One document matched: draft-ietf-eman-requirements-04.xml
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<rfc category="info" docName="draft-ietf-eman-requirements-04" ipr="trust200902">
<front>
<title>Requirements for Energy Management</title>
<author fullname="Jürgen Quittek" initials="J." role="editor"
surname="Quittek">
<organization>NEC Europe Ltd.</organization>
<address>
<postal>
<street>NEC Laboratories Europe</street>
<street>Network Research Division</street>
<street>Kurfuersten-Anlage 36</street>
<code>69115</code>
<city>Heidelberg</city>
<country>DE</country>
</postal>
<phone>+49 6221 4342-115</phone>
<email>quittek@neclab.eu</email>
</address>
</author>
<author fullname="Rolf Winter" initials="R." surname="Winter">
<organization>NEC Europe Ltd.</organization>
<address>
<postal>
<street>NEC Laboratories Europe</street>
<street>Network Research Division</street>
<street>Kurfuersten-Anlage 36</street>
<code>69115</code>
<city>Heidelberg</city>
<country>DE</country>
</postal>
<phone>+49 6221 4342-121</phone>
<email>Rolf.Winter@neclab.eu</email>
</address>
</author>
<author fullname="Thomas Dietz" initials="T." surname="Dietz">
<organization>NEC Europe Ltd.</organization>
<address>
<postal>
<street>NEC Laboratories Europe</street>
<street>Network Research Division</street>
<street>Kurfuersten-Anlage 36</street>
<code>69115</code>
<city>Heidelberg</city>
<country>DE</country>
</postal>
<phone>+49 6221 4342-128</phone>
<email>Thomas.Dietz@neclab.eu</email>
</address>
</author>
<author fullname="Benoit Claise" initials="B." surname="Claise">
<organization>Cisco Systems, Inc.</organization>
<address>
<postal>
<street>De Kleetlaan 6a b1</street>
<city>Degem</city>
<code>1831</code>
<country>BE</country>
</postal>
<phone>+32 2 704 5622</phone>
<email>bclaise@cisco.com</email>
</address>
</author>
<author fullname="Mouli Chandramouli" initials="M." surname="Chandramouli">
<organization>Cisco Systems, Inc.</organization>
<address>
<postal>
<street>Sarjapur Outer Ring Road</street>
<city>Bangalore</city>
<region></region>
<code></code>
<country>IN</country>
</postal>
<phone>+91 80 4426 3947</phone>
<email>moulchan@cisco.com</email>
</address>
</author>
<date month="July" year="2011" />
<abstract>
<t>This document defines requirements for standards specifications
for energy management. Defined requirements concern monitoring
functions as well as control functions. Covered functions include
identification of powered entities, monitoring of their power
state, power inlets, power outlets, actual power, consumed energy,
and contained batteries. Further included is control of powered
entities' 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.</t>
</abstract>
</front>
<middle>
<!-- Introduction =================================================== -->
<section title="Introduction">
<t>With rising energy cost and with an increasing awareness of the
ecological impact of running IT and networking equipment, energy
management is becoming an additional basic requirement for network
management systems and frameworks.</t>
<t>This document defines requirements for standards specifications
for energy management. Defined requirements concern monitoring
functions as well as control functions. Covered functions include
identification of powered entities, monitoring of their power
state, power inlets, power outlets, actual power, consumed energy,
and contained batteries. Further included is control of powered
entities' power supply and power state. Note that 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.</t>
<t>The main subject of energy management are powered entities
that consume electric energy. Powered entities include devices
that have an IP address and can be addressed directly, such as
hosts, routers, and middleboxes, as well as devices indirectly
connected to an IP network, for which a proxy with an IP address
provides a management interface, for example, devices in a building
management infrastructure using BACNET or MODBUS protocols.</t>
<t>The requirements specified in this document explicitly 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. But which
of the features specified by these
standards will be mandatory, recommended, or optional for compliant
implementations is to be defined by the concrete standards track
document(s) and not in this document.</t>
<t>This document first discusses general objectives of
energy management in <xref target="goals"/>. Requirements
for an energy management standard are specified in Sections
<xref format="counter" target="identity"/> to
<xref format="counter" target="controlother"/>.</t>
<section anchor="conventional"
title="Conventional requirements for energy management">
<t>The specification of requirements for an energy management
standard starts with <xref target="identity"/> addressing
the identification of powered entities and the granularity of
reporting of energy-related information. A standard must
support unique identification of powered entities. Furthermore,
it must support more than just reporting per powered device.
Support is required for also reporting energy-related information
on individual components of a device or subtended devices.
This is why this draft uses the more general term "powered
entity" rather than "powered device". A powered entity may be a
device or a component of a device.</t>
<t><xref target="properties"/> specifies requirements related
to monitoring of powered 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 powered
entities is covered by requirements specified in
<xref target="control"/>.</t>
</section>
<section title="Specific requirements for energy management">
<t>At first glance the rather conventional requirements
summarized above seem to be all that would be needed for
energy management. But it turns out that there are
some significant differences between energy management and
most of the well known conventional network management functions.
The most significant difference from many other management
functions is the need for some devices to report on other
entities. There are three major reasons for this.
<list style="symbols">
<t>For monitoring and controlling a particular powered
entity in general it is not sufficient to communicate with
the powered entity only, but in many cases also communication with
other powered entities along the power distribution path may be
necessary, for example, with power switches and power meters.
Indeed, there are situations where a power or energy meter
is not located in the powered entity, but in a different
physical location. For example, a Power Distribution Unit
(PDU), which supplies power for a server connected to a
PDU socket, would meter the power supplied, while the server
may not have the capability to measure its power consumption.
A second example is a Power over Ethernet port, which
provides power to the attached device, and which can meter
how much power/energy it delivers to the attached device.</t>
<t>Energy management often extends its scope beyond
powered entities with IP network interfaces, for example toward
non-IP building networks, that are accessed via an IP gateway.
