Energy Management Framework
draft-ietf-eman-framework-06
The information below is for an old version of the document.
| Document | Type |
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| Authors | Benoît Claise , John Parello , Brad Schoening , Juergen Quittek , Bruce Nordman | ||
| Last updated | 2012-10-21 | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
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draft-ietf-eman-framework-06
Network Working Group B. Claise
Internet-Draft J. Parello
Intended Status: Informational Cisco Systems, Inc.
Expires: March 12, 2013 B. Schoening
Independent Consultant
J. Quittek
NEC Europe Ltd.
B. Nordman
Lawrence Berkeley
National Laboratory
October 21, 2012
Energy Management Framework
draft-ietf-eman-framework-06
Status of this Memo
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Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as
the document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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Provisions and are provided without warranty as described in
the Simplified BSD License.
Abstract
This document defines a framework for providing Energy
Management for devices within or connected to communication
networks, and components thereof. The framework defines an
Energy Management Domain as a set of Energy Objects, for which
each Energy Object is identified, classified and given
context. Energy Objects can be monitored and/or controlled
with respect to Power, Power State, Energy, Demand, Power
Quality, and battery. Additionally the framework models
relationships and capabilities between Energy Objects.
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Table of Contents
1. Introduction............................................ 5
1.1. Energy Management Document Overview................ 6
2. Terminology............................................. 6
Device.................................................. 6
Component............................................... 6
Energy Management....................................... 7
Energy Management System (EnMS)......................... 7
ISO Energy Management System............................ 8
Energy.................................................. 8
Power................................................... 8
Demand.................................................. 9
Power Characteristics................................... 9
Power Quality........................................... 9
Electrical Equipment................................... 10
Non-Electrical Equipment (Mechanical Equipment)........ 10
Energy Object.......................................... 10
Electrical Energy Object............................... 10
Non-Electrical Energy Object........................... 11
Energy Monitoring...................................... 11
Energy Control......................................... 11
Provide Energy:........................................ 11
Receive Energy:........................................ 11
Power Interface........................................ 11
Energy Management Domain............................... 12
Energy Object Identification........................... 12
Energy Object Context.................................. 12
Energy Object Relationship............................. 13
Aggregation Relationship............................... 13
Metering Relationship.................................. 13
Power Source Relationship.............................. 14
Proxy Relationship..................................... 14
Energy Object Parent................................... 14
Energy Object Child.................................... 14
Power State............................................ 15
Power State Set........................................ 15
Nameplate Power........................................ 15
3. Requirements & Use Cases............................... 16
4. Energy Management Issues............................... 17
4.1. Power Supply...................................... 18
4.2. Power and Energy Measurement...................... 23
4.3. Reporting Sleep and Off States.................... 24
4.4. Device and Device Components...................... 25
4.5. Non-Electrical Equipment.......................... 25
5. Energy Management Reference Model...................... 26
5.1. Reference Topologies.............................. 26
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5.2. Generalized Relationship Model.................... 35
5.3. Energy Object, Energy Object Components and
Containment Tree....................................... 37
6. Framework High Level Concepts and Scope................ 38
6.1. Energy Object and Energy Management Domain........ 39
6.2. Power Interface................................... 39
6.3. Energy Object Identification and Context.......... 40
6.4. Energy Object Relationships....................... 42
6.5. Energy Monitoring................................. 47
6.6. Energy Control.................................... 50
7. Structure of the Information Model: UML Representation. 54
8. Configuration.......................................... 59
9. Fault Management....................................... 60
10. Examples.............................................. 60
Example I: Simple Device with one Source............... 61
Example II: Multiple Inlets............................ 62
Example III: Multiple Sources.......................... 62
11. Relationship with Other Standards Development
Organizations............................................. 63
11.1. Information Modeling............................. 63
12. Security Considerations............................... 64
12.1 Security Considerations for SNMP.................. 64
13. IANA Considerations................................... 65
14. Acknowledgments....................................... 65
15. References............................................ 66
Normative References................................... 66
Informative References................................. 66
OPEN ISSUES:
Are Tracked via Issue Tracker. See
https://trac.tools.ietf.org/wg/eman/trac/report/1
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1. Introduction
Network management is divided into the five main areas defined
in the ISO Telecommunications Management Network model: Fault,
Configuration, Accounting, Performance, and Security
Management (FCAPS) [X.700]. Absent from this management model
is any consideration of Energy Management, which is now
becoming a critical area of concern worldwide as seen in
[ISO50001].
Note that Energy Management has particular challenges in that
a power distribution network is responsible for the supply of
energy to various devices and components, while a separate
communication network is typically used to monitor and control
the power distribution network.
This document defines a framework for providing Energy
Management for devices within or connected to communication
networks. The framework describes how to identify, classify
and provide context for a device in a communications network
from the point of view of Energy Management.
The identified device or identified components within a device
can then be monitored for Energy Management by obtaining
measurements for Power, Energy, Demand and Power Quality. If
a device contains batteries, they can be also be monitored and
managed. An Energy Object state can be monitored or
controlled by providing an interface expressed as one or more
Power State Sets. The most basic example of Energy Management
is a single Energy Object reporting information about itself.
However, in many cases, energy is not measured by the Energy
Object itself, but by a meter located upstream in the power
distribution tree. An example is a power distribution unit
(PDU) that measures energy received by attached devices and
may report this to an Energy Management System (EnMS).
Therefore, Energy Objects are recognized as having
relationships to other devices in the network from the point
of view of Energy Management. These relationships include
Aggregation Relationship, Metering Relationship, Power Source
Relationship, and Proxy Relationship.
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1.1. Energy Management Document Overview
The EMAN standard provides a set of specifications for Energy
Management. This document specifies the framework, per the
Energy Management requirements specified in [EMAN-REQ].
The applicability statement document [EMAN-AS] provides a list
of use cases, a cross-reference between existing standards and
the EMAN standard, and shows how this framework relates to
other frameworks.
The Energy-aware Networks and Devices MIB [EMAN-AWARE-MIB]
specifies objects for addressing Energy Object Identification,
classification, context information, and relationships from
the point of view of Energy Management.
The Power and Energy Monitoring MIB [EMAN-MON-MIB] contains
objects for monitoring of Power, Energy, Demand, Power Quality
and Power States.
Further, the battery monitoring MIB [EMAN-BATTERY-MIB] defines
managed objects that provide information on the status of
batteries in managed devices.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described
in RFC 2119 [RFC2119].
EDITOR'S NOTE:
All terms are copied over from the version 6 of the [EMAN-
TERMINOLOGY] draft.
Device
A piece of electrical or non-electrical equipment.
Reference: Adapted from [IEEE100]
Component
A part of an electrical or non-electrical equipment
(Device).
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Reference: Adapted from [ITU-T-M-3400]
Energy Management
Energy Management is a set of functions for
measuring, modeling, planning, and optimizing
networks to ensure that the network elements and
attached devices use energy efficiently and is
appropriate for the nature of the application and
the cost constraints of the organization.
Reference: Adapted from [ITU-T-M-3400]
Example: A set of computer systems that will poll
electrical meters and store the readings
NOTES:
1. Energy management refers to the activities,
methods, procedures and tools that pertain to
measuring, modeling, planning, controlling and
optimizing the use of energy in networked
systems [NMF].
2. Energy Management is a management domain which
is congruent to any of FCAPS areas of
management in the ISO/OSI Network Management
Model [TMN]. Energy Management for
communication networks and attached devices is
a subset or part of an organization's greater
Energy Management Policies.
Energy Management System (EnMS)
An Energy Management System is a combination of
hardware and software used to administer a
network with the primary purpose being Energy
Management.
Reference: Adapted from [1037C]
Example: A single computer system that polls data
from devices using SNMP
NOTES:
1. An Energy Management System according to
[ISO50001] (ISO-EnMS) is a set of systems or
procedures upon which organizations can develop
and implement an energy policy, set targets,
action plans and take into account legal
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requirements related to energy use. An EnMS
allows organizations to improve energy
performance and demonstrate conformity to
requirements, standards, and/or legal
requirements.
2. Example ISO-EnMS: Company A defines a set of
policies and procedures indicating there should
exist multiple computerized systems that will
poll energy from their meters and pricing /
source data from their local utility. Company A
specifies that their CFO should collect
information and summarize it quarterly to be
sent to an accounting firm to produce carbon
accounting reporting as required by their local
government.
3. For the purposes of EMAN, the definition from
[1037C] is the preferred meaning of an Energy
Management System (EnMS). The definition from
[ISO50001] can be referred to as ISO Energy
Management System (ISO-EnMS).
ISO Energy Management System
Energy Management System as defined by [ISO50001]
Energy
That which does work or is capable of doing work.
As used by electric utilities, it is generally a
reference to electrical energy and is measured in
kilo-watt hours (kWh).
Reference: [IEEE100]
NOTES
1. Energy is the capacity of a system to produce
external activity or perform work [ISO50001]
Power
The time rate at which energy is emitted,
transferred, or received; usually expressed in
watts (or in joules per second).
Reference: [IEEE100]
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Demand
The average value of power or a related quantity
over a specified interval of time. Note: Demand
is expressed in kilowatts, kilovolt-amperes,
kilovars, or other suitable units.
Reference: [IEEE100]
NOTES:
1. Typically kilowatts.
2. Energy providers typically bill by Demand
measurements as well as for maximum Demand per
billing periods. Power values may spike during
short-terms by devices, but Demand measurements
recognize that maximum Demand does not equal
maximum Power during an interval.
Power Characteristics
Measurements of the electrical current, voltage, phase and
frequencies at a given point in an electrical power system.
Reference: Adapted from [IEC60050]
NOTES:
1. Power Characteristics is not intended to be judgmental
with respect to a reference or technical value and are
independent of any usage context.
Power Quality
Characteristics of the electric current, voltage, phase and
frequencies at a given point in an electric power system,
evaluated against a set of reference technical parameters.
These parameters might, in some cases, relate to the
compatibility between electricity supplied in an electric
power system and the loads connected to that electric power
system.
Reference: [IEC60050]
NOTES:
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1. Electrical characteristics representing power quality
information are typically required by customer facility
energy management systems. It is not intended to satisfy the
detailed requirements of power quality monitoring. Standards
typically also give ranges of allowed values; the
information attributes are the raw measurements, not the
"yes/no" determination by the various standards.
Reference: [ASHRAE-201]
Electrical Equipment
A general term including materials, fittings,
devices, appliances, fixtures, apparatus,
machines, etc., used as a part of, or in
connection with, an electric installation.
Reference: [IEEE100]
Non-Electrical Equipment (Mechanical Equipment)
A general term including materials, fittings,
devices appliances, fixtures, apparatus,
machines, etc., used as a part of, or in
connection with, non-electrical power
installations.
Reference: Adapted from [IEEE100]
Energy Object
An Energy Object (EO) is a piece of equipment
that is part of or attached to a communications
network that is monitored, controlled, or aids in
the management of another device for Energy
Management.
