover the powered devices that provide services for users, but
        also the power supply devices (which are powered devices as
        well) that monitor or control the power supply for other
        powered devices.
        A simple device such as a light bulb can be switched on or off
        only by switching its power supply.  More complex devices may
        have the ability to switch off themselves or to bring
        themselves to states in which they consume very little power.
        For these devices as well, it is desirable to monitor and
        control their power supply.
        This extends the basic scenario from Figure 1 by a power
        supply device, see Figure 2.
                    |         energy management system        |
                          ^  ^                       ^  ^
               monitoring |  | control    monitoring |  | control
                          v  v                       v  v
                    +--------------+        +-----------------+
                    | power supply |########| powered device  |
                    +--------------+        +-----------------+
                            ######## power supply line
                            Figure 2: Power Supply
        The power supply device can be as simple as a plain power
        switch.  It may offer interfaces to the EnMS to monitor and to
        control the status of its power outlets, as with PDUs and
        Power over Ethernet (PoE) [IEEE-802.3at] switches.
        The relationship between supply devices and the powered
        devices they serve creates several problems for managing power
           o  Identification of corresponding devices
              *  A given powered device may be need to identify the
                 supplying power supply device.
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              *  A given power supply device may need to identify the
                 corresponding supplied powered device(s).
           o  Aggregation of monitoring and control for multiple
                 powered devices
              *  A power supply device may supply multiple powered
                 devices with a single power supply line.
           o  Coordination of power control for devices with multiple
              power inlets
              *  A powered device may receive power via multiple power
                 lines controlled by the same or different power
                 supply devices.
     Identification of Power Supply and Powered Devices
        When a power supply device controls or monitors power supply
        at one of its power outlets, the effect on other devices is
        not always clear without knowledge about wiring of power
        lines.  The same holds for monitoring.  The power supplying
        device can report that a particular socket is powered, and it
        may even be able to measure power and conclude that there is a
        consumer drawing power at that socket, but it may not know
        which powered device(s)receives the provided power.
        In many cases it is obvious which other device is supplied by
        a certain outlet, but this always requires additional
        (reliable) information about power line wiring.  Without
        knowing which device(s) are powered via a certain outlet,
        monitoring data are of limited value and the consequences of
        switching power on or off may be hard to predict.
        Even in well organized operations, powered devices' power
        cords can be plugged into the wrong socket, or wiring plans
        changed without updating the EnMS accordingly.
        For reliable monitoring and control of power supply devices,
        additional information is needed to identify the device(s)
        that receive power provided at a particular monitored and
        controlled socket.
        This problem also occurs in the opposite direction.  If power
        supply control or monitoring for a certain device is needed,
        then the supplying power supply device has to be identified.
        To conduct Energy Management tasks for both power supply
        devices and other powered devices, sufficiently unique
        identities are needed, and knowledge of their power supply
        relationship is required.
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     Multiples Devices Supplied by a Single Power Line
        The second fundamental problem is the aggregation of
        monitoring and control that occurs when multiple powered
        devices are supplied by a single power supply line.  It is
        often required for the EnMS to discover the full list of
        powered devices connected to a power supply line, as in Figure
                      |       energy management system        |
                         ^  ^                       ^  ^
              monitoring |  | control    monitoring |  | control
                         v  v                       v  v
                      +--------+        +------------------+
                      | power  |########| powered device 1 |
                      | supply |   #    +------------------+-+
                      +--------+   #######| powered device 2 |
                                     #    +------------------+-+
                                     #######| powered device 3 |
                 Figure 3: Multiple Powered Devices Supplied
                             by Single Power Line
        With this list, the single status value has clear meaning and
        is the sum of all powered devices.  Control functions are
        limited by the fact that supply for the concerned devices can
        only be switched on or off for all of them at once.
        Individual control at the supply is not possible.
        If the full list of devices powered by a single supply line is
        not known by the controlling power supply device, then control
        of power supply is problematic, because the consequences of
        control actions can only be partially known.
     Multiple Power Supply for a Single Powered Device
        The third problem arises from the fact that there are devices
        with multiple power supplies.  Some have this for redundancy
        of power supply, some for just making internal power
        converters (for example, from AC mains power to DC internal
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        power) redundant, and some because the capacity of a single
        supply line is insufficient.
                   |          energy management system            |
                       ^  ^              ^  ^              ^  ^
                  mon. |  | ctrl.   mon. |  | ctrl.   mon. |  | ctrl.
                       v  v              v  v              v  v
                   +----------+      +----------+      +----------+
                   | power    |######| powered  |######| power    |
                   | supply 1 |######| device   |      | supply 2 |
                   +----------+      +----------+      +----------+
          Figure 4: Multiple Power Supply for Single Powered Device
        The example in Figure 4 does not necessarily show a real world
        scenario, but it shows the two cases to consider:
           o  multiple power supply lines between a single power
              device and a powered device
           o  different power supply devices supplying a single
              powered device
        In any such case there may be a need to identify the supplying
        power supply device individually for each power inlet of a
        powered device.
        Without this information, monitoring and control of power
        supply for the powered device may be limited.
     Bidirectional Power Interfaces
        Some power technologies (mostly low power DC) allow power to
        be delivered bi-directionally.  In the example, energy stored
        in batteries on one device can be delivered back to a power
        hub which redirects the power to another device.  In this
        situation, the interface can function as both an inlet and
        outlet (at different times).
        A Power Interface can model a power inlet or a power outlet,
        depending on the conditions.  Information of interest Power
        Interfaces include the power direction, as well as the energy
        received, provided, and the net result.
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     Relevance of Power Supply Issues
        In some scenarios, the problems with power supply do not exist
        or can be sufficiently solved.  With Power over Ethernet (PoE)
        [IEEE-802.3at], there is always a one-to-one relationship
        between a Power Sourcing Equipment (PSE) and a Powered Device
        (PD).  Also, the Ethernet link on the line used for powering
        can be used to identify the PD and in many cases also the PSE.
        For supply of AC mains power, the three problems described
        above cannot be solved in general.  There is no commonly
        available protocol or automatic mechanism for identifying
        endpoints of a power line.
        And, AC power lines support supplying multiple powered devices
        with a single line and commonly do.
     Remote Power Supply Control
        There are three ways for an energy management system to change
        the Power State of powered devices.  First is for the EnMS to
        provide policy or other useful information (like the
        electricity price) to the powered device for it to use in
        determining its Power State.  The second is sending the
        powered devices a command to switch to another Power State.
        The third is to utilize an upstream device (to the powered
        device) that has capabilities to switch on and off power at
        its outlet.
        Some devices do not have capabilities for receiving commands
        or changing their Power States by themselves.  Such Energy
        Objects may be controlled by switching on and off the power
        supply for them and so have particular need for the third
        In Figure 4, the power supply can switch on and off power at
        its power outlet and thereby switch on and off power supply
        for the connected powered device.
       3.2.  Power and Energy Measurement
        Some devices include hardware to directly measure their Power
        and Energy consumption.  However, most common networked
        devices do not provide an interface that gives access to
        Energy and Power measurements.  Hardware instrumentation for
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        this kind of measurements is typically not in place and adding
        it incurs an additional cost.
        With the increasing cost of Energy and the growing importance
        of Energy Monitoring, it is expected that in future more
        devices will include instrumentation for power and energy
        measurements, but this may take quite some time.
     Local Estimates
        One solution to this problem is for the powered device to
        estimate its own Power and consumed Energy.  For many Energy
        Management tasks, getting an estimate is much better than not
        getting any information at all.  Estimates can be based on
        actual measured activity level of a device or it can just
        depend on the power state (on, sleep, off, etc.).
        An advantage of estimates is that they can be realized locally
        and with much lower cost than hardware instrumentation.  Local
        estimates can be dealt with in traditional ways.  They don't
        need an extension of the basic scenarios above.  However, the
        powered device needs an energy model of itself to make
     Management System Estimates
        Another approach to the lack of instrumentation is estimation
        by the EnMS.  The EnMS can estimate Power based on basic
        information on the powered device, such as the type of device,
        or also its brand/model and functional characteristics.
        Energy estimates can combine the typical power level by Power
        State with reported data about the Power State.
        If the EnMS has a detailed energy model of the device, it can
        produce better estimates including the actual power state and
        actual activity level of the device.  Such information can be
        obtained by monitoring the device with conventional means of
        performance monitoring.
       3.3.  Reporting Sleep and Off States
        Low power modes pose special challenges for energy reporting
        because they may preclude a device from listening to and
        responding to network requests.  Devices may still be able to
        reliably track energy use in these modes, as power levels are
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        usually static and internal clocks can track elapsed time in
        these modes.
        Some devices have out-of-band or proxy abilities to respond to
        network requests in low-power modes.  Others could use proxy
        abilities in an energy management protocol to improve this
        reporting, particularly if the powered device sends out
        notifications of power state changes.
       3.4.  Device and Device Components
        While the typical focus of energy management is entire powered
        devices, sometimes it is desirable to manage individual
        components of devices, such as line cards, fans, disks, etc.
        This framework uses a much simpler model for components than
        for entire devices.  The concept of Power Interfaces is not
        used between a device and its contained components.  Reporting
        of energy-related quantities for individual components is
        limited to the most important ones.  Simplifications for
        components in this framework include
           o  identifying components like devices but without
              distinct context information,
           o  reporting a containment relationship to the containing
           o  inheriting all context information from the containing
           o  not modeling power interfaces and power lines between
              the a component and its containing device or other
           o  only reporting real power and energy values for
           o  supporting power state monitoring and control for
        In rare cases where there is a need to model components of a
        device in more detail, components of a device can be modeled
        as an individual device.  Then all considerations for devices
        also apply to these components.  The overhead of this model is
        higher and it should be applied only when needed.  If used, it
        is not necessarily visible whether or not a set of components
        belongs to a single device, but for energy management purposes
        this might not be of high relevance.
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       3.5.  Non-Electrical Equipment
        The primary focus of this framework is for the management of
        Electrical Equipment.  Some Non-Electrical Equipment may be
        connected to a communication networks and could have their
        energy managed if normalized to the electrical units for power
        and energy.
        Some examples of Non-Electrical Equipment that may be
        connected to a communication network are:
        1) A controller for compressed air.  The controller is
          electrical only for its network connection.  The controller
          is fueled by natural gas and produces compressed air.  The
          energy transferred via compressed air is distributed to
          devices on a factory floor via a Power Interface: tools
          (drills, screwdrivers, assembly line conveyor belts). The
          energy measured is non-electrical (compressed air).
        2) A controller for steam. The controller is electrical for its
          network attachment but it burns tallow and produces steam to
          subtended boilers. The energy is non-electrical (steam).
        3) A controller or regulator for gas. The controller is
          electrical for its network attachment but it has physical
          non-electrical components for control. The energy is non-
          electrical (BTU).
       4. Energy Management Abstraction
        Energy Management can be organized into areas of concern that
        - Energy Object Identification and Context - for modeling and
        - Energy Monitoring - for energy measurements
        - Energy Control - for optimization
        - Energy Procurement - for optimization of resources
        While an EnMS may be a central point for corporate reporting,
        cost, environmental impact, and regulatory compliance, Energy
        Management in this framework excludes Energy procurement and
        the environmental impact of energy use.  As such the framework
        does not include:
        - Manufacturing costs of an Energy Object in currency or
        environmental units
        - Embedded carbon or environmental equivalences of an Energy
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        - Cost in currency or environmental impact to dismantle or
        recycle an Energy Object
        - Supply chain analysis of energy sources for Energy Object
        - Conversion of the usage or production of energy to units
        expressed from the source of that energy (such as the
        greenhouse gas emissions associated with 1000kW from a diesel
        The next sections describe Energy Management organized into
        the following areas:
         - Energy Object and Energy Management Domain
         - Energy Object Identification and Context
         - Energy Object Relationships
         - Energy Monitoring
         - Energy Control
         - Deployment Topologies
       4.1.  Energy Object and Energy Management Domain
        A meter is a type of device and any device can perform
        In building management, a meter refers to the meter provided
        by the utility used for billing and measuring power to an
        entire building or unit within a building.  A sub-meter refers
        to a customer or user installed meter that is not used by the
        utility to bill but instead used to get readings from sub
        portions of a building.
        An Energy Management Domain can be any collection of devices
        in a building but is recommended to map 1:1 with a metered or
        sub-metered portion of the site.  An Energy Object is part of
        a single Energy Management Domain.  The Energy Management
        Domain MAY be configured on an Energy Object: the default
        value is a zero-length string.
        If all Energy Objects in the physical containment tree (see
        ENTITY-MIB) are part of the same Energy Management Domain,
        then it is safe to state that the Energy Object at the root of
        that containment tree is in that Energy Management Domain.
        An Energy Object Child may inherit the domain value from an
        Energy Object Parent or the Energy Management Domain may be
        configured directly in an Energy Object Child.
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       4.2.  Power Interface
        There are some similarities between Power Interfaces and
        network interfaces.  A network interface can be used in
        different modes, such as sending or receiving on an attached
        line.  The Power Interface can be receiving or providing
        Most Power Interfaces never change their mode, but as the mode
        is simply a recognition of the current direction of
        electricity flow, there is no barrier to a mode change.
        A power interface can have capabilities for metering power and
        other electric quantities at the shared power transmission
        This capability is modeled by an association to a power meter.
        In analogy to MAC addresses of network interfaces, a globally
        unique identifier is assigned to each Power Interface.
        Physically, a Power Interface can be located at an AC power
        socket, an AC power cord attached to a device, an 8P8C (RJ45)
        PoE socket, etc.
       4.3.  Energy Object Identification and Context
     Energy Object Identification
        A Universal Unique Identifier (UUID) [RFC4122] MUST be used to
        uniquely and persistently identify an Energy Object. Ideally
        the UUID should be used to distinguish the Energy Object among
        all Energy Management Domains within the EnMS.
        Every Energy Object SHOULD have a unique printable name within
        the Energy Management Domain.  Possible naming conventions
        are: textual DNS name, MAC-address of the device, interface
        ifName, or a text string uniquely identifying the Energy
        Object.  As an example, in the case of IP phones, the Energy
        Object name can be the device's DNS name.
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     Context in General
        In order to aid in reporting and in differentiation between
        Energy Objects, each Energy Object optionally contains
        information establishing its business, site, or organizational
        context within a deployment, i.e. the Energy Object Context.
     Context: Importance
        An Energy Object can provide an importance value in the range
        of 1 to 100 to help rank a device's use or relative value to
        the site.  The importance range is from 1 (least important) to
        100 (most important).  The default importance value is 1.
        For example: A typical office environment has several types of
        phones, which can be rated according to their business impact.
        A public desk phone has a lower importance (for example, 10)
        than a business-critical emergency phone (for example, 100).
        As another example: A company can consider that a PC and a
        phone for a customer-service engineer is more important than a
        PC and a phone for lobby use.
        Although EnMS and administrators can establish their own
        ranking, the following is a broad recommendation [CISC0-EW]:
        . 90 to 100 Emergency response
        . 80 to 90 Executive or business-critical
        . 70 to 79 General or Average
        . 60 to 69 Staff or support
        . 40 to 59 Public or guest
        . 1  to 39 Decorative or hospitality
     Context: Keywords
        An Energy Object can provide a set of keywords.  These
        keywords are a list of tags that can be used for grouping,
        summary reporting within or between Energy Management Domains,
        and for searching.  All alphanumeric characters and symbols
        (other than a comma), such as #, (, $, !, and &, are allowed.
        Potential examples are: IT, lobby, HumanResources, Accounting,
        StoreRoom, CustomerSpace, router, phone, floor2, or
        SoftwareLab.  There is no default value for a keyword.
        Multiple keywords can be assigned to a device.  White spaces
        before and after the commas are excluded, as well as within a
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        keyword itself. In such cases, the keywords are separated by
        commas and no spaces between keywords are allowed.  For
        example, "HR,Bldg1,Private".
     Context: Role
        An Energy Object can provide a "role description" string that
        indicates the purpose the Energy Object serves in the EnMS.
        This could be a string describing the context the device
        fulfills in deployment.
        Administrators can define any naming scheme for the role of a
        device.  As guidance a two-word role that combines the service
        the device provides along with type can be used [IPENERGY]
        Example types of devices: Router, Switch, Light, Phone,
        WorkStation, Server, Display, Kiosk, HVAC.
        Example Services by Line of Business:
          Line of Business     Service
           Education            Student, Faculty, Administration,
          Finance              Trader, Teller, Fulfillment
          Manufacturing        Assembly, Control, Shipping
          Retail               Advertising, Cashier
          Support              Helpdesk, Management
          Medical              Patient, Administration, Billing
        Role as a two-word string: "Faculty Desktop", "Teller Phone",
        "Shipping HVAC", "Advertising Display", "Helpdesk Kiosk",
        "Administration Switch".
       4.4.  Energy Object Relationships
        Two Energy Objects MAY establish an Energy Object
        Relationship. Within a relationship one Energy Object becomes
        an Energy Object Parent while the other becomes an Energy
        Object Child.
        The Power Source Relationship gives a view of wiring topology.
        For example: a data center server receiving power from two
        specific Power Interfaces from two different PDUs.
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        Note: A power source relationship may or may not change as the
        direction of power changes between two Energy Objects. The
        relationship may remain to indicate the change of power
        direction was unintended or an error condition.
        The Metering Relationship gives the view of the metering
        topology.  Standalone meters can be placed anywhere in a power
        distribution tree.  For example, utility meters monitor and
        report accumulated power consumption of the entire building.
        Logically, the metering topology overlaps with the wiring
        topology, as meters are connected to the wiring topology.  A
        typical example is meters that clamp onto the existing wiring.
        The Proxy Relationship allows software objects to be inserted
        into the wiring or metering topology to aid in management
        (monitoring and/or control).
        In many situations, the wiring, metering, and management
        topologies overlap.  For example, a Power-over-Ethernet (PoE)
        device (such as an IP phone or an access point) is attached to
        a switch port.  The switch port is the source of power for the
        attached device, so the Energy Object Parent is the switch
        port, which is a Power Interface, and the Energy Object Child
        is the device attached to the switch.  This Energy Object
        Parent (the switch) has three Energy Object Relations with
        this Energy Object Child (the remote Energy Object): Power
        Source Relationship, Metering Relationship, and Proxy
        However, the three topologies (wiring, metering, and
        management) don't always overlap.  For example, when a
        protocol gateways device for Building Management Systems (BMS)
        controls subtended devices, which themselves receive Power
        from PDUs or wall sockets.
        Note: The Aggregation Relationship is slightly different
        compared to the other relationships (Power Source, Metering,
        and Proxy Relationships) as this refers more to a management
        The communication between the parent and child for monitoring
        or collection of power data is left to the device
        manufacturer.  For example: A parent switch may use LLDP to
        communicate with a connected child, and a parent lighting
        controller may use BACNET to communicate with child lighting
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        The Energy Object Child SHOULD keep track of its Energy Object
        Parent(s) along with the Energy Object Relationships type(s).
        The Energy Object Parent SHOULD keep track of its Energy
        Object Child(ren), along with the Energy Object Relationships
     Energy Object Children Discovery
        There are multiple ways that the Energy Object Parent can
        discover its Energy Object Children: :
          . In case of PoE, the Energy Object Parent automatically
             discovers an Energy Object Child when the Child requests
          . The Energy Object Parent and Children may run the Link
             Layer Discovery Protocol [LLDP], or any other discovery
             protocol, such as Cisco Discovery Protocol (CDP).  The
             Energy Object Parent might even support the LLDP-MED MIB
             [LLDP-MED-MIB], which returns extra information on the
             Energy Object Children.
          . The Energy Object Parent may reside on a network
             connected to a facilities gateway.  A typical example is
             a converged building gateway, monitoring several other
             devices in the building, and serving as a proxy between
             SNMP and a protocol such as BACNET.
          . A different protocol between the Energy Object Parent and
             the Energy Object Children.  Note that the communication
             specifications between the Energy Object Parent and
             Children is out of the scope of this document.
        However, in some situations, it is not possible to discover
        the Energy Object Relationships, and they must be set
        manually.  For example, in today' network, an administrator
        must assign the connected Energy Object to a specific PDU
        Power Interface, with no means of discovery other than that
        manual connection.
        When an Energy Object Parent is a Proxy, the Energy Object
        Parent SHOULD enumerate the capabilities it is providing for
        the Energy Object Child.  The child would express that it
        wants its parent to proxy capabilities such as, energy
        reporting, power state configurations, non physical wake
        capabilities (such as WoL)), or any combination of
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     Energy Object Relationship Conventions and Guidelines
        This Energy Management framework does not impose many "MUST"
        rules related to Energy Object Relationships. There are always
        corner cases that could be excluded with too strict
        specifications of relationships. However, this Energy
        Management framework proposes a series of guidelines,
        indicated with "SHOULD" and "MAY".
        Aggregation relationships are intended to identify when one
        device is used to accumulate values from other devices.
        Typically this is for energy or power values among devices and
        not for Components or Power Interfaces on the same device.
        The intent of Aggregation relationships is to indicate when
        one device is providing aggregate values for a set of other
        devices when it is not obvious form the power source or simple
        containment within a device.
        Establishing aggregation relationships within the same device
        would make modeling more complex and the aggregated values can
        be implied form the use of Power Inlets, outlet and Energy
        Object value son the same device.
        Additionally since an EnMS is naturally a point of aggregation
        it is not necessary to model aggregation for an EnMS(s).
        Aggregation SHOULD be used for power and energy. It MAY be
        used for aggregation of other values from the information
        model for example but the rules and logical ability to
        aggregated each attribute is out of scope for this document.
        - A Device SHOULD NOT establish an Aggregation Relationship
          with a Component.
        - A Device SHOULD NOT establish an Aggregation Relationship
          with the Power Interfaces contained on the same device.
        - A Device SHOULD NOT establish an Aggregation Relationship
          with the an EnMS.
        - Aggregators SHOULD log or provide notification in the case
          of errors or missing values while performing aggregation.
        Power Source
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        Power Source relationships are intended to identify the
        connections between Power Interfaces. This is analogous to a
        Layer 2 connection in networking devices (a one hop
        The preferred modeling would be for Power Interfaces to
        participate in Power Source Relationships.
        It may happen that the some Energy Objects may not have the
        capability to model Power Interfaces.  Therefore, it may
        happen that a Power Source Relationship is established between
        two Energy Objects or two non-connected Power Interfaces.
        While strictly speaking Components and Power Interfaces on the
        same device do provide or receive energy from each other the
        Power Source relationship is intended to show energy transfer
        between Devices. Therefore relationship is implied on the same
        - An Energy Object SHOULD NOT establish a Power Source
          Relationship with a Component.
        - A Power Source Relationship SHOULD be established with next
          known Power Interface in the wiring topology.
             o The next known Power Interface in the wiring topology
               would be the next device implementing the framework. In
               some cases the domain of devices under management may
               include some devices that do not implement the
               framework As such the Power Source relationship can be
               established with the next device in the topology that
               implements the framework and logically shows the Power
               Source of the device.
        - Transitive Power Source relationships SHOULD NOT be
          established.  For examples if an Energy Object A has a Power
          Source Relationship "Poweredby" with the Energy Object B,
          and if the Energy Object B has a Power Source Relationship
          "Poweredby" with the Energy Object C, then the Energy Object
          A SHOULD NOT have a Power Source Relationship "PoweredBby"
          the Energy Object C.
        Metering Relationship
        Metering Relationships are intended to show when one Device is
        measuring the power or energy at a point in a power
        distribution system. Since one point of a power distribution
        system may cover many Devices with a complex wiring topology,
        this relationship type can be seen as an arbitrary set.
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        Additionally, Devices may include metering hardware for
        components and Power Interfaces or for the entire Device.
        For example some PDU's may have the ability to measure Power
        for each Power Interface (metered by outlet). Others may only
        be able to control power at each Power Interface but only
        measure Power at the Power Inlet and a total for all Power
        Interfaces (metered by device).
        In such cases a Device SHOULD be modeled as an Energy Object
        that meters all of its Power Outlets and each Power Outlet MAY
        be metered by the Energy Object representing the Device.
        - A Meter Relationship MAY be established with any other
          Energy Object, Component, or Power Interface.
        - Transitive Meter relationships MAY be used.
        - When there is a series of meters for one Energy Object, the
          Energy Object MAY establish a relationship with one or more
          of the meters.
        A Proxy relationship is intended to show when one Device is
        providing the Energy Object capabilities for another Device
        typically for protocol translations. Strictly speaking a  a
        Component of a Device may provide the Energy Object
        capabilities for that Device (and vice versa) this
        relationship is intended to model relationships between
        - A Proxy relationship SHOULD be limited when possible to
          Energy Objects of different Devices.
     Energy Objects Relationship Extensions
        This framework for Energy Management, is based on four Energy
        Objects Relationships: Aggregation Relationship, Metering
        Relationship, Power Source Relationship, and Proxy
        This framework is defined with possible extension of new
        Energy Objects Relationships in mind.  For example, a Power
        Distribution Unit (PDU) that allows physical entities like
        outlets to be "ganged" together as a logical entity for
        simplified management purposes, could be modeled with a future
        extension based on "gang relationship", whose semantic would
        specify the Energy Objects grouping.
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       4.5.  Energy Monitoring
        For the purposes of this framework energy will be limited to
        electrical energy in watt hours.  Other forms of Energy
        Objects that use or produce non-electrical energy may be part
        of an Energy Management Domain (See Section 3.5)  but MUST
        provide information converted to and expressed in watt hours.
        An analogy for understanding power versus energy measurements
        can be made to speed and distance in automobiles. Just as a
        speedometer indicates the rate of change of distance, a power
        meter indicates the rate of transfer of energy. The odometer
        in an automobile measures the cumulative distance traveled and
        an energy meter indicates the accumulate energy transferred.
        So a less formal statement of the analogy is that power meters
        measures "speed" while energy meters measure "distance".
        Each Energy Object will have information that describes power
        information, along with how that measurement was obtained or
        derived (actual measurement, estimated, or presumed).  For
        Energy Objects that can report actual power readings, an
        optional energy measurement can be provided.
        Optionally, an Energy Object can further describe the Power
        information with Power Quality information reflecting the
        electrical characteristics of the measurement.
        Optionally, an Energy Object that can report actual power
        readings can have energy meters that provide the energy used,
        produced, and net energy in kWh. These values are energy
        meters that accumulate the power readings.  If energy values
        are returned then the three energy meters must be provided
        along with a description of accuracy.
        Optionally, an Energy Object can provide demand information
        over time.
     Power Measurement
        A power measurement MUST be qualified with the units,
        magnitude, direction of power flow, and SHOULD be qualified by
        what means the measurement was made (ex: Root Mean Square
        versus Nameplate).
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        In addition, the Energy Object should describe how it intends
        to measure power as one of consumer, producer or meter of
        usage.  Given the intent, readings can be summarized or
        analyzed by an EnMS.  For example metered usage reported by a
        meter and consumption usage reported by a device connected to
        that meter may naturally measure the same usage.  With the two
        measurements identified by intent a proper summarization can
        be made by an EnMS.
        Power measurement magnitude should conform to the IEC 61850
        definition of unit multiplier for the SI (System
        International) units of measure.  Measured values are
        represented in SI units obtained by BaseValue * (10 ^ Scale).
        For example, if current power usage of an Energy Object is 3,
        it could be 3 W, 3 mW, 3 KW, or 3 MW, depending on the value
        of the scaling factor.  3W implies that the BaseValue is 3 and
        Scale = 0, whereas 3mW implies BaseValue = 3 and ScaleFactor =
        Electricity is usually billed in kilowatt-hours (not
        megajoules, the SI units).  Similarly, battery charge is often
        measured as miliamperes-hour (mAh) instead of the SI unit
        coulomb.  The units used in this framework are: W, A, Wh, Ah,
        In addition to knowing the usage and magnitude, it is useful
        to know how an Energy Object usage measurement was obtained:
        . Whether the measurements were made at the device itself or
        from a remote source.
        . Description of the method that was used to measure the
        power and whether this method can distinguish actual or
        estimated values.
        An EnMS can use this information to account for the accuracy
        and nature of the reading between different implementations.
        The EnMS can use the Nameplate Power for provisioning,
        capacity planning and potentially billing.
     6.5.2 Optional Power Attributes
        Given a power measurement, it may be desirable to know
        additional power attributes associated with that measurement.
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        Optional Power Quality
        The information model should adhere to the IEC 61850 7-2
        standard for describing AC measurements.
        Optional Demand
        It is well known in commercial electrical utility rates that
        demand is part of the calculation for billing.  The highest
        peak demand measured over a time horizon, such as 1 month or 1
        year, is often the basis for charges.  A single window of time
        of high usage can penalize the consumer with higher energy
        consumption charges.  However, it is relevant to measure the
        demand only when there are actual power measurements from an
        Energy Object, and not when the power measurement is assumed
        or predicted.
        Optional Battery
        Some Energy Objects may use batteries for storing energy and
        for receiving power supply.  These Energy Objects should
        report their current power supply (battery, power line, etc.)
        and the battery status for each contained battery.   Battery-
        specific information to be reported should include the number
        of batteries contained in the device and per battery the state
        information as defined in [EMAN-REQ].
        Beyond that a device containing a battery should be able to
        generate alarms when the battery charge falls below a given
        threshold and when the battery needs to be replaced.
       4.6.  Control
        An Energy Object can be controlled by setting it to a specific
        Power State.  An Object implements a set of Power States
        consisting of at least two states, an on state and an off
        A Power State is an interface by which an Energy Object can be
        controlled.  Each Energy Object should indicate the set of
        Power States that it implements.  Well known Power States /
        Sets should be registered with IANA.
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        When a device is set to a particular Power State, it may be
        busy. The device will set the desired Power State and then
        update the actual Power State when it changes.  There are then
        two Power State control variables: actual and requested.
        There are many existing standards for and implementations of
        Power States.  An Energy Object can support a mixed set of
        Power States defined in different standards. A basic example
        is given by the three Power States defined in IEEE1621
        [IEEE1621]: on, off, and sleep. The DMTF [DMTF], ACPI [ACPI],
        and PWG define larger numbers of Power States.
        The semantics of a power state is specified by
           a) the functionality provided by an Energy Object in this
           b) a limitation of the power that an Energy Object uses in
        this state,
           c) a combination of a) and b)
        The semantics of a Power State should be clearly defined.
        Limitation (curtailment) of the power used by an Energy Object
        in a state can be specified by
           - an absolute power value
           - a percentage value of power relative to the energy
        object's nameplate power
           - an indication of used power relative to another power
        state - for example: by stating used power in state A is less
        than in state B.
        For supporting Power State management it is useful to provide
        statistics on Power States including the time an Energy Object
        spent in a certain Power State and/or the number of times an
        Energy Object entered a power state.
        Power States should be registered at IANA with a name and a
        When requesting an Energy object to enter a Power State an
        indication of its name or its number can be used. Optionally
        an absolute or percentage of Nameplate Power can be provided
        to allow the Energy Object to transition to a nearest or
        equivalent Power State.
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     EMAN Power State Set
        An EMAN Power State Set represents an attempt for a standard
        approach to model the different levels of power of a device.
        The EMAN Power States are an expansion of the basic Power
        States as defined in [IEEE1621] that also incorporates the
        Power States defined in [ACPI] and [DMTF].  Therefore, in
        addition to the non-operational states as defined in [ACPI]
        and [DMTF] standards, several intermediate operational states
        have been defined.
        There are twelve Power States, that expand on [IEEE1621]. The
        expanded list of Power States are derived from [CISCO-EW] and
        are divided into six operational states, and six non-
        operational states.  The lowest non-operational state is 1 and
        the highest is 6.  Each non-operational state corresponds to
        an [ACPI] Global and System states between G3 (hard-off) and
        G1 (sleeping).  Each operational state represents a
        performance state, and may be mapped to [ACPI] states P0
        (maximum performance power) through P5 (minimum performance
        and minimum power).
        In each of the non-operational states (from mechoff(1) to
        ready(6)), the Power State preceding it is expected to have a
        lower Power value and a longer delay in returning to an
        operational state:
                 mechoff(1) : An off state where no Energy Object
        features are available.  The Energy Object is unavailable.  No
        energy is being consumed and the power connector can be
        removed. This corresponds to ACPI state G3.
                 softoff(2) : Similar to mechoff(1), but some
        components remain powered or receive trace power so that the
        Energy Object can be awakened from its off state.  In
        softoff(2), no context is saved and the device typically
        requires a complete boot when awakened.  This corresponds to
        ACPI state G2.
                hibernate(3): No Energy Object features are
        available.   The Energy Object may be awakened without
        requiring a complete boot, but the time for availability is
        longer than sleep(4). An example for state hibernate(3) is a
        save to-disk state where DRAM context is not maintained.
        Typically, energy consumption is zero or close to zero.  This
        corresponds to state G1, S4 in ACPI.
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                 sleep(4)    : No Energy Object features are
        available, except for out-of-band management, such as wake-up
        mechanisms.  The time for availability is longer than
        standby(5). An example for state sleep(4) is a save-to-RAM
        state, where DRAM context is maintained.  Typically, energy
        consumption is close to zero.  This corresponds to state G1,
        S3 in ACPI.
                 standby(5) : No Energy Object features are available,
        except for out-of-band management, such as wake-up mechanisms.
        This mode is analogous to cold-standy.  The time for
        availability is longer than ready(6).  For example, the
        processor context is not maintained. Typically, energy
        consumption is close to zero.  This corresponds to state G1,
        S2 in ACPI.
                 ready(6)    : No Energy Object features are
        available, except for out-of-band management, such as wake-up
        mechanisms. This mode is analogous to hot-standby.  The Energy
        Object can be quickly transitioned into an operational state.
        For example, processors are not executing, but processor
        context is maintained.  This corresponds to state G1, S1 in
        ACPI.         lowMinus(7) : Indicates some Energy Object
        features may not be available and the Energy Object has
        selected measures/options to provide less than low(8) usage.
        This corresponds to ACPI State G0.  This includes operational
        states lowMinus(7) to full(12).
                 low(8)      : Indicates some features may not be
        available and the Energy Object has taken measures or selected
        options to provideless than mediumMinus(9) usage.
                 mediumMinus(9): Indicates all Energy Object features
        are available but the Energy Object has taken measures or
        selected options to provide less than medium(10) usage.
                 medium(10)  : Indicates all Energy Object features
        are available but the Energy Object has taken measures or
        selected options to provide less than highMinus(11) usage.
                 highMinus(11): Indicates all Energy Object features
        are available and power usage is less than high(12).
                 high(12)    : Indicates all Energy Object features
        are available and the Energy Object is consuming the highest
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        A comparison of Power States can be seen in the following
          IEEE1621  DMTF         ACPI           EMAN
          Non-operational states
          off       Off-Hard     G3, S5         MechOff(1)
          off       Off-Soft     G2, S5         SoftOff(2)
          sleep     Hibernate    G1, S4         Hibernate(3)
          sleep     Sleep-Deep   G1, S3         Sleep(4)
          sleep     Sleep-Light  G1, S2         Standby(5)
          sleep     Sleep-Light  G1, S1         Ready(6)
          Operational states:
          on        on           G0, S0, P5     LowMinus(7)
          on        on           G0, S0, P4     Low(8)
          on        on           G0, S0, P3     MediumMinus(9)
          on        on           G0, S0, P2     Medium(10)
          on        on           G0, S0, P1     HighMinus(11)
          on        on           G0, S0, P0     High(12)
                     Figure 5: Comparison of Power States
     4.7. Energy Management Reference Model
        The scope of this framework is to enable network and network-
        attached devices to be administered for Energy Management.
        The framework recognizes that in complex deployments Energy
        Objects may communicate over varying protocols.  For example
        the communications network may use IP Protocols (SNMP) but
        attached Energy Object Parent may communicate to Energy Object
        Children over serial communication protocols like BACNET,
        MODBUS etc.  The likelihood of getting these different
        topologies to convert to a single protocol is not very high
        considering the rate of upgrades of facilities and energy
        related devices. Therefore the framework must address the
        simple case of a uniform IP network and a more complex mixed
        In this section we will describe the topologies that can exist
        when describing a device, components and the relationships
        among them.
        We will then generalize those topologies by using an
        information model based upon relationships. The most abstract
        and general relationship between devices is a Parent and Child
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        relationship. Specific types of relationships are defined and
        used in concert to describe the topologies.
     4.8 Using Device Relationships to Create Topologies
        The reference models here define physical and logical
        topologies of devices in a communication network.
        The physical topology defined by the model defines
        relationships between devices that reflect provisioning,
        transfer of energy, and aid in management.
        Logical topologies concern monitoring and controlling devices
        and covers metering of energy and power, reporting information
        relevant for energy management, and energy-related control of
     Power Source Topology
        As described in Section 4, the power source(s) of a device is
        important for energy management.  The Energy Management
        reference model addresses this by a "Power Source"
        Relationship.  This is a relationship among devices providing
        energy and devices receiving energy.
        A simple example is a PoE PSE, for example, an Ethernet
        switch, providing power to a PoE PD, for example, a desktop
        phone.  Here the switch provides energy and the phone receives
        energy.  This relationship can be seen in the figure below.
              +----------+   power source  +---------+
              |  switch  | <-------------- |  phone  |
              +----------+                 +---------+
                        Figure 6: Simple Power Source
        A single power provider can act as power source of multiple
        power receivers.  An example is a power distribution unit
        (PDU) providing AC power for multiple switches.
              +-------+   power source  +----------+
              |  PDU  | <----------+--- | switch 1 |
              +-------+            |    +----------+
                                   |    +----------+
                                   +--- | switch 2 |
                                   |    +----------+
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                                   |    +----------+
                                   +--- | switch 3 |
                       Figure 7: Multiple Power Source
        This level of modeling is sufficient if there is no need to
        distinguish in monitoring and control between the individual
        receivers at the switch.
        However, if there is a need to monitor or control power supply
        for individual receivers at the power provider, then a more
        detailed level of modeling is needed.
        Devices receive or provide energy at power interfaces
        connecting them to a transmission medium.  The Power Source
        relationship can be used also between power interfaces at the
        power provider side as well as at the power receiver side.
        The example below shows a power providing device with a power
        interface (PI) per connected receiving device.
              +-------+------+   power source  +----------+
              |       | PI 1 | <-------------- | switch 1 |
              |       +------+                 +----------+
              |       |
              |       +------+   power source  +----------+
              |  PDU  | PI 2 | <-------------- | switch 2 |
              |       +------+                 +----------+
              |       |
              |       +------+   power source  +----------+
              |       | PI 3 | <-------------- | switch 3 |
              +-------+------+                 +----------+
                 Figure 8: Power Source with Power interfaces
        Power interfaces may also be modeled at the receiving device,
        for examples for consistency.
           +-------+------+   power source  +----+----------+
           |       | PI 1 | <-------------- | PI | switch 1 |
           |       +------+                 +----+----------+
           |       |
           |       +------+   power source  +----+----------+
           |  PDU  | PI 2 | <-------------- | PI | switch 2 |
           |       +------+                 +----+----------+
           |       |
           |       +------+   power source  +----+----------+
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           |       | PI 3 | <-------------- | PI | switch 3 |
           +-------+------+                 +----+----------+
                Figure 9: Power Interfaces at Receiving Device
        Power Source relationships are between devices and their
        interfaces.  They are not transitive.  In the examples below
        there is a PDU powering a switch powering a phone.
              +-------+   power   +--------+   power   +---------+
              |  PDU  | <-------- | switch | <-------- |  phone  |
              +-------+   source  +--------+   source  +---------+
                    Figure 10: Power Source Non-Transitive
        Power Source Relationships are between the PDU and the switch
        and between the switch and the phone.  Transitively , there
        exists a Power Source Relationship between the PDU and the
        phone.  .
              +-------+   power   +--------+   power   +---------+
              |  PDU  | <-------- | switch | <-------- |  phone  |
              +-------+   source  +--------+   source  +---------+
                  ^                                          |
                  |              power source                |
                      Figure 11: Power Source Transitive
     Metering Topology
        Case 1: Metering between two devices
        The metering topology between two devices is closely related
        to the power source topology.  It is based on the assumption
        that in many cases the power provided and the power received
        is the same for both peers of a power source relationship.
        Then power measured at one end can be taken as the actual
        power value at the other end.  Obviously, the same applies to
        energy at both ends.
        We define in this case a Metering Relationship between two
        devices or power interfaces of devices that have a power
        source relationship.  Power and energy values measured at one
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        peer of the power source relationship are reported for the
        other peer as well.
        The Metering Relationship is independent of the direction of
        the Power Source Relationship.  The more common case is that
        values measured at the power provider are reported for the
        power receiver, but also the reverse case is possible with
        values measured at the power receiver being reported for the
        power provider.
                                Power                Power
           +-----+----------+   Source  +--------+   Source +-------+
           | PDU |PI + meter| <-------- | switch | <------- | phone |
           +-----+----------+  Metering +--------+          +-------+
                       ^                                           |
                       |                                           |
                    Figure 12: Direct and One Hop Metering
        Case 2: Metering at a point in power distribution
        A Sub-meter in a power distribution system can logically
        measure the power or energy for all devices downstream from
        the meter in the power distribution system.  As such, a Power
        metering relationship can be seen as a relationship between a
        meter and all of the devices downstream from the meter.
        We define in this case a Power Metering relationship between a
        metering device and devices downstream from the meter.
        In cases where the Power Source topology cannot be discovered
        or derived from the information available in the Energy
        Management Domain, the Metering Topology can be used to relate
        the upstream meter to the downstream devices in the absence of
        specific power source relationships.
        A Metering Relationship can occur between devices that are not
        directly connected as shown by the figure 13.
                           |   Device 1    |
                           |      PI       |
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                           |     Meter     |
            +----------+   +----------+   +-----------+
            | Device A |   | Device B |   | Device C  |
            +----------+   +----------+   +-----------+
                     Figure 14: Complex Metering Topology
        An analogy to communication networks would be modeling
        connections between servers (meters) and clients (devices)
        when the complete Layer 2 topology between the servers and
        clients is not known.
     Proxy Topology
        Some devices may provide energy management capabilities on
        behalf of other devices.  For example, a controller may
        logically model power interfaces but the physical topology may
        require that the controller communicate to another device
        using a building management protocol.  These proxied devices
        that are represented as power interfaces may be directly
        connected or may be controlled over a communication network
        with no direct connection.
