Network Working Group J. Quittek Internet-Draft NEC Europe Ltd. Intended status: Informational B. Nordman Expires: September 1, 2011 Lawrence Berkeley National Laboratory February 28, 2011 Reference Model for Energy Management draft-quittek-eman-reference-model-01 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 among them. Considered entities include powered devices, power monitors, and power controllers, and energy management systems. 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 working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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 September 1, 2011. Copyright Notice Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of Quittek & Nordman Expires September 1, 2011 [Page 1] Internet-Draft Reference Model for Energy Management February 2011 the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1. Energy Management . . . . . . . . . . . . . . . . . . . . 4 2.2. Energy Monitoring . . . . . . . . . . . . . . . . . . . . 5 2.3. Power, Energy, and Energy Consumption . . . . . . . . . . 5 2.4. Identity . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Energy Monitoring Reference Model . . . . . . . . . . . . . . 5 3.1. Introduction to Energy Monitoring . . . . . . . . . . . . 6 3.1.1. Basic Energy Monitoring (local metering) . . . . . . . 6 3.1.2. External Metering . . . . . . . . . . . . . . . . . . 6 3.1.3. Functions and Entities . . . . . . . . . . . . . . . . 7 3.1.4. Power Monitors . . . . . . . . . . . . . . . . . . . . 7 3.2. Energy Monitoring Entities . . . . . . . . . . . . . . . . 8 3.2.1. Powered Device . . . . . . . . . . . . . . . . . . . . 9 3.2.2. Power Source . . . . . . . . . . . . . . . . . . . . . 9 3.2.3. Power Meter . . . . . . . . . . . . . . . . . . . . . 9 3.2.4. Power Monitors . . . . . . . . . . . . . . . . . . . . 9 3.2.4.1. Power State Monitor . . . . . . . . . . . . . . . 10 3.2.4.2. Power Source Monitor . . . . . . . . . . . . . . . 10 3.2.4.3. Power Usage Monitor . . . . . . . . . . . . . . . 10 3.2.5. Energy Monitoring System . . . . . . . . . . . . . . . 10 3.3. Standardization Scope . . . . . . . . . . . . . . . . . . 10 3.4. Entity Relationships . . . . . . . . . . . . . . . . . . . 11 3.5. Energy Monitoring Scenarios . . . . . . . . . . . . . . . 11 3.5.1. Simple Device with Power Meter . . . . . . . . . . . . 11 3.5.2. External Power Meter . . . . . . . . . . . . . . . . . 12 3.5.3. External Power Meter for Multiple Powered Devices . . 13 3.5.4. Powered Device with Dual Power Supply . . . . . . . . 14 3.5.5. Two energy monitoring systems . . . . . . . . . . . . 15 3.5.6. Power over Ethernet Switch . . . . . . . . . . . . . . 16 3.5.7. Power Distribution Unit . . . . . . . . . . . . . . . 17 3.5.8. Aggregator . . . . . . . . . . . . . . . . . . . . . . 17 3.5.9. Energy Monitoring Gateway . . . . . . . . . . . . . . 18 3.5.10. Further Scenarios . . . . . . . . . . . . . . . . . . 19 4. Energy Management Reference Model . . . . . . . . . . . . . . 19 4.1. Energy Management Entities . . . . . . . . . . . . . . . . 20 4.1.1. Powered Device . . . . . . . . . . . . . . . . . . . . 20 4.1.2. Power Source . . . . . . . . . . . . . . . . . . . . . 21 4.1.3. Power Meter . . . . . . . . . . . . . . . . . . . . . 21 Quittek & Nordman Expires September 1, 2011 [Page 2] Internet-Draft Reference Model for Energy Management February 2011 4.1.4. Power Controllers . . . . . . . . . . . . . . . . . . 21 4.1.4.1. Power State Controller . . . . . . . . . . . . . . 21 4.1.4.2. Power Source Controller . . . . . . . . . . . . . 21 4.1.4.3. Power Meter Controller . . . . . . . . . . . . . . 21 4.1.5. Energy Management System . . . . . . . . . . . . . . . 21 4.2. Reference Points . . . . . . . . . . . . . . . . . . . . . 22 4.3. Entity Relationships . . . . . . . . . . . . . . . . . . . 22 4.4. Energy Management Scenarios . . . . . . . . . . . . . . . 22 4.4.1. Simple Self-Managed Device . . . . . . . . . . . . . . 22 4.4.2. Simple Managed Device . . . . . . . . . . . . . . . . 24 4.4.3. Power over Ethernet Switch . . . . . . . . . . . . . . 26 4.4.4. Power Distribution Unit . . . . . . . . . . . . . . . 27 4.4.5. Energy Management Gateway . . . . . . . . . . . . . . 27 4.4.6. Further Scenarios . . . . . . . . . . . . . . . . . . 28 5. Security Considerations . . . . . . . . . . . . . . . . . . . 28 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 29 8. Open Isues . . . . . . . . . . . . . . . . . . . . . . . . . . 29 8.1. Short name for the protocol . . . . . . . . . . . . . . . 29 8.2. Identity Monitor . . . . . . . . . . . . . . . . . . . . . 29 8.3. Interactions with the EMS . . . . . . . . . . . . . . . . 29 8.4. Third basic state for power source? . . . . . . . . . . . 30 8.5. Collector and Aggregator . . . . . . . . . . . . . . . . . 30 8.6. Gateways and Proxies . . . . . . . . . . . . . . . . . . . 30 9. Informative References . . . . . . . . . . . . . . . . . . . . 30 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 31 Quittek & Nordman Expires September 1, 2011 [Page 3] Internet-Draft Reference Model for Energy Management February 2011 1. Introduction Managing energy consumption of devices with network connections is different from several well understood network management functions because of the special nature of energy supply and consumption. The most basic example of energy management is a single device reporting information about its own energy status. However, in many cases, energy consumption is not measured by the powered device itself, but by a power meter located upstream in the power distribution tree. An example is a power distribution unit (PDU) that measures energy consumption of attached devices and may report this to an energy management system. Unlike many other management functions, the powered device is not involved in this process. This memo aims to clarify roles of entities involved in energy monitoring and control and the relationships among them. There is already a reference 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. The reference model specification below describes several kinds of entities and interactions between them. According to the current scope of the EMAN WG, only reporting to the energy management system are potential subjects of standardization in this WG. The reference model is described in two stages. Stage one is an energy monitoring model specified in Section 3. It covers only monitoring of power states and energy consumption. On stage two the monitoring model is extended to a full energy management reference model by adding control functions for power supply and power states. see Section 4. 