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Network Working Group                                    J. Quittek, Ed.
Internet-Draft                                           NEC Europe Ltd.
Intended status: Informational                           M. Chandramouli
Expires: April 8, 2013                               Cisco Systems, Inc.
                                                               R. Winter
                                                                T. Dietz
                                                         NEC Europe Ltd.
                                                               B. Claise
                                                     Cisco Systems, Inc.
                                                         October 5, 2012


                   Requirements for Energy Management
                    draft-ietf-eman-requirements-09

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.  In detail, the
   focus of the requirements is on the following features:
   identification of energy-managed devices and their components,
   monitoring of their Power State, power inlets, power outlets, actual
   power, power properties, received energy, provided energy, and
   contained batteries.  Further requirements are included to enable
   control of their power supply and Power State.  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 April 8, 2013.

Copyright Notice



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   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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







































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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  5
     1.1.  Conventional Requirements For Energy Management  . . . . .  6
     1.2.  Specific Requirements for Energy Management  . . . . . . .  6

   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  7

   3.  General Considerations Related to Energy Management  . . . . .  8
     3.1.  Power States . . . . . . . . . . . . . . . . . . . . . . .  8
     3.2.  Saving Energy versus Maintaining Service Level
           Agreements . . . . . . . . . . . . . . . . . . . . . . . .  9
     3.3.  Local Versus network-Wide energy Management  . . . . . . .  9
     3.4.  Energy Monitoring Versus Energy Saving . . . . . . . . . .  9
     3.5.  Overview Of Energy Management Requirements . . . . . . . . 10

   4.  Identification Of Entities . . . . . . . . . . . . . . . . . . 10

   5.  Information On Entities  . . . . . . . . . . . . . . . . . . . 11
     5.1.  General Information On Entities  . . . . . . . . . . . . . 11
     5.2.  Power Interfaces . . . . . . . . . . . . . . . . . . . . . 12
     5.3.  Power  . . . . . . . . . . . . . . . . . . . . . . . . . . 14
     5.4.  Power State  . . . . . . . . . . . . . . . . . . . . . . . 16
     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 . . . . . . . . 23
     8.2.  Controlling Power Supply . . . . . . . . . . . . . . . . . 23

   9.  Security Considerations  . . . . . . . . . . . . . . . . . . . 24

   10. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 24

   11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 24

   12. Informative References . . . . . . . . . . . . . . . . . . . . 24

   Appendix A.  Existing Standards  . . . . . . . . . . . . . . . . . 26
     A.1.  Existing IETF Standards  . . . . . . . . . . . . . . . . . 27
       A.1.1.  ENTITY MIB . . . . . . . . . . . . . . . . . . . . . . 27
       A.1.2.  ENTITY STATE MIB . . . . . . . . . . . . . . . . . . . 27
       A.1.3.  ENTITY SENSOR MIB  . . . . . . . . . . . . . . . . . . 28



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       A.1.4.  UPS MIB  . . . . . . . . . . . . . . . . . . . . . . . 28
       A.1.5.  POWER ETHERNET MIB . . . . . . . . . . . . . . . . . . 29
       A.1.6.  LLDP MED MIB . . . . . . . . . . . . . . . . . . . . . 29

   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 29














































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1.  Introduction

   With rising energy cost and with an increasing awareness of the
   ecological impact of running IT 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.
   Subject of energy management are entities in the network.  An entity
   is either a device or one of a device's components that is subject to
   individual energy monitoring or control or both.

   In detail, the requirements listed are focused on the following
   features: identification of entities, monitoring of their Power
   State, power inlets, power outlets, actual power, power properties,
   received energy, provided energy, and contained batteries.  Further
   included is control of entities' power supply and Power State.

   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
   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.

   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 subtended 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.
   o  Energy management often extends beyond entities with IP network
      interfaces, to non-IP building systems accessed via a gateway.
      Requirements in this document do not cover details of these
      networks, 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.



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   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].

   Energy management

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

   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
      directing influence over network elements and attached devices and
      their components.





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   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,
      provice power, or both.

   Power inlet

      A power inlet is a Power Interface at which a device can receive
      power fro 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.
   Use cases for energy management can be found in
   [I-D.ietf-eman-applicability-statement].

