One document matched: draft-quittek-eman-reference-model-02.xml
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<rfc category="info" docName="draft-quittek-eman-reference-model-02" ipr="trust200902">
<front>
<title>Reference Model for Energy Management</title>
<author fullname="Jürgen Quittek" initials="J."
surname="Quittek">
<organization>NEC Europe Ltd.</organization>
<address>
<postal>
<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="Bruce Nordman" initials="B."
surname="Nordman">
<organization>Lawrence Berkeley National Laboratory</organization>
<address>
<postal>
<street>1 Cyclotron Road</street>
<code>94720</code>
<city>Berkeley</city>
<country>US</country>
</postal>
<phone>+1 510 486 7089</phone>
<email>bnordman@lbl.gov</email>
</address>
</author>
<date month="July" year="2011" />
<abstract>
<t>This memo proposes a reference model for energy consumption
monitoring and control. It claims that the only basic extension
of conventional network management models is the concept of
power interfaces of managed entities. Power interfaces can be
treated similarly to network interfaces. They have different
modes (outlet, inlet, probe) and their connections to transmission
media (lines) define a power supply topology among the involved
managed entities. This memo elaborates an information model
for power interfaces that meets the requirements for energy
management.
</t>
</abstract>
</front>
<middle>
<section title="Introduction">
<t>Managing energy consumption of devices with network connections is
different from several well understood network management functions
because of the special nature of energy supply and consumption.</t>
<t>A simple example of energy management is a single device
reporting information about its own energy status. It may have local
energy control mechanisms, for example putting itself into a sleep mode when
appropriate and it may receive energy control commands from a
management system. This and similar cases are well understood and
can be handled with well established and standardized management
procedures. The only missing components today are standardized ways
for reporting energy consumption information, such as, for example,
specific MIB modules, and for controlling energy consumption, such as,
for example, a specific YANG model. The simple example is also likely
to be most common and cover most energy use for the foreseeable future.</t>
<t>Energy management has some differences from other common
network management tasks. This is caused by the nature of energy
supply and consumption and by the commonly deployed technologies:
<list style="symbols">
<t>Energy supply for powered devices is often controlled by
other devices that we call power sources. Examples of power sources
are Power Distribution Units (PDUs) for AC power supply and Power over
Ethernet (PoE) switches providing DC power over Ethernet cables.
Thus power supply control for a specific powered device is often
conducted through interaction the corresponding power source and
not with the particular device. Also
monitoring of power supply for a specific device may include
interaction with the corresponding power source.</t>
<t>In many cases, energy consumption is not measured by the
powered device itself, but by a power meter located upstream
in the power distribution tree. An example is a power
distribution unit (PDU) that measures energy consumption of
attached devices and may report this to an energy management
system. Unlike many other management functions, the powered
device is not involved in this process.</t>
<t>A power meter measuring at the outlet of a PDU or at a
power supply line may measure the accumulated power of several
powered devices supplied via the outlet or the power line.
In such a case no separate power values can be measured for the
individual powered devices, but only the sum of the power of
all devices powered via the outlet or power line is available.</t>
</list></t>
<t>This memo aims to clarify roles of entities involved in
energy monitoring and control and the relationships among them.
This is achieved by defining a model for energy management that
particularly covers the special issues of energy management
including, but not limited to the three issues listed above.</t>
<t>Version -01 of this model presented in the previous version
of this draft was focusing on devices or entities involved in
energy management. This version -02 is completely different.
It is based on the concept of a power interface. The result is
much simpler and very close to the common concept of a network
interface. For comparison, version -01 of the model is appended
to the end of this memo as
Appendices <xref format="counter" target="monitoring-model"/>
and <xref format="counter" target="control-model"/>.</t>
<t>There is already a reference model defined in section 4 of <xref
target="I-D.ietf-eman-framework"/>. The intention of this
memo is to refine this model based on recent discussions.</t>
<!--
<t>The reference model specification below describes several kinds
of entities and interactions between them. According to the current
scope of the EMAN WG, only reporting to the energy management
system are potential subjects of standardization in this WG.</t>
<t>The reference model is described in two stages. Stage one is an
energy monitoring model specified in <xref target="monitoring-model"/>.
It covers only monitoring of power states and energy consumption.
On stage two the monitoring model is extended to a full energy
management reference model by adding control functions for power
supply and power states. see <xref target="control-model"/>.</t>
-->
</section>
<section anchor="terms" title="Terminology">
<t>This section defines terms used for the description of the
energy management reference model. Terms specific to the reference
model are defined in <xref target="pi"/>.</t>
<section title="Energy Management">
<t>To be agreed on in the EMAN WG.</t>
</section>
<section title="Power">
<t>To be agreed on in the EMAN WG.</t>
</section>
<section title="Energy">
<t>To be agreed on in the EMAN WG.</t>
</section>
<!--
<section title="Power Interface (PI)">
<t>According to the IEEE standard for Power over Ethernet (PoE)
as defined in <xref target="IEEE-802.3af"/> and
<xref target="IEEE-802.3at"/>, the Power Interface (PI) is the
mechanical and electrical interface between a Power Sourcing
Equipment (PS) or Powered Device (PD) and a power transmission
medium.</t>
</section>
<section title="Power Source (PS)">
<t>An entity that provides power to one or more PDs at one or
more Power Interfaces (PIs). Note that this extends the term
PSE compared to it's use in the IEEE standard for
<xref target="IEEE-802.3at">Power over Ethernet (PoE)</xref>,
where at a single PI the PSE proviced only power to a single PD.
</t>
</section>
<section title="Powered Device (PD)">
<t>An entity that has the capability of receiving power at
a Power Interface (PI).</t>
</section>
<section title="Power Meter (PM)">
<t>An entity that has the capability of measuring power at
one or more of its Power Interfaces (PIs).
</t>
</section>
-->
</section>
<section anchor="reference-model" title="Energy Management Reference Model">
<t>This section specifies a reference model for energy monitoring.
The basic extension that the model makes on top of existing network
management models is that it introduced the concept of power interfaces
in addition to network interfaces of managed entities.</t>
<section anchor="pi" title="Power Interface (PI)">
<t>The term 'power interface' is not new. It is already used by the
IEEE standard for <xref target="IEEE-802.3at">Power over Ethernet (PoE)</xref>.