Electrical Energy Object
An Electrical Energy Object (EEO) is an Energy
Object that is a piece of Electrical Equipment
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Non-Electrical Energy Object
A Non-Electrical Energy Object (NEEO) an Energy
Object that is a piece of Non-Electrical
Equipment.
Energy Monitoring
Energy Monitoring is a part of Energy Management
that deals with collecting or reading information
from Energy Objects to aid in Energy Management.
NOTES:
1. This could include Energy, Power, Demand, Power
Quality, Context and/or Battery information.
Energy Control
Energy Control is a part of Energy Management
that deals with directing influence over Energy
Objects.
NOTES:
1. Typically in order to optimize or ensure its
efficiency.
Provide Energy:
An Energy Object "provides" energy to another Energy Object
if there is an energy flow from this Energy Object to the
other one.
Receive Energy:
An Energy Object "receives" energy from another Energy
Object if there is an energy flow from the other Energy
Object to this one.
Power Interface
A Power Interface (or simply interface) is an
interconnection among devices or components where energy
can be provided, received or both.
Power Inlet
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A Power Inlet (or simply inlet) is an interface at which a
device or component receives energy from another device or
component.
Power Outlet
A Power Outlet (or simply outlet) is an interface at which
a device or component provides energy to another device or
component.
Energy Management Domain
An Energy Management Domain is a set of Energy Objects
where all objects in the domain are considered one unit of
management.
For example, power distribution units and all of the
attached Energy Objects are part of the same Energy
Management Domain.
For example, all EEO's drawing power from the
same distribution panel with the same AC voltage
within a building, or all EEO's in a building for
which there is one main meter, would comprise an
Energy Management Domain.
NOTES:
1. Typically, this set will have as members all
EO's that are powered from the same source.
Energy Object Identification
Energy Object Identification is a set of
attributes that enable an Energy Object to be:
uniquely identified among all Energy Management
Domains; linked to other systems; classified as
to type, model, and or manufacturer
Energy Object Context
Energy Object Context is a set of attributes that
allow an Energy Management System to classify the
use of the Energy Object within an organization.
NOTES:
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1. The classification could contain the use and/or
the ranking of the Energy Object as compared to
other Energy Objects in the Energy Management
Domain.
Energy Object Relationship
An Energy Object Relationship is a functional association
among Energy Objects
NOTES
1. Relationships can be named and could include
Aggregation, Metering, Power Source, and Proxy.
2. The Energy Object is the noun or entity in the
relationship with the relationship described as the verb.
Example: If EO x is a piece of Electrical Equipment and EO
y is an electrical meter clamped onto x's power cord, then
x and y have a Metering Relationship. It follows that y
meters x and that x is metered by y.
Reference: Adapted from [CHEN]
Aggregation Relationship
An Aggregation Relationship is an Energy Object
Relationship where one Energy Object aggregates the Energy
Management information of one or more other Energy Objects.
These Energy Objects are referred to as having an
Aggregation Relationship.
NOTES:
Aggregate values may be obtained by collecting values from
multiple Energy Objects and producing a single value of
more significant meaning such as average, count, maximum,
median, minimum, mode and most commonly sum [SQL].
Metering Relationship
A Metering Relationship is an Energy Object Relationship
where one Energy Object measures the Power or Energy of one
or more other Energy Objects. These Energy Objects are
referred to as having a Metering Relationship.
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Example: a PoE port on a switch measures the Power it
provides to the connected Energy Object.
Power Source Relationship
A Power Source Relationship is an Energy Object
Relationship where one Energy Object is the source of or
distributor of Power to one or more other Energy Objects.
These Energy Objects are referred to as having a Power
Source Relationship.
Example: a PDU provides power for a connected device.
Proxy Relationship
A Proxy Relationship is an Energy Object Relationship where
one Energy Object provides the Energy Management
capabilities on behalf of one or more other Energy Objects.
These Energy Objects are referred to as having a Proxy
Relationship.
Example: a protocol gateways device for Building Management
Systems (BMS) with subtended devices.
Energy Object Parent
An Energy Object Parent is an Energy Object that
participates in an Energy Object Relationships
and is considered as providing the capabilities
in the relationship.
Example: in a Metering Relationship, the Energy
Object that is metering is called the Energy
Object Parent, while the Energy Object that is
metered is called the Energy Object Child.
Energy Object Child
An Energy Object Child is an Energy Object that
participates in an Energy Object Relationships
and is considered as receiving the capabilities
in the relationship.
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Example: in a Metering Relationship, the Energy
Object that is metering is called the Energy
Object Parent, while the Energy Object that is
metered is called the Energy Object Child.
Power State
A Power State is a condition or mode of a device
that broadly characterizes its capabilities,
power consumption, and responsiveness to input.
Reference: Adapted from [IEEE1621]
NOTES:
1. A Power State can be seen as a power setting
of an Energy Object that influences the power
consumption, the available functionality, and
the responsiveness of the Energy Object.
2. A Power State can be viewed as one method for
Energy Control
Power State Set
A collection of Power States that comprise one
named or logical grouping of control is a Power
State Set.
Example: The states {on, off, and sleep} as
defined in [IEEE1621], or the 16 power states as
defined by the [DMTF] can be considered two
different Power State Sets.
Nameplate Power
The Nameplate Power is the nominal Power of a
device as specified by the device manufacturer.
NOTES:
1. This is typically determined via load testing
and is specified by the manufacturer as the
maximum value required for operating the
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device. This is sometimes referred to as the
worst-case Power. The actual or average Power
may be lower. The Nameplate Power is
typically used for provisioning and capacity
planning.
3. Requirements & Use Cases
Requirements for Power and Energy monitoring for networking
devices are specified in [EMAN-REQ]. The Energy Management
use cases covered by this framework are covered in the EMAN
applicability statement document in [EMAN-AS]. Typically
requirements and use cases for communication networks cover
the devices that make up the communication network and
endpoints.
With Energy Management, there exists a wide variety of devices
that may be contained in the same deployments as a
communication network but comprise a separate facility, home,
or power distribution network.
Target devices for Energy Management are all Energy Objects
that can directly or indirectly be monitored or controlled by
an Energy Management System (EnMS) using the Internet
protocol, for example:
- Simple electrical appliances / fixtures
- Hosts, such as a PC, a datacenter server, or a printer
- Routers
- Switches
- A component within devices, such as a battery inside a
PC, a line card inside a switch, etc...
- Power over Ethernet (PoE) endpoints
- Power Distribution Units (PDU)
- Protocol gateway devices for Building Management Systems
(BMS)
- Electrical meters
- Sensor controllers with subtended sensors
There may also exist varying protocols deployed among these
power distributions and communication networks.
For an Energy Management framework to be useful, it should
also apply to these types of separate networks as they connect
and interact with a communications network.
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This is the first version of the IETF Energy Management
framework. Though it already covers a wide range of use
cases, there are still a lot of potential ones that are not
covered, yet. A simple example is the limitation to discrete
power states without parameters. Some devices have energy-
related properties that not well described with discrete power
states, for example a dimmer with a continuous power range
from 0%-100%. Other devices may have even more parameters
than just a single percentage value.
This framework definces an informtion model containing various
values that are measured on a device for the purpose of
monitor and control. The framework does not cover setting
bounds or conditions for these values for the purpose of
policy management - for example specifying that power MUST NOT
exceed a limit. While implementations can set bounds and
notification when exceeding those bounds while monitored,
physically preventing a device to not exceed the bound is
beyond the scope of this framework. It is up to future updates
of this document to select more of such use-cases and to cover
them by extensions or revisions of the present framework.
4. Energy Management Issues
This section explains special issues of Energy Management
particularly concerning power supply, Power and Energy
metering, and the reporting of low Power States.
To illustrate the issues we start with a simple and basic
scenario with a single powered device that receives Energy and
that reports energy-related information about itself to an
Energy Management System (EnMS), see Figure 1
+--------------------------+
| Energy Management System |
+--------------------------+
^ ^
monitoring | | control
v v
+-----------------+
| powered device |
+-----------------+
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Figure 1: Basic energy management scenario
The powered device may have local energy control mechanisms,
for example putting itself into a sleep mode when appropriate,
and it may receive energy control commands for similar
purposes from the EnMS. Information reported from a powered
device to the EnMS includes at least the Power State of the
powered device (on, sleep, off, etc.).
This and similar cases are well understood and likely to
become very common for Energy Management. They can be handled
with well established and standardized management procedures.
The only missing components today are standardized information
and data models for reporting and configuration, such as, for
example, energy-specific MIB modules [RFC2578] and YANG
modules [RFC6020].
However, the nature of energy supply and use introduces some
issues that are special to Energy Management. The following
subsections address these issues and illustrate them by
extending the basic scenario in Figure 1.
4.1. Power Supply
A powered device may supply itself with power. Sensors, for
example, commonly have batteries or harvest Energy. However,
most powered devices that are managed by an EnMS receive
external power.
While a huge number of devices receive Power from unmanaged
supply systems, the number of manageable power supply devices
is increasing.
In datacenters, many Power Distribution Units (PDUs) allow the
EnMS to switch power individually for each socket and also to
measure the provided Power. Here there is a big difference to
many other network management tasks: In such and similar
cases, switching power supply for a powered device or
monitoring its power is not done by communicating with the
actual powered device, but with an external power supply
device (in this case, the PDU). Note that those external power
supply devices may be an external power meter).
Consequently, a standard for Energy Management must not just
cover the powered devices that provide services for users, but
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also the power supply devices (which are powered devices as
well) that monitor or control the power supply for other
powered devices.
A very simple device such as a plain light bulb can be
switched on or off only by switching its power supply. More
complex devices may have the ability to switch off themselves
or to bring themselves to states in which they consume very
little power. For these devices as well, it is desirable to
monitor and control their power supply.
This extends the basic scenario from Figure 1 by a power
supply device, see Figure 2.
+-----------------------------------------+
| energy management system |
+-----------------------------------------+
^ ^ ^ ^
monitoring | | control monitoring | | control
v v v v
+--------------+ +-----------------+
| power supply |########| powered device |
+--------------+ +-----------------+
######## power supply line
Figure 2: Power Supply
The power supply device can be as simple as a plain power
switch. It may offer interfaces to the EnMS to monitor and to
control the status of its power outlets, as with PDUs and
Power over Ethernet (PoE) [IEEE-802.3at] switches.
The relationship between supply devices and the powered
devices they serve creates several problems for managing power
supply:
o Identification of corresponding devices
* A given powered device may be need to identify the
supplying power supply device.
* A given power supply device may need to identify the
corresponding supplied powered device(s).
o Aggregation of monitoring and control for multiple
powered
devices
* A power supply device may supply multiple powered
devices with a single power supply line.
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o Coordination of power control for devices with multiple
power inlets
* A powered device may receive power via multiple power
lines controlled by the same or different power
supply devices.
