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Versions: 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 RFC 6988

Network Working Group                                    J. Quittek, Ed.
Internet-Draft                                           M. Chandramouli
Intended status: Informational                       Cisco Systems, Inc.
Expires: November 03, 2013                                     R. Winter
                                                         NEC Europe Ltd.
                                                                T. Dietz
                                                         NEC Europe Ltd.
                                                               B. Claise
                                                     Cisco Systems, Inc.
                                                            May 02, 2013


                   Requirements for Energy Management
                    draft-ietf-eman-requirements-14

Abstract

   This document defines requirements for standards specifications for
   energy management.  The requirements defined in this document concern
   monitoring functions as well as control functions.  Monitoring
   functions include identification of energy-managed devices and their
   components, monitoring of their power states, power inlets, power
   outlets, actual power (the instantaneous power, as opposed to the
   demand, which is an averaged power), power attributes, received
   energy, provided energy, and contained batteries.  Control functions
   serve for controlling power supply and power state of energy-managed
   devices and their components.
   This document does not specify the features that must be implemented
   by compliant implementations but rather features that must be
   supported by standards for energy management.

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on November 03, 2013.




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Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Conventional Requirements For Energy Management . . . . .   4
     1.2.  Specific Requirements For Energy Management . . . . . . .   4
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   5
   3.  General Considerations Related To Energy Management . . . . .   6
     3.1.  Power States  . . . . . . . . . . . . . . . . . . . . . .   7
     3.2.  Saving Energy Versus Maintaining Service Level  . . . . .   7
     3.3.  Local Versus Network-Wide Energy Management . . . . . . .   7
     3.4.  Energy Monitoring Versus Energy Saving  . . . . . . . . .   8
     3.5.  Overview Of Energy Management Requirements  . . . . . . .   8
   4.  Identification Of Entities  . . . . . . . . . . . . . . . . .   9
   5.  Information On Entities . . . . . . . . . . . . . . . . . . .  10
     5.1.  General Information On Entities . . . . . . . . . . . . .  10
     5.2.  Power Interfaces  . . . . . . . . . . . . . . . . . . . .  11
     5.3.  Power . . . . . . . . . . . . . . . . . . . . . . . . . .  13
     5.4.  Power State . . . . . . . . . . . . . . . . . . . . . . .  15
     5.5.  Energy  . . . . . . . . . . . . . . . . . . . . . . . . .  17
     5.6.  Battery State . . . . . . . . . . . . . . . . . . . . . .  18
     5.7.  Time Series Of Measured Values  . . . . . . . . . . . . .  19
   6.  Control Of Entities . . . . . . . . . . . . . . . . . . . . .  21
   7.  Reporting On Other Entities . . . . . . . . . . . . . . . . .  21
   8.  Controlling Other Entities  . . . . . . . . . . . . . . . . .  22
     8.1.  Controlling Power States Of Other Entities  . . . . . . .  22
     8.2.  Controlling Power Supply  . . . . . . . . . . . . . . . .  23
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  23
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  24
   11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  25
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .  25
     12.1.  Normative References . . . . . . . . . . . . . . . . . .  25
     12.2.  Informative References . . . . . . . . . . . . . . . . .  26
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  27



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1.  Introduction

   With rising energy cost and with an increasing awareness of the
   ecological impact of running information technology equipment, energy
   management functions and interfaces are becoming an additional basic
   requirement for network management systems and devices connected to a
   network.

   This document defines requirements for standards specifications for
   energy management, both monitoring functions and control functions.
   The main subject of energy management are entities in the network,
   i.e.  device or one of a device's components, that receive and
   provide electric energy.  Devices may have an IP address, such as
   hosts, routers, and middleboxes, or they are connected indirectly to
   the Internet via a proxy with an IP address providing a management
   interface for the device.  An example are devices in a building
   infrastructure using non-IP protocols and a gateway to the Internet.

   The main subject of energy management are devices and their
   components that receive and provide electric energy.  Devices may
   have an IP address, such as hosts, routers, and middleboxes, or they
   might be connected indirectly to the Internet via a proxy with an IP
   address providing a management interface for the device.  An example
   are devices in a building infrastructure using non-IP protocols and a
   gateway to the Internet.

   These requirements concern the standards specification process and
   not the implementation of specified standards.  All requirements in
   this document must be reflected by standards specifications to be
   developed.  However, which of the features specified by these
   standards will be mandatory, recommended, or optional for compliant
   implementations is to be defined by standards track document(s) and
   not in this document.

   Section 3 elaborates a set of general needs for energy management.
   Requirements for an energy management standard are specified in
   Sections 4 to 8.

   Sections 4 to 6 contain conventional requirements specifying
   information on entities and control functions.

   Sections 7 and 8 contain requirements specific to energy management.
   Due to the nature of power supply, some monitoring and control
   functions are not conducted by interacting with the entity of
   interest, but with other entities, for example, entities upstream in
   a power distribution tree.





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1.1.  Conventional Requirements For Energy Management

   The specification of requirements for an energy management standard
   starts with Section 4 addressing the identification of entities and
   the granularity of reporting of energy-related information.  A
   standard must support unique identification of entities, reporting
   per entire device, and reporting energy-related information on
   individual components of a device or attached devices.