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 and Section 4.1. 2.1. 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 Quittek & Nordman Expires September 1, 2011 [Page 4] Internet-Draft Reference Model for Energy Management February 2011 the network. This objective may be limited by other objectives of a general network management system, such as service level objectives. 2.2. Energy Monitoring Energy monitoring is a part of energy management. It only covers monitoring and does not include influencing the consumption of energy. 2.3. Power, Energy, and Energy Consumption Power is the rate of energy conversion. In energy management scenarios, electrical energy is delivered to a device that consumes it by converting the energy to other forms. 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 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 this document we use this ambiguous term for addressing both power and consumed energy. 2.4. Identity Identity is basic information about what a device is, in function, in its specific instance of manufacture, and its specific local human- readable name. Identity is not energy-specific, but essential for useful interpretation of energy information. Some identify information never changes. The rest of it rarely or never changes. Thus, it needs to be queried much less frequently than the energy data. 3. Energy Monitoring Reference Model This section specifies a reference model for energy monitoring. After introducing basic concepts of energy monitoring in Section 3.1 it defines entities of the model and their interactions in Section 3.2. Examples of devices and scenarios are illustrated in Section 3.5. Quittek & Nordman Expires September 1, 2011 [Page 5] Internet-Draft Reference Model for Energy Management February 2011 3.1. Introduction to Energy Monitoring In this section we introduce basic concepts of energy monitoring starting with the most basic scenario and extending it stepwise to our full reference model. The main subject of energy monitoring is a powered device. An energy monitoring system collects information about powered devices, their current power state (for example: on, sleep, off) and their actual power consumption. 3.1.1. Basic Energy Monitoring (local metering) The most basic interaction in an energy monitoring system is a powered device directly reporting its own energy-related information, with no other devices involved, as shown below. energy monitoring system ^ | device 3.1.2. External Metering Reporting its current power state is a relatively easy task for a powered device because usually information on the current power state is locally available at the device and a reporting function just needs some additional software to implement it. Reporting the current power level of a device and its accumulated energy consumption is a harder task, particularly if there are strict requirements for accuracy. Today very few devices are instrumented with means for measuring their own energy consumption as that usually implies adding hardware for this purpose. This can be addressed by external meters, that is, dedicated probes that can meter energy consumption on a power source (line). Some Power Distributions Units (PDUs) and Power over Ethernet (PoE) [IEEE-802.3af] switches integrate power source and power metering for individual devices. For supporting scenarios with external meters we extend the basic model from above by an external power meter and a power source as shown below. Quittek & Nordman Expires September 1, 2011 [Page 6] Internet-Draft Reference Model for Energy Management February 2011 energy monitoring system ^ ^ ^ | | | power power powered source meter device ############### symbols ######### represent a power supply line All three potentially report to the energy monitoring system. The power meter may report the current power and accumulated energy consumption and the power source may report if the power supply for the device is switched on or if it is off. Implementation may be incomplete. For example, an energy management system may have access to only one or two of these three types of data. 3.1.3. Functions and Entities This reference model operates at two levels/layers. One is simple basic functions that are implemented. The second is how they are arranged in devices. A device in this model may implement only a single function, or may implement many. That is, having multiple entities does not require that all of them need to be instantiated by individual devices. For example, the power meter function may be co-located and integrated with the powered device, with the power source, or it may be implemented by a separate device. 3.1.4. Power Monitors In the models above, the powered device and other components deliver reports directly to an energy monitoring system. However, there are energy monitoring scenarios where this is not possible or not desirable. Extreme examples are energy consumers that do not have IP interfaces but can communicate by other means. For delivering their reports to an IP-based energy monitoring system, it may be required to use a gateway that can communicate with the energy monitoring system. However, even if all involved devices (PDUs, power meters, and powered devices) can communicate via IP, it may be desirable to have mediation functions in place between powered devices and the energy monitoring system. An example, is an aggregating device that aggregates and reports information on several powered devices. Quittek & Nordman Expires September 1, 2011 [Page 7] Internet-Draft Reference Model for Energy Management February 2011 There are several further useful scenarios. To generalize the model (and to not exclude any kind of gateway, proxy, relay, mediator or other device) we define reporting entities called 'monitors'. The figure below shows three monitors, each of which reports to the energy monitoring