There are some similarities between power interfaces and network
interfaces. A network interface can be used in different modes,
such as sending or receiving on an attached line. A PI can have
the following modes:</t>
<t><list style="symbols">
<t>inlet: receiving power</t>
<t>outlet: providing power</t>
</list></t>
<t>In addition, like a network interface, it can be monitoring
the shared (power) transmission media and meter power and other
electric quantities on it. PIs with metering capability is called
a meter PI.</t>
<t>Physically, a power interface can be located at an AC power
socket, an AC power cord attached to a device, an 8P8C (RJ45)
PoE socket, a current clamp of an ammeter, etc.</t>
<t>Derived from the terminology defined by the IEEE standard for
Power over Ethernet (PoE) in <xref target="IEEE-802.3af"/> and
<xref target="IEEE-802.3at"/> we define the following terms:</t>
<section anchor="pd" title="Powered Entity (PE)">
<t>An entity with one or more PIs in mode "inlet"
is called a Powered Entity (PE). This extends the term Powered
Device (PD) used in <xref target="IEEE-802.3af"/> and
<xref target="IEEE-802.3at"/> to cover not only entities that
are individual devices, but also entities that are just
components of devices.</t>
</section>
<section anchor="pse" title="Power Source (PS)">
<t>An entity with one or more PIs in mode "outlet"
is called a Power Source (PS). Note that this
extends the term Power Source Equipment (PSE) used in the
IEEE PoE standards <xref target="IEEE-802.3af"/> and
<xref target="IEEE-802.3at"/> where at a single PI the PSE
provides power to a single PD only. Here a PS may supply
arbitrary numbers of PEs at a single PI. Note further that most
PSs have also PIs in mode "inlet" and thus are also a PE.</t>
</section>
<section anchor="pm" title="Power Meter (PM)">
<t>An entity with a meter PI is called a Power Meter
(PM) for this PI.</t>
</section>
</section>
<section anchor="topology" title="Power supply topology">
<t>Similar to network interfaces, power interface can be connected
to each other. The most simple connection is a single outlet
connected to a single inlet as shown in <xref target="simple"/>.</t>
<figure anchor="simple" title="Simple one-to-one power supply topology">
<artwork><![CDATA[
+--------------------------+ +----------------+
| Power Source | | Powered Entity |
| +---------+ | | +---------+ |
| | PI | | | | PI | |
| | (outlet)########## (inlet) | |
| +---------+ | | +---------+ |
+--------------------------+ +----------------+
######## power supply line
]]></artwork>
</figure>
<t><xref target="complex"/> shows a more complex example. Here
a PS has two power outlets, one of them with metering
capability. Note that because is has also a PI in mode "inlet"
it is also a PE. At one outlet, the PE supplies two PEs. The
power supply line connected to this PI is also monitored by a
PM. Note that the PM can only measure the accumulated power
of the two supplied PEs. It cannot differentiate which part
of the measured values relates to an individual PE.</t>
<figure anchor="complex" title="More complex power supply topology">
<artwork><![CDATA[
+----------------+
| Powered Entity |
| +------------+ |
+-------------+ | | PI (inlet, | |
| Power Meter | ##### meter) | |
| +---------+ | # | +------------+ |
| | PI | | # +----------------+
+--------------------------+ | | (meter) | | #
| PS/PE | | +----#----+ | # +----------------+
| +---------+ | +------#------+ # | Powered Entity |
| | PI #2 | | # # | +------------+ |
| | (outlet)########################### PI (inlet) | |
| +---------+ +---------+ | | +------------+ |
| | PI #1 | | +----------------+
##### (inlet) | |
| +---------+ +---------+ | +----------------+
| | PI #3 | | | Powered Entity |
| | (outlet,| | | +------------+ |
| | meter) | ########################### PI (inlet) |
| +---------+ | | +------------+ |
+--------------------------+ +----------------+
######## power supply line
]]></artwork>
</figure>
<t><xref target="complex"/> shows an example in which the metering
function is not within the PE being metered. We see that for energy
management in this type of deployment it is important to monitor
power interfaces and as well to detect the energy supply topology
by finding out which PIs are connected with each other by power
supply lines.</t>
<t>Also from the example scenario in <xref target="complex"/>
we can identify the following issues for energy management:</t>
<section anchor="instrumentation" title="Lack of instrumentation">
<t>Many PEs and PSs are not sufficiently instrumented to monitor
their own power interface(s). If there is no other entity that
has capabilities to collect data on these interfaces, then this
information is not available for energy management.</t>
</section>
<section anchor="remotemeter" title="Remote power measurement">
<t>In many cases PSs or PMs have the capability to provide power
measurements for other entities. Examples are a Power
Distribution Unit (PDU) and a Power over Ethernet (PoE) Power
Sourcing Equipment (PSE). These entities often have the
capability to measure power per power outlet. In such a case
an association between the measurement values and the
(potentially remote) entities that consume the measured power
needs to be established. the association is given by the
power supply topology.</t>
<t>There are two examples for this in <xref target="complex"/>.
The first one is PI #3 of the PS/PE that provides power
measurement for the PE connected to this PI. The second one
is the PM that provides power metering for PI #2 of
the PS/PE which is an aggregated power measurement for
the two PEs connected to this PI.</t>
</section>
<section anchor="aggregatedmeter" title="Aggregated power measurement">
<t>An entity providing power at outlets may supply more than
one other entity with a single outlet. In such a case power
measurements conducted at the outlet are aggregated measurement
for all powered entities that have their power inlets connected
to this outlet. Separate values for the individual supplied
entities are not available in this case. Furthermore, for the
energy management system it would be highly desirable to receive
information on which entities are actually receiving the power
provided at the outlet.</t>
<t>An examples for this is the PM in <xref target="complex"/>.
It provides an aggregated power measurement for the two PEs
connected to this PI. Only with additional power metering
at the PI of one of the PEs power values for the individual
PEs can be determined.</t>
<t>Note that in some cases, some or all of the PEs attached to an
aggregated outlet will have their own metering capabilities.
A typical AC mains circuit breaker is an example of an aggregated
outlet with many devices powered off of a single supply point.</t>
</section>
<section anchor="remotecontrol" title="Remote power supply control">
<t>There are three ways for an energy management system to change
the power state of a managed entity. First is for a management system
to provide policy or other useful information (like the electricity
price) to the PE for it to use in determining its power state.
The second is sending the entity
a command to switch to another state.
The third is to utilize an upstream device (to the PE)
that has capabilities
to switch on and off power at its outlet.
Some entities do not
have capabilities for receiving commands or changing their power
states by themselves. Such devices may be controlled by switching
on and off the power supply for them and so have particular need
for the third method.</t>
<t>In <xref target="complex"/> the PS/PE can switch on and off
power at its two PIs in outlet mode and thereby switch on and off
power supply for the respective connected PEs.</t>
</section>
<section anchor="aggregatedcontrol" title="Aggregated power supply control">
<t>The issue of supplying multiple PEs via a single power
outlet of a device is also relevant for power control. Here it
must be considered that by switching off power at such an outlet,
multiple entities might be switched on or off simultaneously.</t>
<t>The example for this in <xref target="complex"/> is PI #2 of
the PS/PE. It cannot switch power separately for an individual
PE. Every power switching action affects the two connected PEs
in the same way.</t>
</section>
</section>
<section anchor="functions" title="Basic functions of energy management">
<t>Based on the concept of power interfaces and the implications of
potential power supply topologies discussed above, the basic
functions of energy management can be defined. For our energy
management reference model we consider five basic energy
management functions:
<list style="numbers">
<t>monitoring power states (on, off, sleep, etc.) of PEs</t>
<t>controlling power states of PEs</t>
<t>monitoring PIs (inlets, outlets, probes)</t>
<t>controlling PIs</t>
<t>detecting power supply topologies</t>
</list></t>
<t>Monitoring and controlling power states of PEs
(functions 1. and 2.) has many similarities with conventional
network management functions. The reference model includes them
for completeness,
but not many special arrangements are necessary for dealing
with them. One special issue might be finding ways to monitor
and control entities that are in a sleep state or an off state,
as these may lack the normal network interaction capabilities of
entities that are fully on.
