Energy Management Working Group                 Brad Schoening
     Internet Draft                          Independent Consultant
     Intended status: Informational              Mouli Chandramouli
     Expires: October 18, 2014                     Cisco Systems Inc.
                                                      Bruce Nordman
                              Lawrence Berkeley National Laboratory
                                                     April 21, 2014
                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 framework to a
        variety of scenarios.  This document lists use cases and target
        devices that can potentially implement the EMAN framework and
        associated SNMP MIB modules.  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
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        This Internet-Draft will expire on October 18, 2014.
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     Copyright Notice
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     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 ............................... 7
        2.1. Network Infrastructure Energy Objects .................. 7
        2.2. Devices Powered by and Connected to a Network Device ... 8
        2.3. Devices Connected to a Network ......................... 9
        2.4. Power Meters .......................................... 10
        2.5. Mid-level Managers .................................... 11
        2.6. Non-residential Building System Gateways .............. 11
        2.7. Home Energy Gateways .................................. 12
        2.8. Data Center Devices ................................... 13
        2.9. Energy Storage Devices ................................ 14
        2.10. Industrial Automation Networks ....................... 15
        2.11. Printers ............................................. 15
       2.12. Off-Grid Devices ..................................... 16
        2.13. Demand Response ...................................... 17
        2.14. Power Capping ........................................ 17
      3. Use Case Patterns ......................................... 18
        3.1. Metering .............................................. 18
        3.2. Metering and Control .................................. 18
        3.3. Power Supply, Metering and Control .................... 18
        3.4. Multiple Power Sources ................................ 18
      4. Relationship of EMAN to other Standards ................... 19
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        4.1. Data Model and Reporting .............................. 19
              4.1.1. IEC - CIM...................................... 19
              4.1.2. DMTF........................................... 19
              4.1.3. ODVA........................................... 21
              4.1.4. Ecma SDC....................................... 21
              4.1.5. PWG............................................ 22
              4.1.6. ASHRAE......................................... 22
              4.1.7. ZigBee......................................... 23
        4.2. Measurement ........................................... 23
              4.2.1. ANSI C12....................................... 24
              4.2.2. IEC 62301...................................... 24
        4.3. Other ................................................. 24
              4.3.1. ISO............................................ 24
              4.3.2. Energy Star.................................... 25
              4.3.3. Smart Grid..................................... 25
      5. Limitations ............................................... 26
      6. Security Considerations ................................... 26
      7. IANA Considerations ....................................... 27
      8. Acknowledgements .......................................... 27
      9. References ................................................ 27
        9.1. Normative References .................................. 27
        9.2. Informative References ................................ 27
     1. Introduction
        The focus of the Energy Management (EMAN) framework is energy
        monitoring and management of energy objects [EMAN-DEF].  The
        scope of devices considered are network equipment and its
        components, and devices connected directly or indirectly to
        the network.  The EMAN framework enables monitoring
        (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 [EMAN-FRAMEWORK] 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
        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 to EMAN 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 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 drafts define SNMP MIB modules based on the
        information model. By implementing the SNMP MIB modules, any
        energy object can report its energy consumption according to the
        information model.  While the MIB drafts contain MIB modules,
        the information model can be adapted to other mechanisms such as
        YANG modules, NETCONF etc.
        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 objects.
        Target devices and scenarios considered for energy management
        are presented in Section 2 with detailed examples.
     1.2. EMAN Document Overview
        The EMAN working group charter called for producing a series of
        Internet standard drafts in the area of energy management.  The
        following drafts were created by the working group.
          Applicability Statement [EMAN-AS] this document presents use
          cases and scenarios for energy management.  In addition, other
          relevant energy standards and architectures are discussed.
          Requirements [EMAN-REQ] this document presents requirements of
          energy management and the scope of the devices considered.
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          Framework [EMAN-FRAMEWORK] This document defines a framework
          for providing energy management for devices within or
          connected to communication networks.
          Energy-Aware MIB [EMAN-AWARE-MIB] This document proposes a MIB
          module that characterizes a device identity, context and
          relationships to other entities.
          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 contains a MIB
          module for monitoring characteristics of an internal battery.
          Energy Management Terminology [EMAN-DEF] This document lists
          the definitions for the common terms used in the Energy
          Management Working Group.