4.1.1 Identification of Power Supply and Powered Devices
When a power supply device controls or monitors power supply
at one of its power outlets, the effect on other devices is
not always clear without knowledge about wiring of power
lines. The same holds for monitoring. The power supplying
device can report that a particular socket is powered, and it
may even be able to measure power and conclude that there is a
consumer drawing power at that socket, but it may not know
which powered device receives the provided power.
In many cases it is obvious which other device is supplied by
a certain outlet, but this always requires additional
(reliable) information about power line wiring. Without
knowing which device(s) are powered via a certain outlet,
monitoring data are of limited value and the consequences of
switching power on or off may be hard to predict.
Even in well organized operations, powered devices' power
cords can be plugged into the wrong socket, or wiring plans
changed without updating the EnMS accordingly.
For reliable monitoring and control of power supply devices,
additional information is needed to identify the device(s)
that receive power provided at a particular monitored and
controlled socket.
This problem also occurs in the opposite direction. If power
supply control or monitoring for a certain device is needed,
then the supplying power supply device has to be identified.
To conduct Energy Management tasks for both power supply
devices and other powered devices, sufficiently unique
identities are needed, and knowledge of their power supply
relationship is required.
4.1.2 Multiples Devices Supplied by a Single Power Line
The second fundamental problem is the aggregation of
monitoring and control that occurs when multiple powered
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devices are supplied by a single power supply line. It is
often required that the EnMS has the full list of powered
devices connected to a single outlet as in Figure 3.
+---------------------------------------+
| energy management system |
+---------------------------------------+
^ ^ ^ ^
monitoring | | control monitoring | | control
v v v v
+--------+ +------------------+
| power |########| powered device 1 |
| supply | # +------------------+-+
+--------+ #######| powered device 2 |
# +------------------+-+
#######| powered device 3 |
+------------------+
Figure 3: Multiple Powered Devices Supplied
by Single Power Line
With this list, the single status value has clear meaning and
is the sum of all powered devices. Control functions are
limited by the fact that supply for the concerned devices can
only be switched on or off for all of them at once.
Individual control at the supply is not possible.
If the full list of devices powered by a single supply line is
not known by the controlling power supply device, then control
of power supply is problematic, because the consequences of
control actions can only be partially known.
4.1.3 Multiple Power Supply for a Single Powered Device
The third problem arises from the fact that there are devices
with multiple power supplies. Some have this for redundancy
of power supply, some for just making internal power
converters (for example, from AC mains power to DC internal
power) redundant, and some because the capacity of a single
supply line is insufficient.
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+----------------------------------------------+
| energy management system |
+----------------------------------------------+
^ ^ ^ ^ ^ ^
mon. | | ctrl. mon. | | ctrl. mon. | | ctrl.
v v v v v v
+----------+ +----------+ +----------+
| power |######| powered |######| power |
| supply 1 |######| device | | supply 2 |
+----------+ +----------+ +----------+
Figure 4: Multiple Power Supply for Single Powered Device
The example in Figure 4 does not necessarily show a real world
scenario, but it shows the two cases to consider:
o multiple power supply lines between a single power
supply
device and a powered device
o different power supply devices supplying a single
powered
device
In any such case there may be a need to identify the supplying
power supply device individually for each power inlet of a
powered device.
Without this information, monitoring and control of power
supply for the powered device may be limited.
4.1.4 Bidirectional Power Interfaces
Low wattage DC systems may allow power to be delivered bi-
directionally. Energy stored in batteries on one device can
be delivered back to a power hub which redirects the current
to power another device. In this situation, the interface can
function as both an inlet and outlet.
The framework for Energy Management introduces the notion of
Power Interface, which can model a power inlet and a power
outlet, depending on the conditions. The Power Interface
reports power direction, as well as the energy received,
supplied and the net result.
4.1.5 Relevance of Power Supply Issues
In some scenarios, the problems with power supply do not exist
or can be sufficiently solved. With Power over Ethernet (PoE)
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[IEEE-802.3at], there is always a one-to-one relationship
between a Power Sourcing Equipment (PSE) and a Powered Device
(PD). Also, the Ethernet link on the line used for powering
can be used to identify the two connected devices.
For supply of AC mains power, the three problems described
above cannot be solved in general. There is no commonly
available protocol or automatic mechanism for identifying
endpoints of a power line.
And, AC power lines support supplying multiple powered devices
with a single line and commonly do.
4.1.6 Remote Power Supply Control
There are three ways for an energy management system to change
the Power State of an powered devices. First is for the EnMS
to provide policy or other useful information (like the
electricity price) to the powered device for it to use in
determining its Power State. The second is sending the
powered devices a command to switch to another Power State.
The third is to utilize an upstream device (to the powered
device) that has capabilities to switch on and off power at
its outlet.
Some Energy Objects do not have capabilities for receiving
commands or changing their Power States by themselves. Such
Energy Objects may be controlled by switching on and off the
power supply for them and so have particular need for the
third method.
In Figure 4, the power supply can switch on and off power at
its power outlet and thereby switch on and off power supply
for the connected powered device.
4.2. Power and Energy Measurement
Some devices include hardware to directly measure their Power
and Energy consumption. However, most common networked
devices do not provide an interface that gives access to
Energy and Power measurements. Hardware instrumentation for
this kind of measurements is typically not in place and adding
it incurs an additional cost.
With the increasing cost of Energy and the growing importance
of Energy Monitoring, it is expected that in future more
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devices will include instrumentation for power and energy
measurements, but this may take quite some time.
4.2.1 Local Estimates
One solution to this problem is for the powered device to
estimate its own Power and consumed Energy. For many Energy
Management tasks, getting an estimate is much better than not
getting any information at all.
Estimates can be based on actual measured activity level of a
device or it can just depend on the power state (on, sleep,
off, etc.).
The advantage of estimates is that they can be realized
locally and with much lower cost than hardware
instrumentation. Local estimates can be dealt with in
traditional ways. They don't need an extension of the basic
scenarios above. However, the powered device needs an energy
model of itself to make estimates.
4.2.2 Management System Estimates
Another approach to the lack of instrumentation is estimation
by the EnMS. The EnMS can estimate Power based on basic
information on the powered device, such as the type of device,
or also its brand/model and functional characteristics.
Energy estimates can combine the typical power level by Power
State with reported data about the Power State.
If the EnMS has a detailed energy model of the device, it can
produce better estimates including the actual power state and
actual activity level of the device. Such information can be
obtained by monitoring the device with conventional means of
performance monitoring.
4.3. Reporting Sleep and Off States
Low power modes pose special challenges for energy reporting
because they may preclude a device from listening to and
responding to network requests. Devices may still be able to
reliably track energy use in these modes, as power levels are
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usually static and internal clocks can track elapsed time in
these modes.
Some devices do have out-of-band or proxy abilities to respond
to network requests in low-power modes. Others could use
proxy abilities in an energy management protocol to improve
this reporting, particularly if the powered device sends out
notifications of power state changes.
4.4. Device and Device Components
While the primary focus of energy management is entire powered
Devices, sometimes it is necessary or desirable to manage
Components such as line cards, fans, disks, etc.
The concept of a Power Interface may not apply to Components
since they may receive Energy from a pool available from the
encompassing device. For example, a DC-powered blade server
in a chassis may have its own identity on the network and be
managed as a single device but its energy may be received from
a shared power source among all blades in the chassis.
4.5. Non-Electrical Equipment
The primary focus of this framework is for the management of
Electrical Equipment. Some Non-Electrical Equipment may be
connected to a communication networks and could have their
energy managed if normalize to the electrical units for power
and energy.
Some examples of Non-Electrical Equipment that may be
connected to a communication network are:
1) A controller for compressed air. The controller is
electrical only for its network connection. The controller
is fueled by natural gas and produces compressed air. The
energy transferred via compressed air is distributed to
devices on a factory floor via a Power Interface: tools
(drills, screwdrivers, assembly line conveyor belts). The
energy measured is non-electrical (compressed air).
EDITOR'S NOTE: Note that, in such as case, some might argue
that the "energy interface" term might be more accurate than
Power Interface. To be discussed.
2) A controller for steam. The controller is electrical for its
network attachment but it burns tallow and produces steam to
subtended boilers. The energy is non-electrical (steam).
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3) A controller or regulator for gas. The controller is
electrical for its network attachment but it has physical
non-electrical components for control. The energy is non-
electrical (BTU).
5. Energy Management Reference Model
The scope of this framework is to enable network and network-
attached devices to be administered for Energy Management.
The framework recognizes that in complex deployments Energy
Objects may communicate over varying protocols. For example
the communications network may use IP Protocols (SNMP) but
attached Energy Object Parent may communicate to Energy Object
Children over serial communication protocols like BACNET,
MODBUS etc. The likelihood of getting these different
topologies to convert to a single protocol is not very high
considering the rate of upgrades of facilities and energy
related devices. Therefore the framework must address the
simple case of a uniform IP network and a more complex mixed
topology/deployment.
In this section we will describe the topologies that can exist
when describing a device, components and the relationships
among them in an Energy Management Domain.
We will then generalize those topologies by using an
information model based upon relationships. The most abstract
and general relationship between devices is a Parent and Child
relationship. Specific types of relationships are defined and
used in concert to describe the topologies of an Energy
Management Domain.
5.1. Reference Topologies
The reference model defines physical and logical topologies of
devices and the relationship among them in a communication
network.
The physical topology defined by the model defines
relationships between devices that reflect provisioning,
transfer of energy, and aid in management.
Logical topologies concern monitoring and controlling devices
and covers metering of energy and power, reporting information
relevant for energy management, and energy-related control of
devices.
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5.1.1 Power Source Topology
As described in Section 4, the power source(s) of a device is
important for energy management. The energy management
reference model addresses this by a "Power Source"
Relationship. This is a relationship among devices providing
energy and devices receiving energy.
A simple example is a PoE PSE, for example, an Ethernet
switch, providing power to a PoE PD, for example, a desktop
phone. Here the switch provides energy and the phone receives
energy. This relationship can be seen in the figure below.
+----------+ power source +---------+
| switch | <-------------- | phone |
+----------+ +---------+
Figure 5: Simple Power Source
A single power provider can act as power source of multiple
power receivers. An example is a power distribution unit
(PDU) providing AC power for multiple switches.
+-------+ power source +----------+
| PDU | <----------+--- | switch 1 |
+-------+ | +----------+
|
| +----------+
+--- | switch 2 |
| +----------+
|
| +----------+
+--- | switch 3 |
+----------+
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Figure 6: Multiple Power Source
This level of modeling is sufficient if there is no need to
distinguish in monitoring and control between the individual
receivers at the switch.
However, if there is a need to monitor or control power supply
for individual receivers at the power provider, then a more
detailed level of modeling is needed.
Devices receive or provide energy at power interfaces
connecting them to a transmission medium. . The Power Source
relationship can be used also between power interfaces at the
power provider side as well as at the power receiver side.