Requirements in this document do not fully cover all these
networks, but they cover means for opening IP network
management towards them.</t>
<t>For monitoring of particular powered entities, it is
sometimes not a scalable approach to communicate directly
with all the powered entities directly from a central energy
management system as the number of powered entities keeps
increasing.</t>
</list></t>
<t>This specific issue of energy management and a set of
further ones are covered by requirements specified in Sections
<xref format="counter" target="reportonother"/> and
<xref format="counter" target="controlother"/>.</t>
</section>
</section>
<!-- Terminology ==================================================== -->
<section anchor="terminology" title="Terminology">
<section toc="exclude" title="Energy">
<!--
<t>Electric Energy is needed for operating electric
entities. These powered entities "consume" electric energy by
converting it to thermal energy (heat) or other kinds of
energy while conducting their operational tasks. For energy
management, the total energy converted by a powered entitiy during
a time interval is of interest.</t>
-->
<t>the definition of the term energy is to be agreed on in the EMAN WG.</t>
<t>The term 'energy consumption' is commonly used for both,
for referring to the amount of consumed energy and also
for referring to the rate of consuming energy. In the
first case it addresses consumed energy measured by joule,
watthour, or another energy unit, in the second one
it addresses power, typically an average power measured by watt.</t>
<t>However, in this document the term "consumed energy" always
refers to an energy quantity (measured in joule, watthour, etc.)
and not to a power quantity (measured in watt, etc.).</t>
</section>
<section toc="exclude" title="Power">
<!--
<t>Power is defined as energy conversion rate. For energy
management, the instantaneous power of a managed entity may
be of interest as well as the average power over a time
interval.</t>
-->
<t>the definition of the term power is to be agreed on in the EMAN WG.</t>
</section>
<!-- ????
<section title="Demand">
<t>Demand is defined as energy measurement over finite time intervals </t>
</section>
-->
<section toc="exclude" title="Powered entity">
<t>A powered entity is a consumer of energy that is subject
to energy management. In general, all managed physical
entities in a communication network consume electric energy
and thus are subject to energy management including
particularly energy monitoring and energy control.</t>
<t>A powered entity can be a managed device or a component
of a managed device, which is monitored or controlled
individually.</t>
</section>
<section toc="exclude" title="Power state">
<t>Power state of a powered entitiy is defined as a specific settings
of a powered entitiy that influences its power. Examples of power
states of a powered entitiy are on, off, and sleep.</t>
</section>
<section toc="exclude" title="Power monitor">
<t>Energy management requires retrieving energy-related
information on powered entities. In many cases this
information is not available at the powered entities themselves,
but at other powered entities. For example measurement of power and
energy consumption can be conducted by power meters at
other locations along the power distribution tree for
the powered entity.</t>
<t>A power monitor is a module that reports energy-related
information on powered entities. A power monitor may be
integrated into a powered entity or located remotely of
the powered entity. Instances of power monitors may report
information on, for example, power supply, power, and power
state of a powered entity. There may be multiple power
monitors reporting information on the same powered entity.
</t>
</section>
<section toc="exclude" title="Power inlet">
<t>Powered entities receive power at their power inlets.
Powered entities may have multiple inlets, for example,
servers with redundant power supply. Examples for
power inlets are AC power cords of a powered entity or an
Ethernet port at which the powered entity receives DC Power
over Ethernet (PoE).</t>
</section>
<section toc="exclude" title="Power outlet">
<t>Powered entities may have means to supply others with electrical
power. Power is delivered to other powered entities through power
outlets. Power sourcing entities often have more than one power
outlet. Examples for power outlets are AC power sockets at
a Power Distribution Unit (PDU) and Ethernet ports at a
Power over Ethernet (PoE) Power Sourcing Equipment (PSE),
that can supply powered entities with DC power using the Ethernet
cable.</t>
</section>
<section toc="exclude" title="Energy management">
<!--
<t>Energy management deals with assessing and influencing the
consumption of energy in a network of powered entities.
A typical objective of energy management is reducing the energy
consumption in the network. Ways towards achieving this
objective may be limited by other objectives of a general
network management system, such as service level objectives.</t>
-->
<t>the definition of the term power is to be agreed on in the EMAN WG.</t>
</section>
<section toc="exclude" title="Energy management standard">
<t>This document specifies requirements for an energy management
standard. This term refers to a collections of documents
specifying standards for energy-related monitoring and control.
The energy management standard specifies means for building
energy management systems.</t>
<t>Requirements specified in this document
concern the means that an energy management standard must
provide. It does not imply that all required means must be
implemented in all energy standard scenarios. Which means and
features must be implemented by compliant implementations is to
be specified by the energy management standard itself, not by
this requirements document.</t>
<t>Note that for meeting individual requirements specified
in this document, new standards are not necessarily required.
It is recommended to rather use existing standards than
specify new ones.</t>
</section>
</section>
<!-- Objectives ===================================================== -->
<section anchor="goals" title="General Objectives of Energy Management">
<t>The basic objective of energy management is operating
communication networks and other equipment with minimal amount
of energy, while maintaining a certain level of service.
A set of use cases for energy management can be found in
<xref target="I-D.tychon-eman-applicability-statement"></xref>.
</t>
<section anchor="powerstates" title="Power states">
<t>One approach to achieve this goal is by setting all
powered entities to an operational state that results in
lower energy consumption, but still meets the service level
performance objectives. The sufficient performance level
may vary over time and can depend on several factors.
In principle, there are four basic types of power states
for a powered entity or for a whole system:
<list style="symbols">
<t>full power state</t>
<t>reduced power states (lower clock rate for processor,
lower data rate on a link, etc.)</t>
<t>sleep state (not functional, but immediately
available)</t>
<t>off state (may imply requiring significant time
for becoming operational)</t>
</list>
In actual implementations the number of power
states and their properties vary a lot. Very simple powered
entities may just have only the extreme states, full power
and off state. Some implementations might use
IEEE1621 model of three states on, off, and sleep. However,
more granular power states can be implemented with many
levels of off, sleep, and reduced power states.</t>
</section>
<section anchor="tradeoffs" title="Trade-offs">
<t>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 consumption
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 efficiency.
In other cases a reduction of energy consumption can easily
be achieved while still maintaining sufficient service level
performance, for example, by switching powered entities to
lower power states when higher performance is not needed.</t>
</section>
<section anchor="localglobal" title="Local and network-wide
energy management">
<t>Many energy saving functions can be executed locally by
a powered entitiy. The basic principle is that a powered
entitiy monitors its usage and dynamically adapts its energy
consumption according to the required performance. It may
switch to a sleep state when it is not in use at all.
