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Versions: 00 01 02 03 04 05 06 07 08 09 10 11            Standards Track
     Energy Management Working Group                 Brad Schoening
     Internet Draft                          Independent Consultant
     Intended status: Standards Track            Mouli Chandramouli
     Expires: July 11, 2015                      Cisco Systems Inc.
                                                      Bruce Nordman
                              Lawrence Berkeley National Laboratory
                                                  February 11, 2015
                Energy Management (EMAN) Applicability Statement
        The objective of Energy Management (EMAN) is to provide an
        energy management framework for networked devices.  This
        document presents the applicability of the EMAN information
        model in a variety of scenarios with cases and target devices.
        These use cases are useful for identifying requirements for the
        framework and MIBs.  Further, we describe the relationship of
        the EMAN framework to relevant other energy monitoring standards
        and architectures.
     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
        Engineering Task Force (IETF), its areas, and its working
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        The list of current Internet-Drafts can be accessed at
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        This Internet-Draft will expire on July 11, 2015.
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     Copyright Notice
        Copyright (c) 2015 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
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        without warranty as described in the Simplified BSD License.
     Table of Contents
      1. Introduction ............................................ 3
        1.1. Energy Management Overview .......................... 4
        1.2. EMAN Document Overview .............................. 4
        1.3. Energy Measurement .................................. 5
        1.4. Energy Management ................................... 5
        1.5. EMAN Framework Application .......................... 6
      2. Scenarios and Target Devices ............................ 6
        2.1. Network Infrastructure Energy Objects ............... 6
        2.2. Devices Powered and Connected by a Network Device ... 7
        2.3. Devices Connected to a Network ...................... 8
        2.4. Power Meters ........................................ 9
        2.5. Mid-level Managers ................................. 10
        2.6. Non-residential Building System Gateways ........... 11
        2.7. Home Energy Gateways ............................... 11
        2.8. Data Center Devices ................................ 12
        2.9. Energy Storage Devices ............................. 13
        2.10. Industrial Automation Networks .................... 14
        2.11. Printers .......................................... 14
        2.12. Off-Grid Devices .................................. 15
        2.13. Demand Response ................................... 16
        2.14. Power Capping ..................................... 16
      3. Use Case Patterns ...................................... 17
        3.1. Metering ........................................... 17
        3.2. Metering and Control ............................... 17
        3.3. Power Supply, Metering and Control ................. 17
        3.4. Multiple Power Sources ............................. 17
      4. Relationship of EMAN to Other Standards ................ 18
        4.1. Data Model and Reporting ........................... 18
              4.1.1. IEC - CIM................................... 18
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              4.1.2. DMTF........................................ 18
              4.1.3. ODVA........................................ 20
              4.1.4. Ecma SDC.................................... 20
              4.1.5. PWG......................................... 21
              4.1.6. ASHRAE...................................... 21
              4.1.7. ANSI/CEA.................................... 22
              4.1.8. ZigBee...................................... 22
        4.2. Measurement ........................................ 23
              4.2.1. ANSI C12.................................... 23
              4.2.2. IEC 62301................................... 23
        4.3. Other .............................................. 24
              4.3.1. ISO......................................... 24
              4.3.2. Energy Star................................. 24
              4.3.3. Smart Grid.................................. 25
      5. Limitations ............................................ 26
      6. Security Considerations ................................ 26
      7. IANA Considerations .................................... 26
      8. Acknowledgements ....................................... 26
      9. References ............................................. 26
        9.1. Normative References ............................... 26
        9.2. Informative References ............................. 27
     1. Introduction
        The focus of the Energy Management (EMAN) framework is energy
        monitoring and management of energy objects [RFC7326].  The
        scope of devices considered are network equipment and their
        components, and devices connected directly or indirectly to
        the network.  The EMAN framework enables monitoring of
        heterogeneous devices to report their energy consumption and,
        if permissible, control.  There are multiple scenarios where
        this is desirable, particularly considering the increased
        importance of limiting consumption of finite energy resources
        and reducing operational expenses.
        The EMAN framework [RFC7326] describes how energy information
        can be retrieved from IP-enabled devices using Simple Network
        Management Protocol (SNMP), specifically, Management Information
        Base (MIBs) for SNMP.
        This document describes typical applications of the EMAN
        framework, as well as its opportunities and limitations.  It
        also reviews other standards that are similar in part to EMAN
        but address different domains, describing how those other
        standards relate to the EMAN framework.
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        The rest of the document is organized as follows.  Section 2
        contains a list of use cases or network scenarios that EMAN
        addresses.  Section 3 contains an abstraction of the use case
        scenarios to distinct patterns.  Section 4 deals with other
        standards related and applicable to EMAN.
     1.1. Energy Management Overview
        EMAN addresses the electrical energy consumed by devices
        connected to a network.  A first step to increase the energy
        efficiency in networks and the devices attached to the network
        is to enable energy objects to report their energy usage over
        time.  The EMAN framework addresses this problem with an
        information model for electrical equipment: energy object
        identification, energy object context, power measurement, and
        power characteristics.
        The EMAN framework defines SNMP MIB modules based on the
        information model.  By implementing these SNMP MIB modules, an
        energy object can report its energy consumption according to the
        information model. Based on the information model, the MIB
        drafts specify SNMP MIB modules, but it is equally possible to
        use other mechanisms such as YANG module, NETCONF, etc.
        In that context, it is important to distinguish energy objects
        that can only report their own energy usage from devices that
        can also collect and aggregate energy usage of other energy
     1.2. EMAN Document Overview
        The EMAN work consists of the following Standard Track and
        Informational documents in the area of energy management.
          Applicability Statement (this document)
          Requirements [EMAN-REQ]: This document presents requirements
          of energy management and the scope of the devices considered.
