Network Working Group B. Claise
Internet-Draft J. Parello
Intended Status: Informational B. Schoening
Expires: June 22, 2011 Cisco Systems, Inc.
J. Quittek
NEC Europe Ltd.
December 22, 2010
Energy Management Framework
draft-ietf-eman-framework-00
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Abstract
This document defines an energy management framework.
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Table of Contents
1. Introduction.............................................. 4
1.1. Energy Management Document Overview.................. 5
2. Use Cases & Requirements.................................. 5
3. Terminology............................................... 6
3.1. Functional Entities.................................. 9
4. Energy Management Reference Model......................... 9
5. Architecture High Level Concepts and Scope............... 11
5.1. Power Monitor Information........................... 13
5.2. Power Monitor Topologies: Metering versus Control versus
Power Distribution....................................... 13
5.3. Power Monitor Meter Domain.......................... 14
5.4. Power Monitor Parent and Child...................... 15
5.5. Power Monitor Context............................... 16
5.6. Power Monitor States................................ 17
5.7. Power Monitor Usage Measurement..................... 20
5.8. Optional Power Usage Quality........................ 21
5.9. Optional Energy Measurement......................... 21
5.10. Optional Battery Information....................... 22
6. Structure of the Information Model: UML Representation... 22
7. Power Monitor Children Discovery......................... 28
8. Configuration............................................ 28
9. Fault Management......................................... 30
10. Relationship with Other Standards Development
Organizations............................................... 30
10.1. Information Modeling............................... 30
10.2. Power States....................................... 31
11. Implementation Scenarios................................ 31
Scenario 1: Switch with PoE endpoints.................... 32
Scenario 2: Switch with PoE endpoints with further connected
device(s)................................................ 32
Scenario 3: A switch with Wireless Access Points......... 32
Scenario 4: Network connected facilities gateway......... 32
Scenario 5: Data center network.......................... 32
Scenario 6: Building gateway device...................... 33
Scenario 7: Power consumption of UPS..................... 33
Scenario 8: Power consumption of battery-based devices... 33
12. Security Considerations................................. 33
12.1. Security Considerations for SNMP...................... 33
13. IANA Considerations..................................... 34
14. Acknowledgments......................................... 34
15. References.............................................. 34
Normative References..................................... 34
Informative References................................... 35
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TO DO
. Agree on the terminology
. How many operational power states do we need? If any?
. At some paces in this I-D there is support for devices
producing power. However, this is not done consistently. Is a
generator of electricity a power monitor? If we want to
support generation, then we must check the entire document for
consistency. The same applies if we just focus on consumption
(usage). I tend to exclude generation, but include storage,
such as batteries.
. Should implementation scenarios be incorporated in the
framework draft?
. Can a Power Monitor Parent and/or a Power Monitor Child be
part of multiple Power Monitor Metering Domain?
. Do we agree that the units should W, A, Wh, Ah, V, and not
Joule and Coulombs? Proposal: the MIB variable uses W, A, Wh,
Ah, V, and explain, if appropriate, how to convert into
Joule/Coulomb.
1. Introduction
Network management is typically divided into the five main
network management areas defined in the ISO Telecommunications
Management Network model: Fault, Configuration, Accounting,
Performance, and Security Management. Absent from this model is
any consideration of energy management, which is now becoming a
critical area of concern worldwide.
This document defines a framework for energy management for
devices within or connected to communication networks. This
framework includes monitoring for power state and energy
consumption of networked elements, covering the requirements
specified in [EMAN-REQ]. It also goes a step further in
defining some elements of configuration.
There is a need to apply Energy Management to all devices in
communication networks. Target devices for this specification
include (but are not limited to): hosts, servers, routers,
switches, Power over Ethernet (PoE) endpoints, protocol gateways
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for building management systems, intelligent meters, home energy
gateway, sensor proxies, etc.
Where applicable, device monitoring extends to the individual
components of the device and to any attached dependent devices.
For example: A device can contain components that are
independent from a power-state point of view, such as line
cards, processor cards, hard drives. A device can also have
dependent attached devices, such as a switch with PoE powered
devices or a power distribution unit with attached powered
devices.
1.1. Energy Management Document Overview
The EMAN standards provides network administrators with energy
management. This document specifies the framework, per the
Energy Management requirements specified in [EMAN-REQ], which
allow networks and devices to become energy aware.
Energy-aware Networks and Devices MIB document [EMAN-AWARE-MIB]
allows the monitoring of energy-aware networks and devices, by
addressing devices identification, context information, and
relationship between reporting devices, remote devices, and
monitoring probes.
The Power and Energy Monitoring MIB [EMAN-MON-MIB] contains the
managed objects for monitoring of power states and energy
consumption/production. The monitoring of power states
includes: retrieving power states, properties of power states,
current power state, power state transitions, and power state
statistics. This MIB provides the detailed properties of the
actual energy rate (power) and of accumulated energy, along with
the power quality.
The applicability statement document [EMAN-AS] provides the list
of use cases, cross-reference between existing standards and the
EMAN standard, and shows how the EMAN framework relates to other
frameworks.
EDITOR'S NOTE: [EMAN-MON-MIB] and [EMAN-AS] are not EMAN working
group documents. Hence, these references will be changed in the
futureg.
