-
[show abstract]
[hide abstract]
ABSTRACT: The primary focus of Green IT has been on reducing energy use of the IT infrastructure itself. Additional significant energy savings can be achieved by using the IT infrastructure to enable energy savings in both the IT and non-IT infrastructure. Our premise is that energy can be saved by driving building operation on information gleaned from existing IT infrastructure already installed for non-energy purposes. We call our idea implicit occupancy sensing where existing IT infrastructure can be used to replace and/or supplement traditional dedicated sensors to determine building occupancy. Our implicit sensing methods are largely based on monitoring MAC and IP addresses in routers and wireless access points, and then correlating these addresses to the occupancy of a building, zone, and/or room. Occupancy data can be used to control lighting, HVAC, and other building functions to improve building functionality and reduce energy use. We experimentally evaluate the feasibility of this dual-use of IT infrastructure and assess the accuracy of implicit sensing. Our findings, based on data collected from two facilities, show that there is significant promise in implicit sensing using the existing IT infrastructure present in most modern non-residential buildings.
Green Computing Conference and Workshops (IGCC), 2011 International; 08/2011
-
[show abstract]
[hide abstract]
ABSTRACT: Until recently, research and development in the area of communications networks has been mainly targeted at functionality and performance. Only for battery-driven devices, such as mobile handsets and wireless sensors, was energy efficiency a significant consideration. This has changed significantly with the massive use of communications in public, professional, and private life coupled with the increasing cost of energy, and with the recognition of the critical need to reduce CO<sub>2</sub> emissions. These economic and ecological drivers have induced a new research area with energy efficiency of general communications networks as the objective. Today we see energy efficiency becoming a pervasive issue for all communication layers and in all technology areas from microelectronics to systems planning and management.
IEEE Network 05/2011; · 2.24 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Ethernet is the dominant wireline communications technology for LANs with over 1 billion interfaces installed in the U.S. and over 3 billion worldwide. In 2006 the IEEE 802.3 Working Group started an effort to improve the energy efficiency of Ethernet. This effort became IEEE P802.3az Energy Efficient Ethernet (EEE) resulting in IEEE Std 802.3az-2010, which was approved September 30, 2010. EEE uses a Low Power Idle mode to reduce the energy consumption of a link when no packets are being sent. In this article, we describe the development of the EEE standard and how energy savings resulting from the adoption of EEE may exceed $400 million per year in the U.S. alone (and over $1 billion worldwide). We also present results from a simulation-based performance evaluation showing how packet coalescing can be used to improve the energy efficiency of EEE. Our results show that packet coalescing can significantly improve energy efficiency while keeping absolute packet delays to tolerable bounds. We are aware that coalescing may cause packet loss in downstream buffers, especially when using TCP/IP. We explore the effects of coalescing on TCP/IP flows with an ns-2 simulation, note that coalescing is already used to reduce packet processing load on the system CPU, and suggest open questions for future work. This article will help clarify what can be expected when EEE is deployed.
IEEE Communications Magazine 12/2010; · 3.79 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Proxying is a simple and effective means of allowing network hosts to sleep while maintaining network presence. It is the use of a low-power entity to maintain presence on the network for a high-power device like a PC. The component that does this, the proxy, can be internal to a device (for example, in the network interface chip within a PC), in an immediately adjacent network switch or router, or even another PC on the subnet. The proxy enables a host to transition into and out of sleep transparently to the network. Use of a proxy requires no infrastructure changes such as changing existing protocols, or maintaining state in routers or switches. Network connectivity proxying offers a chance to both save large amounts of energy and add functionality, at very low cost.
Computer 02/2010; · 1.47 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: PC energy use is a growing cost to enterprises, with most machines remaining fully powered on, even while idle, for most of the time. The Network Connectivity Proxy maintains network presence for PCs but lets them sleep while idle, thus saving energy and reducing total cost of ownership.