Potential interactions with an energy management system for
such an entity include the observation of the entity's power
state and the configuration of power saving policies, for
example, by setting thresholds for power state changes.</t>
<t>Energy savings can also be achieved with policies
implemented by a network management system that controls
power states of managed entities. In order to make policy
decisions properly, information about the energy consumption
of powered entities in different power states is required. Often this
information is acquired best through monitoring.</t>
<t>Both methods, network-wide and local energy management,
have advantages and disadvantages. Most buildings use both
of them. In some cases for example,
significant energy savings can be achieved by simply setting
all powered entities in a network to sleep, when the network is not
needed. However, in general it is dangerous to set all
powered entities of a group to the same state, because there is a
risk that such actions ignore specifics of individual
powered entities or violate local service level agreements.</t>
</section>
<section anchor="monitoring" title="Energy monitoring">
<t>It should be noted that only monitoring energy consumption
and power states is obviously not a means to reduce the energy
consumption of a powered entitiy. In fact, it is likely to increase
the power consumption of a powered entitiy slightly because
monitoring energy may require instrumentation that consumes
energy when in use. And also reporting of measured quantities
over the network consumes energy. However, the
acquired energy consumption and power state information is
essential for defining energy saving policies and can be used
as input to power state control loops that in total can lead
to energy savings.</t>
<t>Monitoring operational power states and energy consumption
can also be required for other energy management purposes
including but not limited to:
<list style="symbols">
<t>investigating power saving potential</t>
<t>evaluating the effectiveness of energy saving policies
and measures</t>
<t>deriving, implementing, and testing power management
strategies</t>
<t>accounting for the total power consumption of a powered
entity, a network, or a service</t>
<t>predicting a powered entitiy's reliability based on power usage</t>
<t>choosing time of next maintenance cycle for a powered entitiy</t>
</list></t>
</section>
<section anchor="requirements" title="Overview of energy
management requirements">
<t>From the considerations described above the following
basic management functions appear to be required for energy
management:
<list style="symbols">
<t>monitoring power states</t>
<t>monitoring power (energy consumption rate)</t>
<t>monitoring (accumulated) energy consumption</t>
<t>setting power states</t>
<t>setting and enforcing power saving policies</t>
</list></t>
<t>It should be noted that active power control is
complementary (but essential) to other energy savings measures
such as low power electronics, energy saving protocols
(for example, IEEE 802.3az), energy-efficient device design
(for example, sleep and low-power modes for individual
components of a device), and energy-efficient network architectures.
Measurement of energy consumption may also provide useful
input for developing these technologies.</t>
</section>
</section>
<!-- Requirements related to Identity of entities =========== -->
<section anchor="identity" title="Identification of Powered Entities">
<t>As already stated <xref target="conventional"/>, powered entities
on which energy-related information is provided are identified
in a sufficiently unique way. This holds in particular for
powered entities that are components of managed devices and in case
that one powered entity reports information on another one, see
<xref target="reportonother"/>. For powered entities
that control other powered entities it is important to
identify the powered entities they control, see
<xref target="controlother"/>.</t>
<t>Also stated already in <xref target="conventional"/> is the
requirement of providing means for reporting energy-related
information on components of a managed device. An entity in
this document may be an entire managed device or just a
component of it. Examples of components of interest are
a hard drive, a battery, or a line card. For controlling
entities it may be required to be able to address individual
components in order 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 times.</t>
<t>Instrumentation for measuring energy consumption of a
device is typically more expensive than instrumentation for
retrieving the devices power state. It may be a reasonable
compromise in many cases to provide power state information
for all individually switchable components of a device
separately, while the energy consumption is only measured for
the entire device.</t>
<t>Detailed Requirements:</t>
<section toc="exclude" title="Identifying powered entities">
<t>The energy management standard must provide means for
uniquely and persistently identifying powered entities that
are monitored or controlled by an energy management system.
Uniqueness must be given in a domain that is large enough to
avoid collisions of identities at potential receivers of
monitored information.</t>
</section>
<section toc="exclude"
title="Identifying components of powered devices">
<t>The energy management standard must provide means for
identifying not just entire devices as powered entities, but
also individual components of powered devices.</t>
</section>
<section toc="exclude"
title="Persistency of Identifiers">
<t>The energy management standard must provide means for
indicating whether identifiers of powered entities are
persistent across a re-start of the powered entitiy that provides
the identifiers.</t>
</section>
</section>
<!-- Requirements related to powered entities monitoring ===== -->
<section anchor="properties" title="Information on Powered Entities">
<t>This section describes energy-related information on powered
entities for which an energy management standard must provide
means for retrieving and reporting.</t>
<t>Note that the fact that an energy management standard provides
required means does not imply that all of them must be
implemented by every compliant implementation. The concrete
specification of standards based on these requirements may
label individual features as mandatory, recommended, or
optional.</t>
<t>Required information on powered entities can be structured
into six groups.
<!-- <list style="symbols">
<t>general information</t>
<t>power states</t>
<t>power inlets and outlets</t>
<t>power</t>
<t>energy</t>
<t>batteries</t>
</list> -->
<xref target="general"/> specifies requirements for general
information on powered entities, such as type of powered entity or
context information. <xref target="state"/> covers requirements
related to entities' power states. Requirements for information
on power inlets and power outlets of powered entities are specified in
<xref target="inlet"/>. Monitoring of power and energy is covered
by Sections <xref format="counter" target="power"/> and
<xref format="counter" target="energy"/>, respectively. Finally,
<xref target="battery"/> specified requirements for monitoring
batteries.</t>
<section anchor="general" title="General information on powered entities">
<t>For energy management it may be required to understand the role and
context of a powered entitiy. When monitoring, it may be helpful
to group energy consumption per kind of entity. When controlling
and setting power states it may be helpful to understand the
kind and role of a powered entitiy in a network, for example, in order
to avoid switching off vital network components.</t>
<t>Detailed Requirements:</t>
<section anchor="type" toc="exclude"
title="Type of powered entity">
<t>The energy management standard must provide means to
retrieve and report the type of powered entities according
to a standrdized classification scheme.</t>
</section>
<section anchor="context" toc="exclude"
title="Context information on powered entities">
<t>The energy management standard must provide means for
retrieving and reporting context information on powered
entities, for example tags associated with a powered entity that
indicate the powered entitiy's role, or importance.</t>
</section>
<section toc="exclude" title="Grouping of powered entities">
<t>The energy management standard must provide means for
grouping powered entities, for example, into energy
monitoring domains, energy control domains, power supply
domains, groups of powered entities of the same type, etc.</t>
</section>
</section>
<section anchor="state" title="Power state">
<t>Many powered entities have a limited number of discrete