A second issue that may occur is proxying power state information
for other entities, for example when the entities do not have
IP interfaces themselves, but can communicate with the Internet
only via gateways. But for proxying of information, sufficient
conventional means are available.</t>
<t>More challenging are functions 3. to 5. For monitoring
PIs it may be difficult to determine where information
on a PI is available. As shown in <xref target="complex"/> a
PI in inlet mode (without metering capability) may receive power values
from a PM, or from a supplying PI in outlet mode. Vice versa,
a PI in outlet mode without a metering capability may receive
power values
from one or more PMs and PIs in inlet mode. For controlling PIs
it may be difficult to find out where control capabilities are
available and which PEs would be affected by switching an PI
in outlet mode at a PS.</t>
<t>Most of these problems can be resolved by the availability of
power supply topology information. The information model for PIs
described in the following section reflects the need for topology
detection by offering information elements for each PI that identify
other PEs that are connected to the same power transmission medium.
How this information is obtained remains an open issue. In case of
Power over Ethernet (PoE), devices may detect the device at the other
end of the line via the coupled Ethernet connection. Other information
may have been entered manually when setting up devices, or automatically
determined through other means.</t>
</section>
<!--
<t>Issues arising from these scenarios can be summarized by
<list style="numbers">
<t>Detecting the power supply topology, i.e. finding out which
power interfaces are connected to the same shared power line.</t>
<t>Dealing with incomplete or not precise energy-related information</t>
<t>Dealing with aggregated energy-related information</t>
</list></t>
-->
<section anchor="informationmodel"
title="Energy management information model">
<t>This section specifies an information model for monitoring
entities and Power Interfaces (PIs). It addresses the issues discussed in the
previous sections and meets all the requirements for energy
management specified in <xref target="I-D.ietf-eman-requirements"/>.
except for the reporting of time series of energy and power values.
But these can easily be added.</t>
<t>The model assumes that there is a given mechanism to identify
managed entities by a network management system and that this
mechanism uses a sufficiently unique entity identifier (EID).
Then the information model for PIs is specified by the diagram
in <xref target="im"/>.</t>
<figure anchor="im" title="Information model for energy management">
<artwork><![CDATA[
+---------------------------------+
| ManagedEntity | +-----------------+
+---------------------------------+ | PowerState |
| EID | 1 +-----------------+
| Type | . | Number |
| Tags | . | Description |
| | 1 N | MaxPower |
| PowerStates |----- | AveragePower |
| ActualStateSet | | TimeInState |
| ActualState | | LastTimeInState |
+---------------------------------+ | TimesEntered |
1 | | TotalEnergy |
| +-----------------+
0..N |
+---------------------------------+
| PowerInterface |
+---------------------------------+
| Index | 0 +-----------------+
| Tags (for grouping) | . | PiId |
| Mode (inlet,outlet) | . +-----------------+
| MeteringCapability | 1 N | EID |
| ConnectedTo (PIs of others) |------| PI Index |
| TypeOfCurrent (AC,DC) | +-----------------+
| NominalVoltage |
| NominalAcFrequency |
| NumberOfAcPhases |
| ControlCapability (switch) |
| | +-----------------+
| PowerAvaialbility (on,off) | | Phase |
| InUse (current>0) | +-----------------+
| RealPower | 1 | PowerFactor |
| PowerMeasurementInterval | . | ActualVoltage |
| PowerMeasurementConfidence | . | ActualFrequency |
| PowerMeasurementAccuracy | 1 3 | TotalHarmonic- |
| Phases |------| Distortion |
| | | SupplyImpedance |
| TotalEnergy | +-----------------+
+---------------------------------+
]]></artwork>
</figure>
<t>We further assume that existing mechanisms for reporting values
on behalf of other entities or devices are sufficient for meeting
requirements in Sections 7 and 8 of
<xref target="I-D.ietf-eman-requirements"/>.</t>
<t>The information model in <xref target="im"/> contains five
kinds of objects. The ManagedEntity object contains attributes
describing the monitored entity. Instances of class PowerState
describe a single power state of the managed entity. PIs are
described by PowerInterface objects. Instances of class PiId
identify PIs of other managed entities connected to the same
power transmission medium and can be used for describing the
power supply topology. Objects Phase are used for representing
actual power quality values. For DC current only one object is
required per PI, for AC current up to three objects may be needed.
</t>
</section>
</section>
<section title="Security Considerations">
<t>This memo currently does not impose any security considerations.</t>
</section>
<section title="IANA Considerations">
<t>This memo has no actions for IANA..</t>
</section>
<section title="Acknowledgements">
<t>This memo was inspired by discussions with Benoit Claise,
John Parello, Mouli Chandramouli, Rolf Winter, Thomas Dietz,
Bill Mielke, and Chris Verges.</t>
</section>
<section title="Open Issues">
<section title="Change mode from inlet to outlet?">
<t>Is it needed to support a PI to be in mode "inlet" to be
able to change to mode "outlet" and back?</t>
</section>
<section title="Collector and Aggregator">
<t>It looks like we need to extend the model by a collector function
and an aggregator function. A collector would collect energy-related
information on other devices and report for multiple of them.
