Network Working Group B. Nordman Internet-Draft Lawrence Berkeley National Intended status: Informational Laboratory Expires: April 28, 2011 R. Winter NEC Labs Europe October 25, 2010 Considerations for Power and Energy Management draft-norwin-energy-consider-01 Abstract With rising cost and an increasing awareness of the environmental impact of energy consumption, a desirable feature of networked devices is to be able to assess their power state and energy consumption at will. With this data available, one can build sophisticated applications such as monitoring applications or even active energy management systems. These systems themselves are out of scope of this memo, as it discusses only considerations for the monitored devices. Implementation specifics such as the definition of a Management Information Base are also outside the scope of this document. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on April 28, 2011. Copyright Notice Copyright (c) 2010 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents Nordman & Winter Expires April 28, 2011 [Page 1] Internet-Draft Consider Energy October 2010 (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3 2. Overview/Goals . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Scope of Devices . . . . . . . . . . . . . . . . . . . . . . . 5 4. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6 4.1. Power States . . . . . . . . . . . . . . . . . . . . . . . 6 4.2. Power Levels . . . . . . . . . . . . . . . . . . . . . . . 6 4.3. Devices . . . . . . . . . . . . . . . . . . . . . . . . . 6 5. Energy Manangement . . . . . . . . . . . . . . . . . . . . . . 7 5.1. Control . . . . . . . . . . . . . . . . . . . . . . . . . 7 5.2. Identity . . . . . . . . . . . . . . . . . . . . . . . . . 7 5.3. NMS Considerations . . . . . . . . . . . . . . . . . . . . 7 5.4. Proxy Considerations . . . . . . . . . . . . . . . . . . . 8 5.5. MIB Considerations . . . . . . . . . . . . . . . . . . . . 8 5.6. Power Considerations . . . . . . . . . . . . . . . . . . . 8 5.7. Power State Monitoring . . . . . . . . . . . . . . . . . . 9 5.8. Power Distribution . . . . . . . . . . . . . . . . . . . . 9 6. Use Context and Use Cases . . . . . . . . . . . . . . . . . . 10 7. Outstanding Questions and Future Directions . . . . . . . . . 11 8. Security Considerations . . . . . . . . . . . . . . . . . . . 12 9. Normative References . . . . . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14 Nordman & Winter Expires April 28, 2011 [Page 2] Internet-Draft Consider Energy October 2010 1. Requirements notation 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 [RFC2119]. Nordman & Winter Expires April 28, 2011 [Page 3] Internet-Draft Consider Energy October 2010 2. Overview/Goals This document aims at framing discussions on power and energy management within the IETF and recording their results. To this end, it clarifies terminology that is routinely used to have multiple contrary meanings, which results in unnecessary confusion. The document further describes how energy and power reporting differs from other reporting tasks that have been defined by the IETF (e.g. IPFIX) and the resulting implications for mechanisms the IETF will define in the future. This document is intended to be a living document that also captures why certain decisions were made in the process of defining power and energy management mechanisms. Another goal is to cover use cases that go beyond the traditional IETF ones to keep emerging standards open with respect to diverse product types. Participating entities are monitoring systems that receive information and networked devices that provide information on energy consumption and power state information concerning themselves or potentially also other devices. Not in the scope of this memo are means for controlling the energy consumption and the power state of monitored devices; we focus on power monitoring and basic identity only. It is assumed that most devices will manage their own power state. This may be informed by external devices, by proprietary and standardized solutions (that are or will become available), or as a consequence of functional applications. Nordman & Winter Expires April 28, 2011 [Page 4] Internet-Draft Consider Energy October 2010 3. Scope of Devices All devices that have a network connection should be in scope. While first adopters will surely be devices such as switches, routers, and servers (some of which already report power levels and power state through proprietary means), in the future networked electronic devices, appliances, and even lights will also need such capability. These devices may have different ways of accomplishing discovery and management for functional purposes, but will share the common energy and power reporting capability. While some devices will directly measure power, other devices will not be able to measure their power, but may be able to reliably estimate it. These devices are still in scope. This document does not address the power consumption levels of internal components of