power states, such as, for example, full power, low power, sleep,
and off.</t>
<t>Obviously, there is a need to report the actual power state
of a powered entitiy. Beyond that, there is also a requirement for
standardizing means for retrieving the list of all supported
power states of a powered entitiy.</t>
<t>Different standards bodies have already defined their own
sets of power states for powered entities. Further organizations
are in the process of adding more of these sets. In order to
support multiple management systems possibly using different
power state sets, while simultaneously interfacing with a
particular powered entity, the energy management standard must provide
means for supporting multiple power state sets used
simultaneously at a powered entity. </t>
<t>Power states have parameters that describe its properties
It is required to have standardized means for reporting some
key properties, such as mean power and maximum power of a
powered entitiy in a certain state.</t>
<t>There also is a need to report statistics on power states
including the time spent an the energy consumed in a power state.</t>
<t>For some network management tasks, it may be desirable to
receive notifications from powered entities, for example, when the
components or the entire entity change their power state.</t>
<t>Detailed Requirements:</t>
<section toc="exclude" title="Actual power state">
<t>The energy management standard must provide means for
reporting the actual power state of a powered entitiy.</t>
</section>
<section toc="exclude" title="List of supported power states">
<t>The energy management standard must provide means for
retrieving the list of all potential power states of a powered entitiy.</t>
</section>
<section toc="exclude" title="Multiple power state sets">
<t>The energy management standard must provide means for
supporting multiple power state sets simultaneously at a
powered entity. </t>
</section>
<section toc="exclude" title="List of supported power state sets">
<t>The energy management standard must provide means for retrieving
the list of all power state sets supported by a powered entitiy.</t>
</section>
<section toc="exclude" title="List of supported power states">
<t>Referring to the "list of supported power state sets"
requirement, the energy management standard must provide
means for retrieving the list of all potential power states
of a powered entitiy that belong to a given power state set.</t>
</section>
<section toc="exclude"
title="Maximum and average power per power state">
<t>The energy management standard must provide means for
retrieving the maximum power and the average power as a
typically static property for each supported power state.</t>
</section>
<section toc="exclude"
anchor="statistics" title="Power state statistics">
<t>The energy management standard must provide means for monitoring
statistics per power state including at least the total time spent
in a power state, the number of times a state was entered
and the last time a state was entered. More power state
statistics are addressed by requirement
<xref format="counter" target="energyperstate"/>.</t>
</section>
<section toc="exclude" title="Power state changes">
<t>The energy management standard must provide means for
generating a notification when the actual power state
of a powered entity changes.</t>
</section>
</section>
<section anchor="inlet" title="Power inlet and power outlet">
<t>Powered entities have power inlets at which they are
supplied with electric power. Most powered entities just have a
single power inlet, while some have multiple ones.
Often different power inlets are connected to separate
power distribution trees. For energy monitoring,
it is important information which power inlets a powered entitiy has,
if power is available at an inlet and which of them are
actually in use.</t>
<t>Some powered entities have power outlets for supplying
other powered entities with electric power. A powered entitiy
may have multiple power outlets. Examples are Power
Distribution Units (PDUs) and Power over Ethernet (PoE)
Power Sourcing Equipment (PSE).</t>
<t>For identifying and potentially controlling the source of
power received at an inlet, it may be required to identify the power
outlet of another powered 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.</t>
<t>Static properties of each power inlet and each power outlet
are required information for energy management. Static properties
include the kind of electric current (Alternating Current
(AC) or Direct Current (DC)), the nominal voltage, the nominal
AC frequency, and the number of AC phases.</t>
<t>Detailed Requirements:</t>
<section toc="exclude"
title="List of power inlets and power outlets">
<t>The energy management standard must provide means for monitoring
the list of power inlets and power outlets at a powered entitiy.</t>
</section>
<section toc="exclude" title="Corresponding power outlet">
<t>The energy management standard must provide means for
identifying the power outlet that provides the power
received at a power inlet.</t>
</section>
<section toc="exclude" title="Corresponding power inlets">
<t>The energy management standard must provide means for
identifying the list of power inlets that receive the power
provided at a power outlet.</t>
</section>
<!--
It would be useful to explain the context of this requirement.
This seems tracing the power distribution tree.
Yes, good point. Let's add such text to the next version.
-->
<section anchor="availability" toc="exclude"
title="Availability of power">
<t>The energy management standard must provide means for monitoring
the availability of power at each power inlet and each power outlet.
This information indicates whether at a power providing outlet
power supply is switched on or off.</t>
</section>
<section toc="exclude" title="Use of power">
<t>The energy management standard must provide means for monitoring
for each power inlet and each power outlet if it is in actual use.
For the inlet this means that the powered entitiy actually receives power
at the inlet. For the outlet this means that actually power
is provided to one or more powered entities at the outlet.</t>
</section>
<section toc="exclude" title="Type of current">
<t>The energy management standard must provide means for
reporting the type of current (Alternating Current (AC) or
Direct Current (DC)) for each power inlet and each power
outlet of a powered entity.</t>
</section>
<section toc="exclude" title="Nominal voltage">
<t>The energy management standard must provide means for
reporting the nominal voltage for each power inlet and
each power outlet of a powered entity.</t>
</section>
<section toc="exclude" title="Nominal AC frequency">
<t>The energy management standard must provide means for
reporting the nominal AC frequency for each power inlet and
each power outlet of a powered entity.</t>
</section>
<section toc="exclude" title="number of AC phases">
<t>The energy management standard must provide means for
reporting the number of AC phases for each power inlet and
each power outlet of a powered entity.</t>
</section>
</section>
<section anchor="power" title="Power">
<t>Power is a quantity measured as instantaneous power or
as average power over a time interval. In contrast to power
state values, this quantity may change continuously.</t>
<t>Obtaining highly accurate values for power and energy may be costly.
Often dedicated metering hardware is needed for this purpose.
Powered entities without the ability to measure their power and energy
consumption with high accuracy may just report estimated values,
for example based on load monitoring or even just the entity type.</t>
<t>Depending on how power and energy consumption values are
obtained the confidence in the reported value and its accuracy
may vary. Powered 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 <xref target="IEC.62053-21">IEC 62053-21</xref>
and <xref target="IEC.62053-22">IEC 62053-22</xref> should be
considered.</t>
<t>In addition to the plain real power value, also further
properties of the supplied power are subject
to monitoring. In case of AC power supply, there are more
power values beyond the real power to be reported including
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 quality is also subject of monitoring.
Power quality 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 quality monitoring should be in line with
existing standards, such as <xref target="IEC.61850-7-4"/>.</t>
<t>For some network management tasks, it is required to
obtain time series of power values (or energy consumption
values). In general these could be obtained in many different
ways. It should be avoided that such time series can only be
obtained by regular polling by the energy management system.