The example below shows a power providing device with a power
interface (PI) per connected receiving device.
+-------+------+ power source +----------+
| | PI 1 | <-------------- | switch 1 |
| +------+ +----------+
| |
| +------+ power source +----------+
| PDU | PI 2 | <-------------- | switch 2 |
| +------+ +----------+
| |
| +------+ power source +----------+
| | PI 3 | <-------------- | switch 3 |
+-------+------+ +----------+
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Figure 7: Power Source with Power interfaces
Power interfaces may also be modeled at the receiving device,
for examples for consistency.
+-------+------+ power source +----+----------+
| | PI 1 | <-------------- | PI | switch 1 |
| +------+ +----+----------+
| |
| +------+ power source +----+----------+
| PDU | PI 2 | <-------------- | PI | switch 2 |
| +------+ +----+----------+
| |
| +------+ power source +----+----------+
| | PI 3 | <-------------- | PI | switch 3 |
+-------+------+ +----+----------+
Figure 8: Power Interfaces at Receiving Device
Power Source relationships are between peering devices and
their interfaces. They are not transitive. In the examples
below there is a PDU powering a switch powering a phone.
+-------+ power +--------+ power +---------+
| PDU | <-------- | switch | <-------- | phone |
+-------+ source +--------+ source +---------+
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Figure 9: Power Source Non-Transitive
Power Source Relationships are between the PDU and the switch
and between the switch and the phone.
Power Source Relationships are between the PDU and the
switchand between the switch and the phone. Consequently,
there is logically exists a power source relation between the
PDU and the phone.
+-------+ power +--------+ power +---------+
| PDU | <-------- | switch | <-------- | phone |
+-------+ source +--------+ source +---------+
^ |
| power source |
+------------------------------------------+
Figure 10: Power Source Transitive
5.1.2 Metering Topology
Metering Between Two Device
The power metering topology between two devices is closely
related to the power source topology. It is based on the
assumption that in many cases the power provided and the power
received is the same for both peers of a power source
relationship. Then power measured at one end can be taken as
the actual power value at the other end. Obviously, the same
applies to energy at both ends.
We define in this case a Power Metering Relationship between
two devices or power interfaces of devices that have a power
source relationship. Power and energy values measured at one
peer of the power source relationship are reported for the
other peer as well.
The Power Metering Relationship is independent of the
direction of the Power source Relationship. The more common
case is that values measured at the power provider are
reported for the power receiver, but also the reverse case is
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possible with values measured at the power receiver being
reported for the power provider.
power power
+-----+----------+ source +--------+ source +-------+
| PDU |PI + meter| <-------- | switch | <------- | phone |
+-----+----------+ metering +--------+ +-------+
^ |
| |
+-------------------------------------------+
metering
Figure 11: Direct and One Hop Metering
Metering At a Point in Power Distribution
A Sub-meter in a power distribution system can logically
measure the power or energy for all devices downstream from
the meter in the power distribution system. As such a Power
metering relationship can be seen as a relationship between a
meter and all of the devices downstream from the meter.
We define in this case a Power Metering relationship between a
metering device and devices downstream from the meter.
In cases where the Power Source topology cannot be discovered
or derived from the information available in the Energy
Management Domain, the Metering Topology can be used to relate
the upstream meter to the downstream devices in the absence of
specific power source relationships.
A metering relationship can occur between devices that are
notdirectly connected as shown by the figure below.
An analogy to communication networks would be modeling
connections between servers (meters) and clients (devices)
when the complete Layer 2 topology between the servers and
clients is not known.
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+---------------+
| Device 1 |
+---------------+
| PI |
+---------------+
|
+---------------+
| Meter |
+---------------+
.
:
+----------+ +----------+ +-----------+
| Device A | | Device B | | Device C |
+----------+ +----------+ +-----------+
Figure 12: Complex Metering Topology
5.1.3 Proxy Topology
Some devices may provide energy management capabilities on
behalf of other devices. For example a controller may
logically model power interfaces but the physical topology may
require that the controller communicate to another device
using a BMS protocol. These subtended devices that are
represented as power interfaces may be directly connected or
may be controlled over a communication network with no direct
connection.
While the EnMS may look at the logical representation of the
controller as a device with power interfaces, it may require
to report the physical topology and relationship to the
subtended devices. To model this we define a proxy
relationship to provide this visibility.
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+-------+------+
| | PI 1 |
| +------+
| |
| +------+
| PDU | PI 2 |
| +------+
| |
| +------+
| | PI 3 |
+-------+------+
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+-------+ proxy +----+----------+
| |<-------- | PI 1 Physical |
| + +----+----------+
| |
| + proxy +----+----------+
| PDU |<--------- | PI 2 Physical |
| + +----+----------+
| |
| + proxy +----+----------+
| |<--------- | PI 3 Physical |
+-------+ +----+----------+
Figure 13: Proxy Relationship Virtual and Physical
5.1.4 Aggregation Topology
Some devices in a domain can act as aggregation points for
other devices. For example a PDU contoller device may contain
the summation of power and energy readings for many PDU
devices. The PDU controller will have aggregate values for
power and energy for a group of PDU devices.
This aggregation is independent of the physical power or
communication topology.
The functions that the aggregation point may perform include
values such as average, count, maximum, median, minimum or
listing (collection) of the aggregation.
We define in this case an Aggregation Relationship between a
device containing aggregate values for arbitrary groups of
other devices.
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While any power or energy values monitored from a device/power
interface can be seen as a summation for all devices
downstream from the monitoring device, the aggregation
relationship is used to represent a summation when it is not
obvious from the powering topology or a device to component
containment.
5.2. Generalized Relationship Model
As displayed in Figure 5, the most basic energy management
reference model is composed of an EnMS that obtains Energy
Management information from Energy Objects. The Energy Object
(EO) returns information for Energy Management directly to the
EnMS.
The protocol of choice for Energy Management is SNMP, as three
MIBs are specified for Energy Management: the energy-aware MIB
[EMAN-AWARE-MIB], the energy monitoring MIB [EMAN-MON-MIB],
and the battery MIB [EMAN-BATTERY-MIB]. However, the EMAN
requirement document [EMAN-REQ] also requires support for a
push model distribution of time series values. The following
diagrams mention IPFIX [RFC5101] as one possible solution for
implementing a push mode transfer, however this is for
illustration purposes only. The EMAN standard does not
require the use of IPFIX and acknowledges that other
alternative solutions may also be acceptable.
+---------------+
| EnMS | - -
+-----+---+-----+ ^ ^
| | | |
| | |S |I
+---------+ +----------+ |N |P
| | |M |F
| | |P |I
+-----------------+ +--------+--------+ | |X
| EO 1 | ... | EO N | v |
+-----------------+ +-----------------+ - -
Figure 14: Simple Energy Management
As displayed in the Figure 5, a more complex energy reference
model includes Energy Managed Object Parents and Children.
The Energy Managed Object Parent returns information for
themselves as well as information according to the Energy
Managed Object Relationships.
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+---------------+
| EnMS | - -
+-----+--+------+ ^ ^
| | | |
| | |S |I
+------------+ +--------+ |N |P
| | |M |F
| | |P |I
+------------------+ +------+-----------+ | |X
| EO | | EO | v |
| Parent 1 | ... | Parent N | - -
+------------------+ +------------------+
||| .
One or ||| .
Multiple ||| .
Energy ||| .
Object ||| .
Relationship(s): |||
- Aggregation ||| +-----------------------+
- Metering |||------| EO Child 1 |
- Power Source || +-----------------------+
- Proxy ||
|| +-----------------------+
||-------| EO Child 2 |
| +-----------------------+
|
|
|-------- ...
|
|
| +-----------------------+
|--------| EO Child M |
+-----------------------+
Figure 15: Complex Energy Management Model
While both the simple and complex Energy Management models
contain an EnMS, this framework doesn't impose any
requirements regarding a topology with a centralized EnMS or
one with distributed Energy Management via the Energy Objects
within the deployment.
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Given the pattern in Figure 6, the complex relationships
between Energy Objects can be modeled (refer also to section
5.3):
- A PoE device modeled as an Energy Object Parent with
the Power Source, Metering, and Proxy Relationships for
one or more Energy Object Children
- A PDU modeled as an Energy Object Parent with the Power
Source and Metering Relationships for the plugged in
Electrical Equipment (the Energy Object Children)
- Building management gateway, used as proxy for non IP
protocols, is modeled as an Energy Object Parent with
the Proxy Relationship, and potentially the Aggregation
Relationship to the managed Electrical Equipment
- Etc.
The communication between the Energy Object Parent and Energy
Object Children is out of the scope of this framework.
5.3. Energy Object, Energy Object Components and Containment Tree
The framework for Energy Management manages two different
types of Energy Objects: Devices and Components. A typical
example of an Device is a switch. However, a port within the
switch, which provides Power to one end point, is also an
Energy Object if it meters the power provided. A second
example is PC, which is a typical Device, while the battery
inside the PC is a Component, managed as an individual Energy
Object. Some more examples of Components: power supply within
a router, an outlet within a smart PDU, etc...
In the [EMAN-AWARE-MIB], each Energy Object is managed with an
unique value of the entPhysicalIndex index from the ENTITY-MIB
[RFC4133]
The ENTITY-MIB [RFC4133] specifies the notion of physical
containment tree, as:
"Each physical component may be modeled as 'contained'
within
another physical component. A "containment-tree" is the
conceptual sequence of entPhysicalIndex values that uniquely
specifies the exact physical location of a physical
component within the managed system. It is generated by
'following and recording' each 'entPhysicalContainedIn'
instance 'up the tree towards the root', until a value of
zero indicating no further containment is found."
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A Energy Object Component in the Energy Management context is
a special Energy Object that is a physical component as
specified by the ENTITY-MIB physical containment tree.
6. Framework High Level Concepts and Scope
Energy Management can be organized into areas of concern that
include:
- Energy Object Identification and Context - for modeling and
planning
- Energy Monitoring - for energy measurements
- Energy Control - for optimization
- Energy Procurement - for optimization of resources
While an EnMS may be a central point for corporate reporting,
cost, environmental impact, and regulatory compliance, Energy
Management in this framework excludes Energy procurement and
the environmental impact of energy use. As such the framework
does not include:
- Manufacturing costs of an Energy Object in currency or
environmental units
- Embedded carbon or environmental equivalences of an Energy
Object
- Cost in currency or environmental impact to dismantle or
recycle an Energy Object
- Supply chain analysis of energy sources for Energy Object
deployment
- Conversion of the usage or production of energy to units
expressed from the source of that energy (such as the
greenhouse gas emissions associated with 1000kW from a diesel
source).
