Network Working Group J. Quittek Internet-Draft NEC Europe Ltd. Intended status: Informational November 8, 2010 Expires: May 12, 2011 Reference Model for Energy Management draft-quittek-eman-reference-model-00 Abstract This memo discusses suggest a reference model for energy consumption monitoring and control. It defines entities involved in energy management, their roles, and relationships between them. Considered entities include energy consumers, energy consumption meters, energy consumption reporters, energy consumption controllers, and energy consumption management systems. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as Quittek Expires May 12, 2011 [Page 1] Internet-Draft Reference Model for Energy Management November 2010 described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1. Energy Management . . . . . . . . . . . . . . . . . . . . 4 2.2. Power, Energy, and Energy Consumption . . . . . . . . . . 4 3. Energy Management Entities . . . . . . . . . . . . . . . . . . 5 3.1. Energy Consumer . . . . . . . . . . . . . . . . . . . . . 6 3.2. Power Source . . . . . . . . . . . . . . . . . . . . . . . 6 3.3. Energy Consumption Meter . . . . . . . . . . . . . . . . . 6 3.4. Energy Consumption Reporter . . . . . . . . . . . . . . . 6 3.5. Power Controller . . . . . . . . . . . . . . . . . . . . . 7 3.6. Power Provisioning Controller . . . . . . . . . . . . . . 7 3.7. Energy Consumption Controller . . . . . . . . . . . . . . 7 3.8. Energy Management System . . . . . . . . . . . . . . . . . 7 4. Interactions between Energy Management Entities . . . . . . . 7 4.1. Interactions of the Energy Management System . . . . . . . 8 4.1.1. Interactions with Energy Consumption Reporters . . . . 8 4.1.2. Interactions with Energy Consumption Controllers . . . 8 4.2. Other Interactions Between Entities . . . . . . . . . . . 8 4.2.1. Energy Consumption Reporters and Energy Consumption Meters . . . . . . . . . . . . . . . . . . 9 4.2.2. Power Controllers and Energy Consumers . . . . . . . . 9 4.2.3. Power Provisioning Controllers and Power Sources . . . 9 5. Energy Management Scenarios . . . . . . . . . . . . . . . . . 9 5.1. Simple Device equipped with Energy Consumption Meter . . . 9 5.2. Device Energy Consumption Meter and Power Control . . . . 10 5.3. External Energy Consumption Meter . . . . . . . . . . . . 11 5.4. Power over Ethernet Switch . . . . . . . . . . . . . . . . 11 5.5. Power Distribution Unit . . . . . . . . . . . . . . . . . 12 5.6. Energy Consumption Reporting Proxy . . . . . . . . . . . . 12 5.7. Energy-Aware Consumer . . . . . . . . . . . . . . . . . . 13 6. Security Considerations . . . . . . . . . . . . . . . . . . . 14 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14 9. Informative References . . . . . . . . . . . . . . . . . . . . 14 Quittek Expires May 12, 2011 [Page 2] Internet-Draft Reference Model for Energy Management November 2010 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 15 Quittek Expires May 12, 2011 [Page 3] Internet-Draft Reference Model for Energy Management November 2010 1. Introduction Managing energy consumption of devices with network connections is different to several well understood network management functions because of the special nature of energy consumption. One particular difference, for example, is that in many typical cases energy consumption is not measured by the consumer itself, but by a power meter located somewhere in the power distribution tree, for example, at a power distribution unit (PDU). The PDU measures the energy consumption for attached devices and may report this to an energy management system. Different to many other management functions, the energy consumer is not involved in this process. This memo aims at clarifying roles of entities involved in energy monitoring and control and the relationships between these entities. There is already a system model defined in section 4 of [I-D.claise-power-management-arch]. The intention of this memo is to refine this model based on recent discussions on the mailing list. The system model specification below describes several kinds of entities and interactions between them. According to the current scope of the EMAN WG, only interactions with the energy management system are potenial subjects of standardization in this WG. 2. Terminology This section defines terms used for the description of the energy management reference model. Names for entities of the model are not defined here but in Section 3. 2.1. Energy Management Energy management deals with assessing and influencing the consumption of energy in a network of energy consumers. A typical objective of energy management is reducing the energy consumption in the network. This objective may conflict with other objectives of a general network management system, for example, with service level objectives. 