Means should be provided to either push such values from the
place they are available to the management system or to have
them stored at the powered entitiy for a sufficiently long period of
time such that a management system can retrieve a stored time
series of values.</t>
<t>Detailed Requirements:</t>
<section toc="exclude" title="Real power">
<t>The energy management standard must provide means for
reporting the real power for each power inlet and each
power outlet of a powered entity.</t>
</section>
<section toc="exclude" title="Power measurement interval">
<t>The energy management 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.</t>
</section>
<section toc="exclude" title="Confidence in power values">
<t>The energy management standard must provide means for
reporting the confidence in reported power values by
indicating the way these values have been obtained.
for example, by power measurement, by estimation based on
performance values, or hard coding average power values
for a powered entity.</t>
</section>
<section toc="exclude"
title="Accuracy of power and energy values">
<t>The energy management standard must provide means for
reporting the accuracy of reported power values.</t>
</section>
<section toc="exclude" title="Complex power">
<t>The energy management standard must provide means for
reporting the complex power for each power inlet and each
power outlet of a powered entity. 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. In case of AC power supply, means must
be provided for reporting the complex power per phase.</t>
</section>
<section toc="exclude" title="Actual voltage and current">
<t>The energy management standard must provide means for
reporting the actual voltage and actual current for each
power inlet and each power outlet of a powered entity.
In case of AC power supply, means must be provided for
reporting the actual voltage and actual current per phase.</t>
</section>
<section toc="exclude" title="Actual AC frequency">
<t>The energy management standard must provide means for
reporting the actual AC frequency for each power inlet and
each power outlet of a powered entity.</t>
</section>
<section toc="exclude" title="Total harmonic distortion">
<t>The energy management standard must provide means for
reporting the Total Harmonic Distortion (THD) of voltage and
current for each power inlet and each power outlet of a
powered entity. In case of AC power supply, means must be
provided for reporting the THD per phase.</t>
</section>
<section toc="exclude" title="Power supply impedance">
<t>The energy management standard must provide means for
reporting the impedance of power supply for each power
inlet and each power outlet of a powered entity.
In case of AC power supply, means must be provided for
reporting the impedance per phase.</t>
</section>
<section toc="exclude" title="Time series of power values">
<t>The energy management standard must provide means for
collecting time series of real power values for each power
inlet and for each power outlet of a powered entitiy without requiring
to regularly poll the powered entitiy from an energy management
station. A solution for this is that the concerned powered entity
or another powered entity closely interacting with the concerned
powered entity collect time series of power values and make them
available via push or pull mechanisms to receivers of the
information.</t>
</section>
</section>
<section anchor="energy" title="Energy">
<t>Monitoring of electrical energy consumed (or converted) at
a powered entitiy can be done in various ways. One is collecting
time series of power values for the powered entitiy and calculating
the consumed energy from these values. An alternative is the
powered entity itself or another powered entity taking care of energy
measurement and reporting energy consumption values for
certain time intervals. Time intervals of interest are
the time from the last restart of the powered entitiy to the reporting
time, the time from another past event to the reporting time,
or the last given amount of time before the reporting time.</t>
<t>In order to monitor energy consumption in different power
states, it is useful if powered entities record their energy
consumption per power state and report these quantities.</t>
<t>For some network management tasks, it is required to
obtain time series of energy values. In general these could
be obtained in many different ways. It should be avoided that
such time series can only be obtained by regular polling by
the energy management system.
Means should be provided to either push such values from the
place they are available to the management system or to have
them stored at the powered entitiy for a sufficiently long period of
time such that a management system can retrieve a stored time
series of values.</t>
<t>Detailed Requirements:</t>
<section toc="exclude" title="Energy">
<t>The energy management standard must provide means for
reporting the consumed energy received at a power input or
provided at a power outlet of a powered entitiy. Reports must be
made for a clearly specified time interval.</t>
</section>
<section toc="exclude" title="Time intervals">
<t>The energy management standard must provide means for
reporting the consumed energy of a powered entitiy for certain time
intervals.
<list style="symbols">
<t>Reports must be supported for the time interval starting
at the last restart of the powered entitiy and ending at a certain
point in time, such as the time when a report was delivered.
</t>
<t>Reports must be supported for a sequence of consecutive
non-overlapping time intervals of fixed size (periodic
reports).</t>
<t>Reports must be supported for a sequence of consecutive
overlapping time intervals of fixed size (periodic reports).</t>
<t>Reports must be supported for an interval of given length
ending at a certain point in time, such as the time when a
report was delivered (sliding window)</t>
</list></t>
</section>
<section anchor="energyperstate" toc="exclude"
title="Energy per power state">
<t>The energy management standard must provide means for
reporting the consumed energy individually for each power state.
This extends the requirement
<xref format="counter" target="statistics"/> on power state
statistics.</t>
</section>
<section toc="exclude" title="Time series of energy values">
<t>The energy management standard must provide means for
collecting time series of energy values for each power
inlet and for each power outlet of a powered entitiy without requiring
to regularly poll the powered entitiy from an energy management
station. A solution for this is that the concerned powered entity
or another powered entity closely interacting with the concerned
powered entity collect time series of energy values and make them
available via push or pull mechanisms to receivers of the
information.</t>
</section>
</section>
<section anchor="battery" title="Battery State">
<t>Today more and more powered entities contain batteries that
supply them with power when disconnected from electrical power
distribution grids. Common examples are nomadic and mobile
devices, such as notebook computers, netbooks, and smart phones.
The status of batteries in such an powered entity, particularly the
charging status is typically controlled by automatic functions
that act locally on the powered entitiy and manually by users of the
powered entity. In addition to this, there is a need to monitor
the battery status of these entities by network management
systems.</t>
<t>The management requirements discussed above in Sections
<xref target="general" format="counter"/> to
<xref target="energy" format="counter"/> concern energy-related
information on powered entities. Powered entities may be powered devices or
components of powered devices. Devices containing batteries
can be modeled in two ways. The entire device can be modeled
as a single powered entity on which energy-related information is
reported or the battery can be modeled as an individual powered entity
for which energy-related information is monitored individually
according to requirements in Sections
<xref target="general" format="counter"/> to
<xref target="energy" format="counter"/>.</t>
<t>In both cases 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. Also
desirable is to receive notifications if the charge of a battery
becomes very low or if a battery needs to be replaced.</t>
<t>Detailed Requirements:</t>
<section toc="exclude" anchor="charge" title="Battery charge">
<t>The energy management standard must provide means for reporting
the current charge of a battery.</t>
</section>
<section toc="exclude" title="Battery charging state">
<t>The energy management standard must provide means for reporting
the charging state (charged, discharged, etc.) of a battery.</t>
</section>
<section toc="exclude" title="Battery charging cycles">
<t>The energy management standard must provide means for reporting
the number of completed charging cycles of a battery.</t>
</section>
<section toc="exclude" title="Actual battery capacity">
<t>The energy management standard must provide means for reporting
the actual capacity of a battery.</t>
</section>
<section toc="exclude" title="Static battery properties">
<t>The energy management 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.</t>
</section>
<section toc="exclude" title="Low battery charge notification">
<t>The energy management standard must provide means for generating
a notification when a the charge of a battery decreases below a
given threshold.</t>
</section>
<section toc="exclude" anchor="replacement"
title="Battery replacement notification">
<t>The energy management standard must provide means for generating
a notification when the number of charging cycles of battery
exceeds a given threshold.</t>
</section>
<section toc="exclude" title="Multiple batteries">
<t>The energy management standard must provide means for
meeting requirements <xref format="counter" target="charge"/>
to <xref format="counter" target="replacement"/> for each
individual battery contained in a single powered entity.</t>
</section>
</section>
</section>
<!-- Requirements related to Powered Entities Configuration ============= -->
<section anchor="control" title="Control of Powered Entities">
<t>Many powered entities control their power state locally by
self-managed dynamic adaptation to the environment. But other
powered entities without that capability need interfaces for a energy
management system to control their power states in order to
save energy. Even for self-managed powered entities such interface may
be required for overruling local policy decisions by global ones
from an energy management system.</t>
<t>Power supply is typically not self-managed by powered entities.