     1.3. Energy Measurement
        More and more devices are able to measure and report their own
        energy consumption.  Smart 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 minimally useful at the enterprise
        The primary goal of the EMAN MIBs 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
        at any time by leveraging existing networks, across various
        equipment, in a unified and consistent manner.
        Given that an energy object can consume energy and/or 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 provided).
     1.4. Energy Management
        Beyond energy monitoring, the EMAN framework provides mechanisms
        for energy control.
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        There are many cases where reducing energy consumption of
        devices is desirable, such as when the device utilization is low
        or when the electricity is expensive or in short supply.
        In some cases, energy control requires considering the energy
        object context.  For instance, in a building during non-business
        hours: usually not all phones would be turned off to keep some
        phones available in case of emergency; and office cooling is
        usually not turned off totally, but the comfort level is
        Energy object control requires flexibility and support for
        different polices and mechanisms: from centralized management
        with a network management station, to autonomous management by
        individual devices, and alignment with dynamic demand-response
        The EMAN framework can be used as a tool for the demand/response
        scenario where in response to time-of-day fluctuation of energy
        costs or possible energy shortages, it is possible to respond
        and reduce the energy consumption for the network devices,
        effectively changing its power state.
     1.5. EMAN Framework Application
        A Network Management System (NMS) is the entity that requests
        information from compatible devices using SNMP protocol. An NMS
        implements many network management functions, e.g. security
        management, 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 to the 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.
        The scope of the target devices and the network scenarios
        considered for energy management are listed in Section 2.
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     2. Scenarios and Target Devices
        In this section a selection of scenarios for energy management
        are presented.  The fundamental objective of the use cases is to
        list important network scenarios that the EMAN framework should
        solve.  These use cases then drive the requirements for the EMAN
        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 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 network devices and their components.
        Power management of energy objects is a fundamental requirement
        of energy management of networks.
        It can be important to monitor the energy consumption and
        possibly manage the power state of these devices at a
        granularity level finer than just the entire device.  For these
        devices, the chassis draws power from one or more sources and
        feeds all its internal components.  It is highly desirable to
        have monitoring available for individual components, such as
        line cards, processors, and disk drives as well as 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, service
             modules of the switch.
          .  component view: CPU, ASICs, fans, power supply, ports
             (single port and port groups), storage and memory.
        The ENTITY-MIB provides the containment tree framework, for
        uniquely identifying the physical sub-components of network
        devices.  A component can be an Energy Object and the ENTITY-MIB
        containment tree expresses if one Energy Object belongs to
        another Energy Object (e.g. a line-card Energy Object contained
        in a chassis Energy Object).  The table entPhysicalContainsTable
        which has the index of entPhysicalChildIndex and the MIB object
        entPhysicalContainedIn which points to the containing entity.
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        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 that can report
             on behalf of some components.
     2.2. Devices Powered by and Connected to a Network Device
        This scenario covers Power over Ethernet (PoE) devices.  A PoE
        Power Sourcing Equipment (PSE) device [RFC3621] (e.g. a PoE
        switch) provides power to a Powered Device (PD) (e.g. a desktop
        phone).  For each port, the PSE can control the power supply
        (switching it on and off) and 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
        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 and the power consumption of
        all the IP phones can be aggregated by the switch.  In that
        case, the switch performs the aggregation function for other
        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.
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        This use case can be divided into two sub cases:
        a) The end device supports the EMAN framework, in which case
           this device is an EMAN Energy Object by itself, with its own
           UUID, like in scenario "Devices Connected to a Network"
           below.  The device is responsible for its own power
           reporting and control.
        b) The end device does not have EMAN capabilities, and the
           power measurement may not be able to be performed
           independently, and so is only performed by the supplying
           device.  This scenario is similar to the "Mid-level Manager"
        In the sub case (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.
        It is also possible to illustrate the relationships between
        entities.  The PoE IP phone is powered by the switch. If there
        are many IP phones connected to the same switch and the power
        consumption of all the IP phones can be aggregated by the
        switch.  In that case, the switch performs the aggregation
        function for other entities.
     2.3. Devices Connected to a Network
        The use case covers the metering relationship between an energy
        object and the parent energy object it is connected to, while
        receiving power from a different source.