IT Professional 09/2009;
-
[show abstract]
[hide abstract]
ABSTRACT: Billions of dollars of electricity are being used to keep idle or unused network hosts fully powered-on only to maintain their network presence. We investigate how a network connectivity proxy (NCP) could enable significant energy savings by allowing idle hosts to enter a low-power sleep state and still maintain full network presence. An NCP must handle ARP, ICMP, DHCP, and other low-level network presence tasks for a network host. An NCP must also be able to maintain TCP connections and UDP data flows and to respond to application messages. The focus of this paper is on how TCP connections can be kept alive during periods of host sleep by using a SOCKS-based approach called green SOCKS (gSOCKS) as part of an NCP. The gSOCKS includes awareness of the power state of a host. A prototype implementation of gSOCKS in a Linksys router shows that TCP connections can be preserved.
Performance, Computing and Communications Conference, 2008. IPCCC 2008. IEEE International; 01/2009
-
[show abstract]
[hide abstract]
ABSTRACT: The rapidly increasing energy consumption by computing and communications equipment is a significant economic and environmental problem that needs to be addressed. Ethernet network interface controllers (NICs) in the US alone consume hundreds of millions of US dollars in electricity per year. Most Ethernet links are underutilized and link energy consumption can be reduced by operating at a lower data rate. In this paper, we investigate adaptive link rate (ALR) as a means of reducing the energy consumption of a typical Ethernet link by adaptively varying the link data rate in response to utilization. Policies to determine when to change the link data rate are studied. Simple policies that use output buffer queue length thresholds and fine-grain utilization monitoring are shown to be effective. A Markov model of a state-dependent service rate queue with rate transitions only at service completion is used to evaluate the performance of ALR with respect to the mean packet delay, the time spent in an energy-saving low link data rate, and the oscillation of link data rates. Simulation experiments using actual and synthetic traffic traces show that an Ethernet link with ALR can operate at a lower data rate for over 80 percent of the time, yielding significant energy savings with only a very small increase in packet delay.
IEEE Transactions on Computers 05/2008; 57(4):448-461. · 1.10 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Rapidly increasing energy use by computing and communications equipment is a significant problem that needs to be addressed. Ethernet network interface controllers (NICs) consume hundreds of millions of US$ in electricity per year. Most Ethernet links are underutilized and link power consumption can be reduced by operating at lower data rates. An output buffer threshold policy to change link data rate in response to utilization is investigated. Analytical and simulation models are developed to evaluate the performance of Adaptive Link Rate (ALR) with respect to mean packet delay and time spent in low data rate with Poisson traffic and 100 Mb/s network traces as inputs. A Markov model of a state-dependent service rate queue with rate transitions only at service completion is developed. For the traffic traces, it is found that a link can operate at 10 Mb/s for over 99% of the time yielding energy savings with no user-perceivable increase in packet delay.
Global Telecommunications Conference, 2006. GLOBECOM '06. IEEE; 01/2007
-
[show abstract]
[hide abstract]
ABSTRACT: The Internet and the devices that connect to it consume a growing and significant amount of electricity. The utilization of desktop-to-switch Ethernet links is generally very low and thus there is a potential for energy savings by using an adaptive link rate (ALR) protocol that matches link rate to utilization. In this paper, we design and evaluate a new ALR policy suitable for both bursty and smooth traffic. The policy uses output buffer thresholds and fine-grain utilization monitoring to determine when to switch link data rate. We develop a new traffic model for generating synthetic 1 and 10 Gb/s bursty traffic traces. Using this traffic model and simulation, we show that the new ALR policy is suitable for smooth traffic and also does not degrade performance for bursty traffic. Performance is measured in packet delay versus time in low (and energy saving) data rate
Local Computer Networks, Annual IEEE Conference on. 11/2006;
-
[show abstract]
[hide abstract]
ABSTRACT: Networks are one of the most significant developments in computing and a hallmark of modern society. However, along with increasing efficiency and productivity, both at home and in the workplace, networks have costs. One cost is the additional energy that electronic devices consume when attached to networks. Power management, a standard feature of modern PCs, was primarily developed to increase battery lifetime in laptop PCs, which historically were not network-connected when using battery power. Today, however, many laptops are connected to a network - typically a Wi-Fi network - as are the majority of desktop computers. Three key drivers of energy use are induced consumption by devices prevented by network connections from entering low-power states, increasing link data rates that inherently consume more energy for the network interfaces, and proliferation of network-connected displays that actively update and display data when no one is present.
Computer 09/2004; · 1.47 Impact Factor