   Section 5 specifies requirements related to monitoring of entities.
   This includes general (type, context) information and specific
   information on Power States, power inlets, power outlets, power,
   energy, and batteries.  Control Power State and power supply of
   entities is covered by requirements specified in Section 6.

1.2.  Specific Requirements For Energy Management

   While the conventional requirements summarized above seem to be all
   that would be needed for energy management, there are significant
   differences between energy management and most well known network
   management functions.  The most significant difference is the need
   for some devices to report on other entities.  There are three major
   reasons for this.

   o  For monitoring a particular entity it is not always sufficient to
      communicate with the entity only.  When the entity has no
      instrumentation for determining power, it might still be possible
      to obtain power values for the entity by communication with other
      entities in its power distribution tree.
      A simple example is retrieving power values from a power meter at
      the power line into the entity.  Common examples are a Power
      Distribution Unit (PDU) and a Power over Ethernet (PoE) switch.
      Both supply power to other entities at sockets or ports,
      respectively, and are often instrumented to measure power per
      socket or port.

   o  Similar considerations apply to controlling power supply of a
      entity which often needs direct or indirect communications with
      another entity upstream in the power distribution tree.  Again, a
      PDU and a PoE switch are common examples, if they have the
      capability to switch on or off power at their sockets or ports,
      respectively.









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   o  Energy management often extends beyond entities with IP network
      interfaces, to non-IP building systems accessed via a gateway
      (sometimes called an energy management system or controller).
      Requirements in this document do not cover details of these
      networks and energy devices, but specify means for opening IP
      network management towards them.

   These specific issues of energy management and a set of further ones
   are covered by requirements specified in Sections 7 and 8.

   The requirements in these sections need a new energy management
   framework that deals with the specific nature of energy management.
   The actual standards documents, such as MIB module specifications,
   address conformance by specifying which feature must, should, or may
   be implemented by compliant implementations.

2.  Terminology

   Energy

      That which does work or is capable of doing work.  As used by
      electric utilities, it is generally a reference to electrical
      energy and is measured in kilo-watt hours (kWh) [IEEE-100].

   Power

      The time rate at which Energy is emitted, transferred, or
      received; usually expressed in watts (or in joules per second)
      [IEEE-100].

   Power Attributes

      Measurements of the electrical current, voltage, phase and
      frequencies at a given point in an electrical power system.
      Reference: Adapted from [IEC60050]

      NOTES: 1.  Power Attributes is not intended to be judgmental with
      respect to a reference or technical value and are independent of
      any usage context.

   Energy Management

      Energy Management is a set of functions for measuring, modeling,
      planning, and optimizing networks to ensure that the network
      elements and attached devices use energy efficiently and in a
      manner appropriate to the nature of the application and the cost
      constraints of the organization [ITU-M.3400].




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   Energy Management System

      An Energy Management System is a combination of hardware and
      software used to administer a network with the primary purpose
      being Energy Management [Fed-Std-1037C].

   Energy Monitoring

      Energy Monitoring is a part of Energy Management that deals with
      collecting or reading information from network elements and
      attached devices and their components to aid in Energy Management.

   Energy Control

      Energy Control is a part of Energy Management that deals with
      controlling energy supply and power state of network elements and
      attached devices and their components.

   Power Interface

      A Power Interface is an interface at which a device is connected
      to a Power transmission medium at which it can receive Power,
      provide Power, or both.

   Power Inlet

      A Power Inlet is a Power Interface at which a device can receive
      Power from other devices.

   Power Outlet

      A Power Outlet is a Power Interface at which a device can provide
      Power to other devices.

   Power State

      A Power State is a condition or mode of a device that broadly
      characterizes its capabilities, Power consumption, and
      responsiveness to input [IEEE-1621].

3.  General Considerations Related To Energy Management

   The basic objective of Energy Management is operating sets of devices
   with minimal Energy, while maintaining a certain level of service.
   [I-D.ietf-eman-applicability-statement] presents the applicability of
   the EMAN framework to a variety of scenarios, and lists use cases and
   target devices.




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3.1.  Power States

   Entities can be set to an operational state that results in the
   lowest power level that still meets the service level performance
   objectives.  In principle, there are three basic types of Power
   States for an entity or for a whole system:

   o  full Power State

   o  sleep state (not functional, but immediately available)

   o  off state (may require significant time to become operational)

   In specific devices, the number of Power States and their properties
   varies considerably.  Simple entities may just have only the extreme
   states, full power and off state.  Many devices have three basic
   Power States: on, off, and sleep.  However, more finely grained Power
   States can be implemented.  Examples are various operational low
   power states in which a device requires less energy than in the full
   power "on" state, but - compared to the sleep state - is still
   operational with reduced performance or functionality.

3.2.  Saving Energy Versus Maintaining Service Level

   One of the objectives of Energy Management is to reduce the Energy
   consumption.  While this objective is clear, the way to attain that
   goal is often difficult.  In many cases there is no way of reducing
   power without the consequence of a potential service (performance or
   capacity) degradation.  In this case, a trade-off needs to be made
   between service level objectives and energy minimization.  In other
   cases a reduction of power can easily be achieved while still
   maintaining sufficient service level performance, for example, by
   switching entities to lower Power States when higher performance is
   not needed.