          Framework [RFC7326]: This document defines a framework for
          providing energy management for devices within or connected to
          communication networks, and lists the definitions for the
          common terms used in these documents.
          Energy-Aware MIB [EMAN-AWARE-MIB]: This document defines a MIB
          module that characterizes a device's identity, context and
          relationships to other entities.
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          Monitoring MIB [EMAN-MONITORING-MIB]: This document defines a
          MIB module for monitoring the power and energy consumption of
          a device.  The MIB module contains an optional module for
          metrics associated with power characteristics.
          Battery MIB [EMAN-BATTERY-MIB]: This document defines a MIB
          module for monitoring characteristics of an internal battery.
     1.3. Energy Measurement
        It is increasingly common for today's smart devices to measure
        and report their own energy consumption.  Intelligent power
        strips and some Power over Ethernet (PoE) switches can meter
        consumption of connected devices.  However, when managed and
        reported through proprietary means, this information is
        difficult to view at the enterprise level.
        The primary goal of the EMAN information model is to enable
        reporting and management within a standard framework that is
        applicable to a wide variety of end devices, meters, and
        proxies.  This enables a management system to know who's
        consuming what, when, and how by leveraging existing networks,
        across various equipment, in a unified and consistent manner.
        Because energy objects may both consume energy and provide
        energy to other devices, there are three types of energy
        measurement: energy input to a device, energy supplied to other
        devices, and net (resultant) energy consumed (the difference
        between energy input and supplied).
     1.4. Energy Management
        The EMAN framework provides mechanisms for energy control in
        addition to passive monitoring.  There are many cases where
        active energy control of devices is desirable, such during low
        device utilization or peak electrical price periods.
        Energy control can be as simple as controlling on/off states. In
        many cases, however, energy control requires understanding the
        energy object context.  For instance, in commercial building
        during non-business hours, some phones must remain available in
        case of emergency and office cooling is not usually turned off
        completely, but the comfort level is reduced.
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        Energy object control therefore requires flexibility and support
        for different polices and mechanisms: from centralized
        management by an energy management system, to autonomous control
        by individual devices, and alignment with dynamic demand
        response mechanisms.
        The EMAN framework power states can be used in demand response
        scenarios.  In response to time-of-day fluctuation of energy
        costs or grid power shortages, network devices can respond and
        reduce their energy consumption.
     1.5. EMAN Framework Application
        A Network Management System (NMS) is an entity that requests
        information from compatible devices, typically using the SNMP
        protocol. An NMS may implement many network management
        functions, such as security or identity management.  An NMS that
        deals exclusively with energy is called an Energy Management
        System (EnMS).  It may be limited to monitoring energy use, or
        it may also implement control functions.  An EnMS collects
        energy information for devices in the network.
        Energy management can be implemented by extending existing SNMP
        support with EMAN specific MIBs.  SNMP provides an industry-
        proven and well-known mechanism to discover, secure, measure,
        and control SNMP-enabled end devices.  The EMAN framework
        provides an information and data model to unify access to a
        large range of devices.
     2. Scenarios and Target Devices
        This section presents energy management scenarios that the EMAN
        framework should solve.  Each scenario lists target devices for
        which the energy management framework can be applied, how the
        reported-on devices are powered, and how the reporting or
        control is accomplished.  While there is some overlap between
        some of the use cases, the use cases illustrate network
        scenarios that the EMAN framework supports.
     2.1. Network Infrastructure Energy Objects
        This scenario covers the key use case of network devices and
        their components.  For a device aware of one or more components,
        our information model supports monitoring and control at the
        component level.  Typically, the chassis draws power from one or
        more sources and feeds its internal components.  It is highly
        desirable to have monitoring available for individual
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        components, such as line cards, processors, disk drives and
        peripherals such as USB devices.
        As an illustrative example, consider a switch with the following
        grouping of sub-entities for which energy management could be
          .  Physical view: chassis (or stack), line cards, and service
             modules of the switch.
          .  Component view: CPU, ASICs, fans, power supply, ports
             (single port and port groups), storage, and memory.
        The ENTITY-MIB [RFC6933] provides a containment model for
        uniquely identifying the physical sub-components of network
        devices.  The containment information identifies whether one
        Energy Object belongs to another Energy Object (e.g. a line-card
        Energy Object contained in a chassis Energy Object).  The
        mapping table entPhysicalContainsTable has an index
        entPhysicalChildIndex and the table entPhysicalTable has a MIB
        object entPhysicalContainedIn which points to the containing
        The essential properties of this use case are:
          . Target devices: network devices such as routers and
             switches as well as their components.
          . How powered: typically by a Power Distribution Unit (PDU)
             on a rack or from a wall outlet.  The components of a
             device are powered by the device chassis.
          . Reporting: direct power measurement can be performed at a
             device level.  Components can report their power
             consumption directly or the chassis/device can report on
             behalf of some components.
     2.2. Devices Powered and Connected by a Network Device
        This scenario covers Power Sourcing Equipment (PSE) devices.  A
        PSE device (e.g. a PoE switch) provides power to a Powered
        Device (PD) (e.g. a desktop phone) over a medium such as USB or
        Ethernet [RFC3621].  For each port, the PSE can control the
        power supply (switching it on and off) and usually meter actual
        power provided.  PDs obtain network connectivity as well as
        power over a single connection so the PSE can determine which
        device is associated with each port.
        PoE ports on a switch are commonly connected to devices such as
        IP phones, wireless access points, and IP cameras.  The switch
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        needs power for its internal use and to supply power to PoE
        ports.  Monitoring the power consumption of the switch
        (supplying device) and the power consumption of the PoE end-
        points (consuming devices) is a simple use case of this
        This scenario illustrates the relationships between entities.
        The PoE IP phone is powered by the switch.  If there are many IP
        phones connected to the same switch, the power consumption of
        all the IP phones can be aggregated by the switch.