2.2. Power, Energy, and Energy Consumption Power is a rate of energy conversion. The energy conversion that is typically subject of energy management is called energy consumption. Electrical energy is delivered to a device that "consumes" it by converting the energy. Quittek Expires May 12, 2011 [Page 4] Internet-Draft Reference Model for Energy Management November 2010 Power is a rate of energy conversion. In scenarios relevant to energy management electrical energy is delivered to a device that "consumes" it by converting the energy. Power and consumed energy are essential quantities for network management. Power can be an instantaneous value of the current energy conversion rate or an average value of instantaneous power over a time interval. Consumed energy, is the total energy converted by a consumer during a time interval. The term 'energy consumption' is commonly used for both, for referring to the amount of consumed energy and also for referring to the process of consuming energy. In the first case it addresses consumed energy, in the second one it addresses power, typically an average power. In this document we use this ambiguous term for addressing both, power and consumed energy. The often used term 'power consumption' is not used here because 'consumption of an energy conversion rate' is not a concept that is considered technically useful for energy management. 3. Energy Management Entities This section defines entities of the energy managemet reference model. Interactions between them are defined in Section 4. Examples scenarios are illustrated in Section 5. The following figure gives an overview of all entities and their interactions. +---------+ +-------------+ +--------+ | Energy | commands | Power | commands | Power | | Manage- | -------> | Provisioning| --------------> | Source | | ment | | Controller | +--------+ | System | +-------------+ # | | +-------------+ +-------------+ # | | reports | Energy | reports | Energy | # | | <------- | Consumption | <------ | Consumption |## | | | Reporter | | Meter | # | | +-------------+ +-------------+ # | | +-------------+ # | | commands | | commands +----------+ | | -------> | Power | ------------> | Energy | | | | Controller | | Consumer | +---------+ +-------------+ +----------+ symbols ######### represent a power line Entities may be merged. For example, a Power over Ethernet (PoE) Quittek Expires May 12, 2011 [Page 5] Internet-Draft Reference Model for Energy Management November 2010 [IEEE-802.3af] switch acting as power sourcing equipment may contains a power source, a power supply controller, an energy consumption meter, and an energy consumption reporter. It may even integrate an additional energy consumption controller. In such a case, these entities may not be modeled separately by an implementation interaction between the entities may be entirely internal to the device. In an extreme case, a self-managed device may integrate all entities (incduding the energy management system) except the power source. 3.1. Energy Consumer An energy consumer is provided with energy, typically with electrical energy. Typically, energy is provided via power lines. The power and consumed energy of energy consumers are subject to monitoring and control functions of energy management. 3.2. Power Source A power source provides consumers with electrical energy, typically via a power line. It may have means to switch on and off the power supply for the energy consumer. It's function may be controlled by a power supply controller. A power supply does tyically not not generate power. It may be as simple as a power switch or a power plug. 3.3. Energy Consumption Meter An energy consumption meter measures power and consumed energy. Typically, it is electrically connected to power provisioning lines for energy consumers. It may store energy consumption information and process it, for example, for extracting statistics that are provided to the energy consumption reporter 3.4. Energy Consumption Reporter An energy consumption reporter has access to information on energy consumption of energy consumers and is able to report this information to energy management systems. For getting information on energy consumption it may interact with an energy consumption meter. The energy consumption reporter may also provide information on identity and properties of an energy consumer to the management system. An energy consumption reporter may store energy consumption information and process it, for example, for extracting statistics that are provided to the management system. Quittek Expires May 12, 2011 [Page 6] Internet-Draft Reference Model for Energy Management November 2010 3.5. Power Controller A power controller has means for controlling the energy consumption of a energy consumer by communication with it in order to control its current power (energy consumption rate). 