An aggregator would use information from several devices and excecute
operations on them, for example calculating a sum.</t>
</section>
</section>
</middle>
<back>
<references title="Informative References">
&id.draft-ietf-eman-requirements;
&id.draft-ietf-eman-framework;
&rfc3410;
&rfc6241;
&rfc5101;
&rfc5675;
<reference anchor="IEEE-802.3af">
<front>
<title>IEEE Std 802.3af-2003 - IEEE Standard for Information
technology - Telecommunications and information exchange
between systems - Local and metropolitan area networks -
Specific requirements - Part 3: Carrier Sense Multiple
Access with Collision Detection (CSMA/CD) Access Method
and Physical Layer Specifications - Amendment: Data Terminal
Equipment (DTE) - Power via Media Dependent Interface (MDI)</title>
<author initials="" surname="IEEE 802.3 Working Group"
fullname="IEEE 802.3 Working Group"></author>
<date year="2003" month="July" />
</front>
</reference>
<reference anchor="IEEE-802.3at">
<front>
<title>IEEE Std 802.3at-2009 - IEEE Standard for Information
technology - Telecommunications and information exchange
between systems - Local and metropolitan area networks -
Specific requirements - Part 3: Carrier Sense Multiple
Access with Collision Detection (CSMA/CD) Access Method
and Physical Layer Specifications - Amendment: Data Terminal
Equipment (DTE) - Power via Media Dependent Interface (MDI)
Enhancements</title>
<author initials="" surname="IEEE 802.3 Working Group"
fullname="IEEE 802.3 Working Group"></author>
<date year="2009" month="October" />
</front>
</reference>
</references>
<section anchor="monitoring-model"
title="Energy Monitoring Reference Model Version -01">
<t>This appendix specifies the previous version -01 of the reference model
for energy monitoring. After introducing basic concepts of energy monitoring in
<xref target="monitoring-intro"/> it defines entities of the model and
their interactions in <xref target="monitoring-entities"/>. Examples of
devices and scenarios are illustrated in
<xref target="monitoring-scenarios"/>. </t>
<section anchor="monitoring-intro" title="Introduction to Energy Monitoring">
<t> In this section we introduce basic concepts of energy monitoring
starting with the most basic scenario and extending it stepwise to our
full reference model.</t>
<t>The main subject of energy monitoring is a powered device. An energy
monitoring system collects information about powered devices, their
current power state (for example: on, sleep, off) and their
actual power consumption. </t>
<section title="Basic Energy Monitoring (local metering)">
<t>The most basic interaction in an energy monitoring system
is a powered device directly reporting its own energy-related information,
with no other devices involved, as shown below.</t>
<figure>
<artwork><![CDATA[
energy monitoring
system
^
|
device
]]></artwork>
</figure>
</section>
<section title="External Metering">
<t>Reporting its current power state is a relatively easy task
for a powered device because usually information on the current
power state is locally available at the device and a reporting function
just needs some additional software to implement it.</t>
<t>Reporting the current power level of a
device and its accumulated energy consumption is a
harder task, particularly if there are strict requirements for accuracy.
Today very few devices are
instrumented with means for measuring their own energy consumption
as that usually implies adding hardware for this purpose.
</t>
<t>This can be addressed by external meters, that is,
dedicated probes that can meter energy consumption on a power
source (line). Some Power Distributions Units (PDUs)
and <xref target="IEEE-802.3af">Power over Ethernet (PoE)</xref>
switches integrate power source and power metering for
individual devices.</t>
<t> For supporting scenarios with external meters we extend the
basic model from above by an external power meter and a power
source as shown below.</t>
<figure>
<artwork><![CDATA[
energy monitoring system
^ ^ ^
| | |
power power powered
source meter device
###############
symbols ######### represent a power supply line
]]></artwork>
</figure>
<t>All three potentially report to the energy monitoring system.
The power meter may report the current power and accumulated
energy consumption and the power source may report if the power
supply for the device is switched on or if it is off.</t>
<t>Implementation may be incomplete. For example, an energy management
system may have access to only one or two of these three types of data.</t>
</section>
<section title="Functions and Entities">
<t>This reference model operates at two levels/layers. One is simple basic
functions that are implemented. The second is how they are arranged in
devices. A device in this model may implement only a single function, or
may implement many.</t>
<t>That is, having multiple entities does not require
that all of them need to be instantiated by individual devices.
For example, the power meter function may be co-located and integrated with
the powered device, with the power source, or it may be
implemented by a separate device.</t>
</section>
<section title="Power Monitors">
<t>In the models above, the powered device and other
components deliver reports directly to an
energy monitoring system. However, there are energy monitoring
scenarios where this is not possible or not desirable.</t>
<t>Extreme examples are energy consumers that do not have IP interfaces
but can communicate by other means.
For delivering their reports to an IP-based energy
monitoring system, it may be required to use a gateway that can
communicate with the energy monitoring system.</t>
<t>However, even if all involved devices (PDUs, power meters, and powered devices)
can communicate via IP, it may be desirable to have mediation
functions in place between powered devices and the energy monitoring
system. An example, is an aggregating device that aggregates and
reports information on several powered devices.</t>
<t>There are several further useful scenarios. To generalize the model
(and to not exclude any kind of gateway, proxy, relay, mediator or other device)
we define reporting entities called 'monitors'.
The figure below shows three monitors, each of which
reports to the energy monitoring system.
This figure is the most generic representation of the energy monitoring
reference model described by this document.</t>
<figure>
<artwork><![CDATA[
Energy Monitoring Reference Model
+-------------------------------------------------------------------+
| energy monitoring system |
+-------------------------------------------------------------------+
^ ^ ^
| | |
+-------------------+ +-------------------+ +-------------------+
| power source | | power usage | | power state |
| monitor | | monitor | | monitor |
+-------------------+ +-------------------+ +-------------------+
| | |
+-------------------+ +-------------------+ +-------------------+
| power | | power meter | | powered |
| source | +-------------------+ | device |
+-------------------+###########################+-------------------+
symbols ######### represent a power supply line
]]></artwork>
</figure>
<t>A monitor function reports directly to the energy monitoring
system using the EMON protocol (an Internet protocol).
A monitor must have means to
acquire the information it reports, but how this information
is acquired is not relevant for our model.
That is, only the interactions with a caret symbol in this and following
diagrams is the subject of standardization.
Those with only the vertical bar character are outside the scope of
these documents; they may be IP or non-IP.</t>
<t>The reference model defines the communication between
power monitors an the energy monitoring system. The communication
lines between these entities are reference points of our model
described in more detail in the following.</t>
</section>
</section>
<section anchor="monitoring-entities" title="Energy Monitoring Entities">
<t>This section defines entities of the energy monitoring reference
model and describes interactions between them. Examples scenarios are
illustrated in <xref target="monitoring-scenarios"/>. </t>
<section title="Powered Device">
<t>A powered device is provided with energy (typically electrical)
usuallly provided via power lines. Power state,
power and consumed energy of powered devices are subject to monitoring
and control functions of energy management.</t>
</section>
<section title="Power Source">
<t>A power source provides a powered device with energy,
typically via a power line.
It may have means to switch on and off
the power for the powered device. A power source does not necessarily
generate power, but it may do so. It may be as simple as a power
switch or a power plug, but it may also be a battery or a power
generator. Regardless, the nature of the source does not affect
energy monitoring.</t>
<t>Note that an internal battery within a device, such as the battery
of a notebook PC or of a mobile phone are not considered to be a power
source. When a device runs on battery only, there is n flow of energy
into the device and consequently the power to be reported for this
device is zero. On the other hand, when a device charges its battery,
then the power supplied for charging needs to be accounted, even if the
device is not operational.</t>
</section>
<section title="Power Meter">
<t>A power meter measures power and/or consumed energy, and
typically is electrically connected to power supply lines
for powered devices. However, many devices can also provide
a reliable estimate of their power consumption based on internal
status information without having dedicated metering hardware.
