Internet DRAFT - draft-ietf-eman-requirements
draft-ietf-eman-requirements
Network Working Group J. Quittek, Ed.
Internet-Draft M. Chandramouli
Intended status: Informational Cisco Systems, Inc.
Expires: November 03, 2013 R. Winter
NEC Europe Ltd.
T. Dietz
NEC Europe Ltd.
B. Claise
Cisco Systems, Inc.
May 02, 2013
Requirements for Energy Management
draft-ietf-eman-requirements-14
Abstract
This document defines requirements for standards specifications for
energy management. The requirements defined in this document concern
monitoring functions as well as control functions. Monitoring
functions include identification of energy-managed devices and their
components, monitoring of their power states, power inlets, power
outlets, actual power (the instantaneous power, as opposed to the
demand, which is an averaged power), power attributes, received
energy, provided energy, and contained batteries. Control functions
serve for controlling power supply and power state of energy-managed
devices and their components.
This document does not specify the features that must be implemented
by compliant implementations but rather features that must be
supported by standards for energy management.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on November 03, 2013.
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Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Conventional Requirements For Energy Management . . . . . 4
1.2. Specific Requirements For Energy Management . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. General Considerations Related To Energy Management . . . . . 6
3.1. Power States . . . . . . . . . . . . . . . . . . . . . . 7
3.2. Saving Energy Versus Maintaining Service Level . . . . . 7
3.3. Local Versus Network-Wide Energy Management . . . . . . . 7
3.4. Energy Monitoring Versus Energy Saving . . . . . . . . . 8
3.5. Overview Of Energy Management Requirements . . . . . . . 8
4. Identification Of Entities . . . . . . . . . . . . . . . . . 9
5. Information On Entities . . . . . . . . . . . . . . . . . . . 10
5.1. General Information On Entities . . . . . . . . . . . . . 10
5.2. Power Interfaces . . . . . . . . . . . . . . . . . . . . 11
5.3. Power . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.4. Power State . . . . . . . . . . . . . . . . . . . . . . . 15
5.5. Energy . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.6. Battery State . . . . . . . . . . . . . . . . . . . . . . 18
5.7. Time Series Of Measured Values . . . . . . . . . . . . . 19
6. Control Of Entities . . . . . . . . . . . . . . . . . . . . . 21
7. Reporting On Other Entities . . . . . . . . . . . . . . . . . 21
8. Controlling Other Entities . . . . . . . . . . . . . . . . . 22
8.1. Controlling Power States Of Other Entities . . . . . . . 22
8.2. Controlling Power Supply . . . . . . . . . . . . . . . . 23
9. Security Considerations . . . . . . . . . . . . . . . . . . . 23
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 25
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 25
12.1. Normative References . . . . . . . . . . . . . . . . . . 25
12.2. Informative References . . . . . . . . . . . . . . . . . 26
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27
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1. Introduction
With rising energy cost and with an increasing awareness of the
ecological impact of running information technology equipment, energy
management functions and interfaces are becoming an additional basic
requirement for network management systems and devices connected to a
network.
This document defines requirements for standards specifications for
energy management, both monitoring functions and control functions.
The main subject of energy management are entities in the network,
i.e. device or one of a device's components, that receive and
provide electric energy. Devices may have an IP address, such as
hosts, routers, and middleboxes, or they are connected indirectly to
the Internet via a proxy with an IP address providing a management
interface for the device. An example are devices in a building
infrastructure using non-IP protocols and a gateway to the Internet.
The main subject of energy management are devices and their
components that receive and provide electric energy. Devices may
have an IP address, such as hosts, routers, and middleboxes, or they
might be connected indirectly to the Internet via a proxy with an IP
address providing a management interface for the device. An example
are devices in a building infrastructure using non-IP protocols and a
gateway to the Internet.
These requirements concern the standards specification process and
not the implementation of specified standards. All requirements in
this document must be reflected by standards specifications to be
developed. However, which of the features specified by these
standards will be mandatory, recommended, or optional for compliant
implementations is to be defined by standards track document(s) and
not in this document.
Section 3 elaborates a set of general needs for energy management.
Requirements for an energy management standard are specified in
Sections 4 to 8.
Sections 4 to 6 contain conventional requirements specifying
information on entities and control functions.
Sections 7 and 8 contain requirements specific to energy management.
Due to the nature of power supply, some monitoring and control
functions are not conducted by interacting with the entity of
interest, but with other entities, for example, entities upstream in
a power distribution tree.
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1.1. Conventional Requirements For Energy Management
The specification of requirements for an energy management standard
starts with Section 4 addressing the identification of entities and
the granularity of reporting of energy-related information. A
standard must support unique identification of entities, reporting
per entire device, and reporting energy-related information on
individual components of a device or attached devices.
Section 5 specifies requirements related to monitoring of entities.