system. This figure is the most generic representation of the energy monitoring reference model described by this document. Energy Monitoring Reference Model +-------------------------------------------------------------------+ | energy monitoring system | +-------------------------------------------------------------------+ ^ ^ ^ | | | +-------------------+ +-------------------+ +-------------------+ | power source | | power usage | | power state | | monitor | | monitor | | monitor | +-------------------+ +-------------------+ +-------------------+ | | | +-------------------+ +-------------------+ +-------------------+ | power | | power meter | | powered | | source | +-------------------+ | device | +-------------------+###########################+-------------------+ symbols ######### represent a power supply line A monitor function reports directly to the energy monitoring system using the EMON protocol (an Internet protocol). A monitor must have means to acquire the information it reports, but how this information is acquired is not relevant for our model. That is, only the interactions with a caret symbol in this and following diagrams is the subject of standardization. Those with only the vertical bar character are outside the scope of these documents; they may be IP or non-IP. The reference model defines the communication between power monitors an the energy monitoring system. The communication lines between these entities are reference points of our model described in more detail in the following. 3.2. Energy Monitoring Entities This section defines entities of the energy monitoring reference model and describes interactions between them. Examples scenarios are illustrated in Section 3.5. Quittek & Nordman Expires September 1, 2011 [Page 8] Internet-Draft Reference Model for Energy Management February 2011 3.2.1. Powered Device A powered device is provided with energy (typically electrical) usuallly provided via power lines. Power state, power and consumed energy of powered devices are subject to monitoring and control functions of energy management. 3.2.2. Power Source A power source provides a powered device with energy, typically via a power line. It may have means to switch on and off the power for the powered device. A power source does not necessarily generate power, but it may do so. It may be as simple as a power switch or a power plug, but it may also be a battery or a power generator. Regardless, the nature of the source does not affect energy monitoring. Note that an internal battery within a device, such as the battery of a notebok PC or of a mobile phone are not considered to be a power source. When a device runs on battery only, there is n flow of energy into the device and consequently the power to be reported for this device is zero. On the other hand, when a device charges its battery, then the power supplied for charging needs to be accounted, even if the device is not operational. 3.2.3. Power Meter A power meter measures power and/or consumed energy, and typically is electrically connected to power supply lines for powered devices. However, many devices can also provide a reliable estimate of their power consumption based on internal status information without having dedicated metering hardware. Regardless, all metering information is qualified by an indication of its accuracy. The meter function also includes integrating power consumption over time to provide a "meter reading" with a time stamp to enable an energy monitoring system to track energy consumption over time. 3.2.4. Power Monitors A power monitor has access to energy-related information concerning powered devices and is able to report this information to energy management systems. A power monitor may also provide information on identity and properties of a powered device to the management system. A power monitor may store energy-related information and process it, for example, for aggregating information or for extracting statistics Quittek & Nordman Expires September 1, 2011 [Page 9] Internet-Draft Reference Model for Energy Management February 2011 that are provided to an energy management system. There are three power monitor functions in the energy monitoring reference model: power state monitors, power source monitors, and power usage monitors. 3.2.4.1. Power State Monitor A power state monitor has access to the power state of a powered device and is able to report this information to an energy monitoring system. For acquiring power state information it may interact with powered devices. 3.2.4.2. Power Source Monitor A power state monitor has access to information on the power supply of powered devices and is able to report this information to an energy monitoring system. Typically, it will just report either 'on' or 'off'. In addition, it may report on power availability. For acquiring power source information it may interact with the power sources of powered devices. 3.2.4.3. Power Usage Monitor A power usage monitor has access to information on energy consumption of powered devices and is able to report this information to energy management systems. For acquiring information on energy consumption it may interact with power meters. 3.2.5. Energy Monitoring System An energy monitoring system receives information from power monitors, such as: power states, power source states, and energy consumption. An energy monitoring system may be centralized or distributed. In most of the example scenarios illustrated in Section 3.5 a centralized energy monitoring system is shown but in all cases can be replaced by a distributed monitoring system. 