3.6. Power Provisioning Controller A power provisioning controller has means for influencing the power supply of an energy consumer. Typically, it has means for switching power supply on and off. It may use these means without communicating with the affected energy consumer. 3.7. Energy Consumption Controller An energy consumption controller is a power controlller, or a power provisioning controller, or a combination of both. 3.8. Energy Management System An energy management system interacts with energy consumption reporters and energy consumption controllers in order to achieve objectives of energy management. It receives reports on energy consumption from energy consumption reporters and sends commands to energy consumption controllers. An energy management system may be centralized and consist of a single component only. It also can be distributed and contain several interacting components. In most of the example scenarios illustrated in Section 5 a centralized energy management system is shown. For all examples this can be replaced by a distributed management system. 4. Interactions between Energy Management Entities This section describes the set of potential interactions between entities of the energy management reference model. Examples of these interactions are illustrated in Section 5. Potential subjects of standardization in the EMAN working group are only interactions of the energy management system with other entities as described in section Section 4.1. Other interactions described in Section 4.2 are not subject of standardization according to the EMAN charter. However, describing them is useful for understanding the interactions in which the management system is involved. Quittek Expires May 12, 2011 [Page 7] Internet-Draft Reference Model for Energy Management November 2010 4.1. Interactions of the Energy Management System The energy management system interacts with energy consumption reporters and energy consumption controllers. 4.1.1. Interactions with Energy Consumption Reporters The energy management system receives reports about energy consumption from energy consumption controllers. Reports may contain power and consumed energy of one or more energy consumers and further related information, for example, an identification of the consumer on which energy consumption is reported or statistics of energy consumption and power states. It is argued in [I-D.quittek-power-monitoring-requirements] that the best choice of management protocols for this purpose is SNMP [RFC3410]. For the reference model defined in this memo we assume that SNMP is the protocol used between energy management system and enenergy consumption reporter. However, the model would also be valid if other protocols were used, for example push-based protocols such as Syslog [RFC5675] and IPFIX [RFC5101]. 4.1.2. Interactions with Energy Consumption Controllers The energy management system sends commands to energy consumption controllers concerning energy consumers. Commands to power provisioning controllers concern power provisioning of the affected consumer. Typically, just two commands are used: "power on" and "power off". But also a reduction of supplied power, for example "reduce voltage" may be sent as command. Commands to power controllers concern the power state of the energy consumer. A typical example is a command to bring an energy consumer into a sleep state or to wake it up from a sleep state. There are several choices for the protocol to be used for these interactions. Among them are SNMP [RFC3410] and NETCONF [RFC4741]. 4.2. Other Interactions Between Entities Interactions described in this section do not involve the energy management system and are not subject of standardization according to the EMAN charter. However, their description is useful to fully understand the interactions of the energy management system. This reference model does not make any assumption on the communication means used for these interactions. The involved entities may be located within the same device, inegrated into a single monolithic implementation, and use any kind of internal Quittek Expires May 12, 2011 [Page 8] Internet-Draft Reference Model for Energy Management November 2010 communication. Alternatively they may be located remote of each other and use IP or any other protocol to communicate. 4.2.1. Energy Consumption Reporters and Energy Consumption Meters Energy consumption reporters interact with energy consumption meters in order to receive power consumption information. If they are remote of each other, then the energy consumption reporter acts as relay and potentially also as protocol converter and storage for measured data. 4.2.2. Power Controllers and Energy Consumers Power controllers interact with energy consumers in order to send them power state change commands. 4.2.3. Power Provisioning Controllers and Power Sources Power provisioning controllers interact with power sources in order to send them commands regarding the power supply for energy consumers, such as switchin power on or off. 5. Energy Management Scenarios This section describes a few example scenarios for energy management and how they are modeled with the entities and interactions described in the previous sections. 