Network Working Group B. Claise Internet-Draft J. Parello Intended Status: Informational Cisco Systems, Inc. Expires: July 12, 2013 B. Schoening Independent Consultant J. Quittek NEC Europe Ltd July 9, 2013 Energy Management Framework draft-ietf-eman-framework-08 Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. 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." 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Abstract This document defines a framework for providing Energy Management for devices and device components within or connected to communication networks. The framework defines an Energy Management Domain as a set of Energy Objects. Each Energy Object is identified, classified and given context. Energy Objects can be monitored and controlled with respect to Power, Power State, Energy, Demand, Power Attributes, and Battery. Additionally the framework models relationships and capabilities between Energy Objects. Expires August, 2013 [Page 2] Internet-Draft February 2013 Table of Contents 1. Introduction .......................................... 5 1.1. Energy Management Documents Overview ............. 6 2. Terminology ........................................... 6 Device................................................. 7 Component.............................................. 7 Energy Management...................................... 7 Energy Management System (EnMS)........................ 7 Power.................................................. 9 Demand................................................. 9 Power Attributes....................................... 9 Power Quality.......................................... 9 Electrical Equipment.................................. 10 Non-Electrical Equipment (Mechanical Equipment)....... 10 Energy Object......................................... 10 Energy Monitoring..................................... 10 Energy Control........................................ 11 Provide Energy........................................ 11 Receive Energy........................................ 11 Power Interface....................................... 11 Energy Management Domain.............................. 11 Energy Object Identification.......................... 12 Energy Object Context................................. 12 Energy Object Relationship............................ 12 Aggregation Relationship.............................. 12 Metering Relationship................................. 12 Power Source Relationship............................. 13 Power State........................................... 13 Power State Set....................................... 13 Nameplate Power....................................... 13 3. Concerns Specific to Energy Management ............... 13 3.1. Concern #1: Power Supply ........................ 15 3.2. Concern #2: Power and Energy Measurement ........ 20 3.3. Concern #3: Reporting Sleep and Off States ...... 21 3.4. Concern #4: Devices and Components .............. 22 3.5. Concern #5: Non-Electrical Equipment ............ 22 3.6. Concern #6: Energy Procurement .................. 23 4. Energy Management Abstraction ........................ 24 4.1 Conceptual Model.................................. 24 4.2 Energy Object..................................... 25 4.3 Energy Object Attributes.......................... 25 4.4 Measurements...................................... 28 4.5 Control........................................... 31 4.6 Power State Sets Comparison....................... 37 4.7 Relationships..................................... 38 4.8 Relationship Conventions and Guidelines........... 38 Expires August, 2013 [Page 3] Internet-Draft February 2013 4.9 Energy Object Relationship Extensions............. 41 5. Energy Management Information Model................... 41 6. Example Topologies.................................... 46 6.1 Example I: Simple Device with one Source.......... 47 6.2 Example II: Multiple Inlets....................... 48 6.3 Example III: Multiple Sources..................... 48 6.4 Relationships Between Devices..................... 49 7. Relationship with Other Standards .................... 54 8. Security Considerations .............................. 55 9. IANA Considerations .................................. 56 9.1 IANA Registration of new Power State Set.......... 56 9.2 Updating the Registration......................... 58 10. Acknowledgments ..................................... 59 11. References .......................................... 59 Normative References.................................. 59 Informative References................................ 59 OPEN ISSUES: - Are Tracked via Issue Tracker. See https://trac.tools.ietf.org/wg/eman/trac/report/1 Expires August, 2013 [Page 4] Internet-Draft February 2013 1. Introduction Network management is often divided into the five main areas defined in the ISO Telecommunications Management Network model: Fault, Configuration, Accounting, Performance, and Security Management (FCAPS) [X.700]. Not covered by this traditional management model is Energy Management, which is rapidly becoming a critical area of concern worldwide, as seen in [ISO50001]. This document defines an energy management framework for devices within or connected to communication networks. The devices, or components of these devices (such as router line cards, fans, disks), can then be monitored and controlled. Monitoring includes power, energy, demand, and attributes of power. Energy control can be performed by setting devices' or components' power state. If a device contains batteries, these can also be monitored and controlled. This framework further describes how to identify, classify and provide context for such devices. While the context information is not specific to Energy Management, some context attributes are specified in the framework, addressing the following use cases: how important is a device in terms of its business impact, how should devices be grouped for reporting and searching, and how should a device role be described. These context attributes help in fault management and impact analysis while controlling the power states. Guidelines for using context for energy management are described. The framework introduces the concept of a power interface that is analogous to a network interface. A power interface is defined as an interconnection among devices where energy can be provided, received, or both. The most basic example of Energy Management is a single device reporting information about itself. In many cases, however, energy is not measured by the device itself, but metered upstream in the power distribution tree. For example, a power distribution unit (PDU) may measure the energy it supplies to attached devices and report this to an energy management system. Therefore, devices often have relationships to other devices or components in the power network. An EnMS generally requires an understanding of the power topology (who provides power to whom), the metering topology (who meters whom), and Expires August, 2013 [Page 5] Internet-Draft February 2013 an understanding of the potential aggregation (does a meter aggregate values from other devices). The relationships build on the power interface concept. The different relationships among devices and components, specified in this document, include: power source relationship, metering relationship, and aggregation relationship. 1.1. Energy Management Documents Overview The EMAN standard provides a set of specifications for Energy Management. This document specifies the framework, per the Energy Management requirements specified in [EMAN-REQ]. The applicability statement document [EMAN-AS] includes use cases, a cross-reference between existing standards and the EMAN standard, and a description of this frameworks relationship to other frameworks. The Energy Object Context MIB [EMAN-OBJECT-MIB] specifies objects for addressing Energy Object Identification, classification, context information, and relationships from the point of view of Energy Management. The Power and Energy Monitoring MIB [EMAN-MON-MIB] specifies objects for monitoring of Power, Energy, Demand, Power Attributes, and Power States. The Battery Monitoring MIB [EMAN-BATTERY-MIB] defines managed objects that provide information on the status of batteries in managed devices. 2. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. Some terms have a NOTE that is not part of the definition itself, but accounts for differences between terminologies of different standards organizations or further clarifies the definition. Expires August, 2013 [Page 6] Internet-Draft February 2013 Device A piece of electrical or non-electrical equipment. Reference: Adapted from [IEEE100] Component A part of an electrical or non-electrical equipment (Device). Reference: Adapted from [ITU-T-M-3400] Energy Management Energy Management is a set of functions for measuring, modeling, planning, and optimizing networks to ensure that the network and network attached devices use energy efficiently and appropriately for the nature of the application and the cost constraints of the organization. Reference: Adapted from [ITU-T-M-3400] NOTES: 1. Energy management refers to the activities, methods, procedures and tools that pertain to measuring, modeling, planning, controlling and optimizing the use of energy in networked systems [NMF]. 2. Energy Management is a management domain which is congruent to any of the FCAPS areas of management in the ISO/OSI Network Management Model [TMN]. Energy Management for communication networks and attached devices is a subset or part of an organization's greater Energy Management Policies. Energy Management System (EnMS) An Energy Management System is a combination of hardware and software used to administer a network with the primary purpose of energy management. Expires August, 2013 [Page 7] Internet-Draft February 2013 Reference: Adapted from [1037C] NOTES: 1. An Energy Management System according to [ISO50001] (ISO-EnMS) is a set of systems or procedures upon which organizations can develop and implement an energy policy, set targets, action plans and take into account legal requirements related to energy use. An ISO- EnMS allows organizations to improve energy performance and demonstrate conformity to requirements, standards, and/or legal requirements. 2. Example ISO-EnMS: Company A defines a set of policies and procedures indicating there should exist multiple computerized systems that will poll energy from their meters and pricing / source data from their local utility. Company A specifies that their CFO should collect information and summarize it quarterly to be sent to an accounting firm to produce carbon accounting reporting as required by their local government. 3. For the purposes of EMAN, the definition from [1037C] is the preferred meaning of an Energy Management System (EnMS). The definition from [ISO50001] can be referred to as ISO Energy Management System (ISO-EnMS). Energy That which does work or is capable of doing work. As used by electric utilities, it is generally a reference to electrical energy and is measured in kilowatt hours (kWh). Reference: [IEEE100] NOTES 1. Energy is the capacity of a system to produce external activity or perform work [ISO50001] Expires August, 2013 [Page 8] Internet-Draft February 2013 Power The time rate at which energy is emitted, transferred, or received; usually expressed in watts (joules per second). Reference: [IEEE100] Demand The average value of power or a related quantity over a specified interval of time. Note: Demand is expressed in kilowatts, kilovolt-amperes, kilovars, or other suitable units. Reference: [IEEE100] NOTES: 1. For EMAN we use kilowatts. Power Attributes Measurements of the electrical current, voltage, phase and frequencies at a given point in an electrical power system. Reference: Adapted from [IEC60050] NOTES: 1. Power Attributes are not intended to be judgmental with respect to a reference or technical value and are independent of any usage context. Power Quality Characteristics of the electrical current, voltage, phase and frequencies at a given point in an electric power system, evaluated against a set of reference technical parameters. These parameters might, in some cases, relate to the compatibility between electricity supplied in an electric power system and the loads connected to that electric power system. Reference: [IEC60050] NOTES: Expires August, 2013 [Page 9] Internet-Draft February 2013 1. Electrical characteristics representing power quality information are typically required by customer facility energy management systems. It is not intended to satisfy the detailed requirements of power quality monitoring. Standards typically also give ranges of allowed values; the information attributes are the raw measurements, not the "yes/no" determination by the various standards. Reference: [ASHRAE-201] Electrical Equipment A general term including materials, fittings, devices, appliances, fixtures, apparatus, machines, etc., used as a part of, or in connection with, an electric installation. Reference: [IEEE100] Non-Electrical Equipment (Mechanical Equipment) A general term including materials, fittings, devices appliances, fixtures, apparatus, machines, etc., used as a part of, or in connection with, non-electrical power installations. Reference: Adapted from [IEEE100] Energy Object An Energy Object (EO) is an information model (class) that represents a piece of equipment that is part of, or attached to, a communications network which is monitored, controlled, or aids in the management of another device for Energy Management. Energy Monitoring Energy Monitoring is a part of Energy Management that deals with collecting or reading information from Energy Objects to aid in Energy Management. Expires August, 2013 [Page 10] Internet-Draft February 2013 Energy Control Energy Control is a part of Energy Management that deals with directing influence over Energy Objects. Provide Energy An Energy Object "provides" energy to another Energy Object if there is an energy flow from this Energy Object to the other one. Receive Energy An Energy Object "receives" energy from another Energy Object if there is an energy flow from the other Energy Object to this one. Power Interface A Power Interface (or simply interface) is an information model (class) that represents the interconnections among devices or components where energy can be provided, received, or both. Power Inlet A Power Inlet (or simply inlet) is an interface at which a device or component receives energy from another device or component. Power Outlet A Power Outlet (or simply outlet) is an interface at which a device or component provides energy to another device or component. Energy Management Domain An Energy Management Domain is a set of Energy Objects that is considered one unit of management. Expires August, 2013 [Page 11] Internet-Draft February 2013 Energy Object Identification Energy Object Identification is a set of attributes that enable an Energy Object to be universally unique or linked to other systems. Energy Object Context Energy Object Context is a set of attributes that allow an Energy Management System to classify an Energy Object within an organization. Energy Object Relationship An Energy Object Relationship is an association among Energy Objects. NOTES 1. Relationships can be named and could include Aggregation, Metering, and Power Source. Reference: Adapted from [CHEN] Aggregation Relationship An Aggregation Relationship is an Energy Object Relationship where one Energy Object aggregates Energy Management information of one or more other Energy Objects. The aggregating Energy Object has an Aggregation Relationship with each of the other Energy Objects. Metering Relationship A Metering Relationship is an Energy Object Relationship where one Energy Object measures power, energy, demand or power attributes of one or more other Energy Objects. The measuring Energy Object has a Metering Relationship with each of the measured objects. Expires August, 2013 [Page 12] Internet-Draft February 2013 Power Source Relationship A Power Source Relationship is an Energy Object Relationship where one Energy Object provides power to one or more Energy Objects. These Energy Objects are referred to as having a Power Source Relationship. Power State A Power State is a condition or mode of a device that broadly characterizes its capabilities, power consumption, and responsiveness to input. Reference: Adapted from [IEEE1621] Power State Set A Power State Set is a collection of Power States that comprises a named or logical control grouping. Nameplate Power The Nameplate Power is the nominal Power of a device as specified by the device manufacturer. 3. Concerns Specific to Energy Management With Energy Management, there exists a wide variety of devices that may be contained in the same deployments as a communication network but comprise a separate facility, home, or power distribution network. Target devices for Energy Management are all Energy Objects that can be monitored or controlled (directly or indirectly) by an Energy Management System (EnMS) using the Internet protocol. These target devices include: - Simple electrical appliances and fixtures - Hosts, such as a PC, a server, or a printer - Switches, routers, base stations, and other network equipment and middle boxes - Components within devices, such as a battery inside a PC, a line card inside a switch, etc. Expires August, 2013 [Page 13] Internet-Draft February 2013 - Power over Ethernet (PoE) endpoints - Power Distribution Units (PDU) - Protocol gateway devices for Building Management Systems (BMS) - Electrical meters - Sensor controllers with subtended sensors There may also exist varying protocols deployed among these power distribution and communication networks. An Energy Management framework should also apply to these types of separate networks as they connect to and interact with a communications network. This section explains special issues of Energy Management concerning power supply, Power and Energy metering, and the reporting of Power States. Energy Management has special challenges because a power distribution network supplies energy to devices and components, while a separate communications network monitors and controls the power distribution network. To illustrate this point, consider the basic scenario where a single powered device receives Energy and reports energy- related information about itself to an Energy Management System (EnMS) (see Figure 1). +--------------------------+ | Energy Management System | +--------------------------+ ^ ^ monitoring | | control v v +-----------------+ | powered device | +-----------------+ Figure 1: Basic energy management scenario The powered device may have local energy control mechanisms, such as putting itself into a sleep mode when appropriate, and it may receive energy control commands for similar purposes from the EnMS. Information reported from a powered device to the EnMS includes at least the Power State of the powered device (on, sleep, off, etc.). Expires August, 2013 [Page 14] Internet-Draft February 2013 This and similar cases are well understood and common in Energy Management. They can be handled with well-established and standardized management procedures. The only missing components today are standardized information and data models for reporting and configuration, such as energy-specific MIB modules [RFC2578] and YANG modules [RFC6020]. Energy Management presents no new issues for fault, configuration, performance or security management. We can re- use standard network management procedures to handle these issues in an EnMS. For example, with faults we can re-use rmon or SNMP traps. For security, existing means like SNMPv3 security can be used. But when there are issues specific to Energy Management then this framework adds them. The following subsections address these issues and illustrate them by extending the basic scenario in Figure 1. 3.1. Concern #1: Power Supply Most powered devices that are managed by an EnMS receive external power. While many devices receive Power from unmanaged supply systems, the number of manageable power supply devices is increasing. In datacenters, for example, many Power Distribution Units (PDUs) allow the EnMS to switch power individually for each socket and also to measure the provided Power. This is very different from many other network management tasks. In this and similar cases, switching the power supply for a powered device or monitoring its power is not done by communicating with the actual powered device itself, but with an external device (in this case, the PDU). Consequently, a standard for Energy Management must not only cover the powered devices that provide services for users, but also the power supply devices (which are themselves powered devices) that monitor or control the power supply for other powered devices. A simple device such as a light bulb can be switched on or off only by switching its power supply. More complex devices may have the ability to switch off themselves or to bring Expires August, 2013 [Page 15] Internet-Draft February 2013 themselves to states in which they consume very little power. For these devices as well, it is desirable to monitor and control their power supply. This extends the basic scenario from Figure 1 by adding a power supply device (see Figure 2). +-----------------------------------------+ | energy management system | +-----------------------------------------+ ^ ^ ^ ^ monitoring | | control monitoring | | control v v v v +--------------+ +-----------------+ | power supply |########| powered device | +--------------+ +-----------------+ ######## power supply line Figure 2: Basic Scenario with Power Supply Device The power supply device can be as simple as a plain power switch. It may offer interfaces to the EnMS to monitor and to control the status of its power outlets, as with PDUs and Power over Ethernet (PoE) [IEEE-802.3at] switches. The relationship between supply devices and the powered devices they serve creates several problems for managing power supply: o Identification of corresponding devices: * A given powered device may need to identify the device supplying power. * A given power supply device may need to identify the corresponding power-supplied device(s). o Aggregation of monitoring and control for multiple powered devices: * A power supply device may supply multiple devices from a single power supply line. o Coordination of power control for devices with multiple power inlets: * A powered device may receive power via multiple power lines controlled by the same or different power supply devices. 