The next sections describe Energy Management organized into
the following areas:
- Energy Object and Energy Management Domain
- Energy Object Identification and Context
- Energy Object Relationships
- Energy Monitoring
- Energy Control
- Deployment Topologies
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6.1. Energy Object and Energy Management Domain
In building management, a meter refers to the meter provided
by the utility used for billing and measuring power to an
entire building or unit within a building. A sub-meter refers
to a customer or user installed meter that is not used by the
utility to bill but instead used to get readings from sub
portions of a building.
An Energy Management Domain should map 1:1 with a metered or
sub-metered portion of the site. An Energy Object is part of
a single Energy Management Domain. The Energy Management
Domain MAY be configured on an Energy Object: the default
value is a zero-length string.
If all Energy Objects in the physical containment tree (see
ENTITY-MIB) are part of the same Energy Management Domain,
then it is safe to state that the Energy Object at the root of
that containment tree is in that Energy Management Domain.
An Energy Object Child may inherit the domain value from an
Energy Object Parent or the Energy Management Domain may be
configured directly in an Energy Object Child.
6.2. Power Interface
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. The Power Interface can be receiving or providing
power.
Most Power Interfaces never change their mode, but as the mode
is simply a recognition of the current direction of
electricity flow, there is no barrier to a mode change.
A power interface can have capabilities for metering power and
other electric quantities at the shared power transmission
medium.
This capability is modeled by an association to a power meter.
In analogy to MAC addresses of network interfaces, a globally
unique identifier is assigned to each Power Interface.
Physically, a Power Interface can be located at an AC power
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socket, an AC power cord attached to a device, an 8P8C (RJ45)
PoE socket, etc.
6.3. Energy Object Identification and Context
6.3.1 Energy Object Identification
Energy Objects MUST be associated with a value that uniquely
identifies the Energy Object among all the Energy Management
Domains within an EnMS. A Universal Unique Identifier (UUID)
[RFC4122] MUST be used to uniquely and persistently identify
an Energy Object.
Every Energy Object SHOULD have a unique printable name within
the Energy Management Domain. Possible naming conventions
are: textual DNS name, MAC-address of the device, interface
ifName, or a text string uniquely identifying the Energy
Object. As an example, in the case of IP phones, the Energy
Object name can be the device's DNS name.
6.3.2 Context in General
In order to aid in reporting and in differentiation between
Energy Objects, each Energy Object optionally contains
information establishing its business, site, or organizational
context within a deployment, i.e. the Energy Object Context.
Context: Importance
An Energy Object can provide an importance value in the range
of 1 to 100 to help rank a device's use or relative value to
the site. The importance range is from 1 (least important) to
100 (most important). The default importance value is 1.
For example: A typical office environment has several types of
phones, which can be rated according to their business impact.
A public desk phone has a lower importance (for example, 10)
than a business-critical emergency phone (for example, 100).
As another example: A company can consider that a PC and a
phone for a customer-service engineer is more important than a
PC and a phone for lobby use.
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Although EnMS and administrators can establish their own
ranking, the following is a broad recommendation:
. 90 to 100 Emergency response
. 80 to 90 Executive or business-critical
. 70 to 79 General or Average
. 60 to 69 Staff or support
. 40 to 59 Public or guest
. 1 to 39 Decorative or hospitality
Context: Keywords
An Energy Object can provide a set of keywords. These
keywords are a list of tags that can be used for grouping,
summary reporting within or between Energy Management Domains,
and for searching. All alphanumeric characters and symbols
(other than a comma), such as #, (, $, !, and &, are allowed.
Potential examples are: IT, lobby, HumanResources, Accounting,
StoreRoom, CustomerSpace, router, phone, floor2, or
SoftwareLab. There is no default value for a keyword.
Multiple keywords can be assigned to a device. White spaces
before and after the commas are excluded, as well as within a
keyword itself. In such cases, the keywords are separated by
commas and no spaces between keywords are allowed. For
example, "HR,Bldg1,Private".
Context: Role
An Energy Object can provide a "role description" string that
indicates the purpose the Energy Object serves in the EnMS.
This could be a string describing the context the device
fulfills in deployment.
Administrators can define any naming scheme for the role of a
device. As guidance a two-word role that combines the service
the device provides along with type can be used [IPENERGY]
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Example types of devices: Router, Switch, Light, Phone,
WorkStation, Server, Display, Kiosk, HVAC.
Example Services by Line of Business:
Line of Business Service
Education Student, Faculty, Administration,
Athletic
Finance Trader, Teller, Fulfillment
Manufacturing Assembly, Control, Shipping
Retail Advertising, Cashier
Support Helpdesk, Management
Medical Patient, Administration, Billing
Role as a two-word string: "Faculty Desktop", "Teller Phone",
"Shipping HVAC", "Advertising Display", "Helpdesk Kiosk",
"Administration Switch".
6.4. Energy Object Relationships
Two Energy Objects MAY establish an Energy Object
Relationship. Within a relationship one Energy Object becomes
an Energy Object Parent while the other becomes an Energy
Object Child.
The Power Source Relationship gives the view the wiring
topology. For example: a data center server receiving power
from two specific Power Interfaces from two different PDUs.
The Metering Relationship gives the view of the metering
topology. Standalone meters can be placed anywhere in a power
distribution tree. For example, utility meters monitor and
report accumulated power consumption of the entire building.
Logically, the metering topology overlaps with the wiring
topology, as meters are connected to the wiring topology. A
typical example is meters that clamp onto the existing wiring.
The Proxy Relationship allows software objects to be inserted
into the wiring or metering topology to aid in managing
(monitoring and/or control) the Energy Domain.
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From a EnMS management point of view, this implies that there
is yet another management topology that EnMS will need to be
aware of.
In the ideal situation, the wiring, the metering, and the
management topologies overlap. For Example: A Power-over-
Ethernet (PoE) device (such as an IP phone or an access point)
is attached to a switch port. The switch port is the source
of power for the attached device, so the Energy Object Parent
is the switch port, which acts as a Power Interface, and the
Energy Object Child is the device attached to the switch.
This Energy Object Parent (the switch) has three Energy Object
Relations with this Energy Object Child (the remote Energy
Object): Power Source Relationship, Metering Relationship, and
Proxy Relationship.
However, the three topologies (wiring, metering, and
management) don't always overlap. For example, when a
protocol gateways device for Building Management Systems (BMS)
controls subtended devices, which themselves receive Power
from PDUs or wall sockets.
Note: The Aggregation Relationship is slightly different
compared to the other relationships (Power Source, Metering,
and Proxy Relationships) as this refers more to a management
function.
The communication between the parent and child for monitoring
or collection of power data is left to the device
manufacturer. For example: A parent switch may use LLDP to
communicate with a connected child, and a parent lighting
controller may use BACNET to communicate with child lighting
devices.
The Energy Object Child MUST keep track of its Energy Object
Parent(s) along with the Energy Object Relationships type(s).
The Energy Object Parent MUST keep track of its Energy Object
Child(ren), along with the Energy Object Relationships
type(s).
6.4.1 Energy Object Children Discovery
There are multiple ways that the Energy Object Parent can
discover its Energy Object Children: :
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. In case of PoE, the Energy Object Parent automatically
discovers an Energy Object Child when the Child requests
power.
. The Energy Object Parent and Children may run the Link
Layer Discovery Protocol [LLDP], or any other discovery
protocol, such as Cisco Discovery Protocol (CDP). The
Energy Object Parent might even support the LLDP-MED MIB
[LLDP-MED-MIB], which returns extra information on the
Energy Object Children.
. The Energy Object Parent may reside on a network
connected to a facilities gateway. A typical example is
a converged building gateway, monitoring several other
devices in the building, and serving as a proxy between
SNMP and a protocol such as BACNET.
. A different protocol between the Energy Object Parent and
the Energy Object Children. Note that the communication
specifications between the Energy Object Parent and
Children is out of the scope of this document.
However, in some situations, it is not possible to discover
the Energy Object Relationships, and they must be set
manually. For example, in today' network, an administrator
must assign the connected Energy Object to a specific PDU
Power Interface, with no means of discovery other than that
manual connection.
When an Energy Object Parent is a Proxy, the Energy Object
Parent SHOULD enumerate the capabilities it is providing for
the Energy Object Child. The child would express that it
wants its parent to proxy capabilities such as, energy
reporting, power state configurations, non physical wake
capabilities (such as WoL)), or any combination of
capabilities.
6.4.2 Energy Object Relationship Conventions and Guidelines
This Energy Management framework does not impose many "MUST"
rules related to Energy Object Relationships. There are always
corner cases that could be excluded with too strict
specifications of relationships. However, this Energy
Management framework proposes a series of guidelines,
indicated with "SHOULD" and "MAY".
Aggregation
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Aggregation relationships are intended to identify when one
device is used to accumulate values from other devices.
Typically this is for energy or power values among devices and
not for Components or Power Interfaces on the same device.
The intent of Aggregation relationships is to indicate when
one device is providing aggregate values for a set of other
devices when it is not obvious form the power source or simple
containment within a device.
Establishing aggregation relationships within the same device
would make modeling more complex and the aggregated values can
be implied form the use of Power Inlets, outlet and Energy
Object value son the same device.
Additionally since an EnMS is naturally a point of aggregation
for information in an Energy Management Domain it is not
necessary to model aggregation for an EnMS(s).
Aggregation SHOULD be used for power and energy. It MAY be
used for aggregation of other values from the information
model for example but the rules and logical ability to
aggregated each attribute is out of scope for this document.
- A Device SHOULD NOT establish an Aggregation Relationship
with a Component.
- A Device SHOULD NOT establish an Aggregation Relationship
with the Power Interfaces contained on the same device.
- A Device SHOULD NOT establish an Aggregation Relationship
with the an EnMS.
- Aggregators SHOULD log or provide notification in the case
of errors or missing values while performing aggregation.
Power Source
Power Source relationships are intended to identify the
connections between Power Interfaces. This is analogous to a
Layer 2 connection in networking devices (a "one hop"
connection).
The preferred modeling would be for Power Interfaces to
participate in Power Source Relationships.
It may happen that the some Energy Objects may not have the
capability to model Power Interfaces. Therefore, it may
happen that a Power Source Relationship is established between
two Energy Objects or two non-connected Power Interfaces.
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While strictly speaking Components and Power Interfaces on the
same device do provide or receive energy from each other the
Power Source relationship is intended to show energy transfer
between Devices. Therefore relationship is implied on the same
Device.
- An Energy Object SHOULD NOT establish a Power Source
Relationship with a Component.
- A Power Source Relationship SHOULD be established with next
known Power Interface in the wiring topology.
o The next known Power Interface in the wiring topology
would be the next device implementing the framework. In
some cases the domain of devices under management may
include some devices that do not implement the
framework As such the Power Source relationship can be
established with the next device in the topology that
implements the framework and logically shows the Power
Source of the device.
- Transitive Power Source relationships SHOULD NOT be
established. For examples if an Energy Object A has a Power
Source Relationship "Poweredby" with the Energy Object B,
and if the Energy Object B has a Power Source Relationship
"Poweredby" with the Energy Object C, then the Energy Object
A SHOULD NOT have a Power Source Relationship "PoweredBby"
the Energy Object C.