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.







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3.2.  Saving Energy versus Maintaining Service Level Agreements

   While the general objective of energy management is quite 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
   performance, service, or capacity degradation.  Then a trade-off
   needs to be dealt with 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.

   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:





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   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)
   o  monitoring (accumulated) received and provided energy
   o  monitoring power properties
   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 uniquely identified.  This includes entities that
   are components of managed devices as well as entire devices.

   For entities that report on or control other entities it is important
   to identify the entities they report on or control, see Section 7 or
   Section 8, respectively.

   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.



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   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.

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.  Using entity identifiers of other MIB modules

   The standard must provide means for re-using entity identifiers from
   other 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

   For energy management it may be required to understand the role and
   context of an entity.  An energy management system may aggregate



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   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 vital 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 either an inlet or an outlet.  Some Power
   Interfaces can change over time from being an inlet to being an
   outlet and vice versa.  However most power interfaces never change.

   entities have power inlets at which they are supplied with electric
   power.  Most entities 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



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   monitoring, it is useful to retrieve information on the number of
   inlets of an entity, the availability of power at inlets and which of
   them are actually in use.

   Entities can have one or more power outlets for supplying other
   entities 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 entity 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 entities.

   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.

5.2.1.  Lists of Power Interfaces

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

5.2.2.  Corresponding power outlet

   The standard must provide means for identifying the power outlet that
   provides the power received at a power inlet.

5.2.3.  Corresponding power inlets

   The standard must provide means for identifying the list of power
   inlets that receive the power provided at a power outlet.

5.2.4.  Availability of power

   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.

5.2.5.  Use of power

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




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5.2.6.  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 an entity.

5.2.7.  Nominal voltage

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

5.2.8.  Nominal AC frequency

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

5.2.9.  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.

   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 supplied power are also of interest.  For
   AC power supply, power attributes beyond the real power to be
   reported include the apparent power, the reactive power, and the
   phase angle of the current or the power factor.  For both AC and DC
   power the power characteristics are also subject of monitoring.
   Power parameters include the actual voltage, the actual frequency,
   the Total Harmonic Distortion (THD) of voltage and current, the
   impedance of an AC phase or of the DC supply.  Power monitoring
   should be in line with existing standards, such as [IEC.61850-7-4].




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   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

   The standard must provide means for reporting the real power for each
   Power Interface as well as for an entire 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

   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 an entire
   entity.  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

   The standard must provide means for reporting the complex power for
   each Power Interface and for each phase at a Power Interface.



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   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.

   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.






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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.

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



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   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.

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

   Many entities contain batteries that supply them with power when
   disconnected from electrical power distribution grids.  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, 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.



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5.6.1.  Battery charge

   The standard must provide means for reporting the current charge of a
   battery.

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.

5.6.5.  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.

5.6.6.  Low battery charge notification

   The standard must provide means for generating a notification when
   the charge of a battery decreases below a given threshold.

5.6.7.  Battery replacement notification

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

5.6.8.  Multiple batteries

   The standard must provide means for meeting requirements 5.6.1 to
   5.6.7 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



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   different ways.  It should be avoided that such time series can only
   be obtained through regular polling by the energy management system.
   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)?
   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.



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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

   The management 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 entities.  And
   controlling power supply is typically not conducted as interaction
   between energy management system and the entity itself.  It is rather
   an interaction between the management system and an entity 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 entity.

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 entity.


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



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   is an accumulated value for a set of entities.  All of these entities
   belonging to that set need to be identified.

   If an entity has information about where energy-related information
   on itself can be retrieved, then it would be useful to communicate
   this information.  This applies even if the information only provides
   accumulated quantities for several entities.

7.1.  Reports on other entities

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

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.

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.

7.6.  Indicating source of remote information

   For an entity that has one or more other entities reporting on its
   behalf, the standard must provide means for the entity to indicate
   which information is available at which other entity.


8.  Controlling Other Entities

   This section specifies requirements for controlling Power States and
   power supply of entities by communicating with other entities that



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   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

   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.

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



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   other entities.  This need is already addressed by requirements 5.2.2
   and 5.2.3.