This includes general (type, context) information and specific
information on Power States, power inlets, power outlets, power,
energy, and batteries. Control Power State and power supply of
entities is covered by requirements specified in Section 6.
1.2. Specific Requirements For Energy Management
While the conventional requirements summarized above seem to be all
that would be needed for energy management, there are significant
differences between energy management and most well known network
management functions. The most significant difference is the need
for some devices to report on other entities. There are three major
reasons for this.
o For monitoring a particular entity it is not always sufficient to
communicate with the entity only. When the entity has no
instrumentation for determining power, it might still be possible
to obtain power values for the entity by communication with other
entities in its power distribution tree.
A simple example is retrieving power values from a power meter at
the power line into the entity. Common examples are a Power
Distribution Unit (PDU) and a Power over Ethernet (PoE) switch.
Both supply power to other entities at sockets or ports,
respectively, and are often instrumented to measure power per
socket or port.
o Similar considerations apply to controlling power supply of a
entity which often needs direct or indirect communications with
another entity upstream in the power distribution tree. Again, a
PDU and a PoE switch are common examples, if they have the
capability to switch on or off power at their sockets or ports,
respectively.
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o Energy management often extends beyond entities with IP network
interfaces, to non-IP building systems accessed via a gateway
(sometimes called an energy management system or controller).
Requirements in this document do not cover details of these
networks and energy devices, but specify means for opening IP
network management towards them.
These specific issues of energy management and a set of further ones
are covered by requirements specified in Sections 7 and 8.
The requirements in these sections need a new energy management
framework that deals with the specific nature of energy management.
The actual standards documents, such as MIB module specifications,
address conformance by specifying which feature must, should, or may
be implemented by compliant implementations.
2. Terminology
Energy
That which does work or is capable of doing work. As used by
electric utilities, it is generally a reference to electrical
energy and is measured in kilo-watt hours (kWh) [IEEE-100].
Power
The time rate at which Energy is emitted, transferred, or
received; usually expressed in watts (or in joules per second)
[IEEE-100].
Power Attributes
Measurements of the electrical current, voltage, phase and
frequencies at a given point in an electrical power system.
Reference: Adapted from [IEC60050]
NOTES: 1. Power Attributes is not intended to be judgmental with
respect to a reference or technical value and are independent of
any usage context.
Energy Management
Energy Management is a set of functions for measuring, modeling,
planning, and optimizing networks to ensure that the network
elements and attached devices use energy efficiently and in a
manner appropriate to the nature of the application and the cost
constraints of the organization [ITU-M.3400].
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Energy Management System
An Energy Management System is a combination of hardware and
software used to administer a network with the primary purpose
being Energy Management [Fed-Std-1037C].
Energy Monitoring
Energy Monitoring is a part of Energy Management that deals with
collecting or reading information from network elements and
attached devices and their components to aid in Energy Management.
Energy Control
Energy Control is a part of Energy Management that deals with
controlling energy supply and power state of network elements and
attached devices and their components.
Power Interface
A Power Interface is an interface at which a device is connected
to a Power transmission medium at which it can receive Power,
provide Power, or both.
Power Inlet
A Power Inlet is a Power Interface at which a device can receive
Power from other devices.
Power Outlet
A Power Outlet is a Power Interface at which a device can provide
Power to other devices.
Power State
A Power State is a condition or mode of a device that broadly
characterizes its capabilities, Power consumption, and
responsiveness to input [IEEE-1621].
3. General Considerations Related To Energy Management
The basic objective of Energy Management is operating sets of devices
with minimal Energy, while maintaining a certain level of service.
[I-D.ietf-eman-applicability-statement] presents the applicability of
the EMAN framework to a variety of scenarios, and lists use cases and
target devices.
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3.1. Power States
Entities can be set to an operational state that results in the
lowest power level that still meets the service level performance
objectives. In principle, there are three basic types of Power
States for an entity or for a whole system:
o full Power State
o sleep state (not functional, but immediately available)
o off state (may require significant time to become operational)
In specific devices, the number of Power States and their properties
varies considerably. Simple entities may just have only the extreme
states, full power and off state. Many devices have three basic
Power States: on, off, and sleep. However, more finely grained Power
States can be implemented. Examples are various operational low
power states in which a device requires less energy than in the full
power "on" state, but - compared to the sleep state - is still
operational with reduced performance or functionality.
3.2. Saving Energy Versus Maintaining Service Level
One of the objectives of Energy Management is to reduce the Energy
consumption. While this objective is clear, the way to attain that
goal is often difficult. In many cases there is no way of reducing
power without the consequence of a potential service (performance or
capacity) degradation. In this case, a trade-off needs to be made
between service level objectives and energy minimization. In other
cases a reduction of power can easily be achieved while still
maintaining sufficient service level performance, for example, by
switching entities to lower Power States when higher performance is
not needed.