3.3.  Local Versus Network-Wide Energy Management

   Many Energy saving functions are executed locally by an entity; it
   monitors its usage and dynamically adapts its Power according to the
   required performance.  It may, for example, switch to a sleep state
   when it is not in use or out of scheduled business hours.  An Energy
   Management System may observe an entity's Power State and configure
   its Power saving policies.








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   Energy savings can also be achieved with policies implemented by a
   network management system that controls Power States of managed
   entities.  Information about the Power received and provided by
   entities in different Power States may be required to set policies.
   Often this information is acquired best through monitoring.

   Both methods, network-wide and local Energy Management, have
   advantages and disadvantages and often it is desirable to combine
   them.  Central management is often favorable for setting Power States
   of a large number of entities at the same time, for example, at the
   beginning and end of business hours in a building.  Local management
   is often preferable for Power saving measures based on local
   observations, such as high or low functional load of an entity.

3.4.  Energy Monitoring Versus Energy Saving

   Monitoring Energy, Power, and Power States alone does not reduce the
   Energy needed to run an entity.  In fact, it may even increase it
   slightly due to monitoring instrumentation that needs Energy.
   Reporting measured quantities over the network may also increase
   Energy use, though the acquired information may be an essential input
   to control loops that save Energy.

   Monitoring Energy and Power States can also be required for other
   purposes including:

   o  investigating Energy saving potential

   o  evaluating the effectiveness of Energy saving policies and
      measures

   o  deriving, implementing, and testing Power management strategies

   o  accounting for the total Power received and provided by an entity,
      a network, or a service

   o  predicting an entity's reliability based on Power usage

   o  choosing time of next maintenance cycle for an entity

3.5.  Overview Of Energy Management Requirements

   The following basic management functions are required:

   o  monitoring Power States

   o  monitoring Power (Energy conversion rate)




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   o  monitoring (accumulated) received and provided Energy

   o  monitoring Power attributes

   o  setting Power States

   Power control is complementary to other Energy savings measures such
   as low-power electronics, Energy saving protocols, energy-efficient
   device design (for example, low-power modes for components), and
   energy-efficient network architectures.  Measurement of received and
   provided Energy can provide useful data for developing these
   technologies.

4.  Identification Of Entities

   Entities must be capable of being uniquely identified with the
   context of the management system.  This includes entities that are
   components of managed devices as well as entire devices.

   Entities that report on or control other entities must identify the
   entities they report on or control: see Section 7 or Section 8,
   respectively, for the detailed requirements.

   An entity may be an entire device or a component of it.  Examples of
   components of interest are a hard drive, a battery, or a line card.
   It may be required to be able to control individual components to
   save Energy.  For example, server blades can be switched off when the
   overall load is low or line cards at switches may be powered down at
   night.

   Identifiers for devices and components are already defined in
   standard MIB modules, such as the LLDP MIB module [IEEE-802.1AB] and
   the LLDP-MED MIB module [ANSI-TIA-1057] for devices and the Entity
   MIB module [RFC4133] and the Power Ethernet MIB [RFC3621] for
   components of devices.  Energy Management needs means to link Energy-
   related information to such identifiers.

   Instrumentation for measuring received and provided Energy of a
   device is typically more expensive than instrumentation for
   retrieving its Power State.  Many devices may provide Power State
   information for all individual components separately, while reporting
   the received and provided Energy only for the entire device.









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4.1.  Identifying Entities

   The standard must provide means for uniquely identifying entities.
   Uniqueness must be preserved such that collisions of identities are
   avoided at potential receivers of monitored information.

4.2.  Persistence Of Identifiers

   The standard must provide means for indicating whether identifiers of
   entities are persistent across a re-start of the entity.

4.3.  Change Of Identifiers

   The standard must provide means to indicate any change of entity
   identifiers.

4.4.  Using Entity Identifiers Of Existing MIB Modules

   The standard must provide means for re-using entity identifiers from
   existing standards including at least the following:

   o  the entPhysicalIndex in the Entity MIB module [RFC4133]

   o  the LldpPortNumber in the LLDP MIB module [IEEE-802.1AB] and in
      the LLDP-MED MIB module [ANSI-TIA-1057]

   o  the pethPsePortIndex and the pethPsePortGroupIndex in the Power
      Ethernet MIB [RFC3621]

   Generic means for re-using other entity identifiers must be provided.

5.  Information On Entities

   This section describes information on entities for which the standard
   must provide means for retrieving and reporting.

   Required information can be structured into seven groups.
   Section 5.1 specifies requirements for general information on
   entities, such as type of entity or context information.
   Requirements for information on Power Inlets and Power Outlets of
   entities are specified in Section 5.2.  Monitoring of Power and
   Energy is covered by Sections 5.3 and 5.5, respectively.  Section 5.4
   covers requirements related to entities' Power States.  Section 5.6
   specifies requirements for monitoring batteries.  Finally, the
   reporting of time series of values is covered by Section 5.7.

5.1.  General Information On Entities




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   For Energy Management it may be required to understand the role and
   context of an entity.  An Energy Management System may aggregate
   values of received and provided Energy according to a defined
   grouping of entities.  When controlling and setting Power States it
   may be helpful to understand the grouping of the entity and role of
   an entity in a network, for example, it may be important to exclude
   some mission critical network devices from being switched to lower
   Power or even from being switched off.