        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 the PC is plugged in can be metered for example
        by a Smart PDU, or unmetered.
        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 running on batteries - the PC will report
        its own energy usage as any other Energy Object to the switch,
        and the switch can possibly provide aggregation.
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        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 devices (e.g. PCs) receive power supply
             from the wall outlet (unmetered), or a PDU (metered). That
             can also be powered autonomously (batteries).
          . Reporting: devices can measure and report the power
             consumption directly via the EMAN framework, or,
             communicate it to the network device (switch) and the
             switch can report the device's power consumption via the
             EMAN framework.
     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.  This
        use case covers energy objects able to measure or report the
        power consumption of external electrical devices, not natively
        connected to the network.
        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.
        Power Distribution Unit (PDUs) usually have inbuilt meters for
        each socket and so can measure the power supplied to each device
        in an equipment rack.  The PDUs have remote management
        functionality which can measure and possibly control the power
        supply of each outlet.
        Standalone meters can be placed anywhere in a power distribution
        tree and so may measure the total of groups of devices.  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.
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        The essential properties of this use case are:
          . Target devices: PDUs and meters.
          . How powered: from traditional mains power but as passed
             through a PDU or meter.
          . Reporting: PDUs report power consumption of downstream
             devices, usually a single device per outlet.
        The meters can have a metering relationship and possibly
        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 as well as 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.
          . Reporting: the middle-manager aggregates the energy data
             and reports that data to a NMS or higher mid-level manager.
     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 and
        legacy building automation protocols.  The gateway provides an
        interface between the EMAN framework and relevant building
        management protocols.
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        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 to 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.
        In its simplest form, metering can be performed at home.  Beyond
        the metering, it is also possible to implement energy saving
        policies based on energy pricing from the utility grid.  The
        EMAN information model can be applied to energy management of a
        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.
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        Beyond the canonical setting of a home drawing power from the
        utility, it is also possible to envision an energy neutral
        situation wherein the buildings/homes that can produce and
        consume energy with reduced or zero net importing 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 covers self-contained energy
        generation and 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 datacenters are big
        energy consumers and have expensive infrastructure.  The
        equipment generates heat, and heat needs to be evacuated though
        a 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,
        at the network level, Power Distribution Unit (PDU) level, and
        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 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 such energy storage
        devices is vital from a 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 MIB.
        Thus, for data center energy management, in addition to
        monitoring the energy usage of IT equipment, it is also
        important to monitor the remaining capacity of the UPS.
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        In addition to monitoring the power consumption of a data
        center, additional power characteristic metrics should be
        monitored.  Some of these are dynamic variations in the input
        power supply from the grid referred to as power characteristics
        is one metric.  Secondly, it can be useful to monitor how
        efficiently the devices utilize power.
        The nameplate power consumption (the worst case possible power
        draw) of all devices will make it possible to know an aggregate
        of the potential worst-case power usage and compare it to the
        budgeted power in the data center.
        The essential properties of this use case are:
          . Target devices: all 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
        There are two types of devices with energy storage: those whose
        primary function is to provide power to another device (e.g. a
        UPS), and those with a different primary function, but which
        have 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 used in mobile telecom towers including for
        use in remote locations.  It is important to monitor the
        remaining battery life and raise an alarm when this falls below
        a threshold.
        The essential properties of this use case are:
          . Target devices: devices that have an internal battery.
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          . How powered: from internal batteries or mains power.
          . Reporting: the device reports on its internal battery.
     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 in
        non-process loads.
        The essential properties of this use case are:
          . Target devices: devices used in industrial automation.
          . How powered: any method.
          . Reporting: currently, CIP protocol is currently 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,
        also including multi-function devices (MFDs), copiers, scanners,
        fax machines, and mailing machines.
        Energy use of printers has been an industry concern for several
        decades, and they usually have sophisticated power management
        with 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, and cross-vendor
        management systems manage fleets of printers in enterprises.