2. Use Cases & Requirements
Requirements for power and energy monitoring for networking
devices are specified in [EMAN-REQ]. The requirements in [EMAN-
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REQ] cover devices typically found in communications networks,
such as switches, routers, and various connected endpoints. For
a power monitoring framework to be useful, it should also apply
to facility meters, power distribution units, gateway proxies
for commercial building control, home automation devices, and
devices that interface with the utility and/or smart grid.
Accordingly, this framework, the scope is broader than that
specified in [EMAN-REQ]. Several scenarios that cover these
broader use cases are presented later in Section 11. -
Implementation Scenarios.
3. Terminology
This section contains definitions of important terms used
throughout this specification.
IPFIX-specific terminology used in this document is defined in
section 2 of [RFC5101]. For example: Flow Record, Collector ,
etc... As in [RFC5101], these IPFIX-specific terms have the
first letter of a word capitalized.
Energy Management
Energy Management deals with assessing and influencing the
consumption of energy in a network of powered devices. A
typical objective of energy management is reducing the energy
consumption in the network. This objective may conflict with
other objectives of a general network management system, for
example, with service level objectives.
Energy Monitoring
Energy Monitoring is a part of Energy Management. It deals with
monitoring only and does not include influencing the consumption
of energy.
Power, Energy, and Energy Consumption
Power is a rate of energy conversion. In scenarios relevant to
energy management electrical energy is delivered to a device
that "consumes" it by converting the energy.
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Power and consumed energy are essential quantities for network
management. Power can be an instantaneous value of the current
energy conversion rate or an average value of instantaneous
power over a time interval. Consumed energy, is the total
energy converted by a powered device during a time interval.
The term 'Energy Consumption' is commonly used for both, for
referring to the amount of consumed energy and also for
referring to the process of consuming energy. In the first case
it addresses consumed energy, in the second one it addresses
power, typically an average power. In this document we use this
ambiguous term for addressing both, power and consumed energy.
Power Monitor
A Power Monitor is a component within a system of components
that provides power, draws power, or reports energy consumption
on behalf of another Power Monitor. It can be independently
managed from a power-monitoring and power-state configuration
point of view. Examples of Power Monitors are: a router line
card, a motherboard with a CPU, an IP phone connected with a
switch, etc.
Power Monitor Parent
A Power Monitor Parent is a Power Monitor that is the root of
one or more subtending Power Monitors, called Power Monitor
Children. The Power Monitor Parent is able to collect data
about or report on the power state and energy consumption of its
Power Monitor Children.
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 is the source of power for the attached device, so the
Power Monitor Parent is the switch, and the Power Monitor Child
is the device attached to the switch.
The Power Monitor Parent may report data or implement actions on
behalf of the Power Monitor Child.
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
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connected child, and a parent lighting controller may use BACNET
to communicate with child lighting devices.
Power Monitor Child
A Power Monitor Child is a Power Monitor associated with a Power
Monitor Parent, and which reports its power usage and power
state to its Power Monitor Parent. The Power Monitor Child may
or may not draw power from its Power Monitor Parent. .
Power Monitor Meter Domain
A Power Monitor Meter Domain is a name or name space that
logically groups Power Monitors into a zone of manageable power
usage. Typically, this zone will have as members all Power
Monitors that are powered from the same electrical panel or
panels for which there is a meter or sub meter. For example:
All Power Monitors receiving power from the same distribution
panel of a building, or all Power Monitors in a building for
which there is one main meter, would comprise a Power Monitor
Meter Doman. From the standpoint of power-use monitoring, it is
useful to report the total power usage as the sum of power
consumed by all the Power Monitors within a Power Monitor Meter
Domain and then correlate that value with the metered usage.
Power State
A Power State is a uniform way to classify power settings on a
Power Monitor (e.g., shut, hibernate, sleep, high). Power
States can be viewed as an interface for the underlying device-
implemented power settings.
Manufacturer Power State
A Manufacturer Power State is a device-specific way to classify
power settings implemented on a Power Monitor. For cases where
the implemented power settings cannot be directly mapped to
Power States, we can use the Manufacturer Power States to
enumerate and show the relationship between the implemented
power settings and the Power State interface.
Nameplate Power
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The Nameplate Power is the maximal electrical capacity that a
component can support under electrical load testing. It is
specified by the vendor as the capacity required to power the
device. Often this label is a conservative number and is the
worst-case power draw. While the actual utilization of an
entity can be lower, the Nameplate Power is important for
provisioning, capacity planning and billing.
EDITOR'S NOTE: we should be referring to another SDO/reference.
3.1. Functional Entities
Power Proxy
A Power Proxy is a Power Monitor Parent that reports the power
information on behalf of its Power Monitor Children. For
example, because the Power Monitor Children are non IP devices,
because they can't report the power information themselves, or
simply for scalability reasons.
Power Aggregator
A Power Aggregator is a Power Monitor Parent that aggregates the
power information of its Power Monitor Children.
Power Distributor
A Power Aggregator supplies power to Power Monitors. Only in
rare examples such as PoE is the Power Distributor a Power
Monitor Parent.
4. Energy Management Reference Model
As displayed in the figure 1, the most basic energy reference
model is composed of a Energy Management Systems (EMS) that
manages, via SNMP, the power and energy information from Power
Monitors. The Power Monitor returns information about the power
consumption, the power states, the power quality, the energy
usage, potentially the business context, and other information
as described further.