5.1.1.  Type Of Entity

   The standard must provide means to configure, retrieve and report a
   textual name or a description of an entity.

5.1.2.  Context Of An Entity

   The standard must provide means for retrieving and reporting context
   information on entities, for example, tags associated with an entity
   that indicate the entity's role.

5.1.3.  Significance Of Entities

   The standard must provide means for retrieving and reporting the
   significance of entities within its context, for example, how
   important the entity is.

5.1.4.  Power Priority

   The standard must provide means for retrieving and reporting Power
   priorities of entities.  Power priorities indicate an order in which
   Power States of entities are changed, for example, to lower Power
   States for saving Power.

5.1.5.  Grouping Of Entities

   The standard must provide means for grouping entities.  This can be
   achieved in multiple ways, for example, by providing means to tag
   entities, to assign them to domains, or to assign device types to
   them.

5.2.  Power Interfaces

   A Power Interface is an interface at which a device is connected to a
   Power transmission medium at which it can receive Power, provide
   Power, or both.






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   A Power Interface is either an inlet or an outlet.  Some Power
   Interfaces change over time from being an inlet to being an outlet
   and vice versa.  However most Power Interfaces never change.

   Devices have Power Inlets at which they are supplied with electric
   Power.  Most devices have a single Power Inlet, while some have
   multiple inlets.  Different Power Inlets on a device are often
   connected to separate Power distribution trees.  For Energy
   Monitoring, it is useful to retrieve information on the number of
   inlets of a device, the availability of Power at inlets and which of
   them are actually in use.

   Devices can have one or more Power Outlets for supplying other
   devices with electric Power.

   For identifying and potentially controlling the source of Power
   received at an inlet, it may be required to identify the Power Outlet
   of another device at which the received Power is provided.
   Analogously, for each outlet it is of interest to identify the Power
   Inlets that receive the Power provided at a certain outlet.  Such
   information is also required for constructing the wiring topology of
   electrical Power distribution to devices.

   Static properties of each Power Interface are required information
   for Energy Management.  Static properties include the kind of
   electric current (AC or DC), the nominal voltage, the nominal AC
   frequency, and the number of AC phases.  Note that often the nominal
   voltage is not a single value but a voltage range, such as, for
   example, (100V-120V), (100V-240V), (100V-120V,220V-240V).

5.2.1.  Lists Of Power Interfaces

   The standard must provide means for monitoring the list of Power
   Interfaces of a device.

5.2.2.  Operational Mode Of Power Interfaces

   The standard must provide means for monitoring the operational mode
   of a Power Interface which is either "Power Inlet" or "Power Outlet".

5.2.3.  Corresponding Power Outlet

   The standard must provide means for identifying the Power Outlet that
   provides the Power received at a Power Inlet.

5.2.4.  Corresponding Power Inlets





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   The standard must provide means for identifying the list of Power
   Inlets that receive the Power provided at a Power Outlet.

5.2.5.  Availability Of Power

   If the Power States allow it, the standard must provide means for
   monitoring the availability of Power at each Power Interface.  This
   indicates whether at a Power Interfaces Power supply is switched on
   or off.

5.2.6.  Use Of Power

   The standard must provide means for monitoring for each Power
   Interface if it is in actual use.  For inlets this means that the
   device actually receives Power at the inlet.  For outlets this means
   that Power is actually provided from it to one or more devices.

5.2.7.  Type Of current

   The standard must provide means for reporting the type of current (AC
   or DC) for each Power Interface as well as for a device.

5.2.8.  Nominal Voltage Range

   The standard must provide means for reporting the nominal voltage
   range for each Power Interface.

5.2.9.  Nominal AC Frequency

   The standard must provide means for reporting the nominal AC
   frequency for each Power Interface.

5.2.10.  Number Of AC Phases

   The standard must provide means for reporting the number of AC phases
   for each Power Interface.

5.3.  Power

   Power is measured as an instantaneous value or as the average over a
   time interval.

   Obtaining highly accurate values for Power and Energy may be costly
   if it requires dedicated metering hardware.  Entities without the
   ability to measure their Power and received and provided Energy with
   high accuracy may just report estimated values, for example based on
   load monitoring, Power State, or even just the entity type.




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   Depending on how Power and Energy values are obtained, the confidence
   in the reported value and its accuracy will vary.  Entities reporting
   such values should qualify the confidence in the reported values and
   quantify the accuracy of measurements.  For reporting accuracy, the
   accuracy classes specified in IEC 62053-21 [IEC.62053-21] and IEC
   62053-22 [IEC.62053-22] should be considered.

   Further properties of the Power supplied to a device are also of
   interest.  Particularly for AC Power supply, several Power attributes
   beyond the real Power are of potential interest to Energy Management
   Systems.  The set of these properties include the the complex Power
   attributes (apparent power, reactive power, and phase angle of the
   current or power factor) as well as the actual voltage, the actual AC
   frequency, the Total Harmonic Distortion (THD) of voltage and
   current, and the impedance of an AC phase or of the DC supply.  A new
   standard for monitoring these Power attributes should be in line with
   already existing standards, such as [IEC.61850-7-4].

   For some network management tasks it is desirable to receive
   notifications from entities when their Power value exceeds or falls
   below given thresholds.