And controlling power supply is typically not conducted as
interaction between energy management system and the powered
entity itself. It is rather an interaction between the management
system and an entity providing power at its power outlets.
Still, requirements for power state control apply accordingly
to power supply control.</t>
<t>Note that shutting down the power supply abruptly may have
severe consequences for the powered entity.</t>
<t>Detailed Requirements:</t>
<section toc="exclude" title="Controlling power states">
<t>The energy management standard must provide means for
setting power states of powered entities.</t>
</section>
<section toc="exclude" title="Controlling power supply">
<t>The energy management standard must provide means for
switching power supply off or turning power supply on at
power outlets providing power to one or more powered entity.</t>
</section>
</section>
<section anchor="reportonother"
title="Reporting on Other Powered Entities">
<t>As already discussed in the introduction of
<xref target="properties"/>, not all energy-related information
may be available at the concerned powered entity. Such
information may be provided by other powered entities, such as a
Power Distribution Unit (PDU), external power meter, or a
Power over Ethernet (PoE) Power Sourcing Equipment (PSE).
Some of these entities (PDU, PSE) can also control the power
provided to the other powered entities, while some can just
report on the remote powered entities (external power meter).
This section covers reporting of information (monitoring)
only. See <xref target="controlother"/> for requirements
on controlling other powered entities.</t>
<t>There are cases where a power supply unit switches power
for several powered entities by turning power on or off at a
single power outlet or where a power meter measures the
accumulated power of several powered entities at a single power line.
Consequently, it should be possible to report that a monitored
value does not relate to just a single powered entity,
but is an accumulated value for a set of powered entities.
All of these powered entities belonging to that set need to be
identified.</t>
<t>If a powered entity has information about where
energy-related information on itself can be retrieved, then it
would be very useful if it has a way to communicate this
information to an energy management system. This applies even
if the information only provides accumulated quantities for
several powered entities.</t>
<t>Detailed Requirements:</t>
<section toc="exclude" title="Reports on other powered entities">
<t>The energy management standard must provide means for
a powered entitiy to report energy-related information on another
powered entity. </t>
</section>
<section toc="exclude"
title="Identity of other powered entities on which is reported">
<t>The energy management standard must provide means for
reporting the identity of another powered entity on which
energy-related information is reported.</t>
</section>
<section toc="exclude"
title="Reporting quantities accumulated over multiple powered entities">
<t>For powered entities reporting single values that are
accumulated over multiple powered entities, the energy management
standard must provide means for reporting the list of all
powered entities from which contributions are included in the
accumulated value.</t>
</section>
<section toc="exclude" title="List of all powered entities on which is reported">
<t>The energy management standard must provide means for
a powered entitiy to report the list of all other powered entities on which
it can report energy-related information.</t>
</section>
<section toc="exclude" title="Content of reports on other powered entities">
<t>The energy management standard must provide means for
a powered entitiy to indicate for each other powered entity on which it
can provide energy-related information which energy-related
information can be provided for this powered entity.</t>
</section>
<section toc="exclude" title="Indicating source of remote information">
<t>The energy management standard must provide means for a
powered entity to indicate another powered entity at which
energy-related information on itself can be retrieved.</t>
</section>
<section toc="exclude" title="Indicating source of remote information">
<t>For a powered entity that has another powered entity at which
energy-related information on itself can be retrieved,
the energy management standard must provide means for
indicating the information that is available at other
powered entities per other powered entity.</t>
</section>
</section>
<!-- Requirements Conttrol of Powered Entities ====== -->
<section anchor="controlother"
title="Controlling Other Powered Entities">
<t>This section specifies requirements for controlling
power states and power supply of powered entities by
communicating not with these powered entities themselves, but
with other powered entities that have means for controlling
power state or power supply of others.</t>
<section anchor="statecontrol"
title="Controlling power states of other powered entities">
<t>Some powered entities may have control of power states of other
powered entities. For example a gateway to a building network may
have means to control the power state of powered entities in the
building that do not have an IP interface. For this and
similar cases means are needed to make this control accessible
to the energy management system.</t>
<t>In addition to this, it is required that a powered entitiy
that has its state controlled by other powered entities has means
to report the list of these other powered entities.</t>
<t>Detailed Requirements:</t>
<section toc="exclude" title="Control of power states of other powered entities">
<t>The energy management standard must provide means for
an energy management system to send power state control
commands to a powered entity that concern the power states of other
powered entities than the one the command was send to.</t>
</section>
<section toc="exclude"
title="Identity of other power state controlled entities">
<t>The energy management standard must provide means for
reporting the identity of another powered entity for which the
reporting powered entity has means to control the power state.</t>
</section>
<section toc="exclude"
title="List of all power state controlled entities">
<t>The energy management standard must provide means for
a powered entitiy to report the list of all powered entities for which
it can control the power state.</t>
</section>
<section toc="exclude" title="List of all power state controllers">
<t>The energy management standard must provide means for
a powered entitiy that receives commands controlling its power
state from other powered entities to report the list of all those
entities.</t>
</section>
</section>
<section anchor="supplycontrol"
title="Controlling power supply of other powered entities">
<t>Some powered entities may have control of the power supply of
other powered entities, for example, because the other powered entity
is supplied via a power outlet of the powered entitiy. For this and
similar cases means are needed to make this control
accessible to the energy management system.</t>
<t>In addition to this, it is very required that a powered entitiy
that has its supply controlled by other powered entities has means
to report the list of these other powered entities.</t>
<t>Detailed Requirements:</t>
<section toc="exclude"
title="Control of power supply of other powered entities">
<t>The energy management standard must provide means for
an energy management system to send power supply control
commands to a powered entity that concern the power supply of other
powered entities than the one the command was send to.</t>
</section>
<section toc="exclude"
title="Identity of other power supply controlled powered entities">
<t>The energy management standard must provide means for
reporting the identity of another powered entity for which the
reporting powered entity has means to control the power supply.</t>
</section>
<section toc="exclude"
title="List of all power supply controlled powered entities">
<t>The energy management standard must provide means for
a powered entitiy to report the list of all other powered entities for which
it can control the power supply.</t>
</section>
<section toc="exclude"
title="List of all power supply controllers">
<t>The energy management standard must provide means for
a powered entitiy that has other powered entities controlling its power
supply to report the list of all those powered entities.</t>
</section>
</section>
</section>
<section title="Security Considerations">
<t> The typical security threats for the management protocol for energy
monitoring are similar to the ones specified in the SNMP security framework.