3.3. Local Versus Network-Wide Energy Management
Many Energy saving functions are executed locally by an entity; it
monitors its usage and dynamically adapts its Power according to the
required performance. It may, for example, switch to a sleep state
when it is not in use or out of scheduled business hours. An Energy
Management System may observe an entity's Power State and configure
its Power saving policies.
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Energy savings can also be achieved with policies implemented by a
network management system that controls Power States of managed
entities. Information about the Power received and provided by
entities in different Power States may be required to set policies.
Often this information is acquired best through monitoring.
Both methods, network-wide and local Energy Management, have
advantages and disadvantages and often it is desirable to combine
them. Central management is often favorable for setting Power States
of a large number of entities at the same time, for example, at the
beginning and end of business hours in a building. Local management
is often preferable for Power saving measures based on local
observations, such as high or low functional load of an entity.
3.4. Energy Monitoring Versus Energy Saving
Monitoring Energy, Power, and Power States alone does not reduce the
Energy needed to run an entity. In fact, it may even increase it
slightly due to monitoring instrumentation that needs Energy.
Reporting measured quantities over the network may also increase
Energy use, though the acquired information may be an essential input
to control loops that save Energy.
Monitoring Energy and Power States can also be required for other
purposes including:
o investigating Energy saving potential
o evaluating the effectiveness of Energy saving policies and
measures
o deriving, implementing, and testing Power management strategies
o accounting for the total Power received and provided by an entity,
a network, or a service
o predicting an entity's reliability based on Power usage
o choosing time of next maintenance cycle for an entity
3.5. Overview Of Energy Management Requirements
The following basic management functions are required:
o monitoring Power States
o monitoring Power (Energy conversion rate)
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o monitoring (accumulated) received and provided Energy
o monitoring Power attributes
o setting Power States
Power control is complementary to other Energy savings measures such
as low-power electronics, Energy saving protocols, energy-efficient
device design (for example, low-power modes for components), and
energy-efficient network architectures. Measurement of received and
provided Energy can provide useful data for developing these
technologies.
4. Identification Of Entities
Entities must be capable of being uniquely identified with the
context of the management system. This includes entities that are
components of managed devices as well as entire devices.
Entities that report on or control other entities must identify the
entities they report on or control: see Section 7 or Section 8,
respectively, for the detailed requirements.
An entity may be an entire device or a component of it. Examples of
components of interest are a hard drive, a battery, or a line card.
It may be required to be able to control individual components to
save Energy. For example, server blades can be switched off when the
overall load is low or line cards at switches may be powered down at
night.
Identifiers for devices and components are already defined in
standard MIB modules, such as the LLDP MIB module [IEEE-802.1AB] and
the LLDP-MED MIB module [ANSI-TIA-1057] for devices and the Entity
MIB module [RFC4133] and the Power Ethernet MIB [RFC3621] for
components of devices. Energy Management needs means to link Energy-
related information to such identifiers.
Instrumentation for measuring received and provided Energy of a
device is typically more expensive than instrumentation for
retrieving its Power State. Many devices may provide Power State
information for all individual components separately, while reporting
the received and provided Energy only for the entire device.
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4.1. Identifying Entities
The standard must provide means for uniquely identifying entities.
Uniqueness must be preserved such that collisions of identities are
avoided at potential receivers of monitored information.
4.2. Persistence Of Identifiers
The standard must provide means for indicating whether identifiers of
entities are persistent across a re-start of the entity.
4.3. Change Of Identifiers
The standard must provide means to indicate any change of entity
identifiers.
4.4. Using Entity Identifiers Of Existing MIB Modules
The standard must provide means for re-using entity identifiers from
existing standards including at least the following:
o the entPhysicalIndex in the Entity MIB module [RFC4133]
o the LldpPortNumber in the LLDP MIB module [IEEE-802.1AB] and in
the LLDP-MED MIB module [ANSI-TIA-1057]
o the pethPsePortIndex and the pethPsePortGroupIndex in the Power
Ethernet MIB [RFC3621]
Generic means for re-using other entity identifiers must be provided.
5. Information On Entities
This section describes information on entities for which the standard
must provide means for retrieving and reporting.
Required information can be structured into seven groups.
Section 5.1 specifies requirements for general information on
entities, such as type of entity or context information.
Requirements for information on Power Inlets and Power Outlets of
entities are specified in Section 5.2. Monitoring of Power and
Energy is covered by Sections 5.3 and 5.5, respectively. Section 5.4
covers requirements related to entities' Power States. Section 5.6
specifies requirements for monitoring batteries. Finally, the
reporting of time series of values is covered by Section 5.7.
5.1. General Information On Entities
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For Energy Management it may be required to understand the role and
context of an entity. An Energy Management System may aggregate
values of received and provided Energy according to a defined
grouping of entities. When controlling and setting Power States it
may be helpful to understand the grouping of the entity and role of
an entity in a network, for example, it may be important to exclude
some mission critical network devices from being switched to lower
Power or even from being switched off.
