Flexible application driven network striping over Wireless Wide Area Networks

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.Includes bibliographical references (p. 157-161).Inverse multiplexing, or network striping, allows the construction of a high-bandwidth virtual channel from a collection of multiple low-bandwidth network channels. Striping systems usually employ a packet scheduling policy that allows applications to be oblivious of the way in which packets are routed to specific network channels. Though this is appropriate for many applications, many other applications can benefit from an approach that explicitly involves the application in the determination of the striping policy. Horde is middleware that facilitates flexible striping over Wireless Wide Area Network (WWAN) channels. Horde is unusual in that it separates the striping policy from the striping mechanism. It allows applications to describe network Quality-of-Service (QoS) objectives that the striping mechanism attempts to satisfy. Horde can be used by a set of data streams, each with its own QoS policy, to stripe data over a set of WWAN channels. The WWAN QoS variations observed across different channels and in time, provide opportunities to modulate stream QoS through scheduling. The key technical challenge in Horde is giving applications control over certain aspects of the data striping operation while at the same time shielding the application from low-level details. Horde exports a set of flexible abstractions replacing the application's network stack. Horde allows applications to express their policy goals as succinct network-QoS objectives. Each objective says something, relatively simple, about the sort of network QoS an application would like for some data stream(s). We present the Horde architecture, describe an early implementation, and examine how different policies can be used to modulate the quality-of-service observed across different independent data streams. Through experiments conducted on real and simulated network channels, we confirm our belief that the kind of QoS modulation Horde aims to achieve is realistic for actual applications.by Asfandyar Qureshi.M.Eng

Cost and Profit Efficiencies of Fully-Fledged Islamic Banks and Islamic Windows of Conventional Banks in Pakistan

Pakistan is an emerging and an important country in banking and finance. A lot of emphasis has been made on the Islamic banking sector of Pakistan and its growth in the past decade is plausible. It is opening up the market for international investors. This makes the Islamic banking sector of Pakistan interesting and worth analysing. Furthermore, it has not been taken up widely in the academic literature. The purpose of this research is to present a new perspective on the evaluation of x-efficiencies in Pakistani Islamic banking system. As per the knowledge of the author this is the first time such a study has been conducted for Pakistani banks where a comparison has been made between the cost and profit efficiencies of fully-fledged Islamic banks and the Islamic banking windows of the conventional Banks. We have taken up a sample of four fully fledged Islamic Banks and thirteen conventional banks Islamic banking windows. Stochastic frