One document matched: draft-quittek-eman-reference-model-00.txt
Network Working Group J. Quittek
Internet-Draft NEC Europe Ltd.
Intended status: Informational November 8, 2010
Expires: May 12, 2011
Reference Model for Energy Management
draft-quittek-eman-reference-model-00
Abstract
This memo discusses suggest a reference model for energy consumption
monitoring and control. It defines entities involved in energy
management, their roles, and relationships between them. Considered
entities include energy consumers, energy consumption meters, energy
consumption reporters, energy consumption controllers, and energy
consumption management systems.
Status of this Memo
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This Internet-Draft will expire on May 12, 2011.
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Energy Management . . . . . . . . . . . . . . . . . . . . 4
2.2. Power, Energy, and Energy Consumption . . . . . . . . . . 4
3. Energy Management Entities . . . . . . . . . . . . . . . . . . 5
3.1. Energy Consumer . . . . . . . . . . . . . . . . . . . . . 6
3.2. Power Source . . . . . . . . . . . . . . . . . . . . . . . 6
3.3. Energy Consumption Meter . . . . . . . . . . . . . . . . . 6
3.4. Energy Consumption Reporter . . . . . . . . . . . . . . . 6
3.5. Power Controller . . . . . . . . . . . . . . . . . . . . . 7
3.6. Power Provisioning Controller . . . . . . . . . . . . . . 7
3.7. Energy Consumption Controller . . . . . . . . . . . . . . 7
3.8. Energy Management System . . . . . . . . . . . . . . . . . 7
4. Interactions between Energy Management Entities . . . . . . . 7
4.1. Interactions of the Energy Management System . . . . . . . 8
4.1.1. Interactions with Energy Consumption Reporters . . . . 8
4.1.2. Interactions with Energy Consumption Controllers . . . 8
4.2. Other Interactions Between Entities . . . . . . . . . . . 8
4.2.1. Energy Consumption Reporters and Energy
Consumption Meters . . . . . . . . . . . . . . . . . . 9
4.2.2. Power Controllers and Energy Consumers . . . . . . . . 9
4.2.3. Power Provisioning Controllers and Power Sources . . . 9
5. Energy Management Scenarios . . . . . . . . . . . . . . . . . 9
5.1. Simple Device equipped with Energy Consumption Meter . . . 9
5.2. Device Energy Consumption Meter and Power Control . . . . 10
5.3. External Energy Consumption Meter . . . . . . . . . . . . 11
5.4. Power over Ethernet Switch . . . . . . . . . . . . . . . . 11
5.5. Power Distribution Unit . . . . . . . . . . . . . . . . . 12
5.6. Energy Consumption Reporting Proxy . . . . . . . . . . . . 12
5.7. Energy-Aware Consumer . . . . . . . . . . . . . . . . . . 13
6. Security Considerations . . . . . . . . . . . . . . . . . . . 14
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14
9. Informative References . . . . . . . . . . . . . . . . . . . . 14
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Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 15
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1. Introduction
Managing energy consumption of devices with network connections is
different to several well understood network management functions
because of the special nature of energy consumption.
One particular difference, for example, is that in many typical cases
energy consumption is not measured by the consumer itself, but by a
power meter located somewhere in the power distribution tree, for
example, at a power distribution unit (PDU). The PDU measures the
energy consumption for attached devices and may report this to an
energy management system. Different to many other management
functions, the energy consumer is not involved in this process.
This memo aims at clarifying roles of entities involved in energy
monitoring and control and the relationships between these entities.
There is already a system model defined in section 4 of
[I-D.claise-power-management-arch]. The intention of this memo is to
refine this model based on recent discussions on the mailing list.
The system model specification below describes several kinds of
entities and interactions between them. According to the current
scope of the EMAN WG, only interactions with the energy management
system are potenial subjects of standardization in this WG.
2. Terminology
This section defines terms used for the description of the energy
management reference model. Names for entities of the model are not
defined here but in Section 3.
2.1. Energy Management
Energy management deals with assessing and influencing the
consumption of energy in a network of energy consumers. 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.
2.2. Power, Energy, and Energy Consumption
Power is a rate of energy conversion. The energy conversion that is
typically subject of energy management is called energy consumption.
Electrical energy is delivered to a device that "consumes" it by
converting the energy.
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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.
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 consumer 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.
The often used term 'power consumption' is not used here because
'consumption of an energy conversion rate' is not a concept that is
considered technically useful for energy management.
3. Energy Management Entities
This section defines entities of the energy managemet reference
model. Interactions between them are defined in Section 4. Examples
scenarios are illustrated in Section 5. The following figure gives
an overview of all entities and their interactions.