5.1.1. Type Of Entity
The standard must provide means to configure, retrieve and report a
textual name or a description of an entity.
5.1.2. Context Of An Entity
The standard must provide means for retrieving and reporting context
information on entities, for example, tags associated with an entity
that indicate the entity's role.
5.1.3. Significance Of Entities
The standard must provide means for retrieving and reporting the
significance of entities within its context, for example, how
important the entity is.
5.1.4. Power Priority
The standard must provide means for retrieving and reporting Power
priorities of entities. Power priorities indicate an order in which
Power States of entities are changed, for example, to lower Power
States for saving Power.
5.1.5. Grouping Of Entities
The standard must provide means for grouping entities. This can be
achieved in multiple ways, for example, by providing means to tag
entities, to assign them to domains, or to assign device types to
them.
5.2. Power Interfaces
A Power Interface is an interface at which a device is connected to a
Power transmission medium at which it can receive Power, provide
Power, or both.
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A Power Interface is either an inlet or an outlet. Some Power
Interfaces change over time from being an inlet to being an outlet
and vice versa. However most Power Interfaces never change.
Devices have Power Inlets at which they are supplied with electric
Power. Most devices have a single Power Inlet, while some have
multiple inlets. Different Power Inlets on a device are often
connected to separate Power distribution trees. For Energy
Monitoring, it is useful to retrieve information on the number of
inlets of a device, the availability of Power at inlets and which of
them are actually in use.
Devices can have one or more Power Outlets for supplying other
devices with electric Power.
For identifying and potentially controlling the source of Power
received at an inlet, it may be required to identify the Power Outlet
of another device at which the received Power is provided.
Analogously, for each outlet it is of interest to identify the Power
Inlets that receive the Power provided at a certain outlet. Such
information is also required for constructing the wiring topology of
electrical Power distribution to devices.
Static properties of each Power Interface are required information
for Energy Management. Static properties include the kind of
electric current (AC or DC), the nominal voltage, the nominal AC
frequency, and the number of AC phases. Note that often the nominal
voltage is not a single value but a voltage range, such as, for
example, (100V-120V), (100V-240V), (100V-120V,220V-240V).
5.2.1. Lists Of Power Interfaces
The standard must provide means for monitoring the list of Power
Interfaces of a device.
5.2.2. Operational Mode Of Power Interfaces
The standard must provide means for monitoring the operational mode
of a Power Interface which is either "Power Inlet" or "Power Outlet".
5.2.3. Corresponding Power Outlet
The standard must provide means for identifying the Power Outlet that
provides the Power received at a Power Inlet.
5.2.4. Corresponding Power Inlets
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The standard must provide means for identifying the list of Power
Inlets that receive the Power provided at a Power Outlet.
5.2.5. Availability Of Power
If the Power States allow it, the standard must provide means for
monitoring the availability of Power at each Power Interface. This
indicates whether at a Power Interfaces Power supply is switched on
or off.
5.2.6. Use Of Power
The standard must provide means for monitoring for each Power
Interface if it is in actual use. For inlets this means that the
device actually receives Power at the inlet. For outlets this means
that Power is actually provided from it to one or more devices.
5.2.7. Type Of current
The standard must provide means for reporting the type of current (AC
or DC) for each Power Interface as well as for a device.
5.2.8. Nominal Voltage Range
The standard must provide means for reporting the nominal voltage
range for each Power Interface.
5.2.9. Nominal AC Frequency
The standard must provide means for reporting the nominal AC
frequency for each Power Interface.
5.2.10. Number Of AC Phases
The standard must provide means for reporting the number of AC phases
for each Power Interface.
5.3. Power
Power is measured as an instantaneous value or as the average over a
time interval.
Obtaining highly accurate values for Power and Energy may be costly
if it requires dedicated metering hardware. Entities without the
ability to measure their Power and received and provided Energy with
high accuracy may just report estimated values, for example based on
load monitoring, Power State, or even just the entity type.
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Depending on how Power and Energy values are obtained, the confidence
in the reported value and its accuracy will vary. Entities reporting
such values should qualify the confidence in the reported values and
quantify the accuracy of measurements. For reporting accuracy, the
accuracy classes specified in IEC 62053-21 [IEC.62053-21] and IEC
62053-22 [IEC.62053-22] should be considered.
Further properties of the Power supplied to a device are also of
interest. Particularly for AC Power supply, several Power attributes
beyond the real Power are of potential interest to Energy Management
Systems. The set of these properties include the the complex Power
attributes (apparent power, reactive power, and phase angle of the
current or power factor) as well as the actual voltage, the actual AC
frequency, the Total Harmonic Distortion (THD) of voltage and
current, and the impedance of an AC phase or of the DC supply. A new
standard for monitoring these Power attributes should be in line with
already existing standards, such as [IEC.61850-7-4].
For some network management tasks it is desirable to receive
notifications from entities when their Power value exceeds or falls
below given thresholds.
5.3.1. Real Power / Power Factor
The standard must provide means for reporting the real power for each
Power Interface as well as for an entity. Reporting Power includes
reporting the direction of Power flow.
5.3.2. Power Measurement Interval
The standard must provide means for reporting the corresponding time
or time interval for which a Power value is reported. The Power
value can be measured at the corresponding time or averaged over the
corresponding time interval.
5.3.3. Power Measurement Method
The standard must provide means to indicate the method how these
values have been obtained. Based on how the measurement was
conducted, it is possible to associate a certain degree of confidence
with the reported Power value. For example, there are methods of
measurement such as direct Power measurement, or by estimation based
on performance values, or hard coding average Power values for an
entity.
5.3.4. Accuracy Of Power And Energy Values
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The standard must provide means for reporting the accuracy of
reported Power and Energy values.
5.3.5. Actual Voltage And Current
The standard must provide means for reporting the actual voltage and
actual current for each Power Interface as well as for a device. In
case of AC Power supply, means must be provided for reporting the
actual voltage and actual current per phase.
5.3.6. High/low Power Notifications
The standard must provide means for creating notifications if Power
values of an entity rise above or fall below given thresholds.
5.3.7. Complex Power / Power Factor
The standard must provide means for reporting the complex power for
each Power Interface and for each phase at a Power Interface.
Besides the real power, at least two out of the following three
quantities need to be reported: apparent power, reactive power, phase
angle. The phase angle can be substituted by the power factor.
5.3.8. Actual AC Frequency
The standard must provide means for reporting the actual AC frequency
for each Power Interface.
5.3.9. Total Harmonic Distortion
The standard must provide means for reporting the Total Harmonic
Distortion (THD) of voltage and current for each Power Interface. In
case of AC Power supply, means must be provided for reporting the THD
per phase.
5.3.10. Power Supply Impedance
The standard must provide means for reporting the impedance of Power
supply for each Power Interface. In case of AC Power supply, means
must be provided for reporting the impedance per phase.
5.4. Power State
Many entities have a limited number of discrete Power States.
There is a need to report the actual Power State of an entity, and
means for retrieving the list of all supported Power States.
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Different standards bodies have already defined sets of Power States
for some entities, and others are creating new Power State sets. In
this context, it is desirable that the standard support many of these
Power State standards. In order to support multiple management
systems possibly using different Power State sets, while
simultaneously interfacing with a particular entity, the Energy
Management standard must provide means for supporting multiple Power
State sets used simultaneously at an entity.
Power States have parameters that describe its properties. It is
required to have standardized means for reporting some key
properties, such as the typical Power of an entity in a certain
state.
There also is a need to report statistics on Power States including
the time spent and the received and provided Energy in a Power State.
5.4.1. Actual Power State
The standard must provide means for reporting the actual Power State
of an entity.
5.4.2. List Of Supported Power States
The standard must provide means for retrieving the list of all
potential Power States of an entity.
5.4.3. Multiple Power State Sets
The standard must provide means for supporting multiple Power State
sets simultaneously at an entity.
5.4.4. List Of Supported Power State Sets
The standard must provide means for retrieving the list of all Power
State sets supported by an entity.
5.4.5. List Of Supported Power States Within A Set
The standard must provide means for retrieving the list of all
potential Power States of an entity for each supported Power State
set.
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5.4.6. Typical Power Per Power State
The standard must provide means for retrieving the typical Power for
each supported Power State.
5.4.7. Power State Statistics
The standard must provide means for monitoring statistics per Power
State including the total time spent in a Power State, the number of
times each state was entered and the last time each state was
entered. More Power State statistics are addressed by requirement
5.5.3.
5.4.8. Power State Changes
The standard must provide means for generating a notification when
the actual Power State of an entity changes.
5.5. Energy
Monitoring of electrical Energy received or provided by an entity is
a core function of Energy Management. Since Energy is an accumulated
quantity, it is always reported for a certain interval of time. This
can be, for example, the time from the last restart of the entity to
the reporting time, the time from another past event to the reporting
time, the last given amount of time before the reporting time, or a
certain interval specified by two time stamps in the past.
It is useful for entities to record their received and provided
Energy per Power State and report these quantities.
5.5.1. Energy
The standard must provide means for reporting measured values of
Energy and the direction of the Energy flow received or provided by
an entity. The standard must also provide the means to report the
Energy passing through each Power Interface.
5.5.2. Time Intervals
The standard must provide means for reporting the time interval for
which an Energy value is reported.
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5.5.3. Energy Per Power State
The standard must provide means for reporting the received and
provided Energy for each individual Power State. This extends the
requirement 5.4.7 on Power State statistics.
5.6. Battery State
Batteries are special entities that supply Power. The status of
these batteries is typically controlled by automatic functions that
act locally on the entity and manually by users of the entity. There
is a need to monitor the battery status of these entities by network
management systems.