Metering Relationship
Metering Relationships are intended to show when one Device is
measuring the power or energy at a point in a power
distribution system. Since one point of a power distribution
system may cover many Devices with a complex wiring topology,
this relationship type can be seen as an arbitrary set.
Additionally, Devices may include metering hardware for
components and Power Interfaces or for the entire Device.
For example some PDU's may have the ability to measure Power
for each Power Interface (metered by outlet). Others may only
be able to control power at each Power Interface but only
measure Power at the Power Inlet and a total for all Power
Interfaces (metered by device).
In such cases a Device SHOULD be modeled as an Energy Object
that meters all of its Power Outlets and each Power Outlet MAY
be metered by the Energy Object representing the Device.
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- A Meter Relationship MAY be established with any other
Energy Object, Component, or Power Interface.
- Transitive Meter relationships MAY be used.
- When there is a series of meters for one Enegry Object, the
Energy Object MAY establish a relationship with one or more
of the meters.
Proxy
A Proxy relationship is intended to show when one Device is
providing the Energy Object capabilities for another Device
typically for protocol translations. Strictly speaking a a
Component of a Device may provide the Energy Object
capabilities for that Device (and vice versa) this
relationship is intended to model relationships between
Devices.
- A Proxy relationship SHOULD be limited when possible to
Energy Objects of different Devices.
6.4.3 Energy Objects Relationship Extensions
This framework for Energy Management, is based on four Energy
Objects Relationships: Aggregation Relationship, Metering
Relationship, Power Source Relationship, and Proxy
Relationship.
This framework is defined with possible extension of new
Energy Objects Relationships in mind. For example, a Power
Distribution Unit (PDU) that allows physical entities like
outlets to be "ganged" together as a logical entity for
simplified management purposes, could be modeled with a future
extension based on "gang relationship", whose semantic would
specify the Energy Objects grouping.
6.5. Energy Monitoring
For the purposes of this framework energy will be limited to
electrical energy in watt hours. Other forms of Energy
Objects that use or produce non-electrical energy may be part
of an Energy Management Domain (See Section 4.5. ) but MUST
provide information converted to and expressed in watt hours.
An analogy for understanding power versus energy measurements
can be made to speed and distance in automobiles. Just as a
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speedometer indicates the rate of change of distance, a power
meter indicates the rate of transfer of energy. The odometer
in an automobile measures the cumulative distance traveled and
an energy meter indicates the accumulate energy transferred.
So a less formal statement of the analogy is that power meters
measures "speed" while energy meters measure "distance".
Each Energy Object will have information that describes power
information, along with how that measurement was obtained or
derived (actual measurement, estimated, or presumed). For
Energy Objects that can report actual power readings, an
optional energy measurement can be provided.
Optionally, an Energy Object can further describe the Power
information with Power Quality information reflecting the
electrical characteristics of the measurement.
Optionally, an Energy Object that can report actual power
readings can have energy meters that provide the energy used,
produced, and net energy in kWh. These values are energy
meters that accumulate the power readings. If energy values
are returned then the three energy meters must be provided
along with a description of accuracy.
Optionally, an Energy Object can provide demand information
over time.
6.5.1 Power Measurement
A power measurement MUST be qualified with the units,
magnitude, direction of power flow, and SHOULD be qualified by
what means the measurement was made (ex: Root Mean Square
versus Nameplate).
In addition, the Energy Object should describe how it intends
to measure power as one of consumer, producer or meter of
usage. Given the intent, readings can be summarized or
analyzed by an EnMS. For example metered usage reported by a
meter and consumption usage reported by a device connected to
that meter may naturally measure the same usage. With the two
measurements identified by intent a proper summarization can
be made by an EnMS.
Power measurement magnitude should conform to the IEC 61850
definition of unit multiplier for the SI (System
International) units of measure. Measured values are
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represented in SI units obtained by BaseValue * (10 ^ Scale).
For example, if current power usage of an Energy Object is 3,
it could be 3 W, 3 mW, 3 KW, or 3 MW, depending on the value
of the scaling factor. 3W implies that the BaseValue is 3 and
Scale = 0, whereas 3mW implies BaseValue = 3 and ScaleFactor =
-3.
Energy is often billed in kilowatt-hours instead of megajoules
from the SI units. Similarly, battery charge is often
measured as miliamperes-hour (mAh) instead of coulombs from
the SI units. The units used in this framework are: W, A, Wh,
Ah, V. A conversion from Wh to Joule and from Ah to Coulombs
is obviously possible, and can be described if required.
In addition to knowing the usage and magnitude, it is useful
to know how an Energy Object usage measurement was obtained:
. Whether the measurements were made at the device itself or
from a remote source.
. Description of the method that was used to measure the
power and whether this method can distinguish actual or
estimated values.
An EnMS can use this information to account for the accuracy
and nature of the reading between different implementations.
The EnMS can use the Nameplate Power for provisioning,
capacity planning and potentially billing.
6.5.2 Optional Power Quality
Given a power measurement, it may in certain circumstances be
desirable to know the Power Quality associated with that
measurement. The information model must adhere to the IEC
61850 7-2 standard for describing AC measurements. Note that
the Power Quality includes two sets of characteristics:
characteristics as received from the utility, and
characteristics depending on how the power is used.
In some Energy Management Domains, the power quality may not
be needed, available, or relevant to the EnMS.
Optional Demand
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It is well known in commercial electrical utility rates that
demand is part of the calculation for billing. The highest
peak demand measured over a time horizon, such as 1 month or 1
year, is often the basis for charges. A single window of time
of high usage can penalize the consumer with higher energy
consumption charges. However, it is relevant to measure the
demand only when there are actual power measurements from an
Energy Object, and not when the power measurement is assumed
or predicted.
Optional Battery
Some Energy Objects may use batteries for storing energy and
for receiving power supply. These Energy Objects should
report their current power supply (battery, power line, etc.)
and the battery status for each contained battery. Battery-
specific information to be reported should include the number
of batteries contained in the device and per battery the state
information as defined in [EMAN-REQ].
Beyond that a device containing a battery should be able to
generate alarms when the battery charge falls below a given
threshold and when the battery needs to be replaced.
6.6. Energy Control
An Energy Object can be controlled by setting it to a specific
Power State. An Object implements a set of Power States
consisting of at least two states, an on state and an off
state.
A Power State is an interface by which an Energy Object can be
controlled. Each Energy Object should indicate the set of
Power States that it implements. Well known Power States /
Sets should be registered with IANA.
When a device is set to a particular Power State, it may be
busy. The device will set the desired Power State and then
update the actual Power State when it changes. There are then
two Power State control variables: actual and desired.
There are many existing standards for and implementations of
Power States. An Energy Object can support a mixed set of
Power States defined in different standards. A basic example
is given by the three Power States defined in IEEE1621
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[IEEE1621]: on, off, and sleep. The DMTF [DMTF], ACPI [ACPI],
and PWG define larger numbers of Power States.
The semantics of a power state is specified by
a) the functionality provided by an Energy Object in this
state,
b) a limitation of the power that an Energy Object uses in
this state,
c) a combination of a) and b)
The semantics of a Power State should be clearly defined.
Limitation (curtailment) of the power used by an Energy Object
in a state can be specified by
- an absolute power value
- a percentage value of power relative to the energy
object's nameplate power
- an indication of used power relative to another power
state - for example: by stating used power in state A is less
than in state B.
For supporting Power State management it is useful to provide
statistics on Power States including the time an Energy Object
spent in a certain Power State and/or the number of times an
Energy Object entered a power state.
Power States should be registered at IANA with a name and a
number.
When requesting an Energy object to enter a Power State an
indication of its name or its number can be used. Optionally
an absolute or percentage of Nameplate Power can be provided
to allow the Energy Object to transition to a nearest or
equivalent Power State.
6.6.1 EMAN Power State Set
An EMAN Power State Set represents an attempt for a standard
approach to model the different levels of power of a device.
The EMAN Power States are an expansion of the basic Power
States as defined in [IEEE1621] that also incorporates the
Power States defined in [ACPI] and [DMTF]. Therefore, in
addition to the non-operational states as defined in [ACPI]
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and [DMTF] standards, several intermediate operational states
have been defined.
There are twelve Power States, that expand on [IEEE1621] on,
sleep and off. The expanded list of Power States are divided
into six operational states, and six non-operational states.
The lowest non-operational state is 1 and the highest is 6.
Each non-operational state corresponds to an [ACPI] Global and
System states between G3 (hard-off) and G1 (sleeping). Each
operational state represents a performance state, and may be
mapped to [ACPI] states P0 (maximum performance power) through
P5 (minimum performance and minimum power).
In each of the non-operational states (from mechoff(1) to
ready(6)), the Power State preceding it is expected to have a
lower Power value and a longer delay in returning to an
operational state:
mechoff(1) : An off state where no Energy Object
features are available. The Energy Object is unavailable. No
energy is being consumed and the power connector can be
removed. This corresponds to ACPI state G3.
softoff(2) : Similar to mechoff(1), but some
components remain powered or receive trace power so that the
Energy Object can be awakened from its off state. In
softoff(2), no context is saved and the device typically
requires a complete boot when awakened. This corresponds to
ACPI state G2.
hibernate(3): No Energy Object features are
available. The Energy Object may be awakened without
requiring a complete boot, but the time for availability is
longer than sleep(4). An example for state hibernate(3) is a
save to-disk state where DRAM context is not maintained.
Typically, energy consumption is zero or close to zero. This
corresponds to state G1, S4 in ACPI.
sleep(4) : No Energy Object features are
available, except for out-of-band management, such as wake-up
mechanisms. The time for availability is longer than
standby(5). An example for state sleep(4) is a save-to-RAM
state, where DRAM context is maintained. Typically, energy
consumption is close to zero. This corresponds to state G1,
S3 in ACPI.
standby(5) : No Energy Object features are available,
except for out-of-band management, such as wake-up mechanisms.
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This mode is analogous to cold-standy. The time for
availability is longer than ready(6). For example, the
processor context is not maintained. Typically, energy
consumption is close to zero. This corresponds to state G1,
S2 in ACPI.
ready(6) : No Energy Object features are
available, except for out-of-band management, such as wake-up
mechanisms. This mode is analogous to hot-standby. The Energy
Object can be quickly transitioned into an operational state.
For example, processors are not executing, but processor
context is maintained. This corresponds to state G1, S1 in
ACPI. lowMinus(7) : Indicates some Energy Object
features may not be available and the Energy Object has
selected measures/options to provide less than low(8) usage.