5.1. Simple Device equipped with Energy Consumption Meter A very basic example is an energy consumer that has a built-in meter for measuring its own energy consumption. Quittek Expires May 12, 2011 [Page 9] Internet-Draft Reference Model for Energy Management November 2010 +---------+ +--------+ | Energy | | Power | | Manage- | | Source | | ment | +--------+ | System | +-----------------------------------------#--+ | | | +-------------+ +-------------+ # | | | reports | | Energy | reports | Energy | # | | | <------- | | Consumption | <------ | Consumption |## | | | | | Reporter | | Meter | # | | | | +-------------+ +-------------+ # | | | | # | | | | +----------+ | | | | | Energy | | | | | | Consumer | | | | | +----------+ | | | | Consumer with meter | +---------+ +--------------------------------------------+ The device contains three entities: an energy consumption meter, an enrgy consumption reporter and of course also the energy consumer. 5.2. Device Energy Consumption Meter and Power Control This second exaple extends the previous one by an additional power controller in the device. +---------+ +--------+ | Energy | | Power | | Manage- | | Source | | ment | +--------+ | System | +-----------------------------------------#--+ | | | +-------------+ +-------------+ # | | | reports | | Energy | reports | Energy | # | | | <------- | | Consumption | <------ | Consumption |## | | | | | Reporter | | Meter | # | | | | +-------------+ +-------------+ # | | | | +-------------+ # | | | commands | | | commands +----------+ | | | -------> | | Power | ------------> | Energy | | | | | | Controller | | Consumer | | | | | +-------------+ +----------+ | | | | Consumer with meter and power control | +---------+ +--------------------------------------------+ Quittek Expires May 12, 2011 [Page 10] Internet-Draft Reference Model for Energy Management November 2010 5.3. External Energy Consumption Meter In this example, an energy consumption meter is attached to the power line of an energy consumer that does not have means for measuring enrgy consumption by itself. +---------+ +--------+ | Energy | | Power | | Manage- | | Source | | ment | +--------+ | System | +-----------------------------------------#--+ | | | +-------------+ +-------------+ # | | | reports | | Energy | reports | Energy | # | | | <------- | | Consumption | <------ | Consumption |## | | | | | Reporter | | Meter | # | | | | +-------------+ +-------------+ # | | | | External meter # | | | +-----------------------------------------#--+ | | # | | +----------+ | | | Energy | | | | Consumer | +---------+ +----------+ 5.4. Power over Ethernet Switch This example shows a Power over Ethernet (PoE) [IEEE-802.3af] switch supplying an energy consumer. The switch contains a power source for PoE, a controller for this power that can be controlled by the energy management system and it contains a meter for each port and a reporter for reporting measured energy consumption data. Please note although there may be multiple instances of power sources and energy consumption meters in the switch, only single instances are show. The same applies to the energy consumers that arde represented by a single one only. Quittek Expires May 12, 2011 [Page 11] Internet-Draft Reference Model for Energy Management November 2010 +---------+ +--------------------------------------------+ | Energy | | +-------------+ +--------+ | | Manage- | commands | | Power | commands | Power | | | ment | -------> | | Provisioning| --------------> | Source | | | System | | | Controller | +--------+ | | | | +-------------+ # | | | | +-------------+ +-------------+ # | | | reports | | Energy | reports | Energy | # | | | <------- | | Consumption | <------ | Consumption |## | | | | | Reporter | | Meter | # | | | | +-------------+ +-------------+ # | | | | PoE switch # | | | +-----------------------------------------#--+ | | # | | +----------+ | | | Energy | | | | Consumer | +---------+ +----------+ A problem of this example is the identification of energy consumers. A basic PoE switch does not know which kind of device is attached to a port. But it can observe MAC and IP address of the energy consumers and report them to the energy management system which then in turn can contact the consumer to obtain further information. 5.5. Power Distribution Unit The same figure as used for the PoE switch in the previous section can be used for modeling a power distribution unit (PDU). The PDU receives commands from a management system to switch on and off power at certain sockets. It contains meters for every socket and can report power for each of them. The problem of identifying the energy consumers for is more difficult than in the previous case of the PoE switch, because the PDU does not communicate with the energy consumers and only reports energy consumption per socket. In this case the network management needs to obtain this information by other means, for example by manual configuration. 