Regardless, all metering information is qualified by an
indication of its accuracy.</t>
<t>The meter function also includes integrating power consumption
over time to provide a "meter reading" with a time stamp to
enable an energy monitoring system to track energy consumption over time.</t>
</section>
<section title="Power Monitors">
<t>A power monitor has access to energy-related information
concerning powered devices and is able to report this
information to energy management systems.</t>
<t>A power monitor may also provide information on identity
and properties of a powered device to the management system.</t>
<t>A power monitor may store energy-related information and
process it, for example, for aggregating information or for
extracting statistics that are provided to an energy management
system.</t>
<t>There are three power monitor functions
in the energy monitoring reference model: power state monitors,
power source monitors, and power usage monitors.</t>
<section title="Power State Monitor">
<t>A power state monitor has access to the power state
of a powered device and is able to report this information to an
energy monitoring system. For acquiring power state information
it may interact with powered devices.</t>
</section>
<section title="Power Source Monitor">
<t>A power state monitor has access to information on the power supply
of powered devices and is able to report this information to an
energy monitoring system. Typically, it will just report either
'on' or 'off'. In addition, it may report on power availability.
For acquiring power source information it may interact with the
power sources of powered devices. </t>
</section>
<section title="Power Usage Monitor">
<t>A power usage monitor has access to information on
energy consumption of powered devices and is able to report this
information to energy management systems. For acquiring information
on energy consumption it may interact with power meters.</t>
</section>
</section>
<section title="Energy Monitoring System">
<t>An energy monitoring system receives information
from power monitors, such as: power states, power source states,
and energy consumption.
An energy monitoring system may be centralized or distributed.
In most of the example scenarios
illustrated in <xref target="monitoring-scenarios"/> a centralized
energy monitoring system is shown but in all cases can be
replaced by a distributed monitoring system.</t>
</section>
</section>
<section anchor="monitoring-points" title="Standardization Scope">
<t>The reference model specifies interactions of an
energy monitoring system with power monitors. They reference
points of the model are potential subjects of standardization
(in the EMAN working group).
Interactions of power monitors with other entities are
currently not considered to be subject of standardization.</t>
<t>It is argued in
<xref target="I-D.ietf-eman-requirements"/> that
for most of the relevant scenarios the best choice a management
protocol for the reference points is <xref target="RFC3410">SNMP</xref>.
The reference model defined in this document does not assume a
specific protocol between energy monitoring system and power
monitors. It is also applicable if other protocols, such as,
for example, <xref target="RFC5675">Syslog</xref> or
<xref target="RFC5101">IPFIX</xref> are used.</t>
</section>
<section anchor="monitoring-relationships" title="Entity Relationships">
<t>No restrictions on entity relationships have been identified for
interacting entities of the energy monitoring reference model specified
in this document. This means that all relationships between
entities may be one-to-one, one-to-many, many-to-one, or many-to-many.
For example,
<list style="symbols">
<t>a single power state monitor may report the power state of
multiples powered entities,</t>
<t>a single powered entity may have its power states reported by<
multiple power state monitors,</t>
<t>a single powered device may receive power from several power
sources,</t>
<t>a single power monitor may report to multiple energy monitoring
systems.</t>
</list>
A few of scenarios with multiple instances of units are illustrated
by the examples in the following <xref target="monitoring-scenarios"/>.
</t>
</section>
<section anchor="monitoring-scenarios" title="Energy Monitoring Scenarios">
<t>This section describes common example scenarios for energy
monitoring and how they are modeled with the entities and interactions
described in the previous sections.</t>
<section title="Simple Device with Power Meter">
<t>A very basic example is a powered device that has a built-in meter
for measuring its own energy consumption and that reports its power
state and power usage directly to the energy monitoring system.</t>
<figure>
<artwork><![CDATA[
+-------------------------------------------------------------------+
| energy monitoring system |
+-------------------------------------------------------------------+
^
|
+-----------------------------------------------+
| | |
| +-----------+-----------+ |
| | | |
| +-------------------+ +-------------------+ |
| | power usage | | power state | |
| | monitor | | monitor | |
| +-------------------+ +-------------------+ |
| | | |
+-----------------+ | +-------------------+ +-------------------+ |
| power | | | power meter | | powered | |
| source | | +---------#---------+ | device | |
+-----------------+#|#########################+-------------------+ |
| |
| powered device with meter and power monitors |
+-----------------------------------------------+
Scenario 1: Powered device metering and self-reporting
]]></artwork>
</figure>
<t>Here four entities are combined in a single device: the
powered device, the power meter, and two power monitors.</t>
</section>
<section title="External Power Meter">
<t>The second example shows a power meter that
is attached to the power line of a powered device that does
not have means for measuring its own energy consumption.
The meter is integrated with a power usage monitor that reports
metered data. The powered device may report its own power state
by an integrated power state monitor.</t>
<figure>
<artwork><![CDATA[
+-------------------------------------------------------------------+
| energy monitoring system |
+-------------------------------------------------------------------+
^
|
+-----------------------+
| external | meter |
| +-------------------+ |
| | power usage | |
| | monitor | |
| +-------------------+ |
| | |
| +-------------------+ |
+-----------------+ | | power meter | | +-------------------+
| power | | +---------#---------+ | | powered |
| source | +-----------#-----------+ | device |
+-----------------+#############################+-------------------+
Scenario 2: An external meter
]]></artwork>
</figure>
</section>
<section title="External Power Meter for Multiple Powered Devices">
<t>Power meters may be located at a power line that provides
power for multiple powered devices. In scenario 3, a single
power meter measures the accumulated power and energy consumption
of multiple powered devices. In general, In this scenario it is
usually not possible to derive power values for the individual
powered devices from the accumulated measurement.</t>
<figure>
<artwork><![CDATA[
+-------------------------------------------------------------------+
| energy monitoring system |
+-------------------------------------------------------------------+
^
|
+-----------------------+
| external | meter |
| +-------------------+ |
| | power usage | | +----------------+
| | monitor | | | powered |
| +-------------------+ | | device |
| | | ###+----------------+
| +-------------------+ | #
+-----------------+ | | power meter | | # +----------------+
| power | | +---------#---------+ | # | powered |
| source | +-----------#-----------+ # | device |
+-----------------+################################+----------------+
#
# +----------------+
# | powered |
# | device |
###+----------------+
Scenario 3: An external meter for multiple powered devices
]]></artwork>
</figure>
</section>
<!--
<section title="Device with Power Meter and Battery">
<t>The powered device may be integrated with the power source.