This corresponds to ACPI State G0. This includes operational
states lowMinus(7) to full(12).
low(8) : Indicates some features may not be
available and the Energy Object has taken measures or selected
options to provideless than mediumMinus(9) usage.
mediumMinus(9): Indicates all Energy Object features
are available but the Energy Object has taken measures or
selected options to provide less than medium(10) usage.
medium(10) : Indicates all Energy Object features
are available but the Energy Object has taken measures or
selected options to provide less than highMinus(11) usage.
highMinus(11): Indicates all Energy Object features
are available and power usage is less than high(12).
high(12) : Indicates all Energy Object features
are available and the Energy Object is consuming the highest
power.
A comparison of Power States can be seen in the following
table:
IEEE1621 DMTF ACPI EMAN
Non-operational states
off Off-Hard G3, S5 MechOff(1)
off Off-Soft G2, S5 SoftOff(2)
sleep Hibernate G1, S4 Hibernate(3)
sleep Sleep-Deep G1, S3 Sleep(4)
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sleep Sleep-Light G1, S2 Standby(5)
sleep Sleep-Light G1, S1 Ready(6)
Operational states:
on on G0, S0, P5 LowMinus(7)
on on G0, S0, P4 Low(8)
on on G0, S0, P3 MediumMinus(9)
on on G0, S0, P2 Medium(10)
on on G0, S0, P1 HighMinus(11)
on on G0, S0, P0 High(12)
Figure 16: Comparison of Power States
7. Structure of the Information Model: UML Representation
The following basic UML represents an information model
expression of the concepts in this framework. This
information model, provided as a reference for implementers,
is represented as a MIB in the different related IETF Energy
Monitoring documents. However, other programming structure
with different data models could be used as well.
Notation is a shorthand UML with lowercase types considered
platform or atomic types (i.e. int, string, collection).
Uppercase types denote classes described further. Collections
and cardinality are expressed via qualifier notation.
Attributes labeled static are considered class variables and
global to the class. Algorithms for class variable
initialization, constructors or destructors are not shown
EDITOR'S NOTE: the first part of the UML must be aligned with
the latest [EMAN-AWARE-MIB] document version. Also, received
the following comment referring to the arrows in the following
figure: "It is not clear to me what UML relationships are
being specified here in the ASCIIfied UML relationships.
Please provide a legend to make your conventions for mapping
to UML clear."
EO RELATIONSHIPS AND CONTEXT
+----------------------------+
| _Child Specific Info __ |
|----------------------------|
+---------------------------+ | parentId : UUID |
| Context Information | | parentProxyAbilities |
|---------------------------| | : bitmap |
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| roleDescription : string | | mgmtMacAddress : octets |
| keywords[0..n] : string | | mgmtAddress : inetaddress |
| importance : int | | mgmtAddressType : enum |
| category : enum | | mgmtDNSName : inetaddress |
+---------------------------+ +----------------------------+
| |
| |
| |
v v
+-----------------------------------------+
| Energy Object Information |
|-----------------------------------------|
| index : int |
| energyObjectId | UUID |
| name : string |
| meterDomainName | string |
| alternateKey | string |
+-----------------------------------------+
^
|
|
|
+-------------------------+
| Links Object |
|-------------------------|
| physicalEntity : int |
| ethPortIndex : int |
| ethPortGrpIndex : int |
| lldpPortNumber : int |
+-------------------------+
EO AND MEASUREMENTS
+-----------------------------------------------+
| Energy Object |
|-----------------------------------------------|
| nameplate : Measurement |
| battery[0..n]: Battery |
| measurements[0..n]: Measurement |
| --------------------------------------------- |
| Measurement instantaneousUsage() |
| DemandMeasurement historicalUsage() |
+-----------------------------------------------+
+-----------------------------------+
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| Measurements |
| __________________________________|
+-----------------------------------+
^
|
|
+------------------+----------------------------+
| PowerMeasurement |
|-----------------------------------------------|
| value : long |
| rate : enum {0,millisecond,seconds, |
| minutes,hours,...} |
| multiplier : enum {-24..24} |
| units : "watts" |
| caliber : enum { actual, estimated, |
| trusted, assumed...} |
| accuracy : enum { 0..10000} |
| current : enum {AC, DC} |
| origin : enum { self, remote } |
| time : timestamp |
| quality : PowerQuality |
+-----------------------------------------------+
|
|
+------------------+----------------------------+
| EnergyMeasurement |
|-----------------------------------------------|
| consumed : long |
| generated : long |
| net : long |
| accuracy : enum { 0..10000} |
+-----------------------------------------------+
+-----------------------------------------------+
| TimeMeasurement |
|-----------------------------------------------|
| startTime : timestamp |
| usage : Measurement |
| maxUsage : Measurement |
+-----------------------------------------------+
|
|
+----------------------------------------+
| TimeInterval |
|--------------------------------------- |
|value : long |
|units : enum { seconds, miliseconds..} |
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+----------------------------------------+
|
|
+----------------------------------------+
| DemandMeasurement |
|----------------------------------------|
|intervalLength : TimeInterval |
|intervalNumbers: long |
|intervalMode : enum { period, sliding, |
|total } |
|intervalWindow : TimeInterval |
|sampleRate : TimeInterval |
|status : enum {active, inactive } |
|measurements : TimedMeasurement[] |
+----------------------------------------+
QUALITY
+----------------------------------------+
| PowerQuality |
|----------------------------------------|
| |
+----------------------------------------+
^
|
|
+------------------+--------------------+
| ACQuality |
|---------------------------------------|
| acConfiguration : enum {SNGL, DEL,WYE}|
| avgVoltage : long |
| avgCurrent : long |
| frequency : long |
| unitMultiplier : int |
| accuracy : int |
| totalActivePower : long |
| totalReactivePower : long |
| totalApparentPower : long |
| totalPowerFactor : long |
+---------+-----------------------------+
| 1
|
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|
|
| +------------------------------------+
| | ACPhase |
| * |------------------------------------|
+--------+ phaseIndex : long |
| avgCurrent : long |
| activePower : long |
| reactivePower : long |
| apparentPower : long |
| powerFactor : long |
+------------------------------------+
^ ^
| |
| |
| |
| |
+-------------------------------+---+ |
| DelPhase | |
|-----------------------------------| |
|phaseToNextPhaseVoltage : long | |
|thdVoltage : long | |
|thdCurrent : long | |
+-----------------------------------+ |
|
+------------------+-----------+
| WYEPhase |
|------------------------------|
|phaseToNeutralVoltage : long |
|thdCurrent : long |
|thdVoltage : long |
+------------------------------+
EO & STATES
+----------------------------------------------+
| Energy Object |
|----------------------------------------------|
| currentLevel : int |
| configuredLevel : int |
| configuredTime : timestamp |
| reason: string |
| emanLevels[0..11] : State |
| levelMappings[0..n] : LevelMapping |
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+----------------------------------------------+
+-------------------------------+
| State |
|-------------------------------|
| name : string |
| cardinality : int |
| maxUsage : Measurement |
+-------------------------------+
Figure 17: Information Model UML Representation
8. Configuration
This power management framework allows the configuration of
the following key parameters:
. Energy Object name: A unique printable name for the
Energy Object.
. Energy Object role: An administratively assigned name to
indicate the purpose an Energy Object serves in the
network.
. Energy Object importance: A ranking of how important the
Energy Object is, on a scale of 1 to 100, compared with
other Energy Objects in the same Energy Management
Domain.
. Energy Object keywords: A list of keywords that can be
used to group Energy Objects for reporting or searching.
. Energy Management Domain: Specifies the name of an Energy
Management Domain for the Energy Object.
. Energy Object Power State: Specifies the current Power
State for the Energy Object.
. Demand parameters: For example, which interval length to
report the Demand over, the number of intervals to keep,
etc.
. Assigning an Energy Object Parent to an Energy Object
Child
. Assigning an Energy Object Child to an Energy Object
Parent.
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This framework supports multiple means for setting the Power
State of a specific Energy Objects. However, the Energy Object
might be busy executing an important task that requires the
current Power State for some more time. For example, a PC
might have to finish a backup first, or an IP phone might be
busy with a current phone call. Therefore a second value
contains the actual Power State. A difference in values
between the two objects indicates that the Energy Object is
currently in Power State transition.
Other, already well established means for setting Power
States, such as DASH [DASH], already exist. Such a protocol
may be implemented between the Energy Object Parent and the
Energy Object Child, when the Energy Object Parent acts as a
Proxy. Note that the Wake-up-on-Lan (WoL) mechanism allows to
transition a device out of the Off Power State.
9. Fault Management
[EMAN-REQ] specifies some requirements about Power States such
as "the current state - the time of the last change", "the
total time spent in each state", "the number of transitions to
each state", etc. Such requirements are fulfilled via the
pmPowerStateChange NOTIFICATION-TYPE [EMAN-MON-MIB]. This
SNMP notification is generated when the value(s) of Power
State has changed for the Energy Object.
Regarding high and low thresholding mechanism, the RMON alarm
and event [RFC2819] allows to periodically takes statistical
samples from Energy Object variables, compares them to
previously configured thresholds, and to generate an event
(i.e. an SNMP notification) if the monitored variable crosses
a threshold. The RMON alarm can monitor variables that resolve
to an ASN.1 primitive type of INTEGER (INTEGER, Integer32,
Counter32, Counter64, Gauge32, or TimeTicks), so basically
most the variables in [EMAN-MON-MIB].
10. Examples
In this section we will give examples of how to use the Energy
Management framework. In each example we will show how it can
be applied when Devices have the capability to model Power
Interfaces. We will also show in each example how the
framework can be applied when devices cannot support Power
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Interfaces but only monitor information or control the Device
as a whole. For instance a PDU may only be able to measure
power and energy for the entire unit without the ability to
distinguish among the inlets or outlet.
Together these examples show how the framework can be adapted
for Devices with different capabilities (typically hardware)
for Energy Management.
Given for all Examples:
Device W: A computer with one power supply. Power interface 1
is an inlets for Device W.
Device X: A computer with two power supplies. Power interface
1 and power interface 2 are both inlets for Device X.
Device Y: A PDU with multiple Power Interfaces numbered 0..10,
Power interface 0 is an inlet and power interface 1..10 are
outlets.
Device Z: A PDU with multiple Power Interfaces numbered 0..10,
Power interface 0 is an inlet and power interface 1..10 are
outlets.
Example I: Simple Device with one Source
Topology:
Device W inlet 1 is plugged into Device Y outlet 8.
With Power Interfaces:
Device W has an Energy Object representing the computer
itself as well as one Power Interface defined as an inlet.
Device Y would have an Energy Object representing the PDU
itself (the Device) with a Power Interface 0 defined as an
inlet and Power Interfaces 1..10 defined as outlets.
The interfaces of the devices would have a Power Source
Relationship such that:
Device W inlet 1 is powered by Device Y outlet 8
Without Power Interfaces:
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In this case Device W has an Energy Object representing the
computer. Device Y would have an Energy Object representing
the PDU.
The devices would have a Power Source Relationship such
that:
Device W is powered by Device Y.