In other words, from an energy monitoring point of view, no additional security
requirements have been imposed. </t>
<t>Link layer discovery mechanisms need to ensure that only the trusted powered entities
shall be discovered during discovery and detect/discard powered entities without a
trusted relationship to be included among the powered entities for energy monitoring. </t>
<t> In terms of monitoring, considering that there can be some network entities
which shall be entitled to collect the measured data on behalf of other powered entities,
then it is important to authenticate and/or authorize such powered entities.
In addition, in the case of control of other powered entities, it would be highly desirable
to have some form of an authentication mechanism to ensure that only the designated
powered entities shall control the powered entities within its control domain. It should be possible
to prevent a powered entity which does not have the appropriate authorization and authority
to control or configure powered entities in its control
domain/purview. Secondly, it should be possible to prevent malicious
powered entities from exercising control over entities. </t>
</section>
<section title="IANA Considerations">
<t>This document has no actions for IANA.</t>
</section>
<section title="Acknowledgements">
<t>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.</t>
</section>
<section title="Open issues">
<section title="Revise security considerations">
<t>A discussion of the sensitivity of the content of the
monitoring data is missing.</t>
</section>
<section title="High/Low power notifications">
<t>For some network management tasks it may be desirable to
receive notifications from entities when the power
of an powered entity exceeds or falls below certain thresholds.
Do we want to make this a requirement?</t>
<t>Proposal: added "for example" so that we don't restrict the framework
to only this notification</t>
</section>
<section title="Power and energy time series?">
<t>We have requirements for reporting of time series of power
and energy values. Do we need both or just one of them?
If just one, then which one?</t>
</section>
<section title="Inlet/outlet combinations">
<t>How to model the case that an inlet or outlet changes
during operation from one kind to the other. An example is
a battery that receives power at a socket at one time. Then
the socket is an inlet. At another time the battery provides
power at the same socket. Then it's an outlet. The same
holds for entities with integrated power generators.</t>
<t>One solution would be to introduce a new kind of hybrid
in/outlets. Another one would be to model the same socket
as inlet as well as as outlet. It would appear twice in the
list of all inlets and outlets. Then received power/energy
would be reported under the inlet entry and provided
power/energy would be reported under the outlet entry.</t>
<t>These would be two solutions. What would be the concrete
requirement behind them?</t>
</section>
<section title="Aggregation functions">
<t>Aggregation functions are not covered (yet). Are there
requirements on aggregation? Which are they?</t>
</section>
<section title="Add a definition of 'demand'">
<t></t>
</section>
<section title="IEC references">
<t>References to mentioned IEC standards are missing.
Also these references should be double checked.</t>
</section>
<section title="Standard references for BACNET or MODBUS">
<t>Section 1 mentions BACNET or MODBUS as examples for
building network protocols. We need references to the standards
specifications for these protocols.</t>
</section>
<section title="IEEE 1621 and 802.3az references">
<t>A reference to the IEEE 1621 standard is missing
in section 3.1 and a reference to IEEE 802.3az is missing
in section 3.4. The references should be double checked
if they are well applicable in the respective section.</t>
</section>
<section title="DC power quality covered by IEC standard?">
<t>Is there an IEC standard on DC power quality?</t>
</section>
<section title="Introduce 'disconnected from power' as power state">
<t>We need to introduce the concept of a device being
"disconnected" from power. This is a subset of the Off state.
Shall we do it here or rather in the framework draft?</t>
</section>
<section title="Need for basic state 'reduced power'?">
<t>Are "full power" and "reduced power" really different
basic types of power states? Both may be forms of the on state.
Identifying "full" separately is arbitrary. (For something
like a computer, "idle" is the most common state so would be
the one to call out separately rather than "full".)</t>
</section>
<section title="Local and network-wide energy management">
<t>All but first sentence of the third paragraph in section 3.3
seem to be true not needed here. Proposal: remove them.</t>
</section>
<section title="Do we need entity types?">
<t>Or shall we remove <xref target="type"/>?</t>
</section>
<section title="Power availability mode 'minimum' or 'ready'?">
<t>Do we need an additional mode for power availability
called "minimum" or "ready" for power availability in
xref target="availability"/>? This would reflect a PoE state
at which the PSE is ready to serve the PD.</t>
</section>
<section title="Is there a need for metering power supply inpedance?">
<t> </t>
</section>
<section title="Confidence in power values ">
<t>Shall we rename "confidence in power values" to
"method for determining power values"?</t>
</section>
<section title="Terminology for reporting on other entitites">
<t>In <xref target="reportonother"/> we need some additional
terms here to streamline the text (and ultimately our thinking).
Nominations include:
<list style="symbols">
<t>"powered entity" (which may be "self-reporting")</t>
<t>"reporting entity" (can be "self" or "other")</t>
<t>"other entity" (a reporting entity reporting not on itself;
likely a different term would be better for this)</t>
<t>"controlled entity", "controlling entity" (section 8.1)</t>
<t>"switched entity", "switching entity" (section 8.2)</t>
</list></t>
<t>Also, there are two cases for an "other entity". One is where
the powered entity cannot report the value in question itself
(either because it can't report anything, or doesn't know the
value in question, e.g. when metering is external).</t>
<t>The second is where the powered entity can report, but the
other entity is doing the reporting for some convenience.