+---------------+
| EMS | -
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+-----+---+-----+ |
| | |
| | | S
+---------+ +----------+ | N
| | | M
| | | P
+-----------------+ +--------+--------+ |
| Power Monitor 1 | ... | Power Monitor N | |
+-----------------+ +-----------------+ -
Figure 1: Basic Energy Management Model
As displayed in the figure 2, the advanced energy reference
model manages the Power Monitor Parents. The Power Monitor
Parents returns information for themselves and for any attached
Power Monitor Children. The information returned is the same as
in the basic energy management, plus some extra information
about the relationship between Power Monitor Child and Power
Monitor Parent.
+---------------+
| EMS | -
+-----+--+------+ |
| | |
| | | S
+------------+ +--------+ | N
| | | M
| | | P
+------------------+ +------+-----------+ |
| Power Monitor | | Power Monitor | |
| Parent 1 | ... | Parent N | -
| Power Proxy | ... | Power Proxy |
|(Power Aggregator)| ... |(Power Aggregator)|
+------------------+ +------------------+
||| |
(protocol ||| |
out of ||| +-------------+---------+
the scope)|||------| Power Monitor Child 1 |
|| +-----------------------+
||
|| +-------------+---------+
||-------| Power Monitor Child 2 |
| +-----------------------+
|
|
|-------- ...
|
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|
| +-------------+---------+
|--------| Power Monitor Child M |
+-----------------------+
Figure 2: Advanced Energy Management Model
This advanced energy management model is required when the
scalability of managing all Power Monitor Children becomes an
issue. In such as case, the Power Monitor Parent also acts as a
Power Aggregator, i.e. an aggregation point for other subtended
Power Monitor Children.
The advanced energy management model is also required when the
Power Monitor Child doesn't speak the IP protocol. Indeed, the
Power Monitor Parent may speak to a Power Monitor Child using a
manufacturer selected protocol. In such a case, the Power
Monitor Parent acts as a Power Proxy for protocol translation
between the Power Monitor Parent and Child. Therefore, the
protocol between the Power Monitor Parent and Power Monitor
Children is out of scope of this document.
The Power Monitor Parents may send SNMP notifications regarding
their own state or the state of their Power Monitor Children.
The Power Monitor Children do not send SNMP notifications on
their own.
As discussed in [EMAN-REQ], the Power Monitor Parents may export
IPFIX Flow Records [RFC5101] to a Collector. However, the
framework doesn't mandate it.
While both the basic and advanced energy management models
(figure 1 and 2) contain a EMS, this architecture doesn't impose
any requirements regarding the control, which could be
centralized from the EMS, or distributing in the network.
5. Architecture High Level Concepts and Scope
The scope of this architecture is to enable networking and
network-attached devices to be managed with respect to their
energy consumption or production. The goal is to make IP
devices energy-aware. If those devices don't support IP, then a
Power Proxy acting as a protocol translation can be used.
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The architecture makes the Energy Management System aware of
power usage. . This does not include:
- Manufacturing costs in currency or environmental units
- Embedded carbon or environmental equivalences of the device
itself
- Cost in currency or environmental impact to dismantle or
recycle the device
- Relationship to an electrical or smart grid
- Supply chain analysis
- 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 remainder of this section describes the basic concepts of
the architecture. Each concept is examined in detail in
subsequent sections.
Examples are provided in a later section to show how these
concepts can be implemented.
The basic concepts are:
The Power Monitor will have basic naming and informational
descriptors to identify it in the network.
A Power Monitor can be part of a Power Monitor Meter Domain. A
Power Monitor Meter Domain is a manageable set of devices that
has a meter or sub-meter attached and typically corresponds to a
power distribution point or panel. In building management, the
meter refers to the meter provided by the utility used for
billing or rationing power to the entire building or unit in a
building, while 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.
Examples consists of building with a meter form utility with
submeters installed for data center, HVAC and common areas.
A Power Monitor can be a parent (Power Monitor Parent) or child
(Power Monitor Child) of another Power Monitor. This allows for
Power Monitor Parent to aggregate power reporting and control of
power information.
Each Power Monitor can have information to allow it to be
described in the context of the business or ultimate use. This
is in addition to its networked information. This allows for
tagging, grouping, and differentiation between Power Monitors
for the EMS.
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For control and universal monitoring, each Power Monitor
implements or declares a set of known Power States. The Power
States are mapped to Manufacturer Power States that indicate the
specific power settings for the device implementing the Power
Monitor.
When the Power State is set, a Power Monitor may be busy at the
request time. The Power Monitor will set the desired state and
then update the actual Power State when the priority task is
finished. This mechanism implies two different Power State
variables: actual versus desired.
EDITOR'S NOTE: The transition state will have to be specified.
Each Power Monitor will have usage information that describes
the power information along with how that usage was obtained or
derived.
Optionally, a Power Monitor can further describe the power
information with power quality information reflecting the
electrical characteristics of the measurement.
Optionally, a Power Monitor can provide power usage over time to
describe energy consumption
If a Power Monitor has one or more batteries, it can provide
optional battery information as well.
5.1. Power Monitor Information
Every Power Monitor should have a unique printable name, and
must have a unique Power Monitor index.
Possible naming conventions are: textual DNS name, MAC-address
of the device, interface ifName, or a text string uniquely
identifying the Power Monitor. As an example, in the case of IP
phones, the Power Monitor name can be the device DNS name.