3.1.1 Identification of Power Supply and Powered Devices Expires August, 2013 [Page 16] Internet-Draft February 2013 When a power supply device controls or monitors power supply at one of its power outlets, the effect on other devices is not always clear without knowledge about wiring of power lines. The same holds for monitoring. The power supplying device can report that a particular socket is powered, and it may even be able to measure power and conclude that there is a consumer drawing power at that socket, but it may not know which powered device(s)receives the provided power. In many cases it is obvious which other device is supplied by a certain outlet, but this always requires additional (reliable) information about power line wiring. Without knowing which device(s) are powered via a certain outlet, monitoring data are of limited value and the consequences of switching power on or off may be hard to predict. Even in well-organized operations, powered devices' power cords can be plugged into the wrong socket, or wiring plans changed without updating the EnMS accordingly. For reliable monitoring and control of power supply devices, additional information is needed to identify the device(s) that receive power provided at a particular monitored and controlled socket. This problem also occurs in the opposite direction. If power supply control or monitoring for a certain device is needed, then the supplying power supply device has to be identified. To conduct Energy Management tasks for both power supply devices and other powered devices, sufficiently unique identities are needed, and knowledge of their power supply relationship is required. 3.1.2 Multiple Devices Supplied by a Single Power Line The second fundamental problem is the aggregation of monitoring and control that occurs when multiple powered devices are supplied by a single power supply line. It is often necessary for the EnMS to discover the full list of powered devices connected to a power supply line, as in Figure 3. +---------------------------------------+ | energy management system | +---------------------------------------+ Expires August, 2013 [Page 17] Internet-Draft February 2013 ^ ^ ^ ^ monitoring | | control monitoring | | control v v v v +--------+ +------------------+ | power |########| powered device 1 | | supply | # +------------------+-+ +--------+ #######| powered device 2 | # +------------------+-+ #######| powered device 3 | +------------------+ Figure 3: Multiple Powered Devices Supplied by Single Power Line With this list, the single status value has a clear meaning and is the sum of all powered devices. Control functions are limited by the fact that supply for the concerned devices can only be switched on or off for all of them at once. Individual control at the supply is not possible. If the full list of devices powered by a single supply line is not known by the controlling power supply device, then control of power supply is problematic, because the complete consequences of a control action cannot be known. 3.1.3 Multiple Power Supply for a Single Powered Device The third problem arises from the fact that there are devices with multiple power supplies. Some have this for redundancy of power supply, some for redundancy of internal power converters (for example, from AC mains power to DC internal power), and some because the capacity of a single supply line is insufficient. +----------------------------------------------+ | energy management system | +----------------------------------------------+ ^ ^ ^ ^ ^ ^ mon. | | ctrl. mon. | | ctrl. mon. | | ctrl. v v v v v v +----------+ +----------+ +----------+ | power |######| powered |######| power | | supply 1 |######| device | | supply 2 | +----------+ +----------+ +----------+ Expires August, 2013 [Page 18] Internet-Draft February 2013 Figure 4: Multiple Power Supply for Single Powered Device The example in Figure 4 does not necessarily show a real world scenario, but it shows the two cases to consider: o Multiple power supply lines between a single power supply device and a powered device o Different power supply devices supplying a single powered device In any such case, there may be a need to identify the supplying power supply device individually for each power inlet of a powered device. Without this information, monitoring and control of power supply for the powered device may be limited. 3.1.4 Bidirectional Power Interfaces Some power technologies (mostly low power DC) allow power to be delivered bi-directionally. For example, energy stored in batteries on one device can be delivered back to a power hub, which redirects the power to another device. In this situation, the interface can function as both an inlet and outlet at different times. A Power Interface can model a power inlet or a power outlet, depending on the conditions. Information of interest for Power Interfaces includes the power direction, as well as the energy received, provided, and the net result. 3.1.5 Relevance of Power Supply Concerns In some scenarios, the problems with power supply do not exist or can be solved sufficiently. With Power over Ethernet (PoE) [IEEE-802.3at], there is always a one-to-one relationship between a Power Sourcing Equipment (PSE) and a Powered Device (PD). Also, the Ethernet link on the line used for powering can be used to identify the PD and in many cases also the PSE. For supply of AC mains power, the three problems described above cannot be solved in general. There is no commonly available protocol or automatic mechanism for identifying endpoints of a power line. Expires August, 2013 [Page 19] Internet-Draft February 2013 In addition, AC power lines support supplying multiple powered devices with a single line, and are commonly used in this fashion. 3.1.6 Remote Power Supply Control There are three ways for an energy management system to change the Power State of powered devices. First is for the EnMS to provide policy or other useful information (like the electricity price) to the powered device for it to use in determining its Power State. The second is sending the powered device a command to switch to another Power State. The third is to use an upstream (to the powered device) device that can switch on and off power at its outlet. Some devices cannot receive commands or change their Power State by themselves. Such Energy Objects may be controlled by switching on and off their power supply, and so have a particular need for the third method. In Figure 4, the power supply can switch power at its power outlet and thereby switch on and off power for the connected powered device. 3.2. Concern #2: Power and Energy Measurement Some devices include hardware to directly measure their Power and Energy consumption. However, most common networked devices do not provide an interface that gives access to Energy and Power measurements. Hardware instrumentation for this kind of measurement is typically not in place and adding it incurs an additional cost. With the increasing cost of Energy and the growing importance of Energy Monitoring, it is likely that more devices in future will include instrumentation for power and energy measurements. It is also likely that it will take a long time for this to become commonplace. 3.2.1 Local Estimates One solution to this problem is for the powered device to estimate its own Power and consumed Energy. For many Energy Management tasks, getting an estimate is much better than not Expires August, 2013 [Page 20] Internet-Draft February 2013 getting any information at all. Estimates can be based on actual measured activity level of a device or it can just depend on the power state (on, sleep, off, etc.). An advantage of estimates is that they can be realized locally and with much lower cost than hardware instrumentation. Local estimates can be dealt with in traditional ways. They don't need an extension of the basic scenarios above. However, the powered device needs an energy model of itself to make estimates. 3.2.2 Management System Estimates Another approach to the lack of instrumentation is estimation by the EnMS. The EnMS can estimate Power based on basic information on the powered device, such as the type of device, or its brand/model and functional characteristics. Energy estimates can combine the typical power level by Power State with reported data about the Power State. If the EnMS has a detailed energy model of the device, it can produce better estimates, including the actual power state and actual activity level of the device. This information can be obtained by monitoring the device with conventional means of performance monitoring. 3.3. Concern #3: Reporting Sleep and Off States Low-power states pose special challenges for energy reporting because they may preclude a device from listening to and responding to network requests. Devices may still be able to reliably track energy use in these states, as power levels are usually static and internal clocks can track elapsed time in these states. Some devices have out-of-band or proxy abilities to respond to network requests in low-power states. Others could use proxy abilities in an energy management protocol to improve this reporting, particularly if the powered device sends out notifications of power state changes. Expires August, 2013 [Page 21] Internet-Draft February 2013 3.4. Concern #4: Devices and Components While the typical focus of energy management is entire powered devices, sometimes it is desirable to manage individual components of devices, such as line cards, fans, disks, etc. This framework uses a much simpler model for components than for entire devices. The concept of Power Interfaces is not used between a device and its contained components. Reporting of energy-related quantities for individual components is limited to the most important ones. Simplifications for components in this framework include o identifying components like devices but without distinct context information, o reporting a containment relationship to the containing device, o inheriting all context information from the containing device, o not modeling power interfaces and power lines between a component and its containing device or other components, and o only reporting real power and energy values for components. Power state monitoring and control are not simplified. These have the same functionality for devices and components. In rare cases where there is a need to model components of a device in more detail, components of a device can be modeled as individual devices. Then all considerations for devices also apply to these components. This model has a higher overhead and should be used only when needed. If used, it is not necessarily visible whether a set of components belongs to a single device or not, but for energy management purposes this might not be of high relevance. 3.5. Concern #5: Non-Electrical Equipment The primary focus of this framework is the management of Electrical Equipment. Some Non-Electrical Equipment may be connected to communication networks and could have their energy managed if normalized to the electrical units for power and energy. Some examples of Non-Electrical Equipment that may be connected to a communication network are: Expires August, 2013 [Page 22] Internet-Draft February 2013 1) A controller for compressed air. The controller is electrical only for its network connection. The controller is fueled by natural gas and produces compressed air. The energy transferred via compressed air is distributed to devices on a factory floor via a Power Interface which consists of tools (drills, screwdrivers, assembly line conveyor belts). The energy measured is non-electrical (compressed air). 2) A controller for steam. The controller is electrical for its network attachment but it burns tallow and produces steam to subtended boilers. The energy is non-electrical (steam). 3) A controller or regulator for gas. The controller is electrical for its network attachment but it has physical non-electrical components for control. The energy is non- electrical (BTU). 