Devices containing batteries can be modeled in two ways. The entire
device can be modeled as a single entity on which Energy-related
information is reported or the battery can be modeled as an
individual entity for which Energy-related information is monitored
individually according to requirements in Sections 5.1 to 5.5.
Further information on batteries is of interest for Energy
Management, such as the current charge of the battery, the number of
completed charging cycles, the charging state of the battery, its
temperature, and further static and dynamic battery properties. It
is desirable to receive notifications if the charge of a battery
becomes very low or if a battery needs to be replaced.
5.6.1. Battery Charge
The standard must provide means for reporting the current charge of a
battery, in units of milliampere hours (mAh).
5.6.2. Battery Charging State
The standard must provide means for reporting the charging state
(charging, discharging, etc.) of a battery.
5.6.3. Battery Charging Cycles
The standard must provide means for reporting the number of completed
charging cycles of a battery.
5.6.4. Actual Battery Capacity
The standard must provide means for reporting the actual capacity of
a battery.
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5.6.5. Actual Battery Capacity
The standard must provide means for reporting the actual temperature
of a battery.
5.6.6. Static Battery Properties
The standard must provide means for reporting static properties of a
battery, including the nominal capacity, the number of cells, the
nominal voltage, and the battery technology.
5.6.7. Low battery Charge Notification
The standard must provide means for generating a notification when
the charge of a battery decreases below a given threshold. Note that
the threshold may depend on the battery technology.
5.6.8. Battery Replacement Notification
The standard must provide means for generating a notification when
the number of charging cycles of battery exceeds a given threshold.
5.6.9. Multiple Batteries
If the battery technology allows, the standard must provide means for
meeting requirements 5.6.1 to 5.6.8 for each individual battery
contained in a single entity.
5.7. Time Series Of Measured Values
For some network management tasks, it is required to obtain time
series of measured values from entities, such as Power, Energy,
battery charge, etc.
In general time series measurements could be obtained in many
different ways. Means should be provided to either push such values
from the location where they are available to the management system
or to have them stored locally for a sufficiently long period of time
such that a management system can retrieve full time series.
The following issues are to be considered when designing time series
measurement and reporting functions:
1. Which quantities should be reported?
2. Which time interval type should be used (total, delta, sliding
window)?
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3. Which measurement method should be used (sampled, continuous)?
4. Which reporting model should be used (push or pull)?
The most discussed and probably most needed quantity is Energy. But
a need for others, such as Power and battery charge can be identified
as well.
There are three time interval types under discussion for accumulated
quantities such as Energy. They can be reported as total values,
accumulated between the last restart of the measurement and a certain
timestamp. Alternatively, Energy can be reported as delta values
between two consecutive timestamps. Another alternative is reporting
values for sliding windows as specified in [IEC.61850-7-4].
For non-accumulative quantities, such as Power, different measurement
methods are considered. Such quantities can be reported using values
sampled at certain time stamps or alternatively by mean values for
these quantities averaged between two (consecutive) time stamps or
over a sliding window.
Finally, time series can be reported using different reporting
models, particularly push-based or pull-based. Push-based reporting
can, for example, be realized by reporting Power or Energy values
using the IPFIX protocol [RFC5101],[RFC5102]. SNMP [RFC3411] is an
example for a protocol that can be used for realizing pull-based
reporting of time series.
For reporting time series of measured values the following
requirements have been identified. Further decisions concerning
issues discussed above need to be made when developing concrete
Energy Management standards.
5.7.1. Time Series Of Energy Values
The standard must provide means for reporting time series of Energy
values. If the comparison of time series between multiple entities
is required, then time synchronization between those entities must be
provided (for example, with the Network Time Protocol [RFC5905]).
5.7.2. Time Series Interval Types
The standard must provide means for supporting alternative interval
types. Requirement 5.5.2 applies to every reported time value.
5.7.3. Time Series Storage Capacity
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The standard should provide means for reporting the number of values
of a time series that can be stored for later reporting.
6. Control Of Entities
Many entities control their Power State locally. Other entities need
interfaces for an Energy Management System to control their Power
State.
Power supply is typically not self-managed by devices. And
controlling Power supply is typically not conducted as interaction
between Energy Management System and the device itself. It is rather
an interaction between the management system and a device providing
Power at its Power Outlets. Similar to Power State control, Power
supply control may be policy driven. Note that shutting down the
Power supply abruptly may have severe consequences for the device.
6.1. Controlling Power States
The standard must provide means for setting Power States of entities.
6.2. Controlling Power Supply
The standard must provide means for switching Power supply off or
turning Power supply on at Power Interfaces providing Power to one or
more device.
7. Reporting On Other Entities
As discussed in Section 5, not all Energy-related information may be
available at the concerned entity. Such information may be provided
by other entities. This section covers reporting of information
only. See Section 8 for requirements on controlling other entities.