5.2. Power Monitor Topologies: Metering versus Control versus Power
Distribution
In a simple Power Proxy scenario, the Power Monitor Parent,
which reports on the power state and power consumption of its
Power Monitor Children, would also be controlling the Power
States for its Power Monitor Children and would provide the
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power to the Power Monitor Children. A typical example is the
PoE case, where a switch meters the power consumption, controls
the power state, and also provides the power for the connected
device. In this case, the metering, control and power
distribution topologies are overlapping.
However, this ideal case is not the only situation.
In most cases, the Power Monitor Children communicates his power
consumption to the Power Monitor Parent, while it receives its
energy from a different source. A very simple example is a PC
connected to a switch port, which receives his power from the
outlet, or from its battery. Another example is the
introduction of smart PDU in a datacenter, where the power
distribution is a key aspect. In such cases, metering and power
distribution are two distinct topologies. Note that the power
distribution topology is also known as the power distribution
tree.
In other cases, sub-meters may exist in a building or data
center. These meters monitor the power consumption of one or
more end devices. Since these meters are layered on an existing
infrastructure, they subdivide the domain and might overlap.
They are also distinct from the network control topology. An
example would be a smart PDU metering the power consumption of a
server in a data center, while the server applications could be
moved to a different data center.
To summarize, all combinations of distinct or overlapping
topologies exist: metering, configuration, and power source.
The Power Monitor Metering Domain reflects the metering
topology.
5.3. Power Monitor Meter Domain
When a Power Monitor Parent acts as a Power Aggregator or a
Power Proxy, the Power Monitor Parent and its Power Monitor
Child/Children must be a member of Power Monitor Meter Domain
The Power Monitor Meter Domain should map 1-1 with a metered or
sub-metered portion of the site. The Power Monitor Meter Domain
must be configured on the Power Monitor Parent. The Power
Monitor Children may inherit their domain values from the Power
Monitor Parent or the Power Monitor Meter Domain may be
configured directly in a Power Monitor Child.
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5.4. Power Monitor Parent and Child
When a Power Monitor Parent acts as a Power Aggregator or a
Power Proxy, a Power Monitor Child reports its power usage to
its Power Monitor Parent. A Power Monitor Child has one and
only one Power Monitor Parent in the Power Monitor Metering
Domain. If a Power Monitor had two parents in the same Power
Monitor Metering Domain, there would be a risk of double-
reporting the power usage. Therefore, a Power Monitor cannot be
both a Power Monitor Parent and a Power Monitor Child at the
same time.
A Power Monitor Child can be fully dependent on the Power
Monitor Parent for its power or independent from the parent
(such as a PC connected to a switch). In the dependently
powered case, the Power Monitor Parent provides power for the
Power Monitor Child (as in the case of Power Over Ethernet
devices). In the independently powered case, the Power Monitor
Child draws power from another source (typically a wall outlet).
Since the Power Monitor Parent is not the source of power
supply, the power usage cannot be measured at the Power Monitor
Parent. However, an independent Power Monitor Child reports
Power Monitor information to the Power Monitor Parent. The
Power Monitor Child may listen to the power control settings
from a Power Monitor Parent and could react to the control
messages. However, note that the communication between the
Power Monitor Parent and Power Monitor Child is out of scope for
this document.
A mechanism, outside of the scope of this document, should be in
place to verify the connectivity between the Power Monitor
Parent and its Power Monitor Children. If a Power Monitor Child
is unavailable, the Power Monitor Parent must follow some rules
to determine how long it should wait before removing the Power
Monitor Child entry, along with all associated statistics, from
its database. In some situations, such as a connected building
in which the Power Monitor Children are somewhat static, this
removal-delay period may be long, and persistence across a Power
Monitor Parent reload may make sense. However, in a networking
environment, where endpoints can come and go, there is not much
sense in configuring a long removal timer. In all cases, the
removal timer or persistence must be clearly specified.
Further examples of Power Monitor Parent and Child
implementations are provided in the Implementation Scenarios
section 11.
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5.5. Power Monitor Context
Monitored power data will ultimately be collected by and
reported from an EMS. In order to aid in reporting and in
differentiation between Power Monitors, each Power Monitor
optionally contains information establishing its business or
site context.
A Power Monitor can provide an importance value in the range of
1 to 100 to help differentiate 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.
Although network managers must 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
A Power Monitor can provide a set of keywords. These keywords
are a list of tags that can be used for grouping and summary
reporting within or between Power Monitor Meter Domains. All
alphanumeric characters and symbols, 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. In such cases,
the keywords are separated by commas and no spaces between
keywords are allowed. For example, "HR,Bldg1,Private".
Additionally, a Power Monitor can provide a "role description"
string that indicates the purpose the Power Monitor serves in
the network or for the site/business. This could be a string
describing the context the device fulfills in deployment. For
example, a lighting fixture in a kitchen area could have a role
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of "Hospitality Lighting" to provide context for the use of the
device.
5.6. Power Monitor States
Power States represent universal states of power management of a
Power Monitor. Existing power state models can be roughly
divided into operational and non-operational states. Examples
of operational power state models include PoE power classes and
Windows Power Polices. PoE negotiation may select a power level
from one of four power classes: Very Low power (1), Low power
(2), Mid power (3), and High power (4). Windows default power
policy settings define three states: 'Power Saver', 'Balanced',
and 'High Performance'. Windows allows user defined states, so
many more states are possible. Some new devices starts to have
several operational Power States: an IP phone with an High Power
State and a lower operational Power State for the ability to
only dial 911, IP surveillance cameras with different Power
States depending on the image definition and sampling rate,
etc...