3.6. Concern #6: Energy Procurement While an EnMS may be a central point for corporate reporting, cost, environmental impact, and regulatory compliance, Energy Management in this framework excludes Energy procurement and the environmental impact of energy use. As such the framework does not include: - Cost in currency or environmental units of manufacturing an Energy Object - Embedded carbon or environmental equivalences of an Energy Object - Cost in currency or environmental impact to dismantle or recycle an Energy Object - Supply chain analysis of energy sources for Energy Object deployment - Conversion of the usage or production of energy to units expressed from the source of that energy (such as the greenhouse gas emissions associated with 1000kW from a diesel source) Expires August, 2013 [Page 23] Internet-Draft February 2013 4. Energy Management Abstraction Network management is often divided into the five main areas defined in the ISO Telecommunications Management Network model: Fault, Configuration, Accounting, Performance, and Security Management (FCAPS) [X.700]. This traditional management model does not cover Energy Management. This section describes a conceptual model of information that can be used for Energy Management. The classes and categories of attributes in the model are described with rationale for each. A UML description of the model can be found in Section 5. 4.1 Conceptual Model To address Energy Management this specification describes an information model that can exist along with Network Management while addressing issues specific to Energy Management (Section 3). An information model for Energy Management will need to describe a means to report information, provide control, and model the interconnections among physical entities. Therefore, this section proposes a similar conceptual model for physical entities to that used in Network Management: devices, components, and interfaces. This section then defines the additional attributes specific to Energy Management for those entities that are not available in existing Network Management models. For modeling the physical entities this section describes three classes: a Device, a Component, and a Power Interface. These classes are sub-types of an abstract Energy Object class. For modeling the additional attributes, this section describes attributes of an Energy Object for: identification, classification, context, control, power and energy. Since the interconnections between physical entities for Energy Management may have no relation to the interconnections for Network Management the Energy Object classes contain a separate Relationships class as an attribute to model these types of interconnections. Expires August, 2013 [Page 24] Internet-Draft February 2013 The remainder of this section describes the conceptual model of the classes and categories of attributes in the information model. The exact definitions of the classes and attributes are specified using UML in Section 5. 4.2 Energy Object An Energy Object is an abstract class that contains the base attributes for Energy Management. There are three types of Energy Objects: Device, Component and Power Interface. 4.2.1 Device Class The Device Class is a sub-class of Energy Object that represents a physical piece of equipment. A Device Class instance may represent a device that is a consumer, producer, or meter of energy. A Device Class instance may represent a physical device that contains other components. 4.2.2 Component Class The Component Class is a sub-class of Energy Object that represents a part of a physical piece of equipment. 4.2.3 Power Interface Class The power interface class is a sub-class of Energy Object that represents the interconnection among devices and components. There are some similarities between Power Interfaces and network interfaces. A network interface can be set to different states, such as sending or receiving data on an attached line. Similarly, a Power Interface can be receiving or providing power. Physically, a Power Interface instance can represent an AC power socket, an AC power cord attached to a device, or an 8P8C (RJ45) PoE socket, etc. 4.3 Energy Object Attributes This section describes categories of attributes for an Energy Object. Section 5 contains the specific UML definitions of the modeled attribute. Expires August, 2013 [Page 25] Internet-Draft February 2013 4.3.1 Identification A Universal Unique Identifier (UUID) [RFC4122] is used to uniquely and persistently identify an Energy Object. Ideally the UUID is used to distinguish the Energy Object within the EnMS. Every Energy Object has an optional unique printable name. Possible naming conventions are: textual DNS name, MAC address of the device, interface ifName, or a text string uniquely identifying the Energy Object. As an example, in the case of IP phones, the Energy Object name can be the device's DNS name. Additionally an alternate key is provided to allow an Energy Object to be optionally linked with models in different systems. 4.3.2 Context in General In order to aid in reporting and in differentiation between Energy Objects, each Energy Object optionally contains information establishing its business, site, or organizational context within a deployment 4.3.3 Context: Importance An Energy Object can provide an importance value in the range of 1 to 100 to help rank a device's use or relative value to the site. The importance range is from 1 (least important) to 100 (most important). The default importance value is 1. For example: A typical office environment has several types of phones, which can be rated according to their business impact. A public desk phone has a lower importance (for example, 10) than a business-critical emergency phone (for example, 100). As another example: A company can consider that a PC and a phone for a customer-service engineer are more important than a PC and a phone for lobby use. Although EnMS and administrators can establish their own ranking, the following example is a broad recommendation for commercial deployments [CISCO-EW]: . 90 to 100 Emergency response . 80 to 90 Executive or business-critical Expires August, 2013 [Page 26] Internet-Draft February 2013 . 70 to 79 General or Average . 60 to 69 Staff or support . 40 to 59 Public or guest . 1 to 39 Decorative or hospitality 4.3.4 Context: Keywords An Energy Object can provide a set of keywords. These keywords are a list of tags that can be used for grouping, summary reporting within or between Energy Management Domains, and for searching. All alphanumeric characters and symbols (other than a comma), such as #, (, $, !, and &, are allowed. Potential examples are: IT, lobby, HumanResources, Accounting, StoreRoom, CustomerSpace, router, phone, floor2, or SoftwareLab. There is no default value for a keyword. Multiple keywords can be assigned to a device. White spaces before and after the commas are excluded, as well as within a keyword itself. In such cases, commas separate the keywords and no spaces between keywords are allowed. For example, "HR,Bldg1,Private". 4.3.5 Context: Role An Energy Object contains a "role description" string that indicates the purpose the Energy Object serves in the EnMS. This could be a string describing the context the device fulfills in deployment. Administrators can define any naming scheme for the role of a device. As guidance, a two-word role that combines the service the device provides along with type can be used [IPENERGY]. Example types of devices: Router, Switch, Light, Phone, WorkStation, Server, Display, Kiosk, HVAC. Example Services by Line of Business: Line of Business Service Expires August, 2013 [Page 27] Internet-Draft February 2013 Education Student, Faculty, Administration, Athletic Finance Trader, Teller, Fulfillment Manufacturing Assembly, Control, Shipping Retail Advertising, Cashier Support Helpdesk, Management Medical Patient, Administration, Billing Role as a two-word string: "Faculty Desktop", "Teller Phone", "Shipping HVAC", "Advertising Display", "Helpdesk Kiosk", "Administration Switch". 4.3.6 Context: Domain An Energy Object contains a string to indicate membership in an Energy Management Domain. An Energy Management Domain can be any collection of devices in a deployment, but it is recommended to map 1:1 with a metered or sub-metered portion of the site. In building management, a meter refers to the meter provided by the utility used for billing and measuring power to an entire building or unit within a building. A sub-meter refers to a customer- or user-installed meter that is not used by the utility to bill but is instead used to get readings from sub portions of a building. A meter is a type Energy Object and any Energy Object can perform metering. An Energy Object should be a member of a single Energy Management Domain therefore one field is provided. The Energy Management Domain may be configured on an Energy Object. 4.4 Measurements An Energy Object contains attributes to describe power, energy and demand measurements. Expires August, 2013 [Page 28] Internet-Draft February 2013 For the purposes of this framework, energy will be limited to electrical energy in watt-hours. Other forms of Energy Objects that use or produce non-electrical energy may be modeled as an Energy Object but must provide information converted to and expressed in watt-hours. An analogy for understanding power versus energy measurements can be made to speed and distance in automobiles. Just as a speedometer indicates the rate of change of distance (speed), a power meter indicates the rate of transfer of energy. The odometer in an automobile measures the cumulative distance traveled and an energy meter indicates the accumulated energy transferred. Demand measurements are averages of power measurements over time. So using the same analogy to an automobile: measuring the average vehicle speed over multiple intervals of time for a given distance travelled, demand is the average device power over multiple time intervals for a given energy value. 4.4.1 Measurements: Power Each Energy Object contains a Nameplate Power attribute that describes the nominal power as specified by the manufacturer. Power Measurement. The EnMS can use the Nameplate Power for provisioning, capacity planning and (potentially) billing. Each Energy Object will have information that describes present power information, along with how that measurement was obtained or derived (e.g., measured, estimated, or presumed). A power measurement is be qualified with the units, magnitude and direction of power flow, and is be qualified as to the means by which the measurement was made (e.g., Root Mean Square versus Nameplate). In addition, the Energy Object describes how it intends to measure power. This intention can be described as one of the following: consumer, producer, meter or distributir of power. Given the intent, the EnMS can summarize or analyze the measurement. For example, metered usage reported by a meter and consumption usage reported by a device connected to that meter will naturally measure the same usage. With the two measurements identified by intent, the EnMS can make a proper summarization. Expires August, 2013 [Page 29] Internet-Draft February 2013 Power measurement magnitude conforms to the IEC 61850 definition of unit multiplier for the SI (System International) units of measure. Measured values are represented in SI units obtained by BaseValue * (10 ^ Scale). For example, if current power usage of an Energy Object is 3, it could be 3 W, 3 mW, 3 KW, or 3 MW, depending on the value of the scaling factor. 