There are cases where a Power supply unit switches Power for several
entities by turning Power on or off at a single Power Outlet or where
a Power meter measures the accumulated Power of several entities at a
single power line. Consequently, it should be possible to report
that a monitored value does not relate to just a single entity, but
is an accumulated value for a set of entities. All of these entities
belonging to that set need to be identified.
7.1. Reports On Other Entities
The standard must provide means for an entity to report information
on another entity.
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7.2. Identity Of Other Entities On Which Is Reported
For entities that report on one or more other entities, the standard
must provide means for reporting the identity of other entities on
which information is reported. Note that, in some situations, a
manual configuration might be required to populate this information.
7.3. Reporting Quantities Accumulated Over Multiple Entities
The standard must provide means for reporting the list of all
entities from which contributions are included in an accumulated
value.
7.4. List Of All Entities On Which Is Reported
For entities that report on one or more other entities, the standard
must provide means for reporting the complete list of all those
entities on which Energy-related information can be reported.
7.5. Content Of Reports On Other Entities
For entities that report on one or more other entities, the standard
must provide means for indicating which Energy-related information
can be reported for which of those entities.
8. Controlling Other Entities
This section specifies requirements for controlling Power States and
power supply of entities by communicating with other entities that
have means for doing that control.
8.1. Controlling Power States Of Other Entities
Some entities have control over Power States of other entities. For
example a gateway to a building system may have means to control the
Power State of entities in the building that do not have an IP
interface. For this scenario and other similar cases means are
needed to make this control accessible to the Energy Management
System.
In addition to this, it is required that an entity that has its state
controlled by other entities has means to report the list of these
other entities.
8.1.1. Control Of Power States Of Other Entities
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The standard must provide means for an Energy Management System to
send Power State control commands to an entity that concern the Power
States of entities other than the one the command was sent to.
8.1.2. Identity Of Other Power State Controlled Entities
The standard must provide means for reporting the identities of the
entities for which the reporting entity has means to control their
Power States. Note that, in some situations, a manual configuration
might be required to populate this information.
8.1.3. List Of All Power State Controlled Entities
The standard must provide means for an entity to report the list of
all entities for which it can control the Power State.
8.1.4. List Of All Power State Controllers
The standard must provide means for an entity that receives commands
controlling its Power State from other entities to report the list of
all those entities.
8.2. Controlling Power Supply
Some entities may have control of the Power supply of other entities,
for example, because the other entity is supplied via a Power Outlet
of the entity. For this and similar cases means are needed to make
this control accessible to the Energy Management System. This need
is already addressed by requirement 6.2.
In addition, it is required that an entity that has its supply
controlled by other entities has means to report the list of these
other entities. This need is already addressed by requirements 5.2.3
and 5.2.4.
9. Security Considerations
Controlling Power State and Power supply of entities are highly
sensitive actions since they can significantly affect the operation
of directly and indirectly affected devices. Therefore all control
actions addressed in sections 6 and 8 must be sufficiently protected
through authentication, authorization, and integrity protection
mechanisms.
Entities that are not sufficiently secure to operate directly on the
public Internet do exist and can be a significant cause of risk, for
example, if the remote control functions described in sections 6 and
8 can be exercised on those devices from anywhere on the Internet.
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The standard needs to provide means for dealing with such cases. One
solution is providing means that allow for isolation of such devices,
e.g. behind a sufficiently secured gateway. Another solution is
allowing compliant implementations that have disabled or not
implemented sensitive functions.
Monitoring Energy-related quantities of an entity addressed in
Sections 5 - 8 can be used to derive more information than just the
received and provided Energy, so monitored data requires protection.
This protection includes authentication and authorization of entities
requesting access to monitored data as well as confidentiality
protection during transmission of monitored data. Privacy of stored
data in an entity must be taken into account. Monitored data may be
used as input to control, accounting, and other actions, so integrity
of transmitted information and authentication of the origin may be
needed.
9.1. Secure Energy Management
The standard must provide privacy, integrity, and authentication
mechanisms for all actions addressed in Sections 5 - 8. The security
mechanisms must meet the security requirements elaborated in
Section 1.4 of [RFC3411].
9.2. Isolation Of Insufficiently Secure Entities
The standard must provide means to allow for isolation of entities
that that are not sufficiently secure to operate on the public
Internet, e.g., behind a gateway that does implement sufficient
security so that the vulnerable entities are not directly exposed to
the Internet.
9.3. Optional Restriction Of Functions
The standard must allow for compliant implementations that do not
implement sensitive functions or disable them when operating in not
sufficiently secured environments. This applies particularly to the
control functions described in sections 6 and 8.
10. IANA Considerations
This document has no actions for IANA.
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11. Acknowledgments
The authors would like to thank Ralf Wolter for his first essay on
this draft. Many thanks to William Mielke, John Parello, JinHyeock
Choi, Georgios Karagiannis, and Michael Suchoff for their helpful
comments on the draft. Many thanks for their IESG reviews to Stephen
Farrell, Robert Sparks, Adrian Farrel, Barry Leiba, Brian Haberman,
Peter Resnick, Sean Turner, Stewart Bryant, and Ralph Droms.