        The essential properties of this use case are:
          . Target devices: Power over Ethernet devices such as IP
             phones, wireless access points, and IP cameras.
          . How powered: PoE devices are connected to the switch port
             which supplies power to those devices.
          . Reporting: PoE device power consumption is measured and
             reported by the switch (PSE) which supplies power.  In
             addition, some edge devices can support the EMAN framework.
        This use case can be divided into two subcases:
        a) The end-point device supports the EMAN framework, in which
           case this device is an EMAN Energy Object by itself, with
           its own UUID. The device is responsible for its own power
           reporting and control. See the related scenario "Devices
           Connected to a Network" below.
        b) The end-point device does not have EMAN capabilities, and
           the power measurement may not be able to be performed
           independently, and is therefore only performed by the
           supplying device.  This scenario is similar to the "Mid-
           level Manager" below.
        In subcase (a) note that two power usage reporting mechanisms
        for the same device are available: one performed by the PD
        itself and one performed by the PSE.  Device specific
        implementations will dictate which one to use.
     2.3. Devices Connected to a Network
        This use case covers the metering relationship between an energy
        object and the parent energy object to which it is connected,
        while receiving power from a different source.
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        An example is a PC which has a network connection to a switch,
        but draws power from a wall outlet.  In this case, the PC can
        report power usage by itself, ideally through the EMAN
        The wall outlet to which the PC is plugged in can be unmetered
        or metered, for example, by a Smart PDU.
        a) If metered, the PC has a powered-by relationship to the Smart
        PDU, and the Smart PDU acts as a "Mid-Level Manager".
        b) If unmetered, or operating on batteries, the PC will report
        its own energy usage as any other Energy Object to the switch,
        and the switch may possibly provide aggregation.
        These two cases are not mutually exclusive.
        In terms of relationships between entities, the PC has a
        powered-by relationship to the PDU and if the power consumption
        of the PC is metered by the PDU, then there is a metered-by
        relation between the PC and the PDU.
        The essential properties of this use case are:
          . Target devices: energy objects that have a network
             connection, but receive power supply from another source.
          . How powered: end-point devices (e.g. PCs) receive power
             supply from the wall outlet (unmetered), a PDU (metered),
             or can be powered autonomously (batteries).
          . Reporting: devices can either measure and report the power
             consumption directly via the EMAN framework, communicate it
             to the network device (switch) and the switch can report
             the device's power consumption via the EMAN framework, or
             power can be reported by the PDU.
     2.4. Power Meters
        Some electrical devices are not equipped with instrumentation to
        measure their own power and accumulated energy consumption.
        External meters can be used to measure the power consumption of
        such electrical devices as well as collections of devices.
        Three types of external metering are relevant to EMAN: PDUs,
        standalone meters, and utility meters.  External meters can
        measure consumption of a single device or a set of devices.
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        Power Distribution Units (PDUs) can have built-in meters for
        each socket and can measure the power supplied to each device in
        an equipment rack.  PDUs typically have remote management
        capabilities which can report and possibly control the power
        supply of each outlet.
        Standalone meters can be placed anywhere in a power distribution
        tree and may measure all or part of the total.  Utility meters
        monitor and report accumulated power consumption of the entire
        building.  There can be sub-meters to measure the power
        consumption of a portion of the building.
        The essential properties of this use case are:
          . Target devices: PDUs and meters.
          . How powered: from traditional mains power but supplied
             through a PDU or meter.
          . Reporting: PDUs report power consumption of downstream
             devices, usually a single device per outlet.  Meters may
             report for one or more devices and may require knowledge of
             the topology to associate meters with metered devices.
        Meters have metered-by relationships with devices, and may have
        aggregation relationship between the meters and the devices for
        which power consumption is accumulated and reported by the
     2.5. Mid-level Managers
        This use case covers aggregation of energy management data at
        "mid-level managers" that can provide energy management
        functions for themselves and associated devices.
        A switch can provide energy management functions for all devices
        connected to its ports, whether or not these devices are powered
        by the switch or whether the switch provides immediate network
        connectivity to the devices.  Such a switch is a mid-level
        manager, offering aggregation of power consumption data for
        other devices.  Devices report their EMAN data to the switch and
        the switch aggregates the data for further reporting.
        The essential properties of this use case:
          . Target devices: devices which can perform aggregation;
             commonly a switch or a proxy.
          . How powered: mid-level managers are commonly powered by a
             PDU or from a wall outlet but can be powered by any method.
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          . Reporting: the mid-level manager aggregates the energy data
             and reports that data to an EnMS or higher mid-level
     2.6. Non-residential Building System Gateways
        This use case describes energy management of non-residential
        buildings.  Building Management Systems (BMS) have been in place
        for many years using legacy protocols not based on IP.  In these
        buildings, a gateway can provide a proxy function between IP
        networks and legacy building automation protocols.  The gateway
        provides an interface between the EMAN framework and relevant
        building management protocols.
        Due to the potential energy savings, energy management of
        buildings has received significant attention.  There are gateway
        network elements to manage the multiple components of a building
        energy management system such as Heating, Ventilation, and Air
        Conditioning (HVAC), lighting, electrical, fire and emergency
        systems, elevators, etc.  The gateway device uses legacy
        building protocols to communicate with those devices, collects
        their energy usage, and reports the results.
        The gateway performs protocol conversion and communicates via
        RS-232/RS-485 interfaces, Ethernet interfaces, and protocols
        specific to building management such as BACNET [ASHRAE], MODBUS
        [MODBUS], or ZigBee [ZIGBEE].
        The essential properties of this use case are:
          . Target devices: building energy management devices - HVAC
             systems, lighting, electrical, fire and emergency systems.
          . How powered: any method.