3W implies that the BaseValue is 3 and Scale = 0, whereas 3mW implies BaseValue = 3 and ScaleFactor = -3. In addition to knowing the power and magnitude an Energy Object indicates how the measurement was obtained: - Whether the measurements were made at the device itself or at a remote source. - Description of the method that was used to measure the power and whether this method can distinguish actual or estimated values. An EnMS can use this information to account for the accuracy and nature of the reading between different implementations. 4.4.2 Measurements: Power Attributes Optionally, an Energy Object describes the Power measurements with Power Attribute information reflecting the electrical characteristics of the measurement. These Power Attributes adhere to the IEC 61850 7-2 standard for describing AC measurements. 4.4.3 Measurements: Energy Optionally, an Energy Object that can report actual power readings will have energy attributes that provide the energy used, produced, and net energy in kWh. These values are energy measurements that accumulate the power readings. If energy values are returned, then the three measurements are provided along with a description of accuracy. 4.4.4 Measurements: Demand Optionally, an Energy Object will provide demand information over time. Demand measurements can be provided when the Energy Object is capable of measuring actual power Expires August, 2013 [Page 30] Internet-Draft February 2013 4.5 Control An Energy Object can be controlled by setting it to a specific Power State. An Energy Object implements at least one set of Power States consisting of at least two states, an on state and an off state. Each Energy Object should indicate the sets of Power States that it implements. Well known Power States / Sets are registered with IANA. When a device is set to a particular Power State, it may be busy. The device will set the desired Power State and then update the actual Power State when it changes. There are then two Power State control variables: actual and requested. There are many existing standards for and implementations of Power States. An Energy Object can support a mixed set of Power States defined in different standards. A basic example is given by the three Power States defined in IEEE1621 [IEEE1621]: on, off, and sleep. The DMTF [DMTF], ACPI [ACPI], and PWG define larger numbers of Power States. The semantics of a power state are specified by a) the functionality provided by an Energy Object in this state, b) a limitation of the power that an Energy Object uses in this state, c) a combination of a) and b) The semantics of a Power State should be clearly defined. Limitation (curtailment) of the power used by an Energy Object in a state is be specified by - an absolute power value - a percentage value of power relative to the energy object's nameplate power - an indication of used power relative to another power state. For example: Specify that used power in state A is less than in state B. For supporting Power State management an Energy Object provides statistics on Power States including the time an Expires August, 2013 [Page 31] Internet-Draft February 2013 Energy Object spent in a certain Power State and the number of times an Energy Object entered a power state. When requesting an Energy Object to enter a Power State an indication of the Power State's name or number can be used. Optionally an absolute or percentage of Nameplate Power can be provided to allow the Energy Object to transition to a nearest or equivalent Power State. 4.5.1 Power State Sets There are several standards and implementations of Power State Sets. An Energy Object can support one or multiple Power State Set implementation(s) concurrently. There are currently three Power State Sets advocated: IEEE1621(256) - [IEEE1621] DMTF(512) - [DMTF] EMAN(768) - [EMAN-MONITORING-MIB] The respective specific states related to each Power State Set are specified in the following sections. The guidelines for addition of new Power State Sets are specified in the IANA Considerations Section. 4.5.2 IEEE1621 Power State Set The IEEE1621 Power State Set [IEEE1621] consists of 3 rudimentary states: on, off or sleep. on(0) - The device is fully On and all features of the device are in working mode. off(1) - The device is mechanically switched off and does not consume energy. sleep(2) - The device is in a power saving mode, and some features may not be available immediately. Expires August, 2013 [Page 32] Internet-Draft February 2013 4.5.3 DMTF Power State Set DMTF [DMTF] standards organization has defined a power profile standard based on the CIM (Common Information Model) model that consists of 15 power states ON (2), SleepLight (3), SleepDeep (4), Off-Hard (5), Off-Soft (6), Hibernate(7), PowerCycle Off-Soft (8), PowerCycle Off-Hard (9), MasterBus reset (10), Diagnostic Interrupt (11), Off-Soft-Graceful (12), Off-Hard Graceful (13), MasterBus reset Graceful (14), Power- Cycle Off-Soft Graceful (15), PowerCycle-Hard Graceful (16). DMTF standard is targeted for hosts and computers. Details of the semantics of each Power State within the DMTF Power State Set can be obtained from the DMTF Power State Management Profile specification [DMTF]. DMTF power profile extends ACPI power states. The following table provides a mapping between DMTF and ACPI Power State Set: --------------------------------------------------- | DMTF | ACPI | | Power State | Power State | --------------------------------------------------- | Reserved(0) | | --------------------------------------------------- | Reserved(1) | | --------------------------------------------------- | ON (2) | G0-S0 | -------------------------------------------------- | Sleep-Light (3) | G1-S1 G1-S2 | -------------------------------------------------- | Sleep-Deep (4) | G1-S3 | -------------------------------------------------- Expires August, 2013 [Page 33] Internet-Draft February 2013 | Power Cycle (Off-Soft) (5) | G2-S5 | --------------------------------------------------- | Off-hard (6) | G3 | --------------------------------------------------- | Hibernate (Off-Soft) (7) | G1-S4 | --------------------------------------------------- | Off-Soft (8) | G2-S5 | --------------------------------------------------- | Power Cycle (Off-Hard) (9) | G3 | --------------------------------------------------- | Master Bus Reset (10) | G2-S5 | --------------------------------------------------- | Diagnostic Interrupt (11) | G2-S5 | --------------------------------------------------- | Off-Soft Graceful (12) | G2-S5 | --------------------------------------------------- | Off-Hard Graceful (13) | G3 | --------------------------------------------------- | MasterBus Reset Graceful (14) | G2-S5 | --------------------------------------------------- | Power Cycle off-soft Graceful (15)| G2-S5 | --------------------------------------------------- | Power Cycle off-hard Graceful (16)| G3 | --------------------------------------------------- Expires August, 2013 [Page 34] Internet-Draft February 2013 Figure 5: DMTF and ACPI Powe State Set Mapping 4.5.4 EMAN Power State Set An EMAN Power State Set represents an attempt at a standard approach for modeling the different levels of power of a device. The EMAN Power States are an expansion of the basic Power States as defined in [IEEE1621] that also incorporates the Power States defined in [ACPI] and [DMTF]. Therefore, in addition to the non-operational states as defined in [ACPI] and [DMTF] standards, several intermediate operational states have been defined. An Energy Object may implement fewer or more Power States than a particular EMAN Power State Set specifies. In this case, the Energy Object implementation can determine its own mapping to the predefined EMAN Power States within the EMAN Power State Set. There are twelve EMAN Power States that expand on [IEEE1621]. The expanded list of Power States is derived from [CISCO-EW] and is divided into six operational states and six non- operational states. The lowest non-operational state is 1 and the highest is 6. Each non-operational state corresponds to an [ACPI] Global and System state between G3 (hard-off) and G1 (sleeping). Each operational state represents a performance state, and may be mapped to [ACPI] states P0 (maximum performance power) through P5 (minimum performance and minimum power). In each of the non-operational states (from mechoff(1) to ready(6)), the Power State preceding it is expected to have a lower Power value and a longer delay in returning to an operational state: mechoff(1) : An off state where no Energy Object features are available. The Energy Object is unavailable. No energy is being consumed and the power connector can be removed. softoff(2) : Similar to mechoff(1), but some components remain powered or receive trace power so that the Energy Object can be awakened from its off state. In softoff(2), no context is saved and the device typically requires a complete boot when awakened. Expires August, 2013 [Page 35] Internet-Draft February 2013 hibernate(3): No Energy Object features are available. The Energy Object may be awakened without requiring a complete boot, but the time for availability is longer than sleep(4). An example for state hibernate(3) is a save to-disk state where DRAM context is not maintained. Typically, energy consumption is zero or close to zero. sleep(4) : No Energy Object features are available, except for out-of-band management, such as wake-up mechanisms. The time for availability is longer than standby(5). An example for state sleep(4) is a save-to-RAM state, where DRAM context is maintained. Typically, energy consumption is close to zero. standby(5) : No Energy Object features are available, except for out-of-band management, such as wake-up mechanisms. This mode is analogous to cold-standby. The time for availability is longer than ready(6). For example processor context is may not be maintained. Typically, energy consumption is close to zero. ready(6) : No Energy Object features are available, except for out-of-band management, such as wake-up mechanisms. This mode is analogous to hot-standby. The Energy Object can be quickly transitioned into an operational state. For example, processors are not executing, but processor context is maintained. lowMinus(7) : Indicates some Energy Object features may not be available and the Energy Object has taken measures or selected options to provide less than low(8) usage. low(8) : Indicates some features may not be available and the Energy Object has taken measures or selected options to provide less than mediumMinus(9) usage. mediumMinus(9): Indicates all Energy Object features are available but the Energy Object has taken measures or selected options to provide less than medium(10) usage. medium(10) : Indicates all Energy Object features are available but the Energy Object has taken measures or selected options to provide less than highMinus(11) usage. highMinus(11): Indicates all Energy Object features are available and power usage is less than high(12). Expires August, 2013 [Page 36] Internet-Draft February 2013 high(12) : Indicates all Energy Object features are available and the Energy Object is consuming the highest power. 