Finally, special thanks to the document shepherd Nevil Brownlee, and
to the EMAN working group chairs: Nevil Brownlee and Bruce Nordman.
12. References
12.1. Normative References
[RFC3411] Harrington, D., Presuhn, R., and B. Wijnen, "An
Architecture for Describing Simple Network Management
Protocol (SNMP) Management Frameworks", STD 62, RFC 3411,
December 2002.
[RFC3621] Berger, A. and D. Romascanu, "Power Ethernet MIB", RFC
3621, December 2003.
[RFC4133] Bierman, A. and K. McCloghrie, "Entity MIB (Version 3)",
RFC 4133, August 2005.
[ANSI-TIA-1057]
Telecommunications Industry Association, , "ANSI-
TIA-1057-2006 - TIA Standard - Telecommunications - IP
Telephony Infrastructure - Link Layer Discovery Protocol
for Media Endpoint Devices ", April 2006.
[IEEE-100]
IEEE, , "Authoritative Dictionary of IEEE Standards Terms,
IEEE 100, Seventh Edition ", December 2000.
[IEC.62053-21]
International Electrotechnical Commission, , "Electricity
metering equipment (a.c.) - Particular requirements - Part
22: Static meters for active energy (classes 1 and 2) ",
2003.
[IEC.62053-22]
International Electrotechnical Commission, , "Electricity
metering equipment (a.c.) - Particular requirements - Part
22: Static meters for active energy (classes 0,2 S and 0,5
S) ", 2003.
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[IEC.61850-7-4]
International Electrotechnical Commission, ,
"Communication networks and systems for power utility
automation - Part 7-4: Basic communication structure -
Compatible logical node classes and data object classes ",
2010.
[IEEE-1621]
Institute of Electrical and Electronics Engineers, , "IEEE
P1621-2004 -Draft Standard for User Interface Elements in
Power Control of Electronic Devices Employed in Office
Consumer Environments ", June 2005.
[IEEE-802.1AB]
IEEE Computer Society, , "IEEE Std 802.1AB-2009 - IEEE
Standard for Local and metropolitan area networks -
Station and Media Access Control Discovery ", September
2009.
12.2. Informative References
[RFC5101] Claise, B., "Specification of the IP Flow Information
Export (IPFIX) Protocol for the Exchange of IP Traffic
Flow Information", RFC 5101, January 2008.
[RFC5102] Quittek, J., Bryant, S., Claise, B., Aitken, P., and J.
Meyer, "Information Model for IP Flow Information Export",
RFC 5102, January 2008.
[RFC5905] Mills, D., Martin, J., Burbank, J., and W. Kasch, "Network
Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, June 2010.
[I-D.ietf-eman-applicability-statement]
Schoening, B., Chandramouli, M., and B. Nordman, "Energy
Management (EMAN) Applicability Statement", draft-ietf-
eman-applicability-statement-03 (work in progress), April
2013.
[Fed-Std-1037C]
United States National Communications System Technology
and Standards Division, , "Federal Standard 1037C -
Telecommunications: Glossary of Telecommunication Terms ",
August 1996.
[IEC60050]
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, "International Electrotechnical Vocabulary.
http://www.electropedia.org/iev/iev.nsf/welcome?openform
", .
[ITU-M.3400]
International Telecommunication Union, , "ITU-T
Recommendation M.3400 - Series M: TMN and Network
Maintenance: International Transmission Systems, Telephone
Circuits, Telegraphy, Facsimile and Leased Circuits -
Telecommunications Management Network - TMN management
functions ", February 2000.
Authors' Addresses
Juergen Quittek (editor)
NEC Europe Ltd.
NEC Laboratories Europe
Network Research Division
Kurfuersten-Anlage 36
Heidelberg 69115
Germany
Phone: +49 6221 4342-115
Email: quittek@neclab.eu
Mouli Chandramouli
Cisco Systems, Inc.
Sarjapur Outer Ring Road
Bangalore
India
Phone: +91 80 4426 3947
Email: moulchan@cisco.com
Rolf Winter
NEC Europe Ltd.
NEC Laboratories Europe
Network Research Division
Kurfuersten-Anlage 36
Heidelberg 69115
Germany
Phone: +49 6221 4342-121
Email: Rolf.Winter@neclab.eu
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Thomas Dietz
NEC Europe Ltd.
NEC Laboratories Europe
Network Research Division
Kurfuersten-Anlage 36
Heidelberg 69115
Germany
Phone: +49 6221 4342-128
Email: Thomas.Dietz@neclab.eu
Benoit Claise
Cisco Systems, Inc.
De Kleetlaan 6a b1
Diegem 1831
Belgium
Phone: +32 2 704 5622
Email: bclaise@cisco.com
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