5.6. Energy Consumption Reporting Proxy This example deals with measuring energy consumption of devices that do not necessarily have IP connectivity, but other means of communicating with a proxy. The proxy acts as relay and protocol converter in order to deliver the energy consumption information to the network management system. Quittek Expires May 12, 2011 [Page 12] Internet-Draft Reference Model for Energy Management November 2010 +---------+ +--------+ | Energy | | Power | | Manage- | | Source | | ment | +--------+ | System | +----------------+ +-----------------#--+ | | | +------------+ | | +-------------+ # | | | reports | | Energy | |reports|| | Energy | # | | | <------- | | Consumption| |<------ | | Consumption |## | | | | | Reporter | | | | Meter | # | | | | +------------+ | | +-------------+ # | | | | Proxy | | # | | | +----------------+ | +----------+ | | | | | Energy | | | | | | Consumer | | | | | +----------+ | | | | Consumer with meter| +---------+ +--------------------+ Here again, the problem of identifying the energy consumer has become very difficult, because neither can the energy consumption reporter provide an IP address of the energy consumer to the energy management system nor can the energy management system directy communicate with the energy consumer. Identification must be provided by other means. The Proxy can have a gateway function and relay identification between energy consumer and energy management system or the energy management system needs to acquire information on energy consumers by other means, such as manual configuration. 5.7. Energy-Aware Consumer Last but not least, this example shows a consumer that is energy- aware. It monitors and controls its own energy consumption and for this purpose contains a portion of a distributed energy management system. The energy management function contained in the energy-aware device may still have some interaction with other components of the management system, for example for distributing policies that determine the bahavior of self-management functions. But these interactions between components of the distributed energy management system are not shown here. Quittek Expires May 12, 2011 [Page 13] Internet-Draft Reference Model for Energy Management November 2010 +--------+ | Power | | Source | +--------+ +--------------------------------------------------------------#--+ | +---------+ +-------------+ +-------------+ # | | | Energy | reports | Energy | reports | Energy | # | | | Manage- | <------- | Consumption | <------ | Consumption |## | | | ment | | Reporter | | Meter | # | | | System | +-------------+ +-------------+ # | | | | +-------------+ # | | | | commands | | commands +----------+ | | | | -------> | Power | ------------> | Energy | | | | | | Controller | | Consumer | | | +---------+ +-------------+ +----------+ | | Self-managed energy-aware consumer | +------------------------------------------------------------------ 6. Security Considerations This memo currently does not impose any security considerations. 7. IANA Considerations This memo has no actions for IANA.. 8. Acknowledgements This memo was inspired by discussions with Benoit Claise, Bruce Nordman, John Parello, Mouli Chandramouli, and Rolf Winter at IETF #79. 9. Informative References [I-D.quittek-power-monitoring-requirements] Quittek, J., Winter, R., Dietz, T., Claise, B., and M. Chandramouli, "Requirements for Power Monitoring", draft-quittek-power-monitoring-requirements-02 (work in progress), October 2010. [I-D.claise-power-management-arch] Claise, B., Parello, J., and B. Schoening, "Power Management Architecture", draft-claise-power-management-arch-02 (work in progress), Quittek Expires May 12, 2011 [Page 14] Internet-Draft Reference Model for Energy Management November 2010 October 2010. [RFC3410] Case, J., Mundy, R., Partain, D., and B. Stewart, "Introduction and Applicability Statements for Internet- Standard Management Framework", RFC 3410, December 2002. [RFC4741] Enns, R., "NETCONF Configuration Protocol", RFC 4741, December 2006. [RFC5101] Claise, B., "Specification of the IP Flow Information Export (IPFIX) Protocol for the Exchange of IP Traffic Flow Information", RFC 5101, January 2008. [RFC5675] Marinov, V. and J. Schoenwaelder, "Mapping Simple Network Management Protocol (SNMP) Notifications to SYSLOG Messages", RFC 5675, October 2009. [IEEE-802.3af] IEEE 802.3 Working Group, "IEEE Std 802.3af-2003 - Data Terminal Equipment (DTE) Power via Media Dependent Interface (MDI)", July 2003. Author's Address Juergen Quittek NEC Europe Ltd. Network Research Division Kurfuersten-Anlage 36 Heidelberg 69115 DE Phone: +49 6221 4342-115 Email: quittek@neclab.eu Quittek Expires May 12, 2011 [Page 15]