Scenario 4 shows a device with t built-in battery that is modeled
as power source. In this case the power source monitor may also
send information about power availability, such as, for example,
the remaining charge of the battery.</t>
<figure>
<artwork><![CDATA[
+-------------------------------------------------------------------+
| energy monitoring system |
+-------------------------------------------------------------------+
^
|
+-------------------------------------------------------------------+
| | |
| +---------------------+---------------------+ |
| | | | |
| +-------------------+ +-------------------+ +-------------------+ |
| | power source | | power usage | | power state | |
| | monitor | | monitor | | monitor | |
| +-------------------+ +-------------------+ +-------------------+ |
| | | | |
| +-------------------+ +-------------------+ +-------------------+ |
| | power | | power meter | | powered | |
| | source | +---------#---------+ | device | |
| +-------------------+#######################+-------------------+ |
| |
| powered device with battery and meter |
+-------------------------------------------------------------------+
Scenario 4: Powered device metering and reporting on its own
]]></artwork>
</figure>
<t>Here all entities of our monitoring reference model are
integrated at a single device. Only the energy monitoring
system is separated.</t>
</section>
-->
<section title="Powered Device with Dual Power Supply">
<t>Some powered devices have dual power supply. It may
be that one supply comes from a power grid and the other
one from a battery. High-reliability devices may have two
power sources from different power distribution networks,
as shown in scenarios 4 and 5.</t>
<figure>
<artwork><![CDATA[
+-------------------------------------------------------------------+
| energy monitoring system |
+-------------------------------------------------------------------+
^
|
+-----------------------------------------+
| | |
| +-------------------------------------+ |
| | power usage monitor | |
| +-------------------------------------+ |
| | | |
| +---------+ +-----------+ +---------+ |
+---------+ | | power | | powered | | power | | +---------+
| power | | | meter | | device | | meter | | | power |
| source | | +----#----+ | | +----#----+ | | source |
+---------+##|##############+-----------+##############|##+---------+
| |
| powered device with dual power supply |
| and dual metering |
+-----------------------------------------+
Scenario 4: powered device with dual power supply
]]></artwork>
</figure>
<t>In scenario 4 the device uses two meters, one for each
power line and reports from both to the energy monitoring system.
If the two power sources belong to different power distribution
domains, it may be necessary to report power and energy separately
for each supply.
</t>
</section>
<section title="Two energy monitoring systems">
<t>Scenario 5 is more complex. Both meters are individual
external devices and there are even two separate energy
monitoring systems involved, one for each
power distribution tree.</t>
<figure>
<artwork><![CDATA[
+-------------------------------+ +-------------------------------+
| energy monitoring system | | energy monitoring system |
+-------------------------------+ +-------------------------------+
^ ^
| |
+-----------+ +-----------+
| | | | | |
| +-------+ | | +-------+ |
| |power | | | |power | |
| |usage | | | |usage | |
| |monitor| | | |monitor| |
| +-------+ | | +-------+ |
| | | | | |
| +-------+ | | +-------+ |
| | power | | | | power | |
+--------+ | | meter | | +-------------+ | | meter | | +--------+
| power | | +---#---+ | | powered | | +---#---+ | | power |
| source | +-----#-----+ | device | +-----#-----+ | source |
+--------+#################+-------------+#################+--------+
Scenario 5: powered device with dual power supply
from different power distribution trees
]]></artwork>
</figure>
</section>
<section title="Power over Ethernet Switch">
<t>This example shows a <xref target="IEEE-802.3af">Power over
Ethernet (PoE)</xref> switch supplying a powered device.
The switch contains a power source and a meter for each of its
ports. </t>
<t>There typically are multiple instances of power sources
and power meters in a PoE switch, but the drawing below shows only a single
instance. The same applies to the powered devices that are
represented by a single instance only.</t>
<t>Note that a typical PoE switch has also means to control
power supply for powered devices (not shown here).
Control of power supply is a subject of <xref
target="control-model"/>.</t>
<figure>
<artwork><![CDATA[
+-------------------------------------------------------------------+
| energy monitoring system |
+-------------------------------------------------------------------+
^
|
+---------------------------------------------+
| | |
| +----------+-----------+ |
| | | |
| +-----------------+ +-------------------+ |
| | power source | | power usage | |
| | monitor | | monitor | |
| +-----------------+ +-------------------+ |
| | | |
| +-----------------+ +-------------------+ | +-------------------+
| | power | | power meter | | | powered |
| | source | +---------#---------+ | | device |
| +-----------------+#########################|#+-------------------+
| |
| Power over Ethernet switch |
| or Power Distribution Unit |
+---------------------------------------------+
Scenarios 6 & 7: Power over Ethernet switch or Power Distribution
Unit reporting on power source and power usage of powered devices
]]></artwork>
</figure>
<t>In this scenario the identification of the powered device can
be done by the PoE switch by observing MAC and IP addresses of
the powered devices. The switch can report them to the energy
management system which then in turn can contact the devices
directly to obtain further information.</t>
</section>
<section title="Power Distribution Unit">
<t>The same figure as used for the PoE switch in the previous section
is be used for scenario 7 modeling a power distribution unit (PDU).
A PDU with meters for every socket can report power for each.</t>
<t>Identifying the powered devices can more difficult in this
scenario than in the previous one with the PoE switch, because
the PDU does not necessarily communicate with the powered devices.
In this case the PDU or EMS needs to obtain this information by
other means, for example by manual configuration.</t>
</section>
<section title="Aggregator">
<t>Scenario 8 shows a power usage monitor acting as an aggregator.
It collects power information from three powered devices and
delivers all of the information to the energy monitoring system.
The aggregator
may deliver the full information or aggregated information, for
example, just the sum of the power of all three powered devices.</t>
<figure>
<artwork><![CDATA[
+-------------------------------------------------------------------+
| energy monitoring system |
+-------------------------------------------------------------------+
^
|
+-------------------------------------------------------------------+
| power usage monitor |
+-------------------------------------------------------------------+
| | |
+-------------------+ +-------------------+ +-------------------+
| | | | | | | | |
|+-------+ +-------+| |+-------+ +-------+| |+-------+ +-------+|
|| power | |powered|| || power | |powered|| || power | |powered||
|| meter | |device || || meter | |device || || meter | |device ||
|+-------##+-------+| |+-------##+-------+| |+-------##+-------+|
+--------#----------+ +--------#----------+ +--------#----------+
# # #
+-------------------------------------------------------------------+
| power source |
+-------------------------------------------------------------------+
Scenario 8: An aggregator collecting monitoring information
from three powered devices
]]></artwork>
</figure>
</section>
<section title="Energy Monitoring Gateway">
<t>Some energy monitoring scenarios include
a gateway between the monitored units and the
energy monitoring system. The powered device and the power
meter may use means of communication other than IP.</t>
<t>The gateway is a relay and protocol converter that delivers
energy information to a power monitor.