          . Reporting: the gateway collects energy consumption of non-
             IP systems and communicates the data via the EMAN
     2.7. Home Energy Gateways
        This use case describes the scenario of energy management of a
        home.  The home energy gateway is another example of a proxy
        that interfaces with electrical appliances and other devices in
        a home.  This gateway can monitor and manage electrical
        equipment (e.g. refrigerator, heating/cooling, or washing
        machine) using one of the many protocols that are being
        developed for residential devices.
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        Beyond simply metering, it's possible to implement energy saving
        policies based on time of day, occupancy, or energy pricing from
        the utility grid.  The EMAN information model can be applied to
        energy management of a home.
        The essential properties of this use case are:
          . Target devices: home energy gateway and smart meters in a
          . How powered: any method.
          . Reporting: home energy gateway can collect power
             consumption of device in a home and possibly report the
             metering reading to the utility.
        While the common case is of a home drawing all power from the
        utility, some buildings/homes can produce and consume energy
        with reduced or net-zero energy from the utility grid.  There
        are many energy production technologies such as solar panels,
        wind turbines, or micro generators.  This use case illustrates
        the concept of self-contained energy generation, consumption,
        and possibly the aggregation of the energy use of homes.
       2.8. Data Center Devices
        This use case describes energy management of a data center.
        Energy efficiency of data centers has become a fundamental
        challenge of data center operation, as data centers are big
        energy consumers and have expensive infrastructure.  The
        equipment generates heat, and heat needs to be evacuated through
        an HVAC system.
        A typical data center network consists of a hierarchy of
        electrical energy objects.  At the bottom of the network
        hierarchy are servers mounted on a rack; these are connected to
        top-of-the-rack switches, which in turn are connected to
        aggregation switches, and then to core switches.  Power
        consumption of all network elements, servers, and storage
        devices in the data center should be measured.  Energy
        management can be implemented on different aggregation levels,
        i.e., at the network level, Power Distribution Unit (PDU) level,
        and/or server level.
        Beyond the network devices, storage devices, and servers, data
        centers contain UPSs to provide back-up power for the facility
        in the event of a power outage.  A UPS can provide backup power
        for many devices in a data center for a finite period of time.
        Energy monitoring of energy storage capacity is vital from a
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        data center network operations point of view.  Presently, the
        UPS MIB can be useful in monitoring the battery capacity, the
        input load to the UPS, and the output load from the UPS.
        Currently, there is no link between the UPS MIB and the ENTITY
        In addition to monitoring the power consumption of a data
        center, additional power characteristics should be monitored.
        Some of these are dynamic variations in the input power supply
        from the grid referred to as power quality metrics.  It can also
        be useful to monitor how efficiently the devices utilize power.
        Nameplate capacity of the data center can be estimated from the
        nameplate ratings (the worst case possible power draw) of IT
        equipment at a site.
        The essential properties of this use case are:
          . Target devices: IT devices in a data center, such as
             network equipment, servers, and storage devices, as well as
             power and cooling infrastructure.
          . How powered: any method, but commonly by one or more PDUs.
          . Reporting: devices may report on their own behalf, or for
             other connected devices as described in other use cases.
     2.9. Energy Storage Devices
        Energy storage devices can have two different roles: one type
        whose primary function is to provide power to another device
        (e.g. a UPS), and one type with a different primary function,
        but having energy storage as a component (e.g. a notebook).
        This use case covers both.
        The energy storage can be a conventional battery, or any other
        means to store electricity such as a hydrogen cell.
        An internal battery can be a back-up or an alternative source of
        power to mains power.  As batteries have a finite capacity and
        lifetime, means for reporting the actual charge, age, and state
        of a battery are required.  An internal battery can be viewed as
        a component of a device and so be contained within the device
        from an ENTITY-MIB perspective.
        Battery systems are often used in remote locations such as
        mobile telecom towers.  For continuous operation, it is
        important to monitor the remaining battery life and raise an
        alarm when this falls below a threshold.
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        The essential properties of this use case are:
          . Target devices: devices that have an internal battery or
             external storage.
          . How powered: from batteries or other storage devices.
          . Reporting: the device reports on its power delivered and
     2.10. Industrial Automation Networks
        Energy consumption statistics in the industrial sector are
        staggering.  The industrial sector alone consumes about half of
        the world's total delivered energy, and is a significant user of
        electricity.  Thus, the need for optimization of energy usage in
        this sector is natural.
        Industrial facilities consume energy in process loads and non-
        process loads.
        The essential properties of this use case are:
          . Target devices: devices used in an industrial sector.
          . How powered: any method.
          . Reporting: the CIP protocol is commonly used for reporting
             energy for these devices.
     2.11. Printers
        This use case describes the scenario of energy monitoring and
        management of printers.  Printers in this use case stand in for
        all imaging equipment, including multi-function devices (MFDs),
        scanners, fax machines, and mailing machines.
        Energy use of printers has been a longstanding industry concern
        and sophisticated power management is common.  Printers often
        use a variety of low-power modes, particularly for managing
        energy-intensive thermo-mechanical components.  Printers also
        have long made extensive use of SNMP for end-user system
        interaction and for management generally, with cross-vendor
        management systems able to manage fleets of printers in
        enterprises.  Power consumption during active modes can vary
        widely, with high peak usage levels.
        Printers can expose detailed power state information, distinct
        from operational state information, with some printers reporting
        transition states between stable long-term states.  Many also
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        support active setting of power states and policies such as
        delay times, when inactivity automatically transitions the
        device to a lower power mode.  Other features include reporting
        on components, counters for state transitions, typical power
        levels by state, scheduling, and events/alarms.
        Some large printers also have a "Digital Front End," which is a
        computer that performs functions on behalf of the physical
        imaging system.  These typically have their own presence on the
        network and are sometimes separately powered.