a product, only the energy inputs to the entire product (and net consumption if it provides power to other products). Nordman & Winter Expires April 28, 2011 [Page 5] Internet-Draft Consider Energy October 2010 4. Terminology 4.1. Power States We synonymously use the terms Power Mode and Power State; named modes are general categories only, not individual states with highly- specific meaning. Discussions about energy consumptions and device power states are often confusing as different products define states such as "standby" quite differently. Even the same class of devices often implement named states differently. Named power states are intrinsically difficult to define consistently as they imply not only something about a device's energy consumption but also something about the device's capabilities in that state, and are implementation- dependent. All of this makes highly-specific named modes unsuitable for use in a general context. The term with by far the most different definitions is "standby" and so we therefore deliberately do not refer to standby in this document. We believe that the three named power state categories, on, off and sleep, are broadly understood. These mode categories may each contain a large set of power sub-states. A fourth basic power state of 'ready' may be more appropriate for some devices, particularly appliances. In general, devices that are asleep will be able to wake quickly and will retain network connectivity. Devices that are off usually take much more time to turn on than the wake time and usually lack network connectivity. Devices that are on are fully functional but potentially with reduced performance. 4.2. Power Levels The power level of a device is its current electricity demand. It is an important complement to power mode, providing articulation of power level within the basic mode. It also avoids the need for a large number of named modes. Basic modes are distinguished by important functional differences or power levels. Core power modes are an abstraction from individual implementations. 4.3. Devices The organizing unit for power is a single device with one or more power sources. The term "product" is sometimes used as a synonym, and also covers the case in which a device proxies network presence including power reporting for a second device. Nordman & Winter Expires April 28, 2011 [Page 6] Internet-Draft Consider Energy October 2010 5. Energy Manangement First and foremost, the task of power and energy management is reporting. While a more active role in energy management is conceivable by e.g. putting devices into power states based on policies or other predefined schemes at a network management system (NMS). 5.1. Control There should not be an assumption that power state management of devices is done externally/centrally. Ideally most devices will manage their own power state, implementing distributed intelligence. The control function is accomplished separately from power reporting. A core mechanism many devices will use to manage power consumption is a price (and price forecast) for electricity. 5.2. Identity All devices on a network need to expose identity to others. While some protocols accomplish this for particular applications or contexts, it is desirable to have a simple universal mechanism. This is particularly true for devices that may have a fairly limited degree of participation in the network, such as appliances. This mechanism should directly or indirectly reveal the brand/model of the device, and possible a URL to further information about the device. An example of this is the "Universal Product Code" on many products. Subsequent documents should identify the appropriate mechanism to accomplish this, e.g. an existing MIB. An energy management application could then obtain current energy use for a device like a refrigerator, and compare it to what it is expected to use under normal operation, and alert the building manager if it is significantly out of range. This also can be used to quickly inventory energy-using products in a building, and to summarize by product type where energy is being used. 5.3. NMS Considerations A Network Management System is an entity which collects energy and power reporting data and uses it for advanced applications. One such application correlates energy consumption with other metrics to display efficiency metrics (like watthours/bit). An NMS can also set device policies to control larger networked systems such as a data center. An NMS will query energy MIB data on a periodic basis, with that period dictated by its needs, possibly being dynamic. MIBs should Nordman & Winter Expires April 28, 2011 [Page 7] Internet-Draft Consider Energy October 2010 provide an energy "meter reading" to allow computing of energy use for any period. Thus, the NMS does most of the work to generate time series energy data, and this minimizes burden on the host and the complexity of the Power MIB. The core function of power monitoring is to maintain meters of energy use and of time in different power states (and through summing, total energy and time). The second is to be able to report current power consumption and power state. 