4.6 Power State Sets Comparison A comparison of Power States from different Power State Sets can be seen in the following table: IEEE1621 DMTF ACPI EMAN Non-operational states off Off-Hard G3, S5 MechOff(1) off Off-Soft G2, S5 SoftOff(2) sleep Hibernate G1, S4 Hibernate(3) sleep Sleep-Deep G1, S3 Sleep(4) sleep Sleep-Light G1, S2 Standby(5) sleep Sleep-Light G1, S1 Ready(6) Operational states: on on G0, S0, P5 LowMinus(7) on on G0, S0, P4 Low(8) on on G0, S0, P3 MediumMinus(9) on on G0, S0, P2 Medium(10) on on G0, S0, P1 HighMinus(11) on on G0, S0, P0 High(12) Figure 6: Comparison of Power States Expires August, 2013 [Page 37] Internet-Draft February 2013 4.7 Relationships Two Energy Objects can establish an Energy Object Relationship. Relationships are modeled with a Relationship class that contains the UUID of the participants in the relationship and a description of the type of relationship. The types of relationships are: power source. metering, and aggregations. The Power Source Relationship gives a view of the wiring topology. For example: a data center server receiving power from two specific Power Interfaces from two different PDUs. Note: A power source relationship may or may not change as the direction of power changes between two Energy Objects. The relationship may remain to indicate the change of power direction was unintended or an error condition. The Metering Relationship gives the view of the metering topology. Standalone meters can be placed anywhere in a power distribution tree. For example, utility meters monitor and report accumulated power consumption of the entire building. Logically, the metering topology overlaps with the wiring topology, as meters are connected to the wiring topology. A typical example is meters that clamp onto the existing wiring. The Aggregation Relationship gives a model of devices that may aggregate (sum, average, etc) values for other devices. The Aggregation Relationship is slightly different compared to the other relationships as this refers more to a management function. In some situations, it is not possible to discover the Energy Object Relationships, and they must be set by an EnMS or administrator. Given that relationships can be assigned manually, the following sections describes guidelines for use. 4.8 Energy Object Relationship Conventions and Guidelines This Energy Management framework does not impose many "MUST" rules related to Energy Object Relationships. There are always corner cases that could be excluded with too strict specifications of relationships. However, this Energy Management framework proposes a series of guidelines, indicated with "SHOULD" and "MAY". Expires August, 2013 [Page 38] Internet-Draft February 2013 4.8.1 Guidelines: Power Source Power Source relationships are intended to identify the connections between Power Interfaces. This is analogous to a Layer 2 connection in networking devices (a "one-hop connection"). The preferred modeling would be for Power Interfaces to participate in Power Source Relationships. It may happen that some Energy Objects may not have the capability to model Power Interfaces. Therefore, it may happen that a Power Source Relationship is established between two Energy Objects or two non-connected Power Interfaces. While strictly speaking Components and Power Interfaces on the same device do provide or receive energy from each other, the Power Source relationship is intended to show energy transfer between Devices. Therefore the relationship is implied on the same Device. - An Energy Object SHOULD NOT establish a Power Source Relationship with a Component. - A Power Source Relationship SHOULD be established with next known Power Interface in the wiring topology. o The next known Power Interface in the wiring topology would be the next device implementing the framework. In some cases the domain of devices under management may include some devices that do not implement the framework. In these cases, the Power Source relationship can be established with the next device in the topology that implements the framework and logically shows the Power Source of the device. - Transitive Power Source relationships SHOULD NOT be established. For example, if an Energy Object A has a Power Source Relationship "Poweredby" with the Energy Object B, and if the Energy Object B has a Power Source Relationship "Poweredby" with the Energy Object C, then the Energy Object A SHOULD NOT have a Power Source Relationship "Poweredby" with the Energy Object C. 4.8.2 Guidelines: Metering Relationship Expires August, 2013 [Page 39] Internet-Draft February 2013 Metering Relationships are intended to show when one Device is measuring the power or energy at a point in a power distribution system. Since one point of a power distribution system may cover many Devices with a complex wiring topology, this relationship type can be seen as an arbitrary set. Devices may include metering hardware for components and Power Interfaces or for the entire Device. For example, some PDUs may have the ability to measure Power for each Power Interface (metered by outlet). Others may be able to control power at each Power Interface but can only measure Power at the Power Inlet and a total for all Power Interfaces (metered by device). In such cases a Device SHOULD be modeled as an Energy Object that meters all of its Power Outlets and each Power Outlet MAY be metered by the Energy Object representing the Device. - A Metering Relationship MAY be established with any other Energy Object, Component, or Power Interface. - Transitive Metering relationships MAY be used. - When there is a series of meters for one Energy Object, the Energy Object MAY establish a Metering relationship with one or more of the meters. 4.8.3 Guidelines: Aggregation Aggregation relationships are intended to identify when one device is used to accumulate values from other devices. Typically this is for energy or power values among devices and not for Components or Power Interfaces on the same device. The intent of Aggregation relationships is to indicate when one device is providing aggregate values for a set of other devices when it is not obvious from the power source or simple containment within a device. Establishing aggregation relationships within the same device would make modeling more complex and the aggregated values can be implied from the use of Power Inlets, outlet and Energy Object values on the same device. Since an EnMS is naturally a point of aggregation it is not necessary to model aggregation for Energy Management Systems. Expires August, 2013 [Page 40] Internet-Draft February 2013 Aggregation SHOULD be used for power and energy. It MAY be used for aggregation of other values from the information model, but the rules and logical ability to aggregate each attribute is out of scope for this document. - A Device SHOULD NOT establish an Aggregation Relationship with a Component. - A Device SHOULD NOT establish an Aggregation Relationship with the Power Interfaces contained on the same device. - A Device SHOULD NOT establish an Aggregation Relationship with an EnMS. - Aggregators SHOULD log or provide notification in the case of errors or missing values while performing aggregation. 4.9 Energy Object Relationship Extensions This framework for Energy Management is based on three relationship types: Aggregation , Metering, and Power Source. This framework is defined with possible future extension of new Energy Object Relationships in mind. For example, a Power Distribution Unit (PDU) that allows physical entities like outlets to be "ganged" together as a logical entity for simplified management purposes, could be modeled with an extension called a "gang relationship", whose semantics would specify the Energy Objects' grouping. 5. Energy Management Information Model The following basic UML represents an information model expression of the concepts in this framework. This information model, provided as a reference for implementers, is represented as a MIB in the different related IETF Energy Monitoring documents. However, other programming structures with different data models could be used as well. Data modeling specifications of this information model may where needed specify which attributes are required or optional. The notation use here is 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 Expires August, 2013 [Page 41] Internet-Draft February 2013 variables and global to the class. Arrows indicate inheritance. Algorithms for class variable initialization, constructors, or destructors are not shown. Attributes and structures are considered readable and writeable unless prefixed by a dash (-) that indicates read-only. Expires August, 2013 [Page 42] Internet-Draft February 2013 EDITOR's NOTE: Pseudo-code used until consensus then UML diagram will be substituted class EnergyObject { // identification / classification index : int identifier : uuid alternatekey : string // context domainName : string role : string keywords [0..n] : string importance : int // relationship relationships [0..n] : Relationship // measurements nameplate : Nameplate power : PowerMeasurement energy : EnergyMeasurment demand : DemandMeasurement // control powerControl [0..n] : PowerStateSet } class Device extends EnergyObject { eocategory : enum { producer, consumer, meter, distributor } } class Component extends EnergyObject eocategory : enum { producer, consumer, meter, distributor } } classInterface extends EnergyObject{ eoIfType : enum ( inlet, outlet, both} } Expires August, 2013 [Page 43] Internet-Draft February 2013 class Nameplate { nominalPower : PowerMeasurement details : URI } class Relationship { relationshipType : enum { meters, meteredby, powers, poweredby, aggregates, aggregatedby } relationshipObject : uuid } class Measurement { multiplier: enum { -24..24} caliber : enum { actual, estimated, trusted, assumed } accuracy : enum { 0..10000} // hundreds of percent } class PowerMeasurement extends Measurement { value : long units : "W" powerAttribute : PowerAttribute } class EnergyMeasurement extends Measurement { startTime : time units : "kWh" provided : long used : long produced : long } class TimedMeasurement extends Measurement { startTime : timestamp value : Measurement maximum : Measurement } class TimeInterval { value : long units : enum { seconds, miliseconds,...} } Expires August, 2013 [Page 44] Internet-Draft February 2013 class DemandMeasurement extends Measurement { intervalLength : TimeInterval interval : long intervalMode : enum { periodic, sliding, total } intervalWindow : TimeInterval sampleRate : TimeInterval status : enum { active, inactive } measurements[0..n] : TimedMeasurements } class PowerStateSet { powerSetIdentifier : int name : string powerStates [0..n] : PowerState operState : int adminState : int reason : string configuredTime : timestamp } class PowerState { powerStateIdentifier : int name : string cardinality : int maximumPower : PowerMeasurement totalTimeInState : time entryCount : long } class PowerAttribute { // container for attributes acQuality : ACQuality } class ACQuality { acConfiguration : enum {SNGL, DEL,WYE} avgVoltage : long avgCurrent : long frequency : long unitMultiplier : int accuracy : int totalActivePower : long Expires August, 2013 [Page 45] Internet-Draft February 2013 totalReactivePower : long totalApparentPower : long totalPowerFactor : long phases [0..2] : ACPhase // Could have abstract class Phase to be clear it's ACPhase or one of the subclasses } class ACPhase { phaseIndex : long avgCurrent : long activePower : long reactivePower : long apparentPower : long powerFactor : long } class DelPhase extends ACPhase { phaseToNextPhaseVoltage : long thdVoltage : long thdCurrent : long } class WYEPhase extends ACPhase { phaseToNeutralVoltage : long thdCurrent : long thdVoltage : long } Figure 7: Information Model UML Representation 6. Example Topologies In this section we give examples of how to use the Energy Management framework relationships to model topologies. In each example we show how it can be applied when Devices have the capability to model Power Interfaces. We also show in each example how the framework can be applied when devices cannot support Power Interfaces but only monitor information or control the Device as a whole. For instance, a PDU may only Expires August, 2013 [Page 46] Internet-Draft February 2013 be able to measure power and energy for the entire unit without the ability to distinguish among the inlets or outlet. Together, these examples show how the framework can be adapted for Devices with different capabilities (typically hardware) for Energy Management. Given for all Examples: Device W: A computer with one power supply. Power interface 1 is an inlet for Device W. Device X: A computer with two power supplies. Power interface 1 and power interface 2 are both inlets for Device X. Device Y: A PDU with multiple Power Interfaces numbered 0..10. Power interface 0 is an inlet and power interface 1..10 are outlets. Device Z: A PDU with multiple Power Interfaces numbered 0..10. Power interface 0 is an inlet and power interface 1..10 are outlets. 