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 6 and 8 must be sufficiently protected through
   authentication, authorization, and integrity protection mechanisms.

   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 privacy
   protection.  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 address all threats listed in Section 1.4 of
   [RFC3411].


10.  IANA Considerations

   This document has no actions for IANA.


11.  Acknowledgements

   The authors would like to thank Ralf Wolter for his first essay on
   this draft.  Many thanks to William Mielke, John Parello, Bruce
   Nordman, JinHyeock Choi, Georgios Karagiannis, and Michael Suchoff
   for helpful comments on the draft.


12.  Informative References

   [RFC1628]  Case, J., "UPS Management Information Base", RFC 1628,
              May 1994.

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



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              December 2002.

   [RFC3433]  Bierman, A., Romascanu, D., and K. Norseth, "Entity Sensor
              Management Information Base", RFC 3433, 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.

   [RFC4268]  Chisholm, S. and D. Perkins, "Entity State MIB", RFC 4268,
              November 2005.

   [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.

   [I-D.ietf-eman-applicability-statement]
              Silver, L., Chandramouli, M., and B. Nordman, "Energy
              Management (EMAN) Applicability Statement",
              draft-ietf-eman-applicability-statement-01 (work in
              progress), June 2012.

   [ACPI.R30b]
              Hewlett-Packard Corporation, Intel Corporation, Microsoft
              Corporation, Phoenix Corporation, and Toshiba Corporation,
              "Advanced Configuration and Power Interface
              Specification, Revision 3.0b", October 2006.

   [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.

   [DMTF.DSP1027]
              Dasari (ed.), R., Davis (ed.), J., and J. Hilland (ed.),
              "Power State Management Profile", September 2008.

   [Fed-Std-1037C]
              United States National Communications System Technology &
              Standards Division, "Federal Standard 1037C -
              Telecommunications:  Glossary of Telcommunication Terms",



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              August 1996.

   [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.

   [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.

   [ITU-M.3400]
              International Telcommunication 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.


Appendix A.  Existing Standards

   This section analyzes existing standards for energy and Power State



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   monitoring.  It shows that there are already several standards that
   cover only some part of the requirements listed above, but even all
   together they do not cover all of the requirements for energy
   management.

A.1.  Existing IETF Standards

   There are already RFCs available that address a subset of the
   requirements.

A.1.1.  ENTITY MIB

   The ENTITY-MIB module defined in [RFC4133] was designed to model
   physical and logical entities of a managed system.  A physical entity
   is an identifiable physical component.  A logical entity can use one
   or more physical entities.  From an energy monitoring perspective of
   a managed system, the ENTITY-MIB modeling framework can be reused and
   whenever RFC 4133 [RFC4133] has been implemented.  The
   entPhysicalIndex from entPhysicalTable can be used to identify an
   entity/component.  However, there are use cases of energy monitoring,
   where the application of the ENTITY-MIB does not seem readily
   apparent and some of those entities could be beyond the original
   scope and intent of the ENTITY-MIB.

   Consider the case of remote devices attached to the network, and the
   network device could collect the energy measurement and report on
   behalf of such attached devices.  Some of the remote devices such as
   PoE phones attached to a switch port have been considered in the
   Power-over-Ethernet MIB module [RFC3621].  However, there are many
   other devices such as a computer, which draw power from a wall outlet
   or building HVAC devices which seem to be beyond the original scope
   of the ENTITY-MIB.

   Yet another example, is smart-PDUs, which can report the energy
   provided to the device attached to the power outlet of the PDU.  In
   some cases, the device can be attached to multiple to power outlets.
   Thus, the energy measured at multiple outlets need to be aggregated
   to determine the energy provided to a single device.  From mapping
   perspective, between the PDU outlets and the device this is a many-
   to-one mapping.  It is not clear if such a many-to-one mapping is
   feasible within the ENTITY-MIB framework.