It is foreseen that, with the goal to save energy, this trend
will continue and many more devices will contain Power States.
ACPI and the DMTF Power State models define non-operational
states for when a system is inactive. In our model, each Power
State corresponds to a global, system, and performance state in
the ACPI model [ACPI] and DMTF models.
State DMTF Power ACPI MIB Power
State State State Name
Non-operational states:
1 Off-Hard G3, S5 Mech Off
2 Off-Soft G2, S5 Soft Off
3 Hibernate G1, S4 Hibernate
4 Sleep-Deep G1, S3 Sleep
5 Sleep-Light G1, S2 Standby
6 Sleep-Light G1, S1 Ready
Operational states:
7 On G0, S0, P5 LowMinus
8 On G0, S0, P4 Low
9 On G0, S0, P3 MediumMinus
10 On G0, S0, P2 Medium
11 On G0, S0, P1 HighMinus
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12 On G0, S0, P0 High
Figure 3: DMTF / ACPI Power State Mapping
For example, a Power Monitor with a Power State of 9 would
indicate an operational state with MediumMinus Power State.
The Power States can be considered as guidelines in order to
promote interoperability across device types. Realistically,
each specific feature requiring Power States will require a
complete recommendation of its own. For example, designing IP
phones with consistent Power States across vendors requires a
specification for IP phone design, along with the Power States
mapping.
Manufacturer Power States are required in some situations, such
as when no mappings with the existing Power States are possible,
or when more than the twelve specified Power States are
required.
A first example would be an imaginary device type, with only
five states: "none", "short", "tall", "grande", and "venti".
Manufacturer Power State Respective Name
0 none
1 short
2 tall
3 grande
4 venti
Figure 4: Mapping Example 1
In the unlikely event that there is no possible mapping between
these Manufacturer Power States and the proposed Power Monitor
Power States, the Power State will remain 0 throughout the MIB
module, as displayed below.
Power State / Name Manufacturer Power State / Name
0 / unknown 0 / none
0 / unknown 1 / short
0 / unknown 2 / tall
0 / unknown 3 / grande
0 / unknown 4 / venti
Figure 5: Mapping Example 2
If a mapping between the Manufacturer Power States and the Power
Monitor Power States is achievable, both series of states must
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exist in the MIB module in the Power Monitor Parent, allowing
the EMS to understand the mapping between them by correlating
the Power State with the Manufacturer Power States.
Power State / Name Manufacturer Power State / Name
1 / Mech Off 0 / none
2 / Soft Off 0 / none
3 / Hibernate 0 / none
4 / Sleep, Save-to-RAM 0 / none
5 / Standby 0 / none
6 / Ready 1 / short
7 / LowMinus 1 / short
8 / Low 1 / short
9 / MediumMinus 2 / tall
10 / Medium 2 / tall
11 / HighMinus 3 / grande
12 / High 4 / venti
Figure 6: Mapping Example 3
How the Power Monitor States are then mapped is an
implementation choice. However, it is recommended that the
Manufacturer Power States map to the lowest applicable Power
States, so that setting all Power Monitors to a Power State
would be conservative in terms of disabled functionality on the
Power Monitor.
A second example would be a device type, such as a dimmer or a
motor, with a high number of operational states. For the sake
of the example, 100 operational states are assumed.
Power State / Name Manufacturer Power State / Name
1 / Mech Off 0 / off
2 / Soft Off 0 / off
3 / Hibernate 0 / off
4 / Sleep, Save-to-RAM 0 / off
5 / Standby 1 / off
6 / Ready 2 / off
7 / LowMinus 11 / 1%
7 / LowMinus 12 / 2%
7 / LowMinus 13 / 3%
. .
. .
. .
8 / Low 15 / 15%
8 / Low 16 / 16%
8 / Low 17 / 17%
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. .
. .
. .
9 / MediumMinus 30 / 30%
9 / MediumMinus 31 / 31%
9 / MediumMinus 32 / 32%
. .
. .
. .
10 / Medium 45 / 45%
10 / Medium 46 / 46%
10 / Medium 47 / 47%
. .
. .
. .
etc...
Figure 7: Mapping Example 4
As specified in section 6, this architecture allows the
configuration of the Power State, while configuring the
Manufacturer Power State from the MIB directly is not possible.
5.7. Power Monitor Usage Measurement
A power measurement must be qualified with the units, magnitude,
direction of power flow, and by what means the measurement was
made (ex: Root Mean Square versus Nameplate).
In addition, the Power Monitor should describe how it intends to
measure usage as one of consumer, producer or meter of usage.
Given the intent any readings can be correctly summarized or
analyzed by an EMS. 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 EMS.
The power usage measurement should conform to the IEC 61850
definition of unit multiplier for the SI (System International)
units of measure. The power usage measurement is considered an
instantaneous usage value and does not include the usage over
time.
Measured values are represented in SI units obtained by
BaseValue * 10 raised to the power of the scale. For example,
if current power usage of a Power Monitor is 3, it could be 3 W,
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3 mW, 3 KW, or 3 MW, depending on the value of the scaling
factor. Electric 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. An 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 a Power Monitor 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 EMS can use this information to account for the accuracy and
nature of the reading between different implementations.
The EMS can use the Nameplate Power for provisioning, capacity
planning and potentially billing.