+---------+ +-------------+ +--------+
| Energy | commands | Power | commands | Power |
| Manage- | -------> | Provisioning| --------------> | Source |
| ment | | Controller | +--------+
| System | +-------------+ #
| | +-------------+ +-------------+ #
| | reports | Energy | reports | Energy | #
| | <------- | Consumption | <------ | Consumption |##
| | | Reporter | | Meter | #
| | +-------------+ +-------------+ #
| | +-------------+ #
| | commands | | commands +----------+
| | -------> | Power | ------------> | Energy |
| | | Controller | | Consumer |
+---------+ +-------------+ +----------+
symbols ######### represent a power line
Entities may be merged. For example, a Power over Ethernet (PoE)
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[IEEE-802.3af] switch acting as power sourcing equipment may contains
a power source, a power supply controller, an energy consumption
meter, and an energy consumption reporter. It may even integrate an
additional energy consumption controller. In such a case, these
entities may not be modeled separately by an implementation
interaction between the entities may be entirely internal to the
device. In an extreme case, a self-managed device may integrate all
entities (incduding the energy management system) except the power
source.
3.1. Energy Consumer
An energy consumer is provided with energy, typically with electrical
energy. Typically, energy is provided via power lines. The power
and consumed energy of energy consumers are subject to monitoring and
control functions of energy management.
3.2. Power Source
A power source provides consumers with electrical energy, typically
via a power line. It may have means to switch on and off the power
supply for the energy consumer. It's function may be controlled by a
power supply controller. A power supply does tyically not not
generate power. It may be as simple as a power switch or a power
plug.
3.3. Energy Consumption Meter
An energy consumption meter measures power and consumed energy.
Typically, it is electrically connected to power provisioning lines
for energy consumers. It may store energy consumption information
and process it, for example, for extracting statistics that are
provided to the energy consumption reporter
3.4. Energy Consumption Reporter
An energy consumption reporter has access to information on energy
consumption of energy consumers and is able to report this
information to energy management systems. For getting information on
energy consumption it may interact with an energy consumption meter.
The energy consumption reporter may also provide information on
identity and properties of an energy consumer to the management
system. An energy consumption reporter may store energy consumption
information and process it, for example, for extracting statistics
that are provided to the management system.
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3.5. Power Controller
A power controller has means for controlling the energy consumption
of a energy consumer by communication with it in order to control its
current power (energy consumption rate).
3.6. Power Provisioning Controller
A power provisioning controller has means for influencing the power
supply of an energy consumer. Typically, it has means for switching
power supply on and off. It may use these means without
communicating with the affected energy consumer.
3.7. Energy Consumption Controller
An energy consumption controller is a power controlller, or a power
provisioning controller, or a combination of both.
3.8. Energy Management System
An energy management system interacts with energy consumption
reporters and energy consumption controllers in order to achieve
objectives of energy management. It receives reports on energy
consumption from energy consumption reporters and sends commands to
energy consumption controllers.
An energy management system may be centralized and consist of a
single component only. It also can be distributed and contain
several interacting components. In most of the example scenarios
illustrated in Section 5 a centralized energy management system is
shown. For all examples this can be replaced by a distributed
management system.
4. Interactions between Energy Management Entities
This section describes the set of potential interactions between
entities of the energy management reference model. Examples of these
interactions are illustrated in Section 5.
Potential subjects of standardization in the EMAN working group are
only interactions of the energy management system with other entities
as described in section Section 4.1. Other interactions described in
Section 4.2 are not subject of standardization according to the EMAN
charter. However, describing them is useful for understanding the
interactions in which the management system is involved.
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4.1. Interactions of the Energy Management System
The energy management system interacts with energy consumption
reporters and energy consumption controllers.
4.1.1. Interactions with Energy Consumption Reporters
The energy management system receives reports about energy
consumption from energy consumption controllers. Reports may contain
power and consumed energy of one or more energy consumers and further
related information, for example, an identification of the consumer
on which energy consumption is reported or statistics of energy
consumption and power states.
It is argued in [I-D.quittek-power-monitoring-requirements] that the
best choice of management protocols for this purpose is SNMP
[RFC3410]. For the reference model defined in this memo we assume
that SNMP is the protocol used between energy management system and
enenergy consumption reporter. However, the model would also be
valid if other protocols were used, for example push-based protocols
such as Syslog [RFC5675] and IPFIX [RFC5101].
4.1.2. Interactions with Energy Consumption Controllers
The energy management system sends commands to energy consumption
controllers concerning energy consumers. Commands to power
provisioning controllers concern power provisioning of the affected
consumer. Typically, just two commands are used: "power on" and
"power off". But also a reduction of supplied power, for example
"reduce voltage" may be sent as command. Commands to power
controllers concern the power state of the energy consumer. A
typical example is a command to bring an energy consumer into a sleep
state or to wake it up from a sleep state.
There are several choices for the protocol to be used for these
interactions. Among them are SNMP [RFC3410] and NETCONF [RFC4741].