A.1.2.  ENTITY STATE MIB

   RFC 4268 [RFC4268] defines the ENTITY STATE MIB module.
   Implementations of this module provide information on entities
   including the standby status (hotStandby, coldStandby,
   providingService), the operational status (disabled, enabled,



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   testing), the alarm status (underRepair, critical, major, minor,
   warning), and the usage status (idle, active, busy).  This
   information is already useful as input for policy decisions and for
   other network management tasks.  However, the number of states would
   cover only a small subset of the requirements for Power State
   monitoring and it does not provide means for energy monitoring.  For
   associating the information conveyed by the ENTITY STATE MIB to
   specific components of a device, the ENTITY STATE MIB module makes
   use of the means provided by the ENTITY MIB module [RFC4133].
   Particularly, it uses the entPhysicalIndex for identifying entities.

   The standby status provided by the ENTITY STATE MIB module is related
   to Power States required for energy management, but the number of
   states is too restricted for meeting all energy management
   requirements.  For energy management several more Power States are
   required, such as different sleep and operational states as defined
   by the Advanced Configuration and Power Interface (ACPI) [ACPI.R30b]
   or the DMTF Power State Management Profile [DMTF.DSP1027].

A.1.3.  ENTITY SENSOR MIB

   RFC 3433 [RFC3433] defines the ENTITY SENSOR MIB module.
   Implementations of this module offer a generic way to provide data
   collected by a sensor.  A sensor could be an energy meter delivering
   measured values in Watt.  This could be used for reporting current
   power of an entity and its components.  Furthermore, the ENTITY
   SENSOR MIB can be used to retrieve the accuracy of the used power
   meter.

   Similar to the ENTITY STATE MIB module, the ENTITY SENSOR MIB module
   makes use of the means provided by the ENTITY MIB module [RFC4133]
   for relating provided information to components of a device.

   However, there is no unit available for reporting energy quantities,
   such as, for example, watt seconds or kilowatt hours, and the ENTITY
   SENSOR MIB module does not support reporting accuracy of measurements
   according to the IEC / ANSI accuracy classes, which are commonly in
   use for electric power and energy measurements.  The ENTITY SENSOR
   MIB modules only provides a coarse-grained method for indicating
   accuracy by stating the number of correct digits of fixed point
   values.

A.1.4.  UPS MIB

   RFC 1628 [RFC1628] defines the UPS MIB module.  Implementations of
   this module provide information on the current real power of entities
   attached to an uninterruptible power supply (UPS) device.  This
   application would require identifying which entity is attached to



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   which port of the UPS device.

   UPS MIB provides information on the state of the UPS network.  The
   MIB module contains several variables that are used to identify the
   UPS entity (name, model,..), the Battery State, to characterize the
   input load to the UPS, to characterize the output from the UPS, to
   indicate the various alarm events.  The measurements of power in UPS
   MIB are in Volts, Amperes and Watts.  The units of power measurement
   are RMS volts, RMS Amperes and are not based on Entity-Sensor MIB
   [RFC3433].

A.1.5.  POWER ETHERNET MIB

   Similar to the UPS MIB, implementations of the POWER ETHERNET MIB
   module defined in RFC3621 [RFC3621] provide information on the
   current power of the entities that receive Power over Ethernet (PoE).
   This information can be retrieved at the power sourcing equipment.
   Analogous to the UPS MIB, it is required to identify which entities
   are attached to which port of the power sourcing equipment.

   The POWER ETHERNET MIB does not report power and energy on a per port
   basis, but can report aggregated values for groups of ports.  It does
   not use objects of the ENTITY MIB module for identifying entities,
   although this module existed already when the POWER ETHERNET MIB
   modules was standardized.

A.1.6.  LLDP MED MIB

   The Link Layer Discovery Protocol (LLDP) defined in IEEE 802.1ab is a
   data link layer protocol used by network devices for advertising of
   their identities, capabilities, and interconnections on a LAN
   network.  The Media Endpoint Discovery (MED) (ANSI-TIA-1057) is an
   enhancement of LLDP known as LLDP-MED.  The LLDP-MED enhancements
   specifically address voice applications.  LLDP-MED covers 6 basic
   areas: capabilities discovery, LAN speed and duplex discovery,
   network policy discovery, location identification discovery,
   inventory discovery, and power discovery.














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Authors' Addresses

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

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


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

   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
   DE

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


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

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





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   Benoit Claise
   Cisco Systems, Inc.
   De Kleetlaan 6a b1
   Degem  1831
   BE

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











































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