        The proxied device may or may not be IP connected. When it is
        IP connected the communication may be via SNMP or any other
        While the EnMS may look at the logical representation of the
        controller as a device with power interfaces, it may require
        to report the physical topology and relationship to the
        subtended devices. To model this we define a proxy
        relationship to provide this visibility.
              |       | PI 1 |
              |       +------+
              |       |
              |       +------+
              |  PDU  | PI 2 |
              |       +------+
              |       |
              |       +------+
              |       | PI 3 |
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              +-------+   proxy   +----+----------+
              |       |<--------- | PI 1 Physical |
              |       +           +----+----------+
              |       |
              |       +   proxy   +----+----------+
              |  PDU  |<--------- | PI 2 Physical |
              |       +           +----+----------+
              |       |
              |       +   proxy   +----+----------+
              |       |<--------- | PI 3 Physical |
              +-------+           +----+----------+
              Figure 15: Proxy Relationship Virtual and Physical
     Aggregation Topology
        Some devices can act as aggregation points for other devices.
        For example, a PDU controller device may contain the summation
        of power and energy readings for many PDU devices.  The PDU
        controller will have aggregate values for power and energy for
        a group of PDU devices.
        This aggregation is independent of the physical power or
        communication topology.
        An Aggregation Relationship is an Energy Object Relationship
        where one Energy Object (called the Aggregate Energy Object)
        aggregates the Energy Management information of one or more
        other Energy Objects.  These Energy Objects are referred to as
        having an Aggregation Relationship.
        The functions that the aggregation point may perform include
        the calculation of values such as average, count, maximum,
        median, minimum,  or the listing (collection) of the
        aggregation values, etc.
        Based on the experience gained on aggregations at the IETF
        [draft-ietf-ipfix-a9n-08], the aggregation function in the
        EMAN framework is limited to the summation.
        While any power or energy values monitored from a device/power
        interface can be seen as a summation for all devices
        downstream from the monitoring device, the aggregation
        relationship is used SHOULD BE instantiated to represent a
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        summation when it is not obvious from the powering topology or
        a device to component containment.
        The Aggregation Relationship is then specified between the
        Energy Object device containing aggregate values and each of
        the other Energy Object devices for which the aggregation is
        reported. If it does not exist, a new Aggregate Energy Object
        specific for the Aggregation Relationship MUST be created.
        EDITORs NOTE: add an outlet gang example and expand below.
          A method to report on collections and summations of data is
          to create special pseudo-devices.  These could be tagged
          in the MIB as not being a real device, but this may not be
          needed.  ThisA pseudo-device would have no power PIs Power
          Interfaces, as to make clear that it does not interact with
          the real power world.  It contains components which are
          actually entities from real devices and can be any
          combination of devices, PIs, and real components.  Most
          commonly, a pseudo-device would contain a consistent set of
          entities -
                   - a set of devices, a set of PIs, or a set of
          components.  The power/energy values for the entire pseudo-
          device would be the sum of the components, as on a normal
          device.  This provides an easy way to access the sum, as
          well as full documentation of what the components of that
          sum are.  This method is completely flexible and adds no
          complexity to the EMAN framework or MIBs.  Implementation of
          this mechanism would be completely optional for EMAN
          devices; likely most would not.
        When aggregation occurs across a set of entities, values to be
        aggregated may be missing for some entities.  The EMAN
        framework does not specify how these should be treated, as
        different implementations may have good reason to take
        different approaches.  One common treatment is to define the
        aggregation as missing if any of the constituent elements are
        missing (useful to be most precise). Another is to treat the
        missing value as zero (useful to have continuous data
        The specifications of this aggregation function are out of
        scope of the EMAN framework, but must be clearly specified by
        the equipment vendor.
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          EDITOR'S NOTE: 4 solutions discussed on December 12th
          - pseudo device. Aggregate Energy Object
          - A semantic field (ex: summation): extra index in every
          measurement MIB table.
          - Multiply the variables  => doesn't work
          - Remove aggregation
          PREFERRED: take the proposal from Bruce (below) and let's
          call pseud-device differently. Example Aggregate Energy
     4.9 Generalized Relationship Model
        As displayed in Figure 15, the most basic energy management
        reference model is composed of an EnMS that obtains Energy
        Management information from Energy Objects.  The Energy Object
        (EO) returns information for Energy Management directly to the
        The protocol of choice for Energy Management is SNMP, as three
        MIBs are specified for Energy Management: the energy object
        context MIB [EMAN-OBJECT-MIB], the energy monitoring MIB
        [EMAN-MON-MIB], and the battery MIB [EMAN-BATTERY-MIB].
        However, the EMAN requirement document [EMAN-REQ] also
        requires support for a push model distribution of time series
        values.  The following diagrams mention IPFIX [RFC5101] as one
        possible solution for implementing a push mode transfer,
        however this is for illustration purposes only.  The EMAN
        standard does not require the use of IPFIX and acknowledges
        that other alternative solutions may also be acceptable.
                            |      EnMS     |                -   -
                            +-----+---+-----+                ^   ^
                                  |   |                      |   |
                                  |   |                      |S  |I
                        +---------+   +----------+           |N  |P
                        |                        |           |M  |F
                        |                        |           |P  |I
               +-----------------+      +--------+--------+  |   |X
               | EO            1 |  ... | EO            N |  v   |
               +-----------------+      +-----------------+  -   -
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                     Figure 15: Simple Energy Management
        As displayed in the Figure 16, a more complex energy reference
        model includes Energy Managed Object Parents and Children.
        The Energy Managed Object Parent returns information for
        themselves as well as information according to the Energy
        Managed Object Relationships.
                           |      EnMS     |               -   -
                           +-----+--+------+               ^   ^
                                 |  |                      |   |
                                 |  |                      |S  |I
                    +------------+  +--------+             |N  |P
                    |                        |             |M  |F
                    |                        |             |P  |I
            +------------------+     +------+-----------+  |   |X
            | EO               |     | EO               |  v   |
            | Parent 1         | ... | Parent N         |  -   -
            +------------------+     +------------------+
                           |||                  .
          One or           |||                  .
          Multiple         ||| (*)  .
          Energy           |||                  .
          Object           |||                  .
          Relationship(s): |||
          - Aggregation    |||      +-----------------------+
          - Metering       |||------| EO Child 1            |
          - Power Source   ||       +-----------------------+
          - Proxy          ||
                           ||       +-----------------------+
                           ||-------| EO Child 2            |
                           |        +-----------------------+
                           |--------           ...
                           |        +-----------------------+
                           |--------| EO Child M            |
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                  Figure 16: Complex Energy Management Model
        While both the simple and complex Energy Management models
        contain an EnMS, this framework doesn't impose any
        requirements regarding a topology with a centralized EnMS(s)
        or one with distributed Energy Management via the Energy
        Objects within the deployment.
        Given the pattern in Figure 16, the complex relationships
        between Energy Objects can be modeled (refer also to section
             - A PoE device modeled as an Energy Object Parent with
               the Power Source, Metering, and Proxy Relationships for
               one or more Energy Object Children
             - A PDU modeled as an Energy Object Parent with the Power
               Source and Metering Relationships for the plugged in
               Electrical Equipment (the Energy Object Children)
             - Building management gateway, used as proxy for non IP
               protocols, is modeled as an Energy Object Parent with
               the Proxy Relationship, and potentially the Aggregation
               Relationship to the managed Electrical Equipment
             - Etc.
     (*) If there is any communication between the Energy Object
     Parent and Energy Object Children, it can be via EMAN and SNMP
     (or IPFIX) but may be any other protocol IP or otherwise.
        In the [EMAN-OBJECT-MIB], each Energy Object is managed with
        an unique value of the entPhysicalIndex index from the ENTITY-
        MIB [RFC4133]
        The ENTITY-MIB [RFC4133] specifies the notion of physical
        containment tree, as:
          "Each physical component may be modeled as 'contained'
          another physical component.  A "containment-tree" is the
          conceptual sequence of entPhysicalIndex values that uniquely
          specifies the exact physical location of a physical
          component within the managed system.  It is generated by
          'following and recording' each 'entPhysicalContainedIn'
          instance 'up the tree towards the root', until a value of
          zero indicating no further containment is found."
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        A Energy Object Component is a special Energy Object that is a
        physical component as specified by the ENTITY-MIB physical
        containment tree.
       5. Energy Management Information Model
        The following basic UML represents an information model
        expression of the concepts in this framework.  This
        information model, provided as a reference for implementers,
        is represented as a MIB in the different related IETF Energy
        Monitoring documents.  However, other programming structure
        with different data models could be used as well.
        Notation is a shorthand UML with lowercase types considered
        platform or atomic types (i.e. int, string, collection).
        Uppercase types denote classes described further.  Collections
        and cardinality are expressed via qualifier notation.