4.2. Other Interactions Between Entities
Interactions described in this section do not involve the energy
management system and are not subject of standardization according to
the EMAN charter. However, their description is useful to fully
understand the interactions of the energy management system.
This reference model does not make any assumption on the
communication means used for these interactions. The involved
entities may be located within the same device, inegrated into a
single monolithic implementation, and use any kind of internal
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communication. Alternatively they may be located remote of each
other and use IP or any other protocol to communicate.
4.2.1. Energy Consumption Reporters and Energy Consumption Meters
Energy consumption reporters interact with energy consumption meters
in order to receive power consumption information. If they are
remote of each other, then the energy consumption reporter acts as
relay and potentially also as protocol converter and storage for
measured data.
4.2.2. Power Controllers and Energy Consumers
Power controllers interact with energy consumers in order to send
them power state change commands.
4.2.3. Power Provisioning Controllers and Power Sources
Power provisioning controllers interact with power sources in order
to send them commands regarding the power supply for energy
consumers, such as switchin power on or off.
5. Energy Management Scenarios
This section describes a few example scenarios for energy management
and how they are modeled with the entities and interactions described
in the previous sections.
5.1. Simple Device equipped with Energy Consumption Meter
A very basic example is an energy consumer that has a built-in meter
for measuring its own energy consumption.
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+---------+ +--------+
| Energy | | Power |
| Manage- | | Source |
| ment | +--------+
| System | +-----------------------------------------#--+
| | | +-------------+ +-------------+ # |
| | reports | | Energy | reports | Energy | # |
| | <------- | | Consumption | <------ | Consumption |## |
| | | | Reporter | | Meter | # |
| | | +-------------+ +-------------+ # |
| | | # |
| | | +----------+ |
| | | | Energy | |
| | | | Consumer | |
| | | +----------+ |
| | | Consumer with meter |
+---------+ +--------------------------------------------+
The device contains three entities: an energy consumption meter, an
enrgy consumption reporter and of course also the energy consumer.
5.2. Device Energy Consumption Meter and Power Control
This second exaple extends the previous one by an additional power
controller in the device.
+---------+ +--------+
| Energy | | Power |
| Manage- | | Source |
| ment | +--------+
| System | +-----------------------------------------#--+
| | | +-------------+ +-------------+ # |
| | reports | | Energy | reports | Energy | # |
| | <------- | | Consumption | <------ | Consumption |## |
| | | | Reporter | | Meter | # |
| | | +-------------+ +-------------+ # |
| | | +-------------+ # |
| | commands | | | commands +----------+ |
| | -------> | | Power | ------------> | Energy | |
| | | | Controller | | Consumer | |
| | | +-------------+ +----------+ |
| | | Consumer with meter and power control |
+---------+ +--------------------------------------------+
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5.3. External Energy Consumption Meter
In this example, an energy consumption meter is attached to the power
line of an energy consumer that does not have means for measuring
enrgy consumption by itself.
+---------+ +--------+
| Energy | | Power |
| Manage- | | Source |
| ment | +--------+
| System | +-----------------------------------------#--+
| | | +-------------+ +-------------+ # |
| | reports | | Energy | reports | Energy | # |
| | <------- | | Consumption | <------ | Consumption |## |
| | | | Reporter | | Meter | # |
| | | +-------------+ +-------------+ # |
| | | External meter # |
| | +-----------------------------------------#--+
| | #
| | +----------+
| | | Energy |
| | | Consumer |
+---------+ +----------+
5.4. Power over Ethernet Switch
This example shows a Power over Ethernet (PoE) [IEEE-802.3af] switch
supplying an energy consumer. The switch contains a power source for
PoE, a controller for this power that can be controlled by the energy
management system and it contains a meter for each port and a
reporter for reporting measured energy consumption data. Please note
although there may be multiple instances of power sources and energy
consumption meters in the switch, only single instances are show.
The same applies to the energy consumers that arde represented by a
single one only.
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+---------+ +--------------------------------------------+
| Energy | | +-------------+ +--------+ |
| Manage- | commands | | Power | commands | Power | |
| ment | -------> | | Provisioning| --------------> | Source | |
| System | | | Controller | +--------+ |
| | | +-------------+ # |
| | | +-------------+ +-------------+ # |
| | reports | | Energy | reports | Energy | # |
| | <------- | | Consumption | <------ | Consumption |## |
| | | | Reporter | | Meter | # |
| | | +-------------+ +-------------+ # |
| | | PoE switch # |
| | +-----------------------------------------#--+
| | #
| | +----------+
| | | Energy |
| | | Consumer |
+---------+ +----------+
A problem of this example is the identification of energy consumers.
A basic PoE switch does not know which kind of device is attached to
a port. But it can observe MAC and IP address of the energy
consumers and report them to the energy management system which then
in turn can contact the consumer to obtain further information.