6.1 Example I: Simple Device with one Source Topology: Device W inlet 1 is plugged into Device Y outlet 8. With Power Interfaces: Device W has an Energy Object representing the computer itself as well as one Power Interface defined as an inlet. Device Y would have an Energy Object representing the PDU itself (the Device), with a Power Interface 0 defined as an inlet and Power Interfaces 1..10 defined as outlets. The interfaces of the devices would have a Power Source Relationship such that: Device W inlet 1 is powered by Device Y outlet 8. Without Power Interfaces: Device W has an Energy Object representing the computer. Device Y would have an Energy Object representing the PDU. Expires August, 2013 [Page 47] Internet-Draft February 2013 The devices would have a Power Source Relationship such that: Device W is powered by Device Y. 6.2 Example II: Multiple Inlets Topology: Device X inlet 1 is plugged into Device Y outlet 8. Device X inlet 2 is plugged into Device Y outlet 9. With Power Interfaces: Device X has an Energy Object representing the computer itself. It contains two Power Interfaces defined as inlets. Device Y would have an Energy Object representing the PDU itself (the Device), with a Power Interface 0 defined as an inlet and Power Interfaces 1..10 defined as outlets. The interfaces of the devices would have a Power Source Relationship such that: Device X inlet 1 is powered by Device Y outlet 8. Device X inlet 2 is powered by Device Y outlet 9. Without Power Interfaces: Device X has an Energy Object representing the computer. Device Y has an Energy Object representing the PDU. The devices would have a Power Source Relationship such that: Device X is powered by Device Y. 6.3 Example III: Multiple Sources Topology: Device X inlet 1 is plugged into Device Y outlet 8. Device X inlet 2 is plugged into Device Z outlet 9. With Power Interfaces: Device X has an Energy Object representing the computer itself. It contains two Power Interface defined as inlets. Expires August, 2013 [Page 48] Internet-Draft February 2013 Device Y would have an Energy Object representing the PDU itself (the Device), with a Power Interface 0 defined as an inlet and Power Interfaces 1..10 defined as outlets. Device Z would have an Energy Object representing the PDU itself (the Device), with a Power Interface 0 defined as an inlet and Power Interfaces 1..10 defined as outlets. The interfaces of the devices would have a Power Source Relationship such that: Device X inlet 1 is powered by Device Y outlet 8. Device X inlet 2 is powered by Device Z outlet 9. Without Power Interfaces: Device X has an Energy Object representing the computer. Device Y and Z would both have respective Energy Objects representing each entire PDU. The devices would have a Power Source Relationship such that: Device X is powered by Device Y and powered by Device Z. 6.4 Relationships Between Devices 6.4.1 Power Source Topology As described in Section 4, the power source(s) of a device is important for energy management. The Energy Management reference model addresses this by a Power Source Relationship. This is a relationship among devices providing energy and devices receiving energy. A simple example is a PoE PSE, such as an Ethernet switch providing power to a PoE PD, such as a desktop phone. Here the switch provides energy and the phone receives energy. This relationship can be seen in the figure below. +----------+ power source +---------+ | switch | <-------------- | phone | +----------+ +---------+ Figure 8: Simple Power Source Expires August, 2013 [Page 49] Internet-Draft February 2013 A single power provider can act as power source for multiple power receivers. An example is a power distribution unit (PDU) providing AC power for multiple switches. +-------+ power source +----------+ | PDU | <----------+--- | switch 1 | +-------+ | +----------+ | | +----------+ +--- | switch 2 | | +----------+ | | +----------+ +--- | switch 3 | +----------+ Figure 10: Multiple Power Source This level of modeling is sufficient if there is no need to distinguish in monitoring and control between the individual receivers at the switch. However, if there is a need to monitor or control power supply for individual receivers at the power provider, then a more detailed level of modeling is needed. Devices receive or provide energy at power interfaces connecting them to a transmission medium. The Power Source relationship can be used between power interfaces at the power provider side as well as at the power receiver side. Figure 9 shows a power-providing device with one power interface (PI) per connected receiving device. Expires August, 2013 [Page 50] Internet-Draft February 2013 +-------+------+ power source +----------+ | | PI 1 | <-------------- | switch 1 | | +------+ +----------+ | | | +------+ power source +----------+ | PDU | PI 2 | <-------------- | switch 2 | | +------+ +----------+ | | | +------+ power source +----------+ | | PI 3 | <-------------- | switch 3 | +-------+------+ +----------+ Figure 11: Power Source with Power interfaces When required for consistency, Power interfaces may also be modeled at the receiving device, as shown in Figure 10. +-------+------+ power source +----+----------+ | | PI 1 | <-------------- | PI | switch 1 | | +------+ +----+----------+ | | | +------+ power source +----+----------+ | PDU | PI 2 | <-------------- | PI | switch 2 | | +------+ +----+----------+ | | | +------+ power source +----+----------+ | | PI 3 | <-------------- | PI | switch 3 | +-------+------+ +----+----------+ Figure 12: Power Interfaces at Receiving Device Power Source relationships are between devices and their interfaces. They are not transitive. In the examples below there is a PDU powering a switch powering a phone. +-------+ power +--------+ power +---------+ | PDU | <-------- | switch | <-------- | phone | +-------+ source +--------+ source +---------+ Figure 13: Power Source Non-Transitive Power Source Relationships are between the PDU and the switch and between the switch and the phone. Transitively, there Expires August, 2013 [Page 51] Internet-Draft February 2013 exists a Power Source Relationship between the PDU and the phone. . +-------+ power +--------+ power +---------+ | PDU | <-------- | switch | <-------- | phone | +-------+ source +--------+ source +---------+ ^ | | power source | +------------------------------------------+ Figure 14: Power Source Transitive 6.4.2 Metering Topology Case 1: Metering between two devices The metering topology between two devices is closely related to the power source topology. It is based on the assumption that in many cases the power provided and the power received is the same for both peers of a power source relationship. Then power measured at one end can be taken as the actual power value at the other end. Obviously, the same applies to energy at both ends. We define in this case a Metering Relationship between two devices or power interfaces of devices that have a power source relationship. Power and energy values measured at one peer of the power source relationship are reported for the other peer as well. The Metering Relationship is independent of the direction of the Power Source Relationship. The more common case is that values measured at the power provider are reported for the power receiver, but also the reverse case is possible with values measured at the power receiver being reported for the power provider. Power Power +-----+----------+ Source +--------+ Source +-------+ | PDU |PI + meter| <-------- | switch | <------- | phone | +-----+----------+ Metering +--------+ +-------+ ^ | | | +-------------------------------------------+ metering Expires August, 2013 [Page 52] Internet-Draft February 2013 Figure 15: Direct and One Hop Metering Case 2: Metering at a point in power distribution A Sub-meter in a power distribution system can logically measure the power or energy for all devices downstream from the meter in the power distribution system. As such, a Power metering relationship can be seen as a relationship between a meter and all of the devices downstream from the meter. We define in this case a Power Source relationship between a metering device and devices downstream from the meter. In cases where the Power Source topology cannot be discovered or derived from the information available in the Energy Management Domain, the Metering Topology can be used to relate the upstream meter to the downstream devices in the absence of specific power source relationships. A Metering Relationship can occur between devices that are not directly connected, as shown in Figure 16. +---------------+ | Device 1 | +---------------+ | PI | +---------------+ | +---------------+ | Meter | +---------------+ . . . +----------+ +----------+ +-----------+ | Device A | | Device B | | Device C | +----------+ +----------+ +-----------+ Figure 16: Complex Metering Topology An analogy to communications networks would be modeling connections between servers (meters) and clients (devices) when the complete Layer 2 topology between the servers and clients is not known. Expires August, 2013 [Page 53] Internet-Draft February 2013 6.4.3 Aggregation Topology Some devices can act as aggregation points for other devices. For example, a PDU controller device may contain the summation of power and energy readings for many PDU devices. The PDU controller will have aggregate values for power and energy for a group of PDU devices. This aggregation is independent of the physical power or communication topology. An Aggregation Relationship is an Energy Object Relationship where one Energy Object (called the Aggregate Energy Object) aggregates the Energy Management information of one or more other Energy Objects. These Energy Objects are said to have an Aggregation Relationship. The functions that the aggregation point may perform include the calculation of values such as average, count, maximum, median, minimum, or the listing (collection) of the aggregation values, etc. Based on the experience gained on aggregations at the IETF [draft-ietf-ipfix-a9n-08], the aggregation function in the EMAN framework is limited to the summation. When aggregation occurs across a set of entities, values to be aggregated may be missing for some entities. The EMAN framework does not specify how these should be treated, as different implementations may have good reason to take different approaches. One common treatment is to define the aggregation as missing if any of the constituent elements are missing (useful to be most precise). Another is to treat the missing value as zero (useful to have continuous data streams). The specifications of aggregation functions are out of scope of the EMAN framework, but must be clearly specified by the equipment vendor. 