        There are some unique characteristics of printers from the point
        of view energy management.  While the printer is not in use,
        there are timer-based low power states, which consume little
        power.  On the other hand, while the printer is printing or
        copying, the cylinder is heated so that power consumption is
        quite high but only for a short period of time.  Given this work
        load, periodic polling of power levels alone would not suffice.
        The essential properties of this use case are:
          . Target devices: all imaging equipment.
          . How powered: typically AC from a wall outlet.
          . Reporting: devices report for themselves.
     2.12. Off-Grid Devices
        This use case concerns self-contained devices that use energy
        but are not connected to an infrastructure power delivery grid.
        These devices typically produce energy from sources such as
        solar energy, wind power, or fuel cells.  The device generally
        contains a closely coupled combination of
          . power generation component(s)
          . power storage component(s) (e.g., battery)
          . power consuming component(s)
        With renewable power, the energy input is often affected by
        variations in weather.  These devices therefore require energy
        management both for internal control and remote reporting of
        their state.
        In many cases these devices are expected to operate
        autonomously, as continuous communications for the purposes of
        remote control is not available.  Non-continuous polling
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        requires the ability to store and access later the information
        acquired while off-line.
        The essential properties of this use case are:
            . Target devices: remote area devices that produce and
               consume energy.
            . How powered: site energy sources.
            . Reporting: devices report their power usage, but not
               necessarily continuously.
     2.13. Demand Response
        The theme of demand response from a utility grid spans across
        several use cases.  In some situations, in response to time-of-
        day fluctuation of energy costs or sudden energy shortages due
        power outages, it may be important to respond and reduce the
        energy consumption of the network.
        From the EMAN use case perspective, the demand response scenario
        can apply to a data center, building or home.  Real-time energy
        monitoring is usually a prerequisite, so that during a potential
        energy shortfall the EnMS can provide an active response.  The
        EnMS could shut down selected devices that are considered lower
        priority or uniformly reduce the power supplied to a class of
        devices.  For multi-site data centers it may be possible to
        formulate policies such as follow-the-sun type of approach, by
        scheduling the mobility of VMs across data centers in different
        geographical locations.
        The essential properties of this use case are:
            . Target devices: any device.
            . How powered: traditional mains AC power.
            . Reporting: real-time.
            . Control: demand response based upon policy or priority.
     2.14. Power Capping
        The purpose of power-capping is to run a server without
        exceeding a power usage threshold, and thereby, to remain under
        the critical available power threshold.  This method can be
        useful for power limited data centers.  Based on workload
        measurements, a device can choose the optimal power state in
        terms of performance and power consumption.  When the server
        operates at less than the power supply capacity, the server can
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        operate at full speed.  When the power requirements exceed the
        power supply, the server operates in a reduced power mode so
        that its power consumption matches the available power budget.
        The essential properties of this use case are:
          Target devices: IT devices in a data center.
          How powered: traditional mains AC power.
          Reporting: real-time.
          Control: autonomous power capping by the device.
     3. Use Case Patterns
        The use cases presented above can be abstracted to the following
        broad patterns for energy objects.
     3.1. Metering
        - Energy objects which have capability for internal metering
        - Energy objects which are metered by an external device
     3.2. Metering and Control
        - Energy objects that do not supply power, but can perform power
        metering for other devices
        - Energy objects that do not supply power, but can perform both
        metering and control for other devices
     3.3. Power Supply, Metering and Control
        - Energy objects that supply power for other devices but do not
        perform power metering for those devices
        - Energy objects that supply power for other devices and also
        perform power metering
        - Energy objects that supply power for other devices and also
        perform power metering and control for other devices
     3.4. Multiple Power Sources
        - Energy objects that have multiple power sources, with metering
        and control performed by the same power source
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        - Energy objects that have multiple power sources supplying
        power to the device with metering performed by one or more
        sources and control performed by another source
     4. Relationship of EMAN to Other Standards
        The EMAN framework is tied to other standards and efforts that
        address energy monitoring and control.  EMAN leverages existing
        standards when possible, and it helps enable adjacent
        technologies such as Smart Grid.
        The standards most relevant and applicable to EMAN are listed
        below with a brief description of their objectives, the current
        state, and how that standard relates to EMAN.
     4.1. Data Model and Reporting
     4.1.1. IEC - CIM
        The International Electrotechnical Commission (IEC) has
        developed a broad set of standards for power management.  Among
        these, the most applicable to EMAN is IEC 61850, a standard for
        the design of electric utility automation.  The abstract data
        model defined in 61850 is built upon and extends the Common
        Information Model (CIM).  The complete 61850 CIM model includes
        over a hundred object classes and is widely used by utilities
        This set of standards were originally conceived to automate
        control of a substation (a facility which transfer electricity
        from the transmission to the distribution system).  However, the
        extensive data model has been widely used in other domains,
        including Energy Management Systems (EnMS).
        IEC TC57 WG19 is an ongoing working group with the objective to
        harmonize the CIM data model and 61850 standards.
        Several concepts from IEC Standards have been reused in the EMAN
        drafts.  In particular, AC Power Quality measurements have been
        reused from IEC 61850-7-4.  The concept of Accuracy Classes for
        measurement of power and energy has been adapted from ANSI
        C12.20 and IEC standards 62053-21 and 62053-22.
     4.1.2. DMTF
        The Distributed Management Task Force (DMTF) has defined a Power
        State Management profile [DMTF DSP1027] for managing computer
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        systems using the DMTF's Common Information Model (CIM).  These
        specifications provide physical, logical, and virtual system
        management requirements for power-state control services.  The
        DMTF standard does not include energy monitoring.
        The Power State Management profile is used to describe and
        manage the Power State of computer systems.  This includes
        controlling the Power State of an entity for entering sleep
        mode, awakening, and rebooting.  The EMAN framework references
        the DMTF Power Profile and Power State Set.