        Power consumption during active modes can vary widely, with high
        peak 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
        support active setting of power states, and setting of policies
        such as delay times when no activity will cause automatic
        transition to a lower power mode.  Other features include
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        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 needs to be 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 scavenge energy from environmental
        sources such as solar energy or wind power.  The device
        generally contains a closely coupled combination of
          . power scavenging or generation component(s)
          . power storage component(s) (e.g., battery)
          . power consuming component(s)
        With scavenged power, the energy input is often dependent on the
        random variations of the weather.  These devices therefore
        require energy management both for internal control and remote
        reporting of their state.  In order to optimize the performance
        of these devices and minimize the costs of the generation and
        storage components, it is desirable to vary the activity level,
        and, hopefully, the energy requirements of the consuming
        components in order to make best use of the available stored and
        instantaneously generated energy.  With appropriate energy
        management, the overall device can be optimized to deliver an
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        appropriate level of service without over provisioning the
        generation and storage components.
        In many cases these devices are expected to operate
        autonomously, as continuous communications for the purposes of
        remote control is either impossible or would result in excessive
        power consumption.  Non continuous polling requires the ability
        to store and access later the information collected while the
        communication was not possible.
        The essential properties of this use case are:
          Target Devices: remote network devices (mobile network) that
          consume and produce energy.
          How Powered: can be battery powered or using local energy
          Reporting: devices report their power usage, but only
     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 EMAN use case perspective, the demand response scenario can
        apply to a Data Center or a Building or a residential home.  As
        a first step, it may be important to monitor the energy
        consumption in real-time of a Data center, building or home
        which is already discussed in the previous use cases.  Then
        based on the potential energy shortfall, the EnMS could
        formulate a suitable response.  The EnMS could shut down
        selected devices that are considered lower priority or uniformly
        reduce the power supplied to all 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.
     2.14. Power Capping
        Power capping is a technique to limit the total power
        consumption of a server, and it can be useful for power limited
        data centers.  Based on workload measurements, the server can
        choose the optimal power state of the server in terms of
        performance and power consumption.  When the server operates at
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        less than the power supply capacity, it runs at full speed.
        When the server power would be greater than the power supply
        capacity, it runs at a slower speed so that its power
        consumption matches the available power supply capacity.  This
        gives vendors the option to use smaller, cost-effective power
        supplies that allow real world workloads to run at nominal
     3. Use Case Patterns
        The use cases presented above can be abstracted to the following
        broad patterns.
     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 only
        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 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 and metering
        and control are performed by the same power source
        - energy objects that have multiple power sources supplying
        power to the device and metering is performed by one source and
        control is performed by another source
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     4. Relationship of EMAN to other Standards
        The EMAN framework is tied to other standards and efforts that
        deal with energy.  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 Electro-technical 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 was originally conceived to automate
        control of a substation (facilities 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 (EMS).
        IEC TC57 WG19 is an ongoing working group 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
        measure 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
        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.
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        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, re-awaking, 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 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 ACPI and DMTF power state
        models, although it is not necessary for a managed element to
        support ACPI.  Optionally, a TransitingToPowerState property can
        represent power state transitions in progress.
        DMTF DASH (DSP0232) (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 provides management and control of managed
        elements like power, CPU, etc. using the DMTF's WS-Management
        web services and CIM data model.
        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
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     4.1.3. ODVA
        The Open DeviceNet Vendors Association (ODVA) is an association
        for industrial automation companies and 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 Open DeviceNet Vendors Association (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 management.  In particular,
        one of the concepts being considered different energy meters
        based on if the device consumes electricity or produces
        electricity or a passive device.
        ODVA defines a three-part approach towards energy management:
        awareness of energy usage, consuming energy more efficiently,
        and exchanging energy with the 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 committee on Smart Data Centre (TC38-TG2
        SDC [Ecma-SDC]) is defining 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.
        The 14th draft of SDC process was published in March 2011 and
        the development of the standard is still underway.  When used
        with EMAN, the SDC standard will provide a thin abstraction on
        top of the more detailed data model available in EMAN.
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     4.1.5. PWG
        The IEEE-ISTO Printer Working Group [PWG5106.4] 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 these devices
        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 [DSP0004] and DMTF CIM Power State
        Management Profile [DSP1027] for power states and alerts.
        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, as well as some that are
        specific to imaging equipment.  The PWG also provides for
        vendor-specific extension states (beyond the standard DMTF CIM
        The IETF Printer MIB RFC3805 [RFC3805] has been standardized,
        however, 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 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
        (ASHRAE) and the National Electrical Manufacturers Association
        (NEMA), both ANSI approved SDO's.  The result is to be an
        information model, not a protocol.
