This proposal addresses the increasingly critical need to improve the energy efficiency of the Internet by focusing on the primary and often neglected energy consumer, edge devices. Studies by Lawrence Berkeley National Laboratory (LBNL) show that about 74 TWh/yr of electricity (which is approximately $6 billion per year) is consumed by the Internet in the USA alone, of which 24 TWh/yr or 32% could be saved with full use of power management on desktop computers, currently the most common of edge devices on the Internet. Unfortunately, due to limits of existing protocols and architectures, networked desktop computers typically remain powered-up during frequent and often lengthy periods of idleness. As network devices, they are prevented from operating in an energy-efficient manner due to their need to respond to network transactions of various types without warning. The NSF is currently funding projects to investigate energy-use reduction in first-level LAN switches, server clusters, and supercomputers, but severely lacking is research to reduce energy consumption of the largest portion of Internet energy consumers, the edge devices.

Our approach to addressing this challenge is to investigate and exploit a synergistic set of novel research concepts for protocol and subsystem infrastructure, and algorithms for effectively controlling them based on traffic and system constraints, so that desktop and other edge devices can be put to sleep during periods of relative idleness while network connectivity is maintained by a low-power hardware proxy integrated into the system. Moreover, our approach also promises to provide additional increases in energy efficiency by reducing consumption of network-related resources during active periods where graceful degradation of performance is acceptable, in effect trading off speed for energy. In addition to desktop computers, this approach will lead to similar solutions for a wide variety of emerging wired and wireless edge devices such as television set-top boxes, network appliances, remote cameras, etc.

The novel concepts in our approach include:

1. protocol proxying in the network interface of a desktop computer and/or within a first-level LAN switch to reduce minor use of system resources of the edge device and thus allow system power management to be fully exploited;
2. "smart" wake-up methods to allow power-managed devices to be awoken transparently and only when needed by existing applications and protocols, along with new power-management notification semantics for future network applications;
3. adaptive link rate in Ethernet to trade-off performance (or QoS) for energy efficiency by dynamically operating links at varying data rates (e.g., 1 or 10 Gb/s only when needed, and otherwise at 10 or 100 Mb/s); and
4. architectures for fixed or reconfigurable levels of staged hardware functionality to realize energy-efficient operation via adaptive spatial or temporal assignment of hardware resources to network transactions with power, performance, and functionality scaling.

Intellectual merit:The work proposed is intellectually meritorious in that it is the first significant effort to achieve energy savings for the global Internet in terms of its dominant factor, the network-connected edge devices. This research will define the importance of energy efficiency of network edge devices as an economic and environmental issue and result in the integrated design of power management and network applications, protocols, and architectures.

Broader impact:: The broader impact of this work is threefold. First is the impact upon society within a few years of completion of this project, enabling significant reductions in energy costs here in the USA and abroad, and supporting the expansion of the Internet into the developing world by reducing operating costs. Savings in the hundreds of millions to billions of dollars per year in the USA will be achieved if existing power management capabilities can be enabled in network edge devices based on the new ideas in this proposal. We have existing relationships to allow us to work closely with LBNL, EPA, and industry to disseminate our research outcomes and achieve the expected energy savings. The second broader impact is on the educational process, both in terms of the graduate students directly involved in this project as well as the many university students that will benefit from the materials that will be created and shared from this research. Finally, through the NSF REU and RET programs, outreach will be made to K-12 and underrepresented populations.