5.8. Optional Power Usage Quality
Given a power measurement of a Power Monitor, 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. In some
Power Monitor Domains, the power quality may not be needed,
available, or relevant to the Power Monitor.
5.9. Optional Energy Measurement
In addition to reporting the Power State, an approach to
characterizing the energy demand is required. It is well known
in commercial electrical utility rates that demand charges can
be on par with actual power charges, so it is useful to
characterize the demand. The demand can be described as the
average energy of a Power Monitor over a time window called a
demand interval (typically 15 minutes). The highest peak energy
demand measured over a time horizon, such as 1 month or 1 year,
is often the basis for usage 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 a
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Power Monitor, and not when the power measurement is assumed or
predicted.
Several efficiency metrics can be derived and tracked with the
demand usage data. For example:
. Per-packet power costs for a networking device (router or
switch) can be calculated by an EMS. The packet count can
be determined from the traffic usage in the ifTable
[RFC2863], from the forwarding plane figure, or from the
platform specifications.
. Watt-hour power can be combined with utility energy sources
to estimate carbon footprint and other emission statistics.
5.10. Optional Battery Information
Some Power Monitors may use batteries for storing energy and for
receiving power supply. These Power Monitors 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
. battery type
. nominal and remaining capacity
. current charge
. current state (charging, discharging, not in use, etc.)
. number of charging cycles
. expected remaining time that the battery can serve as power
supply
. expected remaining lifetime of the battery
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. 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 an MIB in the different related IETF Energy Monitoring
documents. However, other programming structure with different
data models could be used as well.
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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
AWARENESS / CONTEXT
+-----------------------------------------------+
| Domain Member |
| _____________________________________________ |
| identity : Identity |
| name : string |
| type : string |
| context : Context |
| meterDomain : string |
| category : enum { producer, consumer, meter} |
| battery : Battery |
| nameplate : Measurement |
| setting: Setting |
| measurements: collection |
| --------------------------------------------- |
| Measurement instantaneousUsage() |
| DemandMeasurement historicalUsage() |
+-----------------------------------------------+
^ ^
| |
| |
+------------+------------+ +---------+-----------+
| Parent | | EndPoint |
| _______________________ | |_____________________|
| neighbors : collection | | parent: uuid |
| children : collection | | |
+-------------------------+ +---------------------+
+---------------------+
| |
| |
| Domain Member | measurements
| |---------------->+--------------+
| | 0..n | Measurement |
+---------------------+ +--------------+
+--------------------+
| |----------------> +--------------+
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| | neighbors 0..n |Parent |
| Parent | +--------------+
| | 1 children 0..n +--------------+
| +----------------->|EndPoint |
+--------------------+ +--------------+
+------------------------------------+
| Identity |
| ___________________________________|
| moid : uuid |
| entPhysIndex : int |
| ethPortIndex : int |
| ethPortGroupIndex: int |
| lldpPort : int |
| macaddress : octets |
| ipaddress : string |
| dnsname : string |
| altkey : string |
| |
+------------------------------------+
+------------------------------------+
| |
| role : string |
| importance : enum {1..100} |
| keywords : strings |
| |
+------------------------------------+
+-----------------------------------+
| Battery |
| __________________________________|
| TBD |
+-----------------------------------+
STATE / LEVELS
NOTE:
This is the Class description of States and Levels
Class. An instance model will show the standard and
manufacturer levels as descibed in the architecture.
+----------------------------------------------+
| Setting |
| _____________________________________________|
| currentLevel : int |
| configuredLevel : int |
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| configuredTime : timestamp |
| reason: string |
| |
+----------------------------------------------+
+-----------------------------------------------+
| Level |
| _____________________________________________ |
| static levels[12]: Level |
| state : State |
| category : enum {operational, |
| nonoperational, standby} |
| color : enum {black, brown, blue, |
| green, yellow, red } |
| --------------------------------------------- |
| static Level() |
| static levelFor( index int) |
+-----------------------------------------------+
+-------------------------------+
| State |
| ---------------------------- |
| name : string |
| cardinality : int |
| maxUsage : Measurement |
+-------------------------------+
+-----------------------------------+
| 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 |
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| quality : MeasurementQuality |
+-----------------------------------------------+
+-----------------------------------------------+
| TimeMeasurement |
| -------------------------------------------- |
| startTime : timestamp |
| usage : Measurement |
| maxUsage : Measurment |
+-----------------------------------------------+
+----------------------------------------+
| TimeInterval |
|--------------------------------------- |
|value : long |
|units : enum { seconds, miliseconds..} |
| |
+----------------------------------------+
+----------------------------------------+
| DemandMeasurement |
|--------------------------------------- |
|intervalLength : TimeInterval |
|intervalNumbers: long |
|intervalMode : enum { period, sliding, |
|total } |
|intervalWindow : TimeInterval |
|sampleRate : TimeInterval |
|status : enum {active, inactive } |
|measurements : TimedMeasurement[] |
+----------------------------------------+
QUALITY
+----------------------------------------+
| MeasurementQuality |
|_______________________________________ |
| |
+----------------------------------------+
^
|
|
+------------------+--------------------+
| ACQuality |
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| --------------------------------------|
| acConfiguration : enum {SNGL, DEL,WYE}|
| avgVoltage : long |
| avgCurrent : long |
| frequency : long |
| unitMultiplier : int |
| accuracy : int |
| totalActivePower : long |
| totalReactivePower : long |
| totalApparentPower : long |
| totalPowerFactor : long |
+---------+-----------------------------+
| 1
|
|
|
| +------------------------------------+
| | ACPhase |
| | -----------------------------------|
| * | - |
+--------+ phaseIndex : long |
| avgCurrent : long |
| activePower : long |
| reactivePower : long |
| apparentPower : long |
| powerFacotr : long |
+------------------------------------+
^ ^
| |
| |
| |
| |
+-------------------------------+---+ |
| DelPhase | |
|--------------------------------- | |
|phaseToNextPhaseVoltage : long | |
|thdVoltage : long | |
|thdCurrent : long | |
| | |
+-----------------------------------+ |
|
+------------------+-----------+
| WYEPhase |
|----------------------------- |
|phaseToNeutralVoltage : long |
|thdCurrent : long |
|thdVoltage : long |
| |
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+------------------------------+
7. Power Monitor Children Discovery
There are multiple ways that the Power Monitor Parent can
discover its Power Monitor Children, if they are not present on
the same physical network element:
. In case of PoE, the Power Monitor Parent automatically
discovers a Power Monitor Child when the Child requests
power.