  Common Information Model Profiles
        The DMTF uses CIM-based (Common Information Model) 'Profiles' to
        represent and manage power utilization and configuration of
        managed elements (note that this is not the 61850 CIM).  Key
        profiles for energy management are 'Power Supply' (DSP 1015),
        'Power State' (DSP 1027), and 'Power Utilization Management'
        (DSP 1085).  These profiles define many features for the
        monitoring and configuration of a Power Managed Element's static
        and dynamic power saving modes, power allocation limits, and
        power states.
        Reduced power modes can be established as static or dynamic.
        Static modes are fixed policies that limit power use or
        utilization.  Dynamic power saving modes rely upon internal
        feedback to control power consumption.
        Power states are eight named operational and non operational
        levels.  These are On, Sleep-Light, Sleep-Deep, Hibernate, Off-
        Soft, and Off-Hard.  Power change capabilities provide
        immediate, timed interval, and graceful transitions between on,
        off, and reset power states.  Table 3 of the Power State Profile
        defines the correspondence between the Advanced Configuration
        and Power Interface [ACPI] and DMTF power state models, although
        it is not necessary for a managed element to support ACPI.
        Optionally, a TransitioningToPowerState property can represent
        power state transitions in progress.
        DMTF DASH [DASH] (Desktop And Mobile Architecture for System
        Hardware) addresses managing heterogeneous desktop and mobile
        systems (including power) via in-band and out-of-band
        communications.  DASH uses the DMTF's WS-Management web services
        and CIM data model to manage and control resources such as
        power, CPU, etc.
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        Both in-service and out-of-service systems can be managed with
        the DASH specification in a fully secured remote environment.
        Full power lifecycle management is possible using out-of-band
     4.1.3. ODVA
        The Open DeviceNet Vendors Association (ODVA) is an association
        for industrial automation companies that defines the Common
        Industrial Protocol (CIP).  Within ODVA, there is a special
        interest group focused on energy and standardization and inter-
        operability of energy-aware devices.
        The ODVA is developing an energy management framework for the
        industrial sector.  There are synergies and similar concepts
        between the ODVA and EMAN approaches to energy monitoring and
        ODVA defines a three-part approach towards energy management:
        awareness of energy usage, energy efficiently, and the exchange
        of energy with a utility or others.  Energy monitoring and
        management promote efficient consumption and enable automating
        actions that reduce energy consumption.
        The foundation of the approach is the information and
        communication model for entities.  An entity is a network-
        connected, energy-aware device that has the ability to either
        measure or derive its energy usage based on its native
        consumption or generation of energy, or report a nominal or
        static energy value.
     4.1.4. Ecma SDC
        The Ecma International standard on Smart Data Centre [Ecma-SDC]
        defines semantics for management of entities in a data center
        such as servers, storage, and network equipment.  It covers
        energy as one of many functional resources or attributes of
        systems for monitoring and control.  It only defines messages
        and properties, and does not reference any specific protocol.
        Its goal is to enable interoperability of such protocols as
        SNMP, BACNET, and HTTP by ensuring a common semantic model
        across them.  Four power states are defined, Off, Sleep, Idle,
        and Active.  The standard does not include actual energy or
        power measurements.
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        When used with EMAN, the SDC standard will provide a thin
        abstraction on top of the more detailed data model available in
     4.1.5. PWG
        The IEEE-ISTO Printer Working Group (PWG) defines open standards
        for printer related protocols, for the benefit of printer
        manufacturers and related software vendors.  The Printer WG
        covers power monitoring and management of network printers and
        imaging systems in the PWG Power Management Model for Imaging
        Systems [PWG5106.4].  Clearly, these devices are within the
        scope of energy management since they receive power and are
        attached to the network.  In addition, there is ample scope of
        power management since printers and imaging systems are not used
        that often.
        The IEEE-ISTO Printer Working Group (PWG) defines SNMP MIB
        modules for printer management and in particular a "PWG Power
        Management Model for Imaging Systems v1.0" [PWG5106.4] and a
        companion SNMP binding in the "PWG Imaging System Power MIB
        v1.0" [PWG5106.5].  This PWG model and MIB are harmonized with
        the DMTF CIM Infrastructure [DMTF DSP0004] and DMTF CIM Power
        State Management Profile [DMTF DSP1027] for power states and
        These MIB modules can be useful for monitoring the power and
        Power State of printers.  The EMAN framework takes into account
        the standards defined in the Printer Working Group.  The PWG may
        harmonize its MIBs with those from EMAN.  The PWG covers many
        topics in greater detail than EMAN, including those specific to
        imaging equipment.  The PWG also provides for vendor-specific
        extension states (beyond the standard DMTF CIM states).
        The IETF Printer MIB RFC3805 [RFC3805] has been standardized,
        but, this MIB module does not address power management.
     4.1.6. ASHRAE
        In the U.S., there is an extensive effort to coordinate and
        develop standards related to the "Smart Grid".  The Smart Grid
        Interoperability Panel, coordinated by the government's National
        Institute of Standards and Technology, identified the need for a
        building side information model (as a counterpart to utility
        models) and specified this in Priority Action Plan (PAP) 17.
        This was designated to be a joint effort by the American Society
        of Heating, Refrigerating and Air-Conditioning Engineers
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        (ASHRAE) and the National Electrical Manufacturers Association
        (NEMA), both ANSI approved SDO's.  The result is to be an
        information model, not a protocol.
        The ASHRAE effort addresses data used only within a building as
        well as data that may be shared with the grid, particularly as
        it relates to coordinating future demand levels with the needs
        of the grid.  The model is intended to be applied to any
        building type, both residential and commercial.  It is expected
        that existing protocols will be adapted to comply with the new
        information model, as would new protocols.