We need to be aware of both even if the framework does not need
to make the distinction.</t>
<t>There may be multiple other reporting entities, not just a
single one.</t>
<t>Do components of devices ever report, or do only devices do
the reporting? This seems like an important point.</t>
</section>
</section>
</middle>
<back>
<references title="Informative References">
&rfc1628;
&rfc3433;
&rfc3621;
&rfc3805;
&rfc4133;
&rfc4268;
&I-D.tychon-eman-applicability-statement;
<reference anchor="ACPI.R30b">
<front>
<title>Advanced Configuration and Power Interface Specification, Revision 3.0b</title>
<author initials="" surname="Hewlett-Packard Corporation" fullname="Hewlett-Packard Corporation"></author>
<author initials="" surname="Intel Corporation" fullname="Intel Corporation"></author>
<author initials="" surname="Microsoft Corporation" fullname="Microsoft Corporation"></author>
<author initials="" surname="Phoenix Corporation" fullname="Phoenix Corporation"></author>
<author initials="" surname="Toshiba Corporation" fullname="Toshiba Corporation"></author>
<date year="2006" month="October" />
</front>
</reference>
<reference anchor="DMTF.DSP1027">
<front>
<title>Power State Management Profile</title>
<author initials="R.R." surname="Dasari (ed.)" fullname="RadhaKrishna R. Dasari (ed.)"></author>
<author initials="J." surname="Davis (ed.)" fullname="Jim Davis (ed.)"></author>
<author initials="J." surname="Hilland (ed.)" fullname="Jeff Hilland (ed.)"></author>
<date year="2008" month="September" />
</front>
</reference>
<reference anchor="IEEE-ISTO">
<front>
<title>PWG 5106.4 - PWG Power Management Model for Imaging Systems 1.0:</title>
<author initials="" surname="Printer Working Group" fullname="IEEE-ISTO"></author>
<date year="2011" month="February" />
</front>
</reference>
<reference anchor="IEC.62053-21">
<front>
<title>Electricity metering equipment (a.c.) -
Particular requirements -
Part 22: Static meters for active energy
(classes 1 and 2)
</title>
<author initials=""
surname="International Electrotechnical Commission"
fullname="International Electrotechnical Commission">
</author>
<date year="2003"/>
</front>
</reference>
<reference anchor="IEC.62053-22">
<front>
<title>Electricity metering equipment (a.c.) -
Particular requirements -
Part 22: Static meters for active energy
(classes 0,2 S and 0,5 S)
</title>
<author initials=""
surname="International Electrotechnical Commission"
fullname="International Electrotechnical Commission">
</author>
<date year="2003"/>
</front>
</reference>
<reference anchor="IEC.61850-7-4">
<front>
<title>Communication networks and systems for
power utility automation -
Part 7-4: Basic communication structure -
Compatible logical node classes and data object classes
</title>
<author initials=""
surname="International Electrotechnical Commission"
fullname="International Electrotechnical Commission">
</author>
<date year="2010"/>
</front>
</reference>
</references>
<section anchor="standards" title="Existing Standards">
<t>This section analyzes existing standards for energy consumption and
power state 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.</t>
<section title="Existing IETF Standards">
<t>There are already RFCs available that address a subset of the
requirements.</t>
<section title="ENTITY MIB">
<t>The ENTITY-MIB module defined in <xref target="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 <xref target="RFC4133">RFC 4133</xref>
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.</t>
<t>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 <xref target="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.</t>
<t>Yet another example, is smart-PDUs, which can report
the energy consumption of 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 consumption
of 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.</t>
</section>
<section title="ENTITY STATE MIB">
<t><xref target="RFC4268">RFC 4268</xref> 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,
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 consumption 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
<xref target="RFC4133">ENTITY MIB module</xref>. Particularly, it
uses the entPhysicalIndex for identifying entities.</t>
<t>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
<xref target="ACPI.R30b">Advanced Configuration and Power Interface (ACPI)</xref>
or the
<xref target="DMTF.DSP1027">DMTF Power State Management Profile</xref>.</t>
</section>
<section title="ENTITY SENSOR MIB">
<t><xref target="RFC3433">RFC 3433</xref> 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
consumption 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.</t>
<t>Similar to the ENTITY STATE MIB module, the ENTITY SENSOR MIB
module makes use of the means provided by the <xref
target="RFC4133">ENTITY MIB module</xref> for relating provided
information to components of a device. </t>
<t>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.</t>
</section>
<section title="UPS MIB">
<t><xref target="RFC1628">RFC 1628</xref> 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 which port of the UPS device.</t>
<t>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].</t>
</section>
<section title="POWER ETHERNET MIB">
<t>Similar to the UPS MIB, implementations of the POWER ETHERNET MIB
module defined in <xref target="RFC3621">RFC3621</xref> provide
information on the current energy consumption 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.</t>
<t>The POWER ETHERNET MIB does not report power and energy
consumption 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.</t>
</section>
<section title="LLDP MED MIB">
<t>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.</t>
</section>
</section>
<section title="Existing standards of other bodies">
<t></t>
<section title="DMTF">
<t>The DMTF has defined a <xref target="DMTF.DSP1027">power state
management profile</xref> that is targeted at computer systems.
It is based on the DMTF's Common Information Model (CIM) and rather
an entity profile than an actual energy consumption monitoring
standard.</t>
<t>The power state management profile is used to describe and to
manage the power state of computer systems. This includes e.g. means
to change the power state of an entity (e.g. to shutdown the entity)
which is an aspect of but not sufficient for active energy management.
</t>
</section>
<section title="OVDA">
<t>ODVA is an association consisting of members from industrial automation
companies. ODVA supports standardization of network technologies based on the Common
Industrial Protocol (CIP). Within ODVA, there is a special interest group
focused on energy and standardization and inter-operability of energy aware entities. </t>
</section>
<section title="IEEE-ISTO Printer WG">
<t> The charter of the IEEE-ISTO Printer Working Group is for
open standards that define printer related protocols, that printer manufacturers and related
software vendors shall benefit from the interoperability provided by conformance to these standards.
One particular aspect the Printer WG is focused on is power monitoring and management of network
printers and imaging systems <xref target="IEEE-ISTO">PWG Power Management Model for Imaging Systems </xref>.
Clearly, these devices are within the scope of energy management since
these devices consume power and are attached to the network. In addition, there is ample
scope of power management since printers and imaging systems are not used that often.
IEEE-ISTO Printer working group has defined MIB modules for monitoring the power consumption
and power state series that can be useful for power management of printers. The energy management
framework should also take into account the standards defined in the Printer working group.
In terms of other standards, IETF Printer MIB <xref target="RFC3805">RFC3805</xref> has been
standardized, however, this MIB module does not address power management of printers. </t>
</section>
</section>
</section>
</back>
</rfc>
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