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        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 with the EMAN framework
        to a large degree, 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. ZigBee
        The ZigBee Smart Energy 2.0 effort [ZIGBEE] focuses on wireless
        communication to appliances and lighting.  ZigBee 1.x is not
        based on IP, whereas ZigBee 2.0 is supposed to interoperate with
        IP. It is intended to enable building energy management and
        enable direct load control by utilities.
        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 looks for completely
        integrated and inexpensive mesh solution.
     4.2. Measurement
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     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
        62053-22.  ANSI C12.20 defines accuracy classes for power
        These standards are oriented to the meter itself, are very
        specific, and used by electricity distributors and producers.
        The EMAN standard references ANSI C12 accuracy classes.
     4.2.2. IEC 62301
        IEC 62301, "Household electrical appliances Measurement of
        standby power", specifies a power level measurement procedure.
        While nominally for appliances and low-power modes, many aspects
        of it apply to other device types and modes and it is commonly
        referenced in test procedures for energy using products.
        While the standard is intended for laboratory measurements of
        devices in controlled conditions, many aspects of it are
        informative to those implementing measurement in products that
        ultimately report via EMAN.
     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 organization 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
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       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.
        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 EnergyStar, 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
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        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.  Both centralized and
        distributed management controls are in scope.
        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.
     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.
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     7. IANA Considerations
        This memo includes no request to IANA.
     8. Acknowledgements
        Firstly, the authors thank Emmanuel Tychon for taking the lead
        for this draft and his substantial contributions to it.   The
        authors 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 response.
     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.
     9.2. Informative References
        [DASH] "Desktop and mobile Architecture for System Hardware",
        [Ecma-SDC] Ecma TC38 / SDC Task Group, "Smart Data Centre
                Resource Monitoring and Control (DRAFT)", March 2011.
        [EMAN-AS] B. Schoening, Mouli Chandramouli, Bruce Nordman,
                "Energy Management (EMAN) Applicability Statement",
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                draft-ietf-eman-applicability-statement-04.txt,  April
        [EMAN-REQ] Quittek, J., Chandramouli, M. Winter, R., Dietz, T.,
                Claise, B., and M. Chandramouli, "Requirements for
                Energy Management ", RFC 6988, September 2013.
        [EMAN-MONITORING-MIB] M. Chandramouli, Schoening, B., Dietz, T.,
                Quittek, J. and B. Claise  "Energy and Power Monitoring
                MIB " draft-ietf-eman-monitoring-mib-06, July  2013.
        [EMAN-AWARE-MIB] J. Parello, B. Claise and Mouli Chandramouli,
                "draft-ietf-eman-energy-aware-mib-09", work in
                progress, July 2013.
        [EMAN-FRAMEWORK] Claise, B., Parello, J., Schoening, B., J.
                Quittek, "Energy Management Framework", draft-ietf-
                eman-framework-10, April 2014.
        [EMAN-BATTERY-MIB] Quittek, J., Winter, R., and T. Dietz,
                "Definition of Managed Objects for Battery Monitoring"
                draft-ietf-eman-battery-mib-09.txt,  July  2013.
        [EMAN-DEF] J. Parello "Energy Management Terminology", draft-
                parello-eman-definitions-08, Work in progress, April
        [DMTF] "Power State Management ProfileDMTFDSP1027  Version 2.0"
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        [DSP0004] DMTF Common Information Model (CIM) Infrastructure,
                DSP0004, May 2009.
        [DSP1027] DMTF Power State Management Profile, DSP1027, December
        [PWG5106.4]IEEE-ISTO PWG Power Management Model for Imaging
                Systems v1.0, PWG Candidate Standard 5106.4-2011,
                February 2011.
        [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.
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     Authors' Addresses
        Brad Schoening
        44 Rivers Edge Drive
        Little Silver, NJ 07739
        Phone: +1 917 304 7190
        Mouli Chandramouli
        Cisco Systems, Inc.
        Sarjapur Outer Ring Road
        Bangalore 560103
        Phone: +91 80 4429 2409
        Bruce Nordman
        Lawrence Berkeley National Laboratory
        1 Cyclotron Road, 90-2000
        Berkeley  94720-8130
        Phone: +1 510 486 7089
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