. The Power Monitor Parent and Children may run the Link
Layer Discovery Protocol [LLDP], or any other discovery
protocol, such as Cisco Discovery Protocol (CDP). The
Power Monitor Parent might even support the LLDP-MED MIB
[LLDP-MED-MIB], which returns extra information on the
Power Monitor Children.
. The Power Monitor Parent may reside on a network connected
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.
. Power Monitor Parent/Power Monitor Child relationships may
be set by manual or automatic network configuration
functions.
When a Power Monitor Child supports only its own Manufacturer
Power States, the Power Monitor Parent will have to discover
those Manufacturer Power States. Note that the communication
specifications between the Power Monitor Parent and Children is
out of the scope of this document. This includes the
Manufacturer Power States discovery, which is protocol-specific.
8. Configuration
This power management architecture allows the configuration of
the following key parameters:
. Power Monitor name: A unique printable name for the Power
Monitor.
. Power Monitor Role: An administratively assigned name to
indicate the purpose a Power Monitor serves in the network.
. Power Monitor Importance: A ranking of how important the
Power Monitor is, on a scale of 1 to 100, compared with
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other Power Monitors in the same Power Monitor Meter
Domain.
. Power Monitor Keywords: A list of keywords that can be used
to group Power Monitors for reporting or searching.
. Power Monitor Domain: Specifies the name of a Power Monitor
Meter Domain for the Power Monitor.
. The Power Monitor State: Specifies the current Power State
(0..12) for the Power Monitor.
. The energy demand parameters: For example, which interval
length to report the energy on, the number of intervals to
keep, etc.
. Assigning a Power Monitor Parent to a Power Monitor Child
. Assigning a Power Monitor Child to a Power Monitor Parent.
When a Power Monitor requires a mapping with the Manufacturer
Power State, the Power Monitor configuration is done via the
Power State settings, and not directly via the Manufacturer
Power States, which are read-only. Taking into account Figure
8, where the LowMinus Power State corresponds to three different
Manufacturer Power States (11 for 1%, 12 for 2%, and 13 for 3%),
the implication is that this architecture will not set the
Manufacturer Power State to one percent granularity without
communicating over or configuring the proprietary protocol for
this Power Monitor.
This architecture supports multiple means for setting the Power
State of a specific Power Monitor. One of them is by setting an
object in the Power State MIB. . However, the Power Monitor
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 MIB object contains
the actual Power State. A difference in values between the two
objects indicates that the Power Monitor 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 Power Monitor Parent and the Power
Monitor Child, when the Power Monitor Parent acts as a Power
Proxy. Note that the Wake-up-on-Lan (WoL) mechanism allows to
transition a device out of the Off Power State.
When a Power Monitor Parent is a Power Proxy, , the Power
Monitor Parent should enumerate the capabilities it is providing
for the Power Monitor Child. The child would express that it
wants its parent to proxy capabilities such as, energy
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reporting, power state configurations, non physical wake
capabilities (such as WoL)), or any combination of capabilities.
Note that for the communication between the Power Monitor Parent
and Children the MIB modules and other communication means
defined for this architecture may be used, but as well other
proprietary protocols may be applied. This includes
communication of power settings and configuration information,
such as the Power Monitor Domain.
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 Power Monitor.
10. Relationship with Other Standards Development Organizations
10.1. Information Modeling
This power management architecture should, as much as possible,
reuse existing standards efforts, especially with respect to
information modeling and data modeling [RFC3444].
The data model for power, energy related objects is based on IEC
61850.
Specific examples include:
. The scaling factor, which represents Power Monitor usage
magnitude, conforms to the IEC 61850 definition of unit
multiplier for the SI (System International) units of
measure.
. The power accuracy model 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.
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. ANSI C12.20 class 0.2, 0.5
. The powerQualityMIB MIB module 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.
10.2. Power States
There are twelve Power Monitor States. They are subdivided into
six operational states, and six non-operational states. The
lowest non-operational state is 1 and the highest is six. Each
non-operational state corresponds to an ACPI state [ACPI].
11. Implementation Scenarios
The scope of power and energy monitoring consists of devices
that consume power within and that are connected to a
communications network. These devices include:
- Network devices and sub-components: Devices such as routers
and switches and their sub-components.
- Network attached endpoints: Devices that use the
communications network, such as endpoints, PCs, and facility
gateways that proxy energy monitor and control for commercial
buildings or home automation.