        Attributes labeled static are considered class variables and
        global to the class.  Arrows indicate inheritance. Algorithms
        for class variable initialization, constructors or destructors
        are not shown. Attrbutes and structures are considered
        readable and writeable prefixed by a dash (-) which indicates
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                         EO RELATIONSHIPS AND CONTEXT
          |  Energy Object Information      |
          | -index : int                    |
          | name : string                   |
          | -energy object Identifier : UUID|
          | domain name : string            |
          | alternate Key : string          |
          |  EO Context Information   |
          |  role : string            |
          |  keywords[0..n] : string  |
          |  importance : int         |
          |  category : enum          |
          |  EO Relationship                |
          | ------------------------------- |
          |  -index : int                   |
          |  relation ID : UUID             |
          |  relationship type: enum        |
          |  EO Proxy Relationship          |
          | ------------------------------- |
          |  -index : int                   |
          |  proxy ID : UUID                |
          |  proxy abilities : enum         |
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                            EO AND MEASUREMENTS
        |                 Energy Object                 |
        |  -nameplate : Measurement                     |
        |  current : enum { AC, DC }                    |
        |  origin : enum { self, remote }               |
        |  battery[0..n]: Battery                       |
        |  measurements[0..n]: Measurement              |
        |  status:                                      |
        | --------------------------------------------- |
        | Measurement instantaneousUsage()              |
        | DemandMeasurement historicalUsage()           |
          |  -Measurement                         |
          | multiplier : enum {-24..24}           |
          | caliber : enum { actual, estimated,   |
          |                  trusted, assumed...} |
          | accuracy : enum { 0..10000}           |
          | time : timestamp                      |
           ^                 ^
           |                 |
           |     +------------------+------------------+
           |     |         -Power Measurement          |
           |     |-------------------------------------|
           |     | value : long                        |
           |     | units : "watts"                     |
           |     | rate : enum {0,millisecond,seconds, |
           |     |              minutes,hours,...}     |
           |     | quality : PowerQuality              |
           |     +-------------------------------------+
         |         -Energy Measurement                   |
         | collection start time : time                  |
         | units : enum                                  |
         | consumed : long                               |
         | produced : long                               |
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         | net : long                                    |
         | max consumed : long                           |
         | max produced : long                           |
         |         -Time                                 |
         | startTime : timestamp                         |
         | usage : Measurement                           |
         | maxUsage : Measurement                        |
         |        -TimeInterval                   |
         |--------------------------------------- |
         |value : long                            |
         |units : enum { seconds, miliseconds..}  |
         |        -DemandMeasurement              |
         |intervalLength :  TimeInterval          |
         |intervalNumbers: long                   |
         |intervalMode :  enum { period, sliding, |
         |total }                                 |
         |intervalWindow : TimeInterval           |
         |sampleRate : TimeInterval               |
         |status : enum {active, inactive }       |
         |measurements : TimedMeasurement[]       |
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         |            -PowerAttributes            |
         |                                        |
         |         -ACQuality                    |
         | acConfiguration : enum {SNGL, DEL,WYE}|
         | avgVoltage   : long                   |
         | avgCurrent   : long                   |
         | frequency    : long                   |
         | unitMultiplier  : int                 |
         | accuracy  : int                       |
         | totalActivePower  : long              |
         | totalReactivePower : long             |
         | totalApparentPower : long             |
         | totalPowerFactor : long               |
                   | 1
                   |        +------------------------------------+
                   |        |         -ACPhase                   |
                   |     *  |------------------------------------|
                   +--------+ phaseIndex : long                  |
                            | avgCurrent : long                  |
                            | activePower : long                 |
                            | reactivePower : long               |
                            | apparentPower : long               |
                            | powerFactor : long                 |
                                        ^           ^
                                        |           |
                                        |           |
                                        |           |
                                        |           |
        +-------------------------------+---+       |
        |        -DelPhase                  |       |
        |-----------------------------------|       |
        |phaseToNextPhaseVoltage  : long    |       |
        |thdVoltage : long                  |       |
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        |thdCurrent : long                  |       |
        +-----------------------------------+       |
                                 |        -WYEPhase             |
                                 |phaseToNeutralVoltage : long  |
                                 |thdCurrent : long             |
                                 |thdVoltage : long             |
                              EO & STATES
           |             Energy Object                    |
           | -currentLevel : int                          |
           | configuredLevel : int                        |
           | -configuredTime : timestamp                  |
           | reason: string                               |
           | powerStateSeries[0..n] : array of State      |
           | adminState : enum                            |
           | operState : enum                             |
            |        State                  |
            | name : string                 |
            | cardinality : int             |
            | maxUsage : Measurement        |
            | totalTime : time              |
            | enterCount : int              |
               Figure 17: Information Model UML Representation
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       6. Example Topologies
        In this section we will give examples of how to use the Energy
        Management framework.  In each example we will show how it can
        be applied when Devices have the capability to model Power
        Interfaces.  We will also show in each example how the
        framework can be applied when devices cannot support Power
        Interfaces but only monitor information or control the Device
        as a whole. For instance a PDU may only be able to measure
        power and energy for the entire unit without the ability to
        distinguish among the inlets or outlet.
        Together these examples show how the framework can be adapted
        for Devices with different capabilities (typically hardware)
        for Energy Management.
        Given for all Examples:
        Device W: A computer with one power supply. Power interface 1
        is an inlets for Device W.
        Device X: A computer with two power supplies. Power interface
        1 and power interface 2 are both inlets for Device X.
        Device Y: A PDU with multiple Power Interfaces numbered 0..10,
        Power interface 0 is an inlet and power interface 1..10 are
        Device Z: A PDU with multiple Power Interfaces numbered 0..10,
        Power interface 0 is an inlet and power interface 1..10 are
     6.1 Example I: Simple Device with one Source
          Device W inlet 1 is plugged into Device Y outlet 8.
        With Power Interfaces:
          Device W has an Energy Object representing the computer
          itself as well as one Power Interface defined as an inlet.
          Device Y would have an Energy Object representing the PDU
          itself (the Device) with a Power Interface 0 defined as an
          inlet and Power Interfaces 1..10 defined as outlets.
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          The interfaces of the devices would have a Power Source
          Relationship such that:
          Device W inlet 1 is powered by Device Y outlet 8
        Without Power Interfaces:
          In this case Device W has an Energy Object representing the
          computer.  Device Y would have an Energy Object representing
          the PDU.
          The devices would have a Power Source Relationship such
          Device W is powered by Device Y.
     6.2 Example II: Multiple Inlets
          Device X inlet 1 is plugged into Device Y outlet 8.
          Device X inlet 2 is plugged into Device Y outlet 9.
        With Power Interfaces:
          Device X has an Energy Object representing the computer
          itself. It contains two Power Interface defined as inlets.
          Device Y would have an Energy Object representing the PDU
          itself  (the Device) with a Power Interface 0 defined as an
          inlet and Power Interface 1..10 defined as outlets.
          The interfaces of the devices would have a Power Source
          Relationship such that:
          Device X inlet 1 is powered by Device Y outlet 8
          Device X inlet 2 is powered by Device Y outlet 9
        Without Power Interfaces:
          In this case Device X has an Energy Object representing the
          computer. Device Y would have an Energy Object representing
          the PDU.
          The devices would have a Power Source Relationship such
          Device X is powered by Device Y.
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     6.3 Example III: Multiple Sources
          Device X inlet 1 is plugged into Device Y outlet 8.
          Device X inlet 2 is plugged into Device Z outlet 9
        With Power Interfaces:
          Device X has an Energy Object representing the computer
          itself. It contains two Power Interface defined as inlets.
          Device Y would have an Energy Object representing the PDU
          itself  (the Device) with a Power Interface 0 defined as an
          inlet and Power Interface 1..10 defined as outlets.
          Device Z would have an Energy Object representing the PDU
          itself  (the Device) with a Power Interface 0 defined as an
          inlet and Power Interface 1..10 defined as outlets.
          The interfaces of the devices would have a Power Source
          Relationship such that:
          Device X inlet 1 is powered by Device Y outlet 8
          Device X inlet 2 is powered by Device Z outlet 9
        Without Power Interfaces:
          In this case Device X has an Energy Object representing the
          computer. Device Y and Z would both have respective Energy
          Objects representing each entire PDU.
          The devices would have a Power Source Relationship such
          Device X is powered by Device Y and powered by Device Z.
     7.    Relationship with Other Standards
        This power management framework should, as much as possible,
        reuse existing standards efforts, especially with respect to
        information modeling and data modeling [RFC3444].
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        The data model for power and energy related objects is based
        on IEC 61850.
        Specific examples include:
        The scaling factor, which represents Energy Object usage
        magnitude, conforms to the IEC 61850 definition of unit
        multiplier for the SI (System International) units of measure.
        The electrical characteristic is based on the ANSI and IEC
        Standards, which require that we use an accuracy class for
        power measurement.  ANSI and IEC define the following accuracy
        classes for power measurement:
        IEC 62053-22  60044-1 class 0.1, 0.2, 0.5, 1  3.
        ANSI C12.20 class 0.2, 0.5
        The electrical characteristics and quality adheres closely to
        the IEC 61850 7-2 standard for describing AC measurements.