A single device may implement logically independent gateways
for multiple devices.</t>
<t> Scenario 9 can easily extended to a gateway that also
contains a power source monitor.</t>
<figure>
<artwork><![CDATA[
+-------------------------------------------------------------------+
| energy monitoring system |
+-------------------------------------------------------------------+
^
|
+---------------------------------------------+
| | |
| +-----------+----------+ |
| | | |
| +-------------------+ +-----------------+ |
| | power usage | | power state | |
| | monitor | | monitor | |
| +-------------------+ +-----------------+ |
| gateway | | |
+---------------------------------------------+
| |
+-------------------+ +-------------------+ +-----------------+
| power | | power meter | | powered |
| source | +---------#---------+ | device |
+-------------------+###########################+-----------------+
Scenario 9: A gateway between monitored devices
and energy monitoring system
]]></artwork>
</figure>
<t>Here again, the problem of identifying the powered device has
become very difficult, because neither can the power monitor
provide an IP address of the powered device to the energy management
system nor can the energy management system directly communicate with
the powered device. Identification must be provided by other means.
The Proxy can have a gateway function and relay identification
between powered device and energy management system or the energy
management system needs to acquire information on powered devices
by other means, such as manual configuration.</t>
</section>
<section title="Further Scenarios">
<t>More scenarios may be added to future versions of this document.
Particularly, scenarios with multiple instances of an entity have not
been elaborated a lot.
<xref target="control-scenarios"/> shows scenarios for energy control.
They can also be considered as further monitoring scenarios if only
their power monitors are considered and power controllers are ignored.
</t>
</section>
</section>
</section>
<section anchor="control-model"
title="Energy Management Reference Model version -01">
<t>This appendix specifies the previous version -01 of the reference model
for energy management. It extends the energy monitoring reference model
specified in the previous <xref target="monitoring-model"/> by adding
power control functions. The resulting model is a complete energy
management reference model.</t>
<t>As in <xref target="monitoring-model"/> we first discuss entities and
their relationships and then illustrate the model with example scenarios.
</t>
<t> The extension from energy monitoring to energy management is straight
forward. To achieve the required control functions the
power source, power meter, and powered device have additional functions
for control.
For each power monitor a corresponding power controller is added
as shown below.</t>
<figure>
<artwork><![CDATA[
Energy Management Reference Model
+-------------------------------------------------------------------+
| energy management system |
+-------------------------------------------------------------------+
^ | ^ | ^ |
| v | v | v
+--------+ +--------+ +--------+ +--------+ +--------+ +--------+
| power | | power | | power | | power | | power | | power |
| source | | source | | usage | | meter | | state | | state |
| monitor| | ctrler | | monitor| | ctrler | | monitor| | ctrler |
+--------+ +--------+ +--------+ +--------+ +--------+ +--------+
| | | | | |
+-------------------+ +-------------------+ +-------------------+
| power | | power meter | | powered |
| source | +-------------------+ | device |
+-------------------+###########################+-------------------+
symbols ######### represent a power line
]]></artwork>
</figure>
<section anchor="control-entities" title="Energy Management Entities">
<t>This section defines entities of the energy management reference
model and describes interactions between them. Examples scenarios are
illustrated in <xref target="control-scenarios"/>. For entities already
specified in <xref target="monitoring-entities"/> of the
energy monitoring reference model, only their additional properties
are mentioned here. Power monitors are not discussed here again,
because their specification in the energy management reference model
do not change.
</t>
<section title="Powered Device">
<t>A powered device may be capable of changing its own power state
from a request from the energy management system. Some devices may
not be able to power up from an off state based on EMS request.
Most devices that are asleep will be able to wake on EMES request.</t>
</section>
<section title="Power Source">
<t>A power source may be capable of switching on and off power for
powered devices.</t>
</section>
<section title="Power Meter">
<t>A power meter may be switched on or off or have its metering
parameters modified.</t>
</section>
<section title="Power Controllers">
<t>A power controller receives commands from an energy management
system to change the status or parameters of power sources,
power meters, or powered devices.</t>
<t>There are three kinds of power controller entities: power state
controllers, power source controllers, and power meter controllers.</t>
<section title="Power State Controller">
<t>A power state controller can initiate a change in the power state
of a powered device.</t>
</section>
<section title="Power Source Controller">
<t>A power source controller can change the
power supply of a powered device. Typically, it has means for
switching power supply on and off. It may use these means without
communicating with the affected powered device.</t>
</section>
<section title="Power Meter Controller">
<t>A power meter controller has means for influencing the
operation of a power meter. It may switch on and off the power
meters and change parameters of their operation. For this purpose
it may interact with power meters.</t>
</section>
</section>
<section title="Energy Management System">
<t>An energy management system is an energy monitoring system
extended by control functions. It interacts with power monitors
and power controllers in order to achieve objectives of energy
management. </t>
<t>It sends commands to power controllers. To power state controllers
it sends requested power states for powered devices. To power
source controllers it requests to switch on or off power for powered
devices. To power meter controllers it sends commands concerning
the operation of power meters.</t>
</section>
</section>
<section anchor="control-points" title="Reference Points">
<t>Relevant for our reference model are interactions of the
energy management system with power monitors and power controllers.
They are reference points of our model and potential subjects of
standardization in the EMAN working group. Interactions of power
monitors and power controllers with other entities are
currently not considered to be subject of standardization.</t>
<t>Monitoring protocols have already been discussed in
<xref target="monitoring-points"/>. There are several choices
of control protocols to be used for energy management.
Among them are <xref target="RFC3410">SNMP</xref> and
<xref target="RFC6241">NETCONF</xref>.</t>
</section>
<section anchor="control-relationships" title="Entity Relationships">
<t>The considerations on entity relationships for the energy monitoring
reference model described in <xref target="monitoring-relationships"/>.
apply as well to the energy management reference model:
No restrictions on entity relationships have been identified.</t>
</section>
<section anchor="control-scenarios" title="Energy Management Scenarios">
<t>This section describes example scenarios for energy management
and how they are modeled with the entities and interactions
described above.</t>
<section title="Simple Self-Managed Device">
<t>The first two examples are expected to become very common
scenarios. Here, a powered device is managing its power state
on its own based on input other than from the energy management system.