7. Relationship with Other Standards This energy management framework uses, as much as possible, existing standards efforts, especially with respect to information modeling and data modeling [RFC3444]. Expires August, 2013 [Page 54] Internet-Draft February 2013 The data model for power- and energy-related objects is based on IEC 61850. Specific examples include: The scaling factor, which represents Energy Object usage magnitude, conforms to the IEC 61850 definition of unit multiplier for the SI (System International) units of measure. The electrical characteristic is based on the ANSI and IEC Standards, which require that we use an accuracy class for power measurement. ANSI and IEC define the following accuracy classes for power measurement: IEC 62053-22 60044-1 class 0.1, 0.2, 0.5, 1 3. ANSI C12.20 class 0.2, 0.5 The electrical characteristics and quality adhere 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. 8. 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. Security Considerations for SNMP Readable objects in 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. Expires August, 2013 [Page 55] Internet-Draft February 2013 The support for SET operations in a non-secure environment without proper protection can have a negative effect on network operations. For example: Unauthorized changes to the Energy Management Domain or business context of an Energy Object may result in misreporting or interruption of power. Unauthorized changes to a power state may disrupt the power settings of the different Energy Objects, and therefore the state of functionality of the respective Energy Objects. Unauthorized changes to the demand history may disrupt proper accounting of energy usage. 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. 9. IANA Considerations 9.1 IANA Registration of new Power State Set This document specifies an initial set of Power State Sets. The list of these Power State Sets with their numeric identifiers is given is Section 4. IANA maintains the lists of Power State Sets. Expires August, 2013 [Page 56] Internet-Draft February 2013 New assignments for Power State Set are administered by IANA through Expert Review [RFC5226], i.e., review by one of a group of experts designated by an IETF Area Director. The group of experts MUST check the requested state for completeness and accuracy of the description. A pure vendor specific implementation of Power State Set shall not be adopted; since it would lead to proliferation of Power State Sets. Power states in a Power State Set are limited to 255 distinct values. New Power State Set must be assigned the next available numeric identifier that is a multiple of 256. 9.1.1 IANA Registration of the IEEE1621 Power State Set This document specifies a set of values for the IEEE1621 Power State Set [IEEE1621]. The list of these values with their identifiers is given in Section 4.6.2. IANA created a new registry for IEEE1621 Power State Set identifiers and filled it with the initial list of identifiers. New assignments (or potentially deprecation) for the IEEE1621 Power State Set is administered by IANA through Expert Review [RFC5226], i.e., review by one of a group of experts designated by an IETF Area Director. The group of experts must check the requested state for completeness and accuracy of the description. 9.1.2 IANA Registration of the DMTF Power State Set This document specifies a set of values for the DMTF Power State Set. The list of these values with their identifiers is given in Section 4. IANA has created a new registry for DMTF Power State Set identifiers and filled it with the initial list of identifiers . New assignments (or potentially deprecation) for the DMTF Power State Set is administered by IANA through Expert Review [RFC5226], i.e., review by one of a group of experts designated by an IETF Area Director. The group of experts must check the conformance with the DMTF standard [DMTF], on the top of checking for completeness and accuracy of the description. Expires August, 2013 [Page 57] Internet-Draft February 2013 9.1.3 IANA Registration of the EMAN Power State Set This document specifies a set of values for the EMAN Power State Set. The list of these values with their identifiers is given in Section 4.6.4. IANA has created a new registry for EMAN Power State Set identifiers and filled it with the initial list of identifiers. New assignments (or potentially deprecation) for the EMAN Power State Set is administered by IANA through Expert Review [RFC5226], i.e., review by one of a group of experts designated by an IETF Area Director. The group of experts must check the requested state for completeness and accuracy of the description. 9.1.4 Batteries Power State Set Batteries have operational and administrational states that could be represented as a power state set. Since the work for battery management is parallel to this document, we are not proposing any Power State Sets for batteries at this time. 9.2 Updating the Registration of Existing Power State Sets With the evolution of standards, over time, it may be important to deprecate some of the existing the Power State Sets, or to add or deprecate some Power States within a Power State Set. The registrant shall publish an Internet-draft or an individual submission with the clear specification on deprecation of Power State Sets or Power States registered with IANA. The deprecation or addition shall be administered by IANA through Expert Review [RFC5226], i.e., review by one of a group of experts designated by an IETF Area Director. The process should also allow for a mechanism for cases where others have significant objections to claims on deprecation of a registration. Expires August, 2013 [Page 58] Internet-Draft February 2013 10. Acknowledgments The authors would like to Michael Brown for improving the text dramatically, and Rolf Winter for his feedback. The award for the best feedback and reviews goes to Bill Mielke. Bruce Nordman helped a lot in the framework brainstorming with numerous conference calls and discussions. Finally, the authors would like to thank the EMAN chairs: Nevil Brownlee, Bruce Nordman, and Tom Nadeau. 11. References Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997 [RFC3410] Case, J., Mundy, R., Partain, D., and B. Stewart, "Introduction and Applicability Statements for Internet Standard Management Framework ", RFC 3410, December 2002 [RFC4122] Leach, P., Mealling, M., and R. Salz," A Universally Unique IDentifier (UUID) URN Namespace", RFC 4122, July 2005 [RFC5226] Narten, T., and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", RFC 5226, May 2008 [RFC6933] Bierman, A. and K. McCloghrie, "Entity MIB (Version4)", RFC 6933, May 2013 Informative References [RFC2578] McCloghrie, K., Perkins, D., and J. Schoenwaelder, "Structure of Management Information Version 2 (SMIv2", RFC 2578, April 1999 [RFC3444] Pras, A., Schoenwaelder, J. "On the Differences between Information Models and Data Models", RFC 3444, January 2003 Expires August, 2013 [Page 59] Internet-Draft February 2013 [RFC5101bis] Claise, B., Ed., and Trammel, T., Ed., "Specification of the IP Flow Information Export (IPFIX) Protocol for the Exchange of IP Traffic Flow Information ", draft-ietf-ipfix-protocol-rfc5101bis- 08, (work in progress), June 2013 [RFC6020] M. Bjorklund, Ed., " YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, October 2010 [ACPI] "Advanced Configuration and Power Interface Specification", http://www.acpi.info/spec30b.htm [IEEE1621] "Standard for User Interface Elements in Power Control of Electronic Devices Employed in Office/Consumer Environments", IEEE 1621, December 2004 [LLDP] IEEE Std 802.1AB, "Station and Media Control Connectivity Discovery", 2005 [LLDP-MED-MIB] ANSI/TIA-1057, "The LLDP Management Information Base extension module for TIA-TR41.4 media endpoint discovery information", July 2005 [EMAN-REQ] Quittek, J., Winter, R., Dietz, T., Claise, B., and M. Chandramouli, "Requirements for Energy Management", draft-ietf-eman-requirements-14, (work in progress), May 2013 [EMAN-OBJECT-MIB] Parello, J., and B. Claise, "Energy Object Contet MIB", draft-ietf-eman-energy-aware-mib-08, (work in progress), April 2013 [EMAN-MON-MIB] Chandramouli, M.,Schoening, B., Quittek, J., Dietz, T., and B. Claise, "Power and Energy Monitoring MIB", draft-ietf-eman-energy-monitoring- mib-05, (work in progress), April 2013 [EMAN-BATTERY-MIB] Quittek, J., Winter, R., and T. Dietz, " Definition of Managed Objects for Battery Monitoring", draft-ietf-eman-battery-mib-08, (work in progress), February 2013 [EMAN-AS] Schoening, B., Chandramouli, M., and B. Nordman, "Energy Management (EMAN) Applicability Statement", Expires August, 2013 [Page 60] Internet-Draft February 2013 draft-ietf-eman-applicability-statement-03, (work in progress), April 2013 [ITU-T-M-3400] TMN recommandation on Management Functions (M.3400), 1997 [NMF] "Network Management Fundamentals", Alexander Clemm, ISBN: 1-58720-137-2, 2007 [TMN] "TMN Management Functions : Performance Management", ITU-T M.3400 [1037C] US Department of Commerce, Federal Standard 1037C, http://www.its.bldrdoc.gov/fs-1037/fs-1037c.htm [IEEE100] "The Authoritative Dictionary of IEEE Standards Terms" http://ieeexplore.ieee.org/xpl/mostRecentIssue.jsp?pu number=4116785 [ISO50001] "ISO 50001:2011 Energy management systems - Requirements with guidance for use", http://www.iso.org/ [IEC60050] International Electrotechnical Vocabulary http://www.electropedia.org/iev/iev.nsf/welcome?openf orm [IEEE-802.3at] IEEE 802.3 Working Group, "IEEE Std 802.3at- 2009 - IEEE Standard for Information technology - Telecommunications and information exchange between systems - Local and metropolitan area networks - Specific requirements - Part 3: Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications - Amendment: Data Terminal Equipment (DTE) - Power via Media Dependent Interface (MDI) Enhancements", October 2009 [DMTF] "Power State Management Profile DMTF DSP1027 Version 2.0" December 2009 http://www.dmtf.org/sites/default/files/standards/doc uments/DSP1027_2.0.0.pdf [IPENERGY] R. Aldrich, J. Parello "IP-Enabled Energy Management", 2010, Wiley Publishing Expires August, 2013 [Page 61] Internet-Draft February 2013 [X.700] CCITT Recommendation X.700 (1992), Management framework for Open Systems Interconnection (OSI) for CCITT applications [ASHRAE-201] "ASHRAE Standard Project Committee 201 (SPC 201)Facility Smart Grid Information Model", http://spc201.ashraepcs.org [CHEN] "The Entity-Relationship Model: Toward a Unified View of Data", Peter Pin-shan Chen, ACM Transactions on Database Systems, 1976 [CISCO-EW] "Cisco EnergyWise Design Guide", John Parello, Roland Saville, Steve Kramling, Cisco Validated Designs, September 2010, http://www.cisco.com/en/US/docs/solutions/Enterprise/ Borderless_Networks/Energy_Management/energywisedg.ht ml Authors' Addresses Benoit Claise Cisco Systems, Inc. De Kleetlaan 6a b1 Diegem 1813 BE Phone: +32 2 704 5622 Email: bclaise@cisco.com John Parello Cisco Systems, Inc. 3550 Cisco Way San Jose, California 95134 US Phone: +1 408 525 2339 Email: jparello@cisco.com Brad Schoening 44 Rivers Edge Drive Little Silver, NJ 07739 US Expires August, 2013 [Page 62] Internet-Draft February 2013 Phone: Email: brad.schoening@verizon.net Juergen Quittek NEC Europe Ltd. Network Laboratories Kurfuersten-Anlage 36 69115 Heidelberg Germany Phone: +49 6221 90511 15 EMail: quittek@netlab.nec.de Expires August, 2013 [Page 63]