        The power state definitions are based on the DMTF Power State
        Profile and ACPI models, with operational state extensions.
     8.       Security Considerations
        Regarding the data attributes specified here, some or all may
        be considered sensitive or vulnerable in some network
        environments. Reading or writing these attributes without
        proper protection such as encryption or access authorization
        may have negative effects on the network capabilities.
        Security Considerations for SNMP
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        Readable objects in a MIB modules (i.e., objects with a MAX-
        ACCESS other than not-accessible) may be considered sensitive
        or vulnerable in some network environments.  It is thus
        important to control GET and/or NOTIFY access to these objects
        and possibly to encrypt the values of these objects when
        sending them over the network via SNMP.
        The support for SET operations in a non-secure environment
        without proper protection can have a negative effect on
        network operations.  For example:
        Unauthorized changes to the Energy Management Domain or
        business context of an Energy Object may result in
        misreporting or interruption of power.
        Unauthorized changes to a power state may disrupt the power
        settings of the different Energy Objects, and therefore the
        state of functionality of the respective Energy Objects.
        Unauthorized changes to the demand history may disrupt proper
        accounting of energy usage.
        With respect to data transport SNMP versions prior to SNMPv3
        did not include adequate security.  Even if the network itself
        is secure (for example, by using IPsec), there is still no
        secure control over who on the secure network is allowed to
        access and GET/SET (read/change/create/delete) the objects in
        these MIB modules.
        It is recommended that implementers consider the security
        features as provided by the SNMPv3 framework (see [RFC3410],
        section 8), including full support for the SNMPv3
        cryptographic mechanisms (for authentication and privacy).
        Further, deployment of SNMP versions prior to SNMPv3 is not
        recommended.  Instead, it is recommended to deploy SNMPv3 and
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        to enable cryptographic security.  It is then a
        customer/operator responsibility to ensure that the SNMP
        entity giving access to an instance of these MIB modules is
        properly configured to give access to the objects only to
        those principals (users) that have legitimate rights to GET or
        SET (change/create/delete) them.
     9.       IANA Considerations
        Initial values for the Power State Sets, together with the
        considerations for assigning them, are defined in [EMAN-MON-
     10.      Acknowledgments
        The authors would like to Michael Brown for improving the text
        dramatically, and Rolf Winter for his feedback.  The award for
        the best feedback and reviews goes to Bill Mielke.
     11.      References
     Normative References
        [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
                Requirement Levels", BCP 14, RFC 2119, March 1997.
        [RFC2819]  S. Waldbusser, "Remote Network Monitoring
                Management Information Base", STD 59, RFC 2819, May
        [RFC3410]  Case, J., Mundy, R., Partain, D., and B. Stewart,
                "Introduction and Applicability Statements for
                Internet Standard Management Framework ", RFC 3410,
                December 2002.
        [RFC4133]  Bierman, A. and K. McCloghrie, "Entity MIB
                (Version3)", RFC 4133, August 2005.
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        [RFC4122] Leach, P., Mealling, M., and R. Salz," A Universally
                Unique IDentifier (UUID) URN Namespace", RFC 4122,
                July 2005
     Informative References
        [RFC2578] McCloghrie, K., Perkins, D., and J. Schoenwaelder,
                "Structure of Management Information Version 2
                (SMIv2", RFC 2578, April 1999
        [RFC3444] Pras, A., Schoenwaelder, J. "On the Differences
                between Information Models and Data Models", RFC
                3444, January 2003.
        [RFC5101] B. Claise, Ed., Specification of the IP Flow
                Information Export (IPFIX) Protocol for the Exchange
                of IP Traffic Flow Information, RFC 5101, January
        [RFC6020] M. Bjorklund, Ed., " YANG - A Data Modeling Language
                for the Network Configuration Protocol (NETCONF)",
                RFC 6020, October 2010.
        [ACPI] "Advanced Configuration and Power Interface
                Specification", http://www.acpi.info/spec30b.htm
        [IEEE1621]  "Standard for User Interface Elements in Power
                Control of Electronic Devices Employed in
                Office/Consumer Environments", IEEE 1621, December
        [LLDP]  IEEE Std 802.1AB, "Station and Media Control
                Connectivity Discovery", 2005.
        [LLDP-MED-MIB]  ANSI/TIA-1057, "The LLDP Management
                Information Base extension module for TIA-TR41.4
                media endpoint discovery information", July 2005.
        [EMAN-REQ] Quittek, J., Winter, R., Dietz, T., Claise, B., and
                M. Chandramouli, "Requirements for Energy
                Management", draft-ietf-eman-requirements-09, (work
                in progress), November 2011.
        [EMAN-OBJECT-MIB] Parello, J., and B. Claise, "Energy Object
                Contet MIB", draft-ietf-eman-energy-aware-mib-07,
                (work in progress), October 2012.
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        [EMAN-MON-MIB] Chandramouli, M.,Schoening, B., Quittek, J.,
                Dietz, T., and B. Claise, "Power and Energy
                Monitoring MIB", draft-ietf-eman-energy-monitoring-
                mib-03, (work in progress), March 2012.
        [EMAN-BATTERY-MIB] Quittek, J., Winter, R., and T. Dietz, "
                Definition of Managed Objects for Battery
                Monitoring", draft-ietf-eman-battery-mib-06, (work in
                progress), March 2012.
        [EMAN-AS] Schoening, B., Chandramouli, M., and B. Nordman,
                "Energy Management (EMAN) Applicability Statement",
                draft-ietf-eman-applicability-statement-02, (work in
                progress), October 2011
        [EMAN-TERMINOLOGY] J. Parello, "Energy Management
                Terminology", draft-parello-eman-definitions-06,
                (work in progress), March 2012
        [ITU-T-M-3400] TMN recommandation on Management Functions
                (M.3400), 1997
        [NMF] "Network Management Fundamentals", Alexander Clemm,
                ISBN: 1-58720-137-2, 2007
        [TMN] "TMN Management Functions : Performance Management",
                ITU-T M.3400
        [1037C] US Department of Commerce, Federal Standard 1037C,
        [IEEE100] "The Authoritative Dictionary of IEEE Standards
        [DASH] "Desktop and mobile Architecture for System Hardware",
        [ISO50001] "ISO 50001:2011 Energy management systems -
                Requirements with guidance for use",
        [IEC60050] International Electrotechnical Vocabulary
        [SQL] ISO/IEC 9075(1-4,9-11,13,14):2008
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        [IEEE-802.3at] IEEE 802.3 Working Group, "IEEE Std 802.3at-
                2009 - IEEE Standard for Information technology -
                Telecommunications and information exchange between
                systems - Local and metropolitan area networks -
                Specific requirements - Part 3: Carrier Sense
                Multiple Access with Collision Detection (CSMA/CD)
                Access Method and Physical Layer Specifications -
                Amendment: Data Terminal Equipment (DTE) -  Power via
                Media Dependent Interface (MDI) Enhancements",
                   October 2009.
        [DMTF] "Power State Management Profile DMTF  DSP1027  Version
                2.0"  December 2009
        [IPENERGY] R. Aldrich, J. Parello "IP-Enabled Energy
                Management", 2010, Wiley Publishing
        [X.700]  CCITT Recommendation X.700 (1992), Management
                framework for Open Systems Interconnection (OSI) for
                CCITT applications.
        [ASHRAE-201] "ASHRAE Standard Project Committee 201
                        (SPC 201)Facility Smart Grid Information
                        Model", http://spc201.ashraepcs.org
        [CHEN] "The Entity-Relationship Model: Toward a Unified View
                of Data",  Peter Pin-shan Chen, ACM Transactions on
                Database Systems, 1976
        [CISCO-EW] "Cisco EnergyWise Design Guide",  John Parello,
                Roland Saville, Steve Kramling, Cisco Validated
                Designs, September 2010,
     Authors' Addresses
      Benoit Claise
      Cisco Systems, Inc.
      De Kleetlaan 6a b1
      Diegem 1813
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      Phone: +32 2 704 5622
      Email: bclaise@cisco.com
      John Parello
      Cisco Systems, Inc.
      3550 Cisco Way
      San Jose, California 95134
      Phone: +1 408 525 2339
      Email: jparello@cisco.com
      Brad Schoening
      44 Rivers Edge Drive
      Little Silver, NJ 07739
      Email: brad.schoening@verizon.net
     Juergen Quittek
     NEC Europe Ltd.
     Network Laboratories
     Kurfuersten-Anlage 36
     69115 Heidelberg
     Phone: +49 6221 90511 15
     EMail: quittek@netlab.nec.de
     Bruce Nordman
     Lawrence Berkeley National Laboratory
     1 Cyclotron Road
     Berkeley  94720
     Phone: +1 510 486 7089
     Email: bnordman@lbl.gov
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