The device may decide to change power state based on observation of
its environment (no current load, high temperature, not sufficient
light, scheduled time for service interruption, etc.) or it may
receive external triggers, such as by a human-operated remote
control.</t>
<figure>
<artwork><![CDATA[
+-------------------------------------------------------------------+
| energy management system |
+-------------------------------------------------------------------+
^
|
+-----------------------+
| | |
| +--------+ +--------+ |
| | power | | power | |
| | state | | state | |
| | monitor| | ctrler | |
| +--------+ +--------+ |
| | | |
+-----------------+ | +-------------------+ |
| power | | | powered | |
| source | | | device | |
+-----------------+#|#########################+-------------------+ |
| |
| powered device with |
| power state control |
+-----------------------+
Scenario 10: A self-managed powered device
]]></artwork>
</figure>
<t>In any way, it's power state control is independent of the
energy management system. The only interaction with the system
is reporting of power state to the energy management system in
scenario 10, and in addition reporting of its current power and/or
accumulated consumed energy in scenario 11.</t>
<figure>
<artwork><![CDATA[
+-------------------------------------------------------------------+
| energy management system |
+-------------------------------------------------------------------+
^
|
+-----------------------------------------------+
| | |
| +-----------------+-----+ |
| | | |
| +--------+ +--------+ +--------+ +--------+ |
| | power | | power | | power | | power | |
| | usage | | meter | | state | | state | |
| | monitor| | ctrler | | monitor| | ctrler | |
| +--------+ +--------+ +--------+ +--------+ |
| | | | | |
+-----------------+ | +-------------------+ +-------------------+ |
| power | | | power meter | | powered | |
| source | | +---------#---------+ | device | |
+-----------------+#|#########################+-------------------+ |
| |
| powered device with built-in meter |
| and autonomous control |
+-----------------------------------------------+
Scenario 11: A self-managed powered device with built-in meter
]]></artwork>
</figure>
<t>In scenario 11 also the control of the power meter is handled
by the device itself.</t>
</section>
<section title="Simple Managed Device">
<t>In our model, the scenario does not change much if the
powered devices are not self-managed but managed by the energy
management system. Scenarios 12 and 13 show that just an
interaction between the energy management system and the powered
device is added that serves for sending commands concerning
power states to the device.</t>
<figure>
<artwork><![CDATA[
+-------------------------------------------------------------------+
| energy management system |
+-------------------------------------------------------------------+
^ |
| |
+-----------------------+
| | v |
| +--------+ +--------+ |
| | power | | power | |
| | state | | state | |
| | monitor| | ctrler | |
| +--------+ +--------+ |
| | | |
+-----------------+ | +-------------------+ |
| power | | | powered | |
| source | | | device | |
+-----------------+#########################|#+-------------------+ |
| |
| powered device with |
| power state control |
+-----------------------+
Scenario 12: A managed powered device
]]></artwork>
</figure>
<t>Control of the power meter by the management system can
easily added to scenario 13. It is not included here, because
for built-in meters this seems not to be necessary in many
common cases.</t>
<figure>
<artwork><![CDATA[
+-------------------------------------------------------------------+
| energy management system |
+-------------------------------------------------------------------+
^ |
| |
+-----------------------------------------------+
| | | |
| +-----------------+-----+ | |
| | | v |
| +--------+ +--------+ +--------+ +--------+ |
| | power | | power | | power | | power | |
| | usage | | meter | | state | | state | |
| | monitor| | ctrler | | monitor| | ctrler | |
| +--------+ +--------+ +--------+ +--------+ |
| | | | | |
+-----------------+ | +-------------------+ +-------------------+ |
| power | | | power meter | | powered | |
| source | | +---------#---------+ | device | |
+-----------------+#|#########################+-------------------+ |
| |
| powered device with built-in meter |
| and autonomous control |
+-----------------------------------------------+
Scenario 13: A managed powered device with built-in meter
]]></artwork>
</figure>
</section>
<section title="Power over Ethernet Switch">
<t>Scenario 14 adds control functions to the PoE switch of
scenario 6 in <xref target="monitoring-scenarios"/>. Here the
energy management system can explicitly request the power for
a powered device to be switched on or off. It also can switch
on and off metering and reporting of energy consumption per
port of the switch</t>
<figure>
<artwork><![CDATA[
+-------------------------------------------------------------------+
| energy management system |
+-------------------------------------------------------------------+
| ^ | ^
| | | |
+-------------------------------------------+ +---------------------+
| | | | | | | |
| +----------------+----+ | | | | |
| | v | v | | | |
|+--------+ +--------+ +--------+ +--------+| |+--------+ +--------+|
|| power | | power | | power | | power || || power | | power ||
|| source | | source | | usage | | meter || || state | | state ||
|| monitor| | ctrler | | monitor| | ctrler || || monitor| | ctrler ||
|+--------+ +--------+ +--------+ +--------+| |+--------+ +--------+|
| | | | | | | | | |
|+-------------------+ +-------------------+| |+-------------------+|
|| power | | power meter || || powered ||
|| source | +---------#---------+| || device ||
|+-------------------+######################|#|+-------------------+|
| | | |
| Power over Ethernet switch | | powered device with |
| or Power Distribution Unit | | power state control |
+-------------------------------------------+ +---------------------+
Scenario 14 & 15: Power over Ethernet switch
or Power Distribution Unit
]]></artwork>
</figure>
<t>Still, the powered device in this scenario is self-managed
controlling its power state on its own and just reporting it
to the energy management system.</t>
</section>
<section title="Power Distribution Unit">
<t>Again, as in <xref target="monitoring-scenarios"/> the scenario
for a power distribution unit looks exactly the same in our
reference model as the scenario for a power distribution unit.</t>
</section>
<section title="Energy Management Gateway">
<t>Starting from an energy monitoring gateway in
<xref target="monitoring-scenarios"/> the extension towards
an energy management gateway is again straight forward.</t>
<figure>
<artwork><![CDATA[
+-------------------------------------------------------------------+
| energy management system |
+-------------------------------------------------------------------+
| ^ |
| | |
+-----------------------------------------------+
| | | | |
| +-----------------+-----+ | |
| | gateway v | v |
| +--------+ +--------+ +--------+ +--------+ |
| | power | | power | | power | | power | |
| | usage | | meter | | state | | state | |
| | monitor| | ctrler | | monitor| | ctrler | |
| +--------+ +--------+ +--------+ +--------+ |
| | | | | |
+-----------------------------------------------+
| | | |
+-----------------+ +-------------------+ +-------------------+
| power | | power meter | | powered |
| source | +---------#---------+ | device |
+-----------------+###########################+-------------------+
Scenario 16: A gateway between powered devices
and energy monitoring system
]]></artwork>
</figure>
<t>Here again, the problem of identifying the powered device has
become very difficult, because neither can the power monitor
provide an IP address of the powered device to the energy management
system nor can the energy management system directly communicate with
the powered device. Identification must be provided by other means.
The Proxy can have a gateway function and relay identification
between powered device and energy management system or the energy
management system needs to acquire information on powered devices
by other means, such as manual configuration.</t>
</section>
<section title="Further Scenarios">
<t>More scenarios may be added to future versions of this document.
Particularly, scenarios with multiple instances of an entity have not
been elaborated, yet.
<xref target="control-scenarios"/> shows scenarios for energy control.
They can also be considered as further monitoring scenarios if only
their power monitors are considered and power controllers are ignored.
</t>
</section>
</section>
</section>
</back>
</rfc>
| PAFTECH AB 2003-2026 | 2026-04-24 09:28:49 |