        There are four basic types of entities in the model: generators,
        loads, meters, and energy managers.  The metering part of the
        model overlaps to a large degree with the EMAN framework, though
        there are features unique to each.  The load part speaks to
        control capabilities well beyond what EMAN covers.  Details of
        generation and of the energy management function are outside of
        EMAN scope.
        A public review draft of the ASHRAE standard was released in
        July, 2012.  There are no apparent major conflicts between the
        two approaches, but there are areas where some harmonization is
     4.1.7. ANSI/CEA
        The Consumer Electronics Association (CEA) has approved
        ANSI/CEA-2047 [ANSICEA] as a standard data model for Energy
        Usage Information.  The primary purpose is to enable home
        appliances and electronics to communicate energy usage
        information over a wide range of technologies with pluggable
        modules that contain the physical layer electronics.  The
        standard can be used by devices operating on any home network
        including Wi-Fi, Ethernet, ZigBee, Z-Wave, and Bluetooth.  The
        Introduction to ANSI/CEA-2047 states that "this standard
        provides an information model for other groups to develop
        implementations specific to their network, protocol and
        needs".  It covers device identification, current power level,
        cumulative energy consumption, and provides for reporting time-
        series data.
     4.1.8. ZigBee
        The ZigBee Smart Energy Profile 2.0 (SEP) effort [ZIGBEE]
        focuses on IP-based wireless communication to appliances and
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        lighting.  It is intended to enable internal building energy
        management and provide for bi-directional communication with the
        power grid.
        ZigBee protocols are intended for use in embedded applications
        with low data rates and low power consumption.  ZigBee defines a
        general-purpose, inexpensive, self-organizing mesh network that
        can be used for industrial control, embedded sensing, medical
        data collection, smoke and intruder warning, building
        automation, home automation, etc.
        ZigBee is currently not an ANSI recognized SDO.
        The EMAN framework addresses the needs of IP-enabled networks
        through the usage of SNMP, while ZigBee provides for completely
        integrated and inexpensive mesh solutions.
     4.2. Measurement
     4.2.1. ANSI C12
        The American National Standards Institute (ANSI) has defined a
        collection of power meter standards under ANSI C12.  The primary
        standards include communication protocols (C12.18, 21 and 22),
        data and schema definitions (C12.19), and measurement accuracy
        (C12.20). European equivalent standards are provided by IEC
        These very specific standards are oriented to the meter itself,
        and are used by electricity distributors and producers.
        The EMAN standard references ANSI C12.20 accuracy classes.
     4.2.2. IEC 62301
        IEC 62301, "Household electrical appliances Measurement of
        standby power", [IEC62301] specifies a power level measurement
        procedure.  While nominally for appliances and low-power modes,
        its concepts apply to other device types and modes and it is
        commonly referenced in test procedures for energy using
        While the standard is intended for laboratory measurements of
        devices in controlled conditions, aspects of it are informative
        to those implementing measurement in products that ultimately
        report via EMAN.
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     4.3. Other
     4.3.1. ISO
        The International Organization for Standardization (ISO) [ISO]
        is developing an energy management standard, ISO 50001, to
        complement ISO 9001 for quality management, and ISO 14001 for
        environmental management.  The intent is to facilitate the
        creation of energy management programs for industrial,
        commercial, and other entities.  The standard defines a process
        for energy management at an organizational level.  It does not
        define the way in which devices report energy and consume
        ISO 50001 is based on the common elements found in all of ISO's
        management system standards, assuring a high level of
        compatibility with ISO 9001 and ISO 14001.  ISO 50001 benefits
       o Integrating energy efficiency into management practices and
          throughout the supply chain.
       o Energy management best practices and good energy management
       o Benchmarking, measuring, documenting, and reporting energy
          intensity improvements and their projected impact on
          reductions in greenhouse gas (GHG) emissions.
       o Evaluating and prioritizing the implementation of new energy-
          efficient technologies.
        ISO 50001 has been developed by ISO project committee ISO PC
        242, Energy management.  EMAN is complementary to ISO 9001.
     4.3.2. Energy Star
        The U.S. Environmental Protection Agency (EPA) and U.S.
        Department of Energy (DOE) jointly sponsor the Energy Star
        program [ESTAR].  The program promotes the development of energy
        efficient products and practices.
        To qualify as Energy Star, products must meet specific energy
        efficiency targets.  The Energy Star program also provides
        planning tools and technical documentation to encourage more
        energy efficient building design.  Energy Star is a program; it
        is not a protocol or standard.
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        For businesses and data centers, Energy Star offers technical
        support to help companies establish energy conservation
        practices.  Energy Star provides best practices for measuring
        current energy performance, goal setting, and tracking
        improvement.  The Energy Star tools offered include a rating
        system for building performance and comparative benchmarks.
        There is no immediate link between EMAN and Energy Star, one
        being a protocol and the other a set of recommendations to
        develop energy efficient products.  However, Energy Star could
        include EMAN standards in specifications for future products,
        either as required or rewarded with some benefit.
     4.3.3. Smart Grid
        The Smart Grid standards efforts underway in the United States
        are overseen by the U.S. National Institute of Standards and
        Technology [NIST].  NIST is responsible for coordinating a
        public-private partnership with key energy and consumer
        stakeholders in order to facilitate the development of Smart
        Grid standards. These activities are monitored and facilitated
        by the SGIP (Smart Grid Interoperability Panel).  This group has
        working groups for specific topics including homes, commercial
        buildings, and industrial facilities as they relate to the grid.
        A stated goal of the group is to harmonize any new standard with
        the IEC CIM and IEC 61850.
        When a working group detects a standard or technology gap, the
        team seeks approval from the SGIP for the creation of a Priority
        Action Plan (PAP), a private-public partnership to close the
        gap.  PAP 17 is discussed in section 4.1.6.