5.3.1.  Real Power / Power Factor

   The standard must provide means for reporting the real power for each
   Power Interface as well as for an entity.  Reporting Power includes
   reporting the direction of Power flow.

5.3.2.  Power Measurement Interval

   The standard must provide means for reporting the corresponding time
   or time interval for which a Power value is reported.  The Power
   value can be measured at the corresponding time or averaged over the
   corresponding time interval.

5.3.3.  Power Measurement Method

   The standard must provide means to indicate the method how these
   values have been obtained.  Based on how the measurement was
   conducted, it is possible to associate a certain degree of confidence
   with the reported Power value.  For example, there are methods of
   measurement such as direct Power measurement, or by estimation based
   on performance values, or hard coding average Power values for an
   entity.

5.3.4.  Accuracy Of Power And Energy Values





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   The standard must provide means for reporting the accuracy of
   reported Power and Energy values.

5.3.5.  Actual Voltage And Current

   The standard must provide means for reporting the actual voltage and
   actual current for each Power Interface as well as for a device.  In
   case of AC Power supply, means must be provided for reporting the
   actual voltage and actual current per phase.

5.3.6.  High/low Power Notifications

   The standard must provide means for creating notifications if Power
   values of an entity rise above or fall below given thresholds.

5.3.7.  Complex Power / Power Factor

   The standard must provide means for reporting the complex power for
   each Power Interface and for each phase at a Power Interface.
   Besides the real power, at least two out of the following three
   quantities need to be reported: apparent power, reactive power, phase
   angle.  The phase angle can be substituted by the power factor.

5.3.8.  Actual AC Frequency

   The standard must provide means for reporting the actual AC frequency
   for each Power Interface.

5.3.9.  Total Harmonic Distortion

   The standard must provide means for reporting the Total Harmonic
   Distortion (THD) of voltage and current for each Power Interface.  In
   case of AC Power supply, means must be provided for reporting the THD
   per phase.

5.3.10.  Power Supply Impedance

   The standard must provide means for reporting the impedance of Power
   supply for each Power Interface.  In case of AC Power supply, means
   must be provided for reporting the impedance per phase.

5.4.  Power State

   Many entities have a limited number of discrete Power States.

   There is a need to report the actual Power State of an entity, and
   means for retrieving the list of all supported Power States.




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   Different standards bodies have already defined sets of Power States
   for some entities, and others are creating new Power State sets.  In
   this context, it is desirable that the standard support many of these
   Power State standards.  In order to support multiple management
   systems possibly using different Power State sets, while
   simultaneously interfacing with a particular entity, the Energy
   Management standard must provide means for supporting multiple Power
   State sets used simultaneously at an entity.

   Power States have parameters that describe its properties.  It is
   required to have standardized means for reporting some key
   properties, such as the typical Power of an entity in a certain
   state.

   There also is a need to report statistics on Power States including
   the time spent and the received and provided Energy in a Power State.

5.4.1.  Actual Power State

   The standard must provide means for reporting the actual Power State
   of an entity.

5.4.2.  List Of Supported Power States

   The standard must provide means for retrieving the list of all
   potential Power States of an entity.

5.4.3.  Multiple Power State Sets

   The standard must provide means for supporting multiple Power State
   sets simultaneously at an entity.

5.4.4.  List Of Supported Power State Sets

   The standard must provide means for retrieving the list of all Power
   State sets supported by an entity.

5.4.5.  List Of Supported Power States Within A Set

   The standard must provide means for retrieving the list of all
   potential Power States of an entity for each supported Power State
   set.









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5.4.6.  Typical Power Per Power State

   The standard must provide means for retrieving the typical Power for
   each supported Power State.

5.4.7.  Power State Statistics

   The standard must provide means for monitoring statistics per Power
   State including the total time spent in a Power State, the number of
   times each state was entered and the last time each state was
   entered.  More Power State statistics are addressed by requirement
   5.5.3.

5.4.8.  Power State Changes

   The standard must provide means for generating a notification when
   the actual Power State of an entity changes.

5.5.  Energy

   Monitoring of electrical Energy received or provided by an entity is
   a core function of Energy Management.  Since Energy is an accumulated
   quantity, it is always reported for a certain interval of time.  This
   can be, for example, the time from the last restart of the entity to
   the reporting time, the time from another past event to the reporting
   time, the last given amount of time before the reporting time, or a
   certain interval specified by two time stamps in the past.

   It is useful for entities to record their received and provided
   Energy per Power State and report these quantities.

5.5.1.  Energy

   The standard must provide means for reporting measured values of
   Energy and the direction of the Energy flow received or provided by
   an entity.  The standard must also provide the means to report the
   Energy passing through each Power Interface.

5.5.2.  Time Intervals

   The standard must provide means for reporting the time interval for
   which an Energy value is reported.









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5.5.3.  Energy Per Power State

   The standard must provide means for reporting the received and
   provided Energy for each individual Power State.  This extends the
   requirement 5.4.7 on Power State statistics.

5.6.  Battery State

   Batteries are special entities that supply Power.  The status of
   these batteries is typically controlled by automatic functions that
   act locally on the entity and manually by users of the entity.  There
   is a need to monitor the battery status of these entities by network
   management systems.