- Network attached meters or supplies: Devices that can monitor
the electrical supply, such as smart meters or Universal
Power Supplies (UPS) that meter and provide availability.
-
This section provides illustrative examples that model different
scenarios for implementation of the Power Monitor, including
Power Monitor Parent and Power Monitor Child relationships.
Each of the scenarios below is explained in more detail in the
Power Monitor MIB document [EMAN-MON-MIB], with a mapping to the
MIB Objects.
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Scenario 1: Switch with PoE endpoints
Consider a PoE IP phone connected to a switch. The IP phone is
supplied with power from the PoE switch.
Scenario 2: Switch with PoE endpoints with further connected
device(s)
Consider the same example as in Scenario 1, but with a PC daisy-
chained from the IP phone for LAN connectivity. The phone is
supplied with power from the PoE port of the switch, while the
PC draws power from the wall outlet.
Scenario 3: A switch with Wireless Access Points
Consider a WAP (Wireless Access Point) connected to the PoE port
of a switch. There are several PCs connected to the Wireless
Access Point over Wireless protocols. All PCs draw power from
the wall outlets.
The switch port is the Power Monitor Parent for the Wireless
Access Point (WAP) and all the PCs. But there is a distinction
among the Power Monitor Children, as the WAP draws power from
the PoE port of the switch and the PCs draw power from the wall
outlet.
Scenario 4: Network connected facilities gateway
At the top of the network hierarchy of a building network is a
gateway device that can perform protocol conversion between many
facility management devices, such as BACNET, MODBUS, DALI, LON,
etc. There are power meters associated with power-consuming
entities (Heating Ventilation & Air Conditioning - HVAC,
lighting, electrical, fire control, elevators, etc). The
proposed MIB can be implemented on the gateway device. The
gateway can be considered as the Power Monitor Parent, while the
power meters associated with the energy consuming entities can
be considered as its Power Monitor Children.
Scenario 5: Data center network
A typical data center network consists of a hierarchy of
switches. At the bottom of the hierarchy there are servers
mounted on a rack, and these are connected to the top-of-the-
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rack switches. The top switches are connected to aggregation
switches that are in turn connected to core switches. As an
example, Server 1 and Server 2 are connected to different switch
ports of the top switch.
The proposed MIB can be implemented on the switches. The switch
can be considered as the Power Monitor Parent. The servers can
be considered as the Power Monitor Children.
Scenario 6: Building gateway device
Similar scenario as the scenario 4.
Scenario 7: Power consumption of UPS
Data centers and commercial buildings can have Uninterruptible
Power Supplies (UPS) connected to the network. The Power Monitor
can be used to model a UPS as a Power Monitor Parent with the
connected devices as Power Monitor Children.
Scenario 8: Power consumption of battery-based devices
A PC is a typical example of a battery-based device.
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:
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. Unauthorized changes to the Power Domain or business
context of a Power Monitor may result in misreporting or
interruption of power.
. Unauthorized changes to a power state may disrupt the power
settings of the different Power Monitors, and therefore the
state of functionality of the respective Power Monitors.
. Unauthorized changes to the demand history may disrupt
proper accounting of energy usage.
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
This document has no actions for IANA.
14. Acknowledgments
The authors would like to Michael Brown for improving the text
dramatically, and Bruce Nordman for his excellent feedback.
15. References
Normative References
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[RFC3410] Case, J., Mundy, R., Partain, D., and B. Stewart,
"Introduction and Applicability Statements for Internet
Standard Management Framework ", RFC 3410, December
2002.
[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.
[EMAN-REQ] Quittek, J., Winter, R., Dietz, T., Claise, B., and
M. Chandramouli, "Requirements for Power Monitoring",
draft-ietf-eman-requirements-00 (work in progress),
December 2010.
[EMAN-AWARE-MIB] Parello, J., and B. Claise, "Energy-aware
Networks and Devices MIB", draft-ietf-eman-energy-
aware-mib-00, (work in progress), December 2010.
[EMAN-MON-MIB] Claise, B., Chandramouli, M., Parello, J., and
Schoening, B., "Power and Energy Monitoring MIB",
draft-claise-energy-monitoring-mib-06, (work in
progress), October 2010.
Informative References
[RFC2863] McCloghrie, K., Kastenholz, F., "The Interfaces Group
MIB", RFC 2863, June 2000.
[RFC3444] Pras, A., Schoenwaelder, J. "On the Differences
between Information Models and Data Models", RFC 3444,
January 2003.
[ACPI] "Advanced Configuration and Power Interface
Specification", http://www.acpi.info/spec30b.htm
[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-AS] Tychon, E., Laherty, M., and B. Schoening, "Energy
Management (EMAN) Applicability Statement",
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draft-tychon-eman-applicability-statement-00, (work in
progress), October 2010
[DASH] "Desktop and mobile Architecture for System Hardware",
http://www.dmtf.org/standards/mgmt/dash/
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
Cisco Systems, Inc.
3550 Cisco Way
San Jose, California 95134
US
Phone: +1 408 525 2339
Email: braschoe@cisco.com
Juergen Quittek
NEC Europe Ltd., Network Laboratories
Kurfuersten-Anlage 36
69115 Heidelberg
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Germany
Phone: +49 6221 90511 15
EMail: quittek@netlab.nec.de
<Claise, et. Al> Expires June 22, 2011 [Page 37]