5.4. Proxy Considerations Devices usually will report on their own input power, but may also report Power supplied to other devices. Those other devices may also have an IP address and so report some information themselves. Other devices may not have an IP presence and so all information will be from the proxy. 5.5. MIB Considerations The MIB should be generic as there are a large number of devices yet to come and power states are and will become more diverse. The MIB should be structured so that the smallest possible set of values/information is applicable to a large range of devices, can be implemented efficiently and is extensible to accommodate additional information objects. As an example, many devices will not be battery powered but it should be easy to add battery monitoring to the basic set of energy-related information. 5.6. Power Considerations Reporting should cover both AC and DC power sources. However, other types should be provided for, and the type of energy is one of the reported values. Standard low-voltage DC (e.g. USB, Power over Ethernet, eMerge) is immediately useful. A core set of values should be available from any device that implements the Power MIB at all so that an NMS can quickly obtain and aggregate uniform data for all devices. There is a fundamental distinction between supplied power from a device And input power to a device, notably losses that occur in transmission, as well as other (possibly unknown) devices that are also using the power. The effect of internal batteries is not revealed by the MIB, as it only reports on net power into or out of a device. It is tempting to add a lot of descriptive information (e.g. on Nordman & Winter Expires April 28, 2011 [Page 8] Internet-Draft Consider Energy October 2010 highly specific power states and periodic energy consumption) into the MIB; however, this information will greatly vary across device types. 5.7. Power State Monitoring For the device power state, the following information is considered to be relevant: o the current state o the time of (or time since) the last change o the current real power (energy consumption rate) o accumulated energy consumption 5.8. Power Distribution Wired networks enable power distribution that is co-incident with network Communication. However, many devices will not communicate on the same Medium that they are powered on, or may lack connectivity entirely (though with the power provider knowing of their identity). Devices can report power for another device only if they are the entity providing the power. Nordman & Winter Expires April 28, 2011 [Page 9] Internet-Draft Consider Energy October 2010 6. Use Context and Use Cases The following are some use contexts that this facility is intended for. These are not necessarily mutually exclusive, and a device can report the same data regardless of the context. o A data center, with a NMS which is integrated with application functionality, and also manages energy use. o A commercial building, in which the energy reporting is separate from any management of devices, and more as background to help understand building operation (including occupancy) and identify inefficiencies or equipment failures. o A house, which shares some of the commercial building characteristics, but with different management approach and security concerns. o A vehicle, which uses the reporting only for automatic management, not for reporting to the user. Use cases include a facility manager or an NMS in an automated fashion: o Understand costs for billing purposes. o Assess savings potentials. o Identify possible device malfunctions. o Reveal unexpected usage patterns. o Plan for future capacity needs. o Understand heat production in a building or space. o A NMS which deals with draws on current power use to deal with an actual or potential shortfall in power supply. Nordman & Winter Expires April 28, 2011 [Page 10] Internet-Draft Consider Energy October 2010 7. Outstanding Questions and Future Directions Questions that need to be answered in the course of developing RFCs for energy management include: o What unit(s) of measurement should the MIB use? Future directions include: o other energy media such as wireless power, non-electric energy (e.g. natural gas) o support for devices with multiple power sources (the initial MIB should cover only the total input power). Nordman & Winter Expires April 28, 2011 [Page 11] Internet-Draft Consider Energy October 2010 8. Security Considerations None. Nordman & Winter Expires April 28, 2011 [Page 12] Internet-Draft Consider Energy October 2010 9. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. Nordman & Winter Expires April 28, 2011 [Page 13] Internet-Draft Consider Energy October 2010 Authors' Addresses Bruce Nordman Lawrence Berkeley National Laboratory Email: bnordman@lbl.gov Rolf Winter NEC Labs Europe Email: rolf.winter@neclab.eu Nordman & Winter Expires April 28, 2011 [Page 14]