   Devices containing batteries can be modeled in two ways.  The entire
   device can be modeled as a single entity on which Energy-related
   information is reported or the battery can be modeled as an
   individual entity for which Energy-related information is monitored
   individually according to requirements in Sections 5.1 to 5.5.

   Further information on batteries is of interest for Energy
   Management, such as the current charge of the battery, the number of
   completed charging cycles, the charging state of the battery, its
   temperature, and further static and dynamic battery properties.  It
   is desirable to receive notifications if the charge of a battery
   becomes very low or if a battery needs to be replaced.

5.6.1.  Battery Charge

   The standard must provide means for reporting the current charge of a
   battery, in units of milliampere hours (mAh).

5.6.2.  Battery Charging State

   The standard must provide means for reporting the charging state
   (charging, discharging, etc.)  of a battery.

5.6.3.  Battery Charging Cycles

   The standard must provide means for reporting the number of completed
   charging cycles of a battery.

5.6.4.  Actual Battery Capacity

   The standard must provide means for reporting the actual capacity of
   a battery.





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5.6.5.  Actual Battery Capacity

   The standard must provide means for reporting the actual temperature
   of a battery.

5.6.6.  Static Battery Properties

   The standard must provide means for reporting static properties of a
   battery, including the nominal capacity, the number of cells, the
   nominal voltage, and the battery technology.

5.6.7.  Low battery Charge Notification

   The standard must provide means for generating a notification when
   the charge of a battery decreases below a given threshold.  Note that
   the threshold may depend on the battery technology.

5.6.8.  Battery Replacement Notification

   The standard must provide means for generating a notification when
   the number of charging cycles of battery exceeds a given threshold.

5.6.9.  Multiple Batteries

   If the battery technology allows, the standard must provide means for
   meeting requirements 5.6.1 to 5.6.8 for each individual battery
   contained in a single entity.

5.7.  Time Series Of Measured Values

   For some network management tasks, it is required to obtain time
   series of measured values from entities, such as Power, Energy,
   battery charge, etc.

   In general time series measurements could be obtained in many
   different ways.  Means should be provided to either push such values
   from the location where they are available to the management system
   or to have them stored locally for a sufficiently long period of time
   such that a management system can retrieve full time series.

   The following issues are to be considered when designing time series
   measurement and reporting functions:

   1.  Which quantities should be reported?

   2.  Which time interval type should be used (total, delta, sliding
       window)?




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   3.  Which measurement method should be used (sampled, continuous)?

   4.  Which reporting model should be used (push or pull)?

   The most discussed and probably most needed quantity is Energy.  But
   a need for others, such as Power and battery charge can be identified
   as well.

   There are three time interval types under discussion for accumulated
   quantities such as Energy.  They can be reported as total values,
   accumulated between the last restart of the measurement and a certain
   timestamp.  Alternatively, Energy can be reported as delta values
   between two consecutive timestamps.  Another alternative is reporting
   values for sliding windows as specified in [IEC.61850-7-4].

   For non-accumulative quantities, such as Power, different measurement
   methods are considered.  Such quantities can be reported using values
   sampled at certain time stamps or alternatively by mean values for
   these quantities averaged between two (consecutive) time stamps or
   over a sliding window.

   Finally, time series can be reported using different reporting
   models, particularly push-based or pull-based.  Push-based reporting
   can, for example, be realized by reporting Power or Energy values
   using the IPFIX protocol [RFC5101],[RFC5102].  SNMP [RFC3411] is an
   example for a protocol that can be used for realizing pull-based
   reporting of time series.

   For reporting time series of measured values the following
   requirements have been identified.  Further decisions concerning
   issues discussed above need to be made when developing concrete
   Energy Management standards.

5.7.1.  Time Series Of Energy Values

   The standard must provide means for reporting time series of Energy
   values.  If the comparison of time series between multiple entities
   is required, then time synchronization between those entities must be
   provided (for example, with the Network Time Protocol [RFC5905]).

5.7.2.  Time Series Interval Types

   The standard must provide means for supporting alternative interval
   types.  Requirement 5.5.2 applies to every reported time value.

5.7.3.  Time Series Storage Capacity





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   The standard should provide means for reporting the number of values
   of a time series that can be stored for later reporting.

6.  Control Of Entities

   Many entities control their Power State locally.  Other entities need
   interfaces for an Energy Management System to control their Power
   State.

   Power supply is typically not self-managed by devices.  And
   controlling Power supply is typically not conducted as interaction
   between Energy Management System and the device itself.  It is rather
   an interaction between the management system and a device providing
   Power at its Power Outlets.  Similar to Power State control, Power
   supply control may be policy driven.  Note that shutting down the
   Power supply abruptly may have severe consequences for the device.

6.1.  Controlling Power States

   The standard must provide means for setting Power States of entities.

6.2.  Controlling Power Supply

   The standard must provide means for switching Power supply off or
   turning Power supply on at Power Interfaces providing Power to one or
   more device.

7.  Reporting On Other Entities

   As discussed in Section 5, not all Energy-related information may be
   available at the concerned entity.  Such information may be provided
   by other entities.  This section covers reporting of information
   only.  See Section 8 for requirements on controlling other entities.