Example II: Multiple Inlets
Topology:
Device X inlet 1 is plugged into Device Y outlet 8.
Device X inlet 2 is plugged into Device Y outlet 9.
With Power Interfaces:
Device X has an Energy Object representing the computer
itself. It contains two Power Interface defined as inlets.
Device Y would have an Energy Object representing the PDU
itself (the Device) with a Power Interface 0 defined as an
inlet and Power Interface 1..10 defined as outlets.
The interfaces of the devices would have a Power Source
Relationship such that:
Device X inlet 1 is powered by Device Y outlet 8
Device X inlet 2 is powered by Device Y outlet 9
Without Power Interfaces:
In this case Device X has an Energy Object representing the
computer. Device Y would have an Energy Object representing
the PDU.
The devices would have a Power Source Relationship such
that:
Device X is powered by Device Y.
Example III: Multiple Sources
Topology:
Device X inlet 1 is plugged into Device Y outlet 8.
Device X inlet 2 is plugged into Device Z outlet 9
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With Power Interfaces:
Device X has an Energy Object representing the computer
itself. It contains two Power Interface defined as inlets.
Device Y would have an Energy Object representing the PDU
itself (the Device) with a Power Interface 0 defined as an
inlet and Power Interface 1..10 defined as outlets.
Device Z would have an Energy Object representing the PDU
itself (the Device) with a Power Interface 0 defined as an
inlet and Power Interface 1..10 defined as outlets.
The interfaces of the devices would have a Power Source
Relationship such that:
Device X inlet 1 is powered by Device Y outlet 8
Device X inlet 2 is powered by Device Z outlet 9
Without Power Interfaces:
In this case Device X has an Energy Object representing the
computer. Device Y and Z would both have respective Energy
Objects representing each entire PDU.
The devices would have a Power Source Relationship such
that:
Device X is powered by Device Y and powered by Device Z.
11. Relationship with Other Standards Development Organizations
11.1. Information Modeling
This power management framework should, as much as possible,
reuse existing standards efforts, especially with respect to
information modeling and data modeling [RFC3444].
The data model for power and energy related objects is based
on IEC 61850.
Specific examples include:
. The scaling factor, which represents Energy Object usage
magnitude, conforms to the IEC 61850 definition of unit
multiplier for the SI (System International) units of
measure.
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. The electrical characteristic is based on the ANSI and
IEC Standards, which require that we use an accuracy
class for power measurement. ANSI and IEC define the
following accuracy classes for power measurement:
. IEC 62053-22 60044-1 class 0.1, 0.2, 0.5, 1 3.
. ANSI C12.20 class 0.2, 0.5
. The electrical characteristics and quality adheres
closely to the IEC 61850 7-2 standard for describing AC
measurements.
. The power state definitions are based on the DMTF Power
State Profile and ACPI models, with operational state
extensions.
12. Security Considerations
Regarding the data attributes specified here, some or all may
be considered sensitive or vulnerable in some network
environments. Reading or writing these attributes without
proper protection such as encryption or access authorization
may have negative effects on the network capabilities.
12.1 Security Considerations for SNMP
Readable objects in a MIB modules (i.e., objects with a MAX-
ACCESS other than not-accessible) may be considered sensitive
or vulnerable in some network environments. It is thus
important to control GET and/or NOTIFY access to these objects
and possibly to encrypt the values of these objects when
sending them over the network via SNMP.
The support for SET operations in a non-secure environment
without proper protection can have a negative effect on
network operations. For example:
. Unauthorized changes to the Power Domain or business
context of an Energy Object may result in misreporting or
interruption of power.
. Unauthorized changes to a power state may disrupt the
power settings of the different Energy Objects, and
therefore the state of functionality of the respective
Energy Objects.
. Unauthorized changes to the demand history may disrupt
proper accounting of energy usage.
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With respect to data transport SNMP versions prior to SNMPv3
did not include adequate security. Even if the network itself
is secure (for example, by using IPsec), there is still no
secure control over who on the secure network is allowed to
access and GET/SET (read/change/create/delete) the objects in
these MIB modules.
It is recommended that implementers consider the security
features as provided by the SNMPv3 framework (see [RFC3410],
section 8), including full support for the SNMPv3
cryptographic mechanisms (for authentication and privacy).
Further, deployment of SNMP versions prior to SNMPv3 is not
recommended. Instead, it is recommended to deploy SNMPv3 and
to enable cryptographic security. It is then a
customer/operator responsibility to ensure that the SNMP
entity giving access to an instance of these MIB modules is
properly configured to give access to the objects only to
those principals (users) that have legitimate rights to GET or
SET (change/create/delete) them.
13. IANA Considerations
AUTHORS NOTE: Section needs to be modified to reflect Power
States text introduce in version 06
Initial values for the Power State Sets, together with the
considerations for assigning them, are defined in [EMAN-MON-
MIB].
14. Acknowledgments
The authors would like to Michael Brown for improving the text
dramatically, and Rolf Winter for his feedback. The award for
the best feedback and reviews goes to Bill Mielke.
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15. References
Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2819] S. Waldbusser, "Remote Network Monitoring
Management Information Base", STD 59, RFC 2819, May
2000
[RFC3410] Case, J., Mundy, R., Partain, D., and B. Stewart,
"Introduction and Applicability Statements for
Internet Standard Management Framework ", RFC 3410,
December 2002.
[RFC4133] Bierman, A. and K. McCloghrie, "Entity MIB
(Version3)", RFC 4133, August 2005.
[RFC4122] Leach, P., Mealling, M., and R. Salz," A Universally
Unique IDentifier (UUID) URN Namespace", RFC 4122,
July 2005
Informative References
[RFC2578] McCloghrie, K., Perkins, D., and J. Schoenwaelder,
"Structure of Management Information Version 2
(SMIv2", RFC 2578, April 1999
[RFC3444] Pras, A., Schoenwaelder, J. "On the Differences
between Information Models and Data Models", RFC
3444, January 2003.
[RFC5101] B. Claise, Ed., Specification of the IP Flow
Information Export (IPFIX) Protocol for the Exchange
of IP Traffic Flow Information, RFC 5101, January
2008.
[RFC6020] M. Bjorklund, Ed., " YANG - A Data Modeling Language
for the Network Configuration Protocol (NETCONF)",
RFC 6020, October 2010.
[ACPI] "Advanced Configuration and Power Interface
Specification", http://www.acpi.info/spec30b.htm
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[IEEE1621] "Standard for User Interface Elements in Power
Control of Electronic Devices Employed in
Office/Consumer Environments", IEEE 1621, December
2004.
[LLDP] IEEE Std 802.1AB, "Station and Media Control
Connectivity Discovery", 2005.
[LLDP-MED-MIB] ANSI/TIA-1057, "The LLDP Management
Information Base extension module for TIA-TR41.4
media endpoint discovery information", July 2005.
[EMAN-REQ] Quittek, J., Winter, R., Dietz, T., Claise, B., and
M. Chandramouli, "Requirements for Energy
Management", draft-ietf-eman-requirements-09, (work
in progress), November 2011.
[EMAN-AWARE-MIB] Parello, J., and B. Claise, "Energy-aware
Networks and Devices MIB", draft-ietf-eman-energy-
aware-mib-07, (work in progress), February 2012.
[EMAN-MON-MIB] Chandramouli, M.,Schoening, B., Quittek, J.,
Dietz, T., and B. Claise, "Power and Energy
Monitoring MIB", draft-ietf-eman-energy-monitoring-
mib-03, (work in progress), March 2012.
[EMAN-BATTERY-MIB] Quittek, J., Winter, R., and T. Dietz, "
Definition of Managed Objects for Battery
Monitoring", draft-ietf-eman-battery-mib-06, (work in
progress), March 2012.
[EMAN-AS] Schoening, B., Chandramouli, M., and B. Nordman,
"Energy Management (EMAN) Applicability Statement",
draft-ietf-eman-applicability-statement-02, (work in
progress), October 2011
[EMAN-TERMINOLOGY] J. Parello, "Energy Management
Terminology", draft-parello-eman-definitions-06,
(work in progress), March 2012
[ITU-T-M-3400] TMN recommandation on Management Functions
(M.3400), 1997
[NMF] "Network Management Fundamentals", Alexander Clemm,
ISBN: 1-58720-137-2, 2007
[TMN] "TMN Management Functions : Performance Management",
ITU-T M.3400
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[1037C] US Department of Commerce, Federal Standard 1037C,
http://www.its.bldrdoc.gov/fs-1037/fs-1037c.htm
[IEEE100] "The Authoritative Dictionary of IEEE Standards
Terms"
http://ieeexplore.ieee.org/xpl/mostRecentIssue.jsp?pu
number=4116785
[DASH] "Desktop and mobile Architecture for System Hardware",
http://www.dmtf.org/standards/mgmt/dash/
[ISO50001] "ISO 50001:2011 Energy management systems -
Requirements with guidance for use",
http://www.iso.org/
[IEC60050] International Electrotechnical Vocabulary
http://www.electropedia.org/iev/iev.nsf/welcome?openf
orm
[SQL] ISO/IEC 9075(1-4,9-11,13,14):2008
[IEEE-802.3at] IEEE 802.3 Working Group, "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",
October 2009.
[DMTF] "Power State Management Profile DMTF DSP1027 Version
2.0" December 2009
http://www.dmtf.org/sites/default/files/standards/doc
uments/DSP1027_2.0.0.pdf
[IPENERGY] R. Aldrich, J. Parello "IP-Enabled Energy
Management", 2010, Wiley Publishing
[X.700] CCITT Recommendation X.700 (1992), Management
framework for Open Systems Interconnection (OSI) for
CCITT applications.
[ASHRAE-201] "ASHRAE Standard Project Committee 201
(SPC 201)Facility Smart Grid Information
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Model", http://spc201.ashraepcs.org
[CHEN] "The Entity-Relationship Model: Toward a Unified View
of Data", Peter Pin-shan Chen, ACM Transactions on
Database Systems, 1976
Authors' Addresses
Benoit Claise
Cisco Systems, Inc.
De Kleetlaan 6a b1
Diegem 1813
BE
Phone: +32 2 704 5622
Email: bclaise@cisco.com
John Parello
Cisco Systems, Inc.
3550 Cisco Way
San Jose, California 95134
US
Phone: +1 408 525 2339
Email: jparello@cisco.com
Brad Schoening
44 Rivers Edge Drive
Little Silver, NJ 07739
US
Phone:
Email: brad.schoening@verizon.net
Juergen Quittek
NEC Europe Ltd.
Network Laboratories
Kurfuersten-Anlage 36
69115 Heidelberg
Germany
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Phone: +49 6221 90511 15
EMail: quittek@netlab.nec.de
Bruce Nordman
Lawrence Berkeley National Laboratory
1 Cyclotron Road
Berkeley 94720
US
Phone: +1 510 486 7089
Email: bnordman@lbl.gov
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