5.5. Power Distribution Unit
The same figure as used for the PoE switch in the previous section
can be used for modeling a power distribution unit (PDU). The PDU
receives commands from a management system to switch on and off power
at certain sockets. It contains meters for every socket and can
report power for each of them.
The problem of identifying the energy consumers for is more difficult
than in the previous case of the PoE switch, because the PDU does not
communicate with the energy consumers and only reports energy
consumption per socket. In this case the network management needs to
obtain this information by other means, for example by manual
configuration.
5.6. Energy Consumption Reporting Proxy
This example deals with measuring energy consumption of devices that
do not necessarily have IP connectivity, but other means of
communicating with a proxy. The proxy acts as relay and protocol
converter in order to deliver the energy consumption information to
the network management system.
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+---------+ +--------+
| Energy | | Power |
| Manage- | | Source |
| ment | +--------+
| System | +----------------+ +-----------------#--+
| | | +------------+ | | +-------------+ # |
| | reports | | Energy | |reports|| | Energy | # |
| | <------- | | Consumption| |<------ | | Consumption |## |
| | | | Reporter | | | | Meter | # |
| | | +------------+ | | +-------------+ # |
| | | Proxy | | # |
| | +----------------+ | +----------+ |
| | | | Energy | |
| | | | Consumer | |
| | | +----------+ |
| | | Consumer with meter|
+---------+ +--------------------+
Here again, the problem of identifying the energy consumer has become
very difficult, because neither can the energy consumption reporter
provide an IP address of the energy consumer to the energy management
system nor can the energy management system directy communicate with
the energy consumer. Identification must be provided by other means.
The Proxy can have a gateway function and relay identification
between energy consumer and energy management system or the energy
management system needs to acquire information on energy consumers by
other means, such as manual configuration.
5.7. Energy-Aware Consumer
Last but not least, this example shows a consumer that is energy-
aware. It monitors and controls its own energy consumption and for
this purpose contains a portion of a distributed energy management
system. The energy management function contained in the energy-aware
device may still have some interaction with other components of the
management system, for example for distributing policies that
determine the bahavior of self-management functions. But these
interactions between components of the distributed energy management
system are not shown here.
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+--------+
| Power |
| Source |
+--------+
+--------------------------------------------------------------#--+
| +---------+ +-------------+ +-------------+ # |
| | Energy | reports | Energy | reports | Energy | # |
| | Manage- | <------- | Consumption | <------ | Consumption |## |
| | ment | | Reporter | | Meter | # |
| | System | +-------------+ +-------------+ # |
| | | +-------------+ # |
| | | commands | | commands +----------+ |
| | | -------> | Power | ------------> | Energy | |
| | | | Controller | | Consumer | |
| +---------+ +-------------+ +----------+ |
| Self-managed energy-aware consumer |
+------------------------------------------------------------------
6. Security Considerations
This memo currently does not impose any security considerations.
7. IANA Considerations
This memo has no actions for IANA..
8. Acknowledgements
This memo was inspired by discussions with Benoit Claise, Bruce
Nordman, John Parello, Mouli Chandramouli, and Rolf Winter at IETF
#79.
9. Informative References
[I-D.quittek-power-monitoring-requirements]
Quittek, J., Winter, R., Dietz, T., Claise, B., and M.
Chandramouli, "Requirements for Power Monitoring",
draft-quittek-power-monitoring-requirements-02 (work in
progress), October 2010.
[I-D.claise-power-management-arch]
Claise, B., Parello, J., and B. Schoening, "Power
Management Architecture",
draft-claise-power-management-arch-02 (work in progress),
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October 2010.
[RFC3410] Case, J., Mundy, R., Partain, D., and B. Stewart,
"Introduction and Applicability Statements for Internet-
Standard Management Framework", RFC 3410, December 2002.
[RFC4741] Enns, R., "NETCONF Configuration Protocol", RFC 4741,
December 2006.
[RFC5101] Claise, B., "Specification of the IP Flow Information
Export (IPFIX) Protocol for the Exchange of IP Traffic
Flow Information", RFC 5101, January 2008.
[RFC5675] Marinov, V. and J. Schoenwaelder, "Mapping Simple Network
Management Protocol (SNMP) Notifications to SYSLOG
Messages", RFC 5675, October 2009.
[IEEE-802.3af]
IEEE 802.3 Working Group, "IEEE Std 802.3af-2003 - Data
Terminal Equipment (DTE) Power via Media Dependent
Interface (MDI)", July 2003.
Author's Address
Juergen Quittek
NEC Europe Ltd.
Network Research Division
Kurfuersten-Anlage 36
Heidelberg 69115
DE
Phone: +49 6221 4342-115
Email: quittek@neclab.eu
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