3.3. Standardization Scope The reference model specifies interactions of an energy monitoring system with power monitors. They reference points of the model are potential subjects of standardization (in the EMAN working group). Interactions of power monitors with other entities are currently not considered to be subject of standardization. It is argued in [I-D.quittek-power-monitoring-requirements] that for most of the relevant scenarios the best choice a management protocol Quittek & Nordman Expires September 1, 2011 [Page 10] Internet-Draft Reference Model for Energy Management February 2011 for the reference points is SNMP [RFC3410]. The reference model defined in this document does not assume a specific protocol between energy monitoring system and power monitors. It is also applicable if other protocols, such as, for example, Syslog [RFC5675] or IPFIX [RFC5101] are used. 3.4. Entity Relationships No restrictions on entity relationships have been identified for interacting entities of the energy monitoring reference model specified in this document. This means that all relationships between entities may be one-to-one, one-to-many, many-to-one, or many-to-many. For example, o a single power state monitor may report the power state of multiples powered entities, o a single powered entity may have its power states reported by< multiple power state monitors, o a single powered device may receive power from several power sources, o a single power monitor may report to multiple energy monitoring systems. A few of scenarios with multiple instances of units are illustrated by the examples in the following Section 3.5. 3.5. Energy Monitoring Scenarios This section describes common example scenarios for energy monitoring and how they are modeled with the entities and interactions described in the previous sections. 3.5.1. Simple Device with Power Meter A very basic example is a powered device that has a built-in meter for measuring its own energy consumption and that reports its power state and power usage directly to the energy monitoring system. Quittek & Nordman Expires September 1, 2011 [Page 11] Internet-Draft Reference Model for Energy Management February 2011 +-------------------------------------------------------------------+ | energy monitoring system | +-------------------------------------------------------------------+ ^ | +-----------------------------------------------+ | | | | +-----------+-----------+ | | | | | | +-------------------+ +-------------------+ | | | power usage | | power state | | | | monitor | | monitor | | | +-------------------+ +-------------------+ | | | | | +-----------------+ | +-------------------+ +-------------------+ | | power | | | power meter | | powered | | | source | | +---------#---------+ | device | | +-----------------+#|#########################+-------------------+ | | | | powered device with meter and power monitors | +-----------------------------------------------+ Scenario 1: Powered device metering and self-reporting Here four entities are combined in a single device: the powered device, the power meter, and two power monitors. 3.5.2. External Power Meter The second example shows a power meter that is attached to the power line of a powered device that does not have means for measuring its own energy consumption. The meter is integrated with a power usage monitor that reports metered data. The powered device may report its own power state by an integrated power state monitor. Quittek & Nordman Expires September 1, 2011 [Page 12] Internet-Draft Reference Model for Energy Management February 2011 +-------------------------------------------------------------------+ | energy monitoring system | +-------------------------------------------------------------------+ ^ | +-----------------------+ | external | meter | | +-------------------+ | | | power usage | | | | monitor | | | +-------------------+ | | | | | +-------------------+ | +-----------------+ | | power meter | | +-------------------+ | power | | +---------#---------+ | | powered | | source | +-----------#-----------+ | device | +-----------------+#############################+-------------------+ Scenario 2: An external meter 3.5.3. External Power Meter for Multiple Powered Devices Power meters may be located at a power line that provides power for multiple powered devices. In scenario 3, a single power meter measures the accumulated power and energy consumption of multiple powered devices. In general, In this scenario it is usually not possible to derive power values for the individual powered devices from the accumulated measurement. Quittek & Nordman Expires September 1, 2011 [Page 13] Internet-Draft Reference Model for Energy Management February 2011 +-------------------------------------------------------------------+ | energy monitoring system | +-------------------------------------------------------------------+ ^ | +-----------------------+ | external | meter | | +-------------------+ | | | power usage | | +----------------+ | | monitor | | | powered | | +-------------------+ | | device | | | | ###+----------------+ | +-------------------+ | # +-----------------+ | | power meter | | # +----------------+ | power | | +---------#---------+ | # | powered | | source | +-----------#-----------+ # | device | +-----------------+################################+----------------+ # # +----------------+ # | powered | # | device | ###+----------------+ Scenario 3: An external meter for multiple powered devices 3.5.4. Powered Device with Dual Power Supply Some powered devices have dual power supply. It may be that one supply comes from a power grid and the other one from a battery. High-reliability devices may have two power sources from different power distribution networks, as shown in scenarios 4 and 5. Quittek & Nordman Expires September 1, 2011 [Page 14] Internet-Draft Reference Model for Energy Management February 2011 +-------------------------------------------------------------------+ | energy monitoring system | +-------------------------------------------------------------------+ ^ | +-----------------------------------------+ | | | | +-------------------------------------+ | | | power usage monitor | | | +-------------------------------------+ | | | | | | +---------+ +-----------+ +---------+ | +---------+ | | power | | powered | | power | | +---------+ | power | | | meter | | device | | meter | | | power | | source | | +----#----+ | | +----#----+ | | source | +---------+##|##############+-----------+##############|##+---------+ | | | powered device with dual power supply | | and dual metering | +-----------------------------------------+ Scenario 4: powered device with dual power supply In scenario 4 the device uses two meters, one for each power line and reports from both to the energy monitoring system. If the two power sources belong to different power distribution domains, it may be necessary to report power and energy separately for each supply. 