        PAP 10 addresses "Standard Energy Usage Information".  Smart
        Grid standards will provide distributed intelligence in the
        network and allow enhanced load shedding.  For example, pricing
        signals will enable selective shutdown of non-critical
        activities during peak price periods.  Actions can be effected
        through both centralized and distributed management controls.
        There is an obvious functional link between Smart Grid and EMAN
        in the form of demand response, even though the EMAN framework
        itself does not address any coordination with the grid.  As EMAN
        enables control, it can be used by an EnMS to accomplish demand
        response through translation of a signal from an outside entity.
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     5. Limitations
        EMAN addresses the needs of energy monitoring in terms of
        measurement and considers limited control capabilities of energy
        monitoring of networks.
        EMAN does not create a new protocol stack, but rather defines a
        data and information model useful for measuring and reporting
        energy and other metrics over SNMP.
        EMAN does not address questions regarding Smart Grid,
        electricity producers, and distributors.
     6. Security Considerations
        EMAN uses the SNMP protocol and thus has the functionality of
        SNMP's security capabilities.  SNMPv3 [RFC3411] provides
        important security features such as confidentiality, integrity,
        and authentication.
     7. IANA Considerations
        This memo includes no request to IANA.
     8. Acknowledgements
        Firstly, the authors thank Emmanuel Tychon for taking the lead
        for the initial draft and his substantial contributions to it.
        The authors also thank Jeff Wheeler, Benoit Claise, Juergen
        Quittek, Chris Verges, John Parello, and Matt Laherty for their
        valuable contributions.  The authors thank Georgios Karagiannis
        for use case involving energy neutral homes, Elwyn Davies for
        off-grid electricity systems, and Kerry Lynn for demand
     9. References
     9.1. Normative References
        [RFC3411] An Architecture for Describing Simple Network
                Management Protocol (SNMP) Management Frameworks, RFC
                3411, December 2002.
        [RFC3621] Power Ethernet MIB, RFC 3621, December 2003.
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     9.2. Informative References
        [ACPI] "Advanced Configuration and Power Interface
                Specification", http://www.acpi.info/spec30b.htm
        [DASH] "Desktop and mobile Architecture for System Hardware",
        [DMTF DSP0004] DMTF Common Information Model (CIM)
                Infrastructure, DSP0004, May 2009.
        [DMTF DSP1027] DMTF Power State Management Profile, DSP1027,
                December 2009.
        [Ecma-SDC] Ecma-400, "Smart Data Centre Resource Monitoring and
                Control (2  Edition)", June 2013.
        [EMAN-REQ] Quittek, J., Chandramouli, M. Winter, R., Dietz, T.,
                Claise, B., and Chandramouli, M. "Requirements for
                Energy Management ", RFC 6988, September 2013.
        [EMAN-MONITORING-MIB] Chandramouli, M., Schoening, B., Dietz,
                T., Quittek, J. and Claise, B. "Energy and Power
                Monitoring MIB ", draft-ietf-eman-monitoring-mib-13,
                May 2015.
        [EMAN-AWARE-MIB] Parello, J., Claise, B. and Chandramouli, M.
                "draft-ietf-eman-energy-aware-mib-16", work in
                progress, July 2014.
        [RFC7326] Claise, B., Parello, J., Schoening, B., Quittek, J.
                "Energy Management Framework", RFC7326, September 2014.
        [EMAN-BATTERY-MIB] Quittek, J., Winter, R., and T. Dietz,
                "Definition of Managed Objects for Battery Monitoring"
                draft-ietf-eman-battery-mib-17.txt, December  2014.
        [ESTAR]  http://www.energystar.gov/
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        [ISO]    http://www.iso.org/iso/pressrelease.htm?refid=Ref1434
        [ASHRAE] http://collaborate.nist.gov/twiki-
        [ZIGBEE] http://www.zigBee.org/
        [ANSICEA] ANSI/CEA-2047, Consumer Electronics - Energy Usage
                Information (CE-EUI), 2013.
        [ISO]  http://www.iso.org/iso/pressrelease.htm?refid=Ref1337
        [PWG5106.4]IEEE-ISTO PWG Power Management Model for Imaging
                Systems v1.0, PWG Candidate Standard 5106.4-2011,
                February 2011.ftp://ftp.pwg.org/pub/pwg/candidates/cs-
        [PWG5106.5] IEEE-ISTO PWG Imaging System Power MIB v1.0, PWG
                Candidate Standard 5106.5-2011, February 2011.
        [IEC62301] International Electrotechnical Commission, "IEC 62301
                Household electrical appliances  Measurement of standby
                power", Edition 2.0, 2011.
        [MODBUS] Modbus-IDA, "MODBUS Application Protocol Specification
                V1.1b", December 2006.
        [NIST]  http://www.nist.gov/smartgrid/
        [RFC3805]  Bergman, R., Lewis, H., and McDonald, I. "Printer MIB
                v2",  RFC 3805, June 2004.
        [RFC6933]  Bierman, A., Romascanu, D., Quittek, J., and
                Chandramouli, M., "Entity MIB v4", RFC 6933, May 2013.
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     Authors' Addresses
        Brad Schoening
        44 Rivers Edge Drive
        Little Silver, NJ 07739
        Phone: +1 917 304 7190
        Email: brad.schoening@verizon.net
        Mouli Chandramouli
        Cisco Systems, Inc.
        Sarjapur Outer Ring Road
        Bangalore 560103
        Phone: +91 80 4429 2409
        Email: moulchan@cisco.com
        Bruce Nordman
        Lawrence Berkeley National Laboratory
        1 Cyclotron Road, 90-4000
        Berkeley  94720-8136
        Phone: +1 510 486 7089
        Email: bnordman@lbl.gov
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