   There are cases where a Power supply unit switches Power for several
   entities by turning Power on or off at a single Power Outlet or where
   a Power meter measures the accumulated Power of several entities at a
   single power line.  Consequently, it should be possible to report
   that a monitored value does not relate to just a single entity, but
   is an accumulated value for a set of entities.  All of these entities
   belonging to that set need to be identified.

7.1.  Reports On Other Entities

   The standard must provide means for an entity to report information
   on another entity.





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7.2.  Identity Of Other Entities On Which Is Reported

   For entities that report on one or more other entities, the standard
   must provide means for reporting the identity of other entities on
   which information is reported.  Note that, in some situations, a
   manual configuration might be required to populate this information.

7.3.  Reporting Quantities Accumulated Over Multiple Entities

   The standard must provide means for reporting the list of all
   entities from which contributions are included in an accumulated
   value.

7.4.  List Of All Entities On Which Is Reported

   For entities that report on one or more other entities, the standard
   must provide means for reporting the complete list of all those
   entities on which Energy-related information can be reported.

7.5.  Content Of Reports On Other Entities

   For entities that report on one or more other entities, the standard
   must provide means for indicating which Energy-related information
   can be reported for which of those entities.

8.  Controlling Other Entities

   This section specifies requirements for controlling Power States and
   power supply of entities by communicating with other entities that
   have means for doing that control.

8.1.  Controlling Power States Of Other Entities

   Some entities have control over Power States of other entities.  For
   example a gateway to a building system may have means to control the
   Power State of entities in the building that do not have an IP
   interface.  For this scenario and other similar cases means are
   needed to make this control accessible to the Energy Management
   System.

   In addition to this, it is required that an entity that has its state
   controlled by other entities has means to report the list of these
   other entities.

8.1.1.  Control Of Power States Of Other Entities






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   The standard must provide means for an Energy Management System to
   send Power State control commands to an entity that concern the Power
   States of entities other than the one the command was sent to.

8.1.2.  Identity Of Other Power State Controlled Entities

   The standard must provide means for reporting the identities of the
   entities for which the reporting entity has means to control their
   Power States.  Note that, in some situations, a manual configuration
   might be required to populate this information.

8.1.3.  List Of All Power State Controlled Entities

   The standard must provide means for an entity to report the list of
   all entities for which it can control the Power State.

8.1.4.  List Of All Power State Controllers

   The standard must provide means for an entity that receives commands
   controlling its Power State from other entities to report the list of
   all those entities.

8.2.  Controlling Power Supply

   Some entities may have control of the Power supply of other entities,
   for example, because the other entity is supplied via a Power Outlet
   of the entity.  For this and similar cases means are needed to make
   this control accessible to the Energy Management System.  This need
   is already addressed by requirement 6.2.

   In addition, it is required that an entity that has its supply
   controlled by other entities has means to report the list of these
   other entities.  This need is already addressed by requirements 5.2.3
   and 5.2.4.

9.  Security Considerations

   Controlling Power State and Power supply of entities are highly
   sensitive actions since they can significantly affect the operation
   of directly and indirectly affected devices.  Therefore all control
   actions addressed in sections 6 and 8 must be sufficiently protected
   through authentication, authorization, and integrity protection
   mechanisms.

   Entities that are not sufficiently secure to operate directly on the
   public Internet do exist and can be a significant cause of risk, for
   example, if the remote control functions described in sections 6 and
   8 can be exercised on those devices from anywhere on the Internet.



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   The standard needs to provide means for dealing with such cases.  One
   solution is providing means that allow for isolation of such devices,
   e.g.  behind a sufficiently secured gateway.  Another solution is
   allowing compliant implementations that have disabled or not
   implemented sensitive functions.

   Monitoring Energy-related quantities of an entity addressed in
   Sections 5 - 8 can be used to derive more information than just the
   received and provided Energy, so monitored data requires protection.
   This protection includes authentication and authorization of entities
   requesting access to monitored data as well as confidentiality
   protection during transmission of monitored data.  Privacy of stored
   data in an entity must be taken into account.  Monitored data may be
   used as input to control, accounting, and other actions, so integrity
   of transmitted information and authentication of the origin may be
   needed.

9.1.  Secure Energy Management

   The standard must provide privacy, integrity, and authentication
   mechanisms for all actions addressed in Sections 5 - 8.  The security
   mechanisms must meet the security requirements elaborated in
   Section 1.4 of [RFC3411].

9.2.  Isolation Of Insufficiently Secure Entities

   The standard must provide means to allow for isolation of entities
   that that are not sufficiently secure to operate on the public
   Internet, e.g., behind a gateway that does implement sufficient
   security so that the vulnerable entities are not directly exposed to
   the Internet.

9.3.  Optional Restriction Of Functions

   The standard must allow for compliant implementations that do not
   implement sensitive functions or disable them when operating in not
   sufficiently secured environments.  This applies particularly to the
   control functions described in sections 6 and 8.

10.  IANA Considerations

   This document has no actions for IANA.









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11.  Acknowledgments

   The authors would like to thank Ralf Wolter for his first essay on
   this draft.  Many thanks to William Mielke, John Parello, JinHyeock
   Choi, Georgios Karagiannis, and Michael Suchoff for their helpful
   comments on the draft.  Many thanks for their IESG reviews to Stephen
   Farrell, Robert Sparks, Adrian Farrel, Barry Leiba, Brian Haberman,
   Peter Resnick, Sean Turner, Stewart Bryant, and Ralph Droms.
   Finally, special thanks to the document shepherd Nevil Brownlee, and
   to the EMAN working group chairs: Nevil Brownlee and Bruce Nordman.

12.  References

12.1.  Normative References

   [RFC3411]  Harrington, D., Presuhn, R., and B. Wijnen, "An
              Architecture for Describing Simple Network Management
              Protocol (SNMP) Management Frameworks", STD 62, RFC 3411,
              December 2002.

   [RFC3621]  Berger, A. and D. Romascanu, "Power Ethernet MIB", RFC
              3621, December 2003.

   [RFC4133]  Bierman, A. and K. McCloghrie, "Entity MIB (Version 3)",
              RFC 4133, August 2005.

   [ANSI-TIA-1057]
              Telecommunications Industry Association, , "ANSI-
              TIA-1057-2006 - TIA Standard - Telecommunications - IP
              Telephony Infrastructure - Link Layer Discovery Protocol
              for Media Endpoint Devices ", April 2006.

   [IEEE-100]
              IEEE, , "Authoritative Dictionary of IEEE Standards Terms,
              IEEE 100, Seventh Edition ", December 2000.

   [IEC.62053-21]
              International Electrotechnical Commission, , "Electricity
              metering equipment (a.c.) - Particular requirements - Part
              22: Static meters for active energy (classes 1 and 2) ",
              2003.

   [IEC.62053-22]
              International Electrotechnical Commission, , "Electricity
              metering equipment (a.c.) - Particular requirements - Part
              22: Static meters for active energy (classes 0,2 S and 0,5
              S) ", 2003.




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   [IEC.61850-7-4]
              International Electrotechnical Commission, ,
              "Communication networks and systems for power utility
              automation - Part 7-4: Basic communication structure -
              Compatible logical node classes and data object classes ",
              2010.

   [IEEE-1621]
              Institute of Electrical and Electronics Engineers, , "IEEE
              P1621-2004 -Draft Standard for User Interface Elements in
              Power Control of Electronic Devices Employed in Office
              Consumer Environments ", June 2005.

   [IEEE-802.1AB]
              IEEE Computer Society, , "IEEE Std 802.1AB-2009 - IEEE
              Standard for Local and metropolitan area networks -
              Station and Media Access Control Discovery ", September
              2009.

12.2.  Informative References

   [RFC5101]  Claise, B., "Specification of the IP Flow Information
              Export (IPFIX) Protocol for the Exchange of IP Traffic
              Flow Information", RFC 5101, January 2008.

   [RFC5102]  Quittek, J., Bryant, S., Claise, B., Aitken, P., and J.
              Meyer, "Information Model for IP Flow Information Export",
              RFC 5102, January 2008.

   [RFC5905]  Mills, D., Martin, J., Burbank, J., and W. Kasch, "Network
              Time Protocol Version 4: Protocol and Algorithms
              Specification", RFC 5905, June 2010.

   [I-D.ietf-eman-applicability-statement]
              Schoening, B., Chandramouli, M., and B. Nordman, "Energy
              Management (EMAN) Applicability Statement", draft-ietf-
              eman-applicability-statement-03 (work in progress), April
              2013.

   [Fed-Std-1037C]
              United States National Communications System Technology
              and Standards Division, , "Federal Standard 1037C -
              Telecommunications: Glossary of Telecommunication Terms ",
              August 1996.

   [IEC60050]





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              , "International Electrotechnical Vocabulary.
              http://www.electropedia.org/iev/iev.nsf/welcome?openform
              ", .

   [ITU-M.3400]
              International Telecommunication Union, , "ITU-T
              Recommendation M.3400 - Series M: TMN and Network
              Maintenance: International Transmission Systems, Telephone
              Circuits, Telegraphy, Facsimile and Leased Circuits -
              Telecommunications Management Network - TMN management
              functions ", February 2000.

Authors' Addresses

   Juergen Quittek (editor)
   NEC Europe Ltd.
   NEC Laboratories Europe
   Network Research Division
   Kurfuersten-Anlage 36
   Heidelberg  69115
   Germany

   Phone: +49 6221 4342-115
   Email: quittek@neclab.eu


   Mouli Chandramouli
   Cisco Systems, Inc.
   Sarjapur Outer Ring Road
   Bangalore
   India

   Phone: +91 80 4426 3947
   Email: moulchan@cisco.com


   Rolf Winter
   NEC Europe Ltd.
   NEC Laboratories Europe
   Network Research Division
   Kurfuersten-Anlage 36
   Heidelberg  69115
   Germany

   Phone: +49 6221 4342-121
   Email: Rolf.Winter@neclab.eu





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   Thomas Dietz
   NEC Europe Ltd.
   NEC Laboratories Europe
   Network Research Division
   Kurfuersten-Anlage 36
   Heidelberg  69115
   Germany

   Phone: +49 6221 4342-128
   Email: Thomas.Dietz@neclab.eu


   Benoit Claise
   Cisco Systems, Inc.
   De Kleetlaan 6a b1
   Diegem  1831
   Belgium

   Phone: +32 2 704 5622
   Email: bclaise@cisco.com






























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