3.5.5. Two energy monitoring systems Scenario 5 is more complex. Both meters are individual external devices and there are even two separate energy monitoring systems involved, one for each power distribution tree. Quittek & Nordman Expires September 1, 2011 [Page 15] Internet-Draft Reference Model for Energy Management February 2011 +-------------------------------+ +-------------------------------+ | energy monitoring system | | energy monitoring system | +-------------------------------+ +-------------------------------+ ^ ^ | | +-----------+ +-----------+ | | | | | | | +-------+ | | +-------+ | | |power | | | |power | | | |usage | | | |usage | | | |monitor| | | |monitor| | | +-------+ | | +-------+ | | | | | | | | +-------+ | | +-------+ | | | power | | | | power | | +--------+ | | meter | | +-------------+ | | meter | | +--------+ | power | | +---#---+ | | powered | | +---#---+ | | power | | source | +-----#-----+ | device | +-----#-----+ | source | +--------+#################+-------------+#################+--------+ Scenario 5: powered device with dual power supply from different power distribution trees 3.5.6. Power over Ethernet Switch This example shows a Power over Ethernet (PoE) [IEEE-802.3af] switch supplying a powered device. The switch contains a power source and a meter for each of its ports. There typically are multiple instances of power sources and power meters in a PoE switch, but the drawing below shows only a single instance. The same applies to the powered devices that are represented by a single instance only. Note that a typical PoE switch has also means to control power supply for powered devices (not shown here). Control of power supply is a subject of Section 4. Quittek & Nordman Expires September 1, 2011 [Page 16] Internet-Draft Reference Model for Energy Management February 2011 +-------------------------------------------------------------------+ | energy monitoring system | +-------------------------------------------------------------------+ ^ | +---------------------------------------------+ | | | | +----------+-----------+ | | | | | | +-----------------+ +-------------------+ | | | power source | | power usage | | | | monitor | | monitor | | | +-----------------+ +-------------------+ | | | | | | +-----------------+ +-------------------+ | +-------------------+ | | power | | power meter | | | powered | | | source | +---------#---------+ | | device | | +-----------------+#########################|#+-------------------+ | | | Power over Ethernet switch | | or Power Distribution Unit | +---------------------------------------------+ Scenarios 6 & 7: Power over Ethernet switch or Power Distribution Unit reporting on power source and power usage of powered devices In this scenario the identification of the powered device can be done by the PoE switch by observing MAC and IP addresses of the powered devices. The switch can report them to the energy management system which then in turn can contact the devices directly to obtain further information. 3.5.7. Power Distribution Unit The same figure as used for the PoE switch in the previous section is be used for scenario 7 modeling a power distribution unit (PDU). A PDU with meters for every socket can report power for each. Identifying the powered devices can more difficult in this scenario than in the previous one with the PoE switch, because the PDU does not necessarily communicate with the powered devices. In this case the PDU or EMS needs to obtain this information by other means, for example by manual configuration. 3.5.8. Aggregator Scenario 8 shows a power usage monitor acting as an aggregator. It collects power information from three powered devices and delivers all of the information to the energy monitoring system. The Quittek & Nordman Expires September 1, 2011 [Page 17] Internet-Draft Reference Model for Energy Management February 2011 aggregator may deliver the full information or aggregated information, for example, just the sum of the power of all three powered devices. +-------------------------------------------------------------------+ | energy monitoring system | +-------------------------------------------------------------------+ ^ | +-------------------------------------------------------------------+ | power usage monitor | +-------------------------------------------------------------------+ | | | +-------------------+ +-------------------+ +-------------------+ | | | | | | | | | |+-------+ +-------+| |+-------+ +-------+| |+-------+ +-------+| || power | |powered|| || power | |powered|| || power | |powered|| || meter | |device || || meter | |device || || meter | |device || |+-------##+-------+| |+-------##+-------+| |+-------##+-------+| +--------#----------+ +--------#----------+ +--------#----------+ # # # +-------------------------------------------------------------------+ | power source | +-------------------------------------------------------------------+ Scenario 8: An aggregator collecting monitoring information from three powered devices 3.5.9. Energy Monitoring Gateway Some energy monitoring scenarios include a gateway between the monitored units and the energy monitoring system. The powered device and the power meter may use means of communication other than IP. The gateway is a relay and protocol converter that delivers energy information to a power monitor. A single device may implement logically independent gateways for multiple devices. Scenario 9 can easily extended to a gateway that also contains a power source monitor. Quittek & Nordman Expires September 1, 2011 [Page 18] Internet-Draft Reference Model for Energy Management February 2011 +-------------------------------------------------------------------+ | energy monitoring system | +-------------------------------------------------------------------+ ^ | +---------------------------------------------+ | | | | +-----------+----------+ | | | | | | +-------------------+ +-----------------+ | | | power usage | | power state | | | | monitor | | monitor | | | +-------------------+ +-----------------+ | | gateway | | | +---------------------------------------------+ | | +-------------------+ +-------------------+ +-----------------+ | power | | power meter | | powered | | source | +---------#---------+ | device | +-------------------+###########################+-----------------+ Scenario 9: A gateway between monitored devices and energy monitoring system Here again, the problem of identifying the powered device has become very difficult, because neither can the power monitor provide an IP address of the powered device to the energy management system nor can the energy management system directly communicate with the powered device. Identification must be provided by other means. The Proxy can have a gateway function and relay identification between powered device and energy management system or the energy management system needs to acquire information on powered devices by other means, such as manual configuration. 3.5.10. Further Scenarios More scenarios may be added to future versions of this document. Particularly, scenarios with multiple instances of an entity have not been elaborated a lot. Section 4.4 shows scenarios for energy control. They can also be considered as further monitoring scenarios if only their power monitors are considered and power controllers are ignored. 4. Energy Management Reference Model This section extends the energy monitoring reference model specified in the previous Section 3 by adding power control functions. The Quittek & Nordman Expires September 1, 2011 [Page 19] Internet-Draft Reference Model for Energy Management February 2011 resulting model is a complete energy management reference model. As in Section 3 we first discuss entities and their relationships and then illustrate the model with example scenarios. The extension from energy monitoring to energy management is straight forward. To achieve the required control functions the power source, power meter, and powered device have additional functions for control. For each power monitor a corresponding power controller is added as shown below. Energy Management Reference Model +-------------------------------------------------------------------+ | energy management system | +-------------------------------------------------------------------+ ^ | ^ | ^ | | v | v | v +--------+ +--------+ +--------+ +--------+ +--------+ +--------+ | power | | power | | power | | power | | power | | power | | source | | source | | usage | | meter | | state | | state | | monitor| | ctrler | | monitor| | ctrler | | monitor| | ctrler | +--------+ +--------+ +--------+ +--------+ +--------+ +--------+ | | | | | | +-------------------+ +-------------------+ +-------------------+ | power | | power meter | | powered | | source | +-------------------+ | device | +-------------------+###########################+-------------------+ symbols ######### represent a power line 4.1. Energy Management Entities This section defines entities of the energy management reference model and describes interactions between them. Examples scenarios are illustrated in Section 4.4. For entities already specified in Section 3.2 of the energy monitoring reference model, only their additional properties are mentioned here. Power monitors are not discussed here again, because their specification in the energy management reference model do not change. 4.1.1. Powered Device A powered device may be capable of changing its own power state from a request from the energy management system. Some devices may not be able to power up from an off state based on EMS request. Most devices that are asleep will be able to wake on EMES request. Quittek & Nordman Expires September 1, 2011 [Page 20] Internet-Draft Reference Model for Energy Management February 2011 4.1.2. Power Source A power source may be capable of switching on and off power for powered devices. 4.1.3. Power Meter A power meter may be switched on or off or have its metering parameters modified. 4.1.4. Power Controllers A power controller receives commands from an energy management system to change the status or parameters of power sources, power meters, or powered devices. There are three kinds of power controller entities: power state controllers, power source controllers, and power meter controllers. 4.1.4.1. Power State Controller A power state controller can initiate a change in the power state of a powered device. 4.1.4.2. Power Source Controller A power source controller can change the power supply of a powered device. Typically, it has means for switching power supply on and off. It may use these means without communicating with the affected powered device. 4.1.4.3. Power Meter Controller A power meter controller has means for influencing the operation of a power meter. It may switch on and off the power meters and change parameters of their operation. For this purpose it may interact with power meters. 4.1.5. Energy Management System An energy management system is an energy monitoring system extended by control functions. It interacts with power monitors and power controllers in order to achieve objectives of energy management. It sends commands to power controllers. To power state controllers it sends requested power states for powered devices. To power source controllers it requests to switch on or off power for powered devices. To power meter controllers it sends commands concerning the Quittek & Nordman Expires September 1, 2011 [Page 21] Internet-Draft Reference Model for Energy Management February 2011 operation of power meters. 4.2. Reference Points Relevant for our reference model are interactions of the energy management system with power monitors and power controllers. They are reference points of our model and potential subjects of standardization in the EMAN working group. Interactions of power monitors and power controllers with other entities are currently not considered to be subject of standardization. Monitoring protocols have already been discussed in Section 3.3. There are several choices of control protocols to be used for energy management. Among them are SNMP [RFC3410] and NETCONF [RFC4741]. 4.3. Entity Relationships The considerations on entity relationships for the energy monitoring reference model described in Section 3.4. apply as well to the energy management reference model: No restrictions on entity relationships have been identified. 4.4. Energy Management Scenarios This section describes example scenarios for energy management and how they are modeled with the entities and interactions described above. 4.4.1. Simple Self-Managed Device The first two examples are expected to become very common scenarios. Here, a powered device is managing its power state on its own based on input other than from the energy management system. The device may decide to change power state based on observation of its environment (no current load, high temperature, not sufficient light, scheduled time for service interruption, etc.) or it may receive external triggers, such as by a human-operated remote control. Quittek & Nordman Expires September 1, 2011 [Page 22] Internet-Draft Reference Model for Energy Management February 2011 +-------------------------------------------------------------------+ | energy management system | +-------------------------------------------------------------------+ ^ | +-----------------------+ | | | | +--------+ +--------+ | | | power | | power | | | | state | | state | | | | monitor| | ctrler | | | +--------+ +--------+ | | | | | +-----------------+ | +-------------------+ | | power | | | powered | | | source | | | device | | +-----------------+#|#########################+-------------------+ | | | | powered device with | | power state control | +-----------------------+ Scenario 10: A self-managed powered device In any way, it's power state control is independent of the energy management system. The only interaction with the system is reporting of power state to the energy management system in scenario 10, and in addition reporting of its current power and/or accumulated consumed energy in scenario 11. Quittek & Nordman Expires September 1, 2011 [Page 23] Internet-Draft Reference Model for Energy Management February 2011 +-------------------------------------------------------------------+ | energy management system | +-------------------------------------------------------------------+ ^ | +-----------------------------------------------+ | | | | +-----------------+-----+ | | | | | | +--------+ +--------+ +--------+ +--------+ | | | power | | power | | power | | power | | | | usage | | meter | | state | | state | | | | monitor| | ctrler | | monitor| | ctrler | | | +--------+ +--------+ +--------+ +--------+ | | | | | | | +-----------------+ | +-------------------+ +-------------------+ | | power | | | power meter | | powered | | | source | | +---------#---------+ | device | | +-----------------+#|#########################+-------------------+ | | | | powered device with built-in meter | | and autonomous control | +-----------------------------------------------+ Scenario 11: A self-managed powered device with built-in meter In scenario 11 also the control of the power meter is handled by the device itself. 4.4.2. Simple Managed Device In our model, the scenario does not change much if the powered devices are not self-managed but managed by the energy management system. Scenarios 12 and 13 show that just an interaction between the energy management system and the powered device is added that serves for sending commands concerning power states to the device. Quittek & Nordman Expires September 1, 2011 [Page 24] Internet-Draft Reference Model for Energy Management February 2011 +-------------------------------------------------------------------+ | energy management system | +-------------------------------------------------------------------+ ^ | | | +-----------------------+ | | v | | +--------+ +--------+ | | | power | | power | | | | state | | state | | | | monitor| | ctrler | | | +--------+ +--------+ | | | | | +-----------------+ | +-------------------+ | | power | | | powered | | | source | | | device | | +-----------------+#########################|#+-------------------+ | | | | powered device with | | power state control | +-----------------------+ Scenario 12: A managed powered device Control of the power meter by the management system can easily added to scenario 13. It is not included here, because for built-in meters this seems not to be necessary in many common cases. Quittek & Nordman Expires September 1, 2011 [Page 25] Internet-Draft Reference Model for Energy Management February 2011 +-------------------------------------------------------------------+ | energy management system | +-------------------------------------------------------------------+ ^ | | | +-----------------------------------------------+ | | | | | +-----------------+-----+ | | | | | v | | +--------+ +--------+ +--------+ +--------+ | | | power | | power | | power | | power | | | | usage | | meter | | state | | state | | | | monitor| | ctrler | | monitor| | ctrler | | | +--------+ +--------+ +--------+ +--------+ | | | | | | | +-----------------+ | +-------------------+ +-------------------+ | | power | | | power meter | | powered | | | source | | +---------#---------+ | device | | +-----------------+#|#########################+-------------------+ | | | | powered device with built-in meter | | and autonomous control | +-----------------------------------------------+ Scenario 13: A managed powered device with built-in meter 4.4.3. Power over Ethernet Switch Scenario 14 adds control functions to the PoE switch of scenario 6 in Section 3.5. Here the energy management system can explicitly request the power for a powered device to be switched on or off. It also can switch on and off metering and reporting of energy consumption per port of the switch Quittek & Nordman Expires September 1, 2011 [Page 26] Internet-Draft Reference Model for Energy Management February 2011 +-------------------------------------------------------------------+ | energy management system | +-------------------------------------------------------------------+ | ^ | ^ | | | | +-------------------------------------------+ +---------------------+ | | | | | | | | | +----------------+----+ | | | | | | | v | v | | | | |+--------+ +--------+ +--------+ +--------+| |+--------+ +--------+| || power | | power | | power | | power || || power | | power || || source | | source | | usage | | meter || || state | | state || || monitor| | ctrler | | monitor| | ctrler || || monitor| | ctrler || |+--------+ +--------+ +--------+ +--------+| |+--------+ +--------+| | | | | | | | | | | |+-------------------+ +-------------------+| |+-------------------+| || power | | power meter || || powered || || source | +---------#---------+| || device || |+-------------------+######################|#|+-------------------+| | | | | | Power over Ethernet switch | | powered device with | | or Power Distribution Unit | | power state control | +-------------------------------------------+ +---------------------+ Scenario 14 & 15: Power over Ethernet switch or Power Distribution Unit Still, the powered device in this scenario is self-managed controlling its power state on its own and just reporting it to the energy management system. 4.4.4. Power Distribution Unit Again, as in Section 3.5 the scenario for a power distribution unit looks exactly the same in our reference model as the scenario for a power distribution unit. 4.4.5. Energy Management Gateway Starting from an energy monitoring gateway in Section 3.5 the extension towards an energy management gateway is again straight forward. Quittek & Nordman Expires September 1, 2011 [Page 27] Internet-Draft Reference Model for Energy Management February 2011 +-------------------------------------------------------------------+ | energy management system | +-------------------------------------------------------------------+ | ^ | | | | +-----------------------------------------------+ | | | | | | +-----------------+-----+ | | | | gateway v | v | | +--------+ +--------+ +--------+ +--------+ | | | power | | power | | power | | power | | | | usage | | meter | | state | | state | | | | monitor| | ctrler | | monitor| | ctrler | | | +--------+ +--------+ +--------+ +--------+ | | | | | | | +-----------------------------------------------+ | | | | +-----------------+ +-------------------+ +-------------------+ | power | | power meter | | powered | | source | +---------#---------+ | device | +-----------------+###########################+-------------------+ Scenario 16: A gateway between powered devices and energy monitoring system Here again, the problem of identifying the powered device has become very difficult, because neither can the power monitor provide an IP address of the powered device to the energy management system nor can the energy management system directly communicate with the powered device. Identification must be provided by other means. The Proxy can have a gateway function and relay identification between powered device and energy management system or the energy management system needs to acquire information on powered devices by other means, such as manual configuration. 4.4.6. Further Scenarios More scenarios may be added to future versions of this document. Particularly, scenarios with multiple instances of an entity have not been elaborated, yet. Section 4.4 shows scenarios for energy control. They can also be considered as further monitoring scenarios if only their power monitors are considered and power controllers are ignored. 5. Security Considerations This memo currently does not impose any security considerations. Quittek & Nordman Expires September 1, 2011 [Page 28] Internet-Draft Reference Model for Energy Management February 2011 6. IANA Considerations This memo has no actions for IANA.. 7. Acknowledgements This memo was inspired by discussions with Benoit Claise, John Parello, Mouli Chandramouli, Rolf Winter, Thomas Dietz, Bill Mielke, and Chris Verges at IETF #79. 8. Open Isues 8.1. Short name for the protocol We talk a lot in this document about reporting energy-related information to an energy management system. For this purpose the SNMP protocol will be used and required MIB modules are under development at the EMAN WG. It may simplify the text if we can refer to the process of reporting energy-related information with a placeholder, for example, 'EMON' for energy monitoring. 8.2. Identity Monitor Shall we add a new building block called 'identity Monitor'?. This would tie in the work of the so-called POWER-AWARE-MIB. 8.3. Interactions with the EMS Shall we discuss different kinds of interactions with the EMS? These would include o broadcasting to a subnet asking for all power monitors to report, o addressing a specific device and asking for all power monitor information it has, o asking a specific device about itself, o asking a specific device for specific information, which could include particular proxied devices, or pieces of EMON (state, meter, source, identity), aggregated data, or collected data. Basically, these interactions are all cvered bythe IETF netwrk management framework. The question is whether to mention it explicitly in the reference model. Quittek & Nordman Expires September 1, 2011 [Page 29] Internet-Draft Reference Model for Energy Management February 2011 8.4. Third basic state for power source? So far, a power source has the two basic states 'on' and 'off'. Should we describe a third basic state for a power source. This would be minimal (?trickle) power to enable communications but not activity. Would this model the way USB and PoE work? EMON would not specify the quantity of this power, but an EMS will know typical levels for relevant physical layer technologies. 8.5. Collector and Aggregator It looks like we need to extend the model by a collctor function and an agregators function. A collector would collect energy-related information on other devices and report for multiple of them. An aggregator would use information from several devices and exceute operations n them, for example calculating a sum. 8.6. Gateways and Proxies Is a gateway rather a scenario or a function? Scenarios 9 and 16 may need to be revised. In scenario 9 we talk about a 'proxy'. We need to explain what we mean with 'proxy'. 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), 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. Quittek & Nordman Expires September 1, 2011 [Page 30] Internet-Draft Reference Model for Energy Management February 2011 [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. Authors' Addresses Juergen Quittek NEC Europe Ltd. Network Research Division Kurfuersten-Anlage 36 Heidelberg 69115 DE Phone: +49 6221 4342-115 Email: quittek@neclab.eu Bruce Nordman Lawrence Berkeley National Laboratory 1 Cyclotron Road Berkeley 94720 US Phone: +1 510 486 7089 Email: bnordman@lbl.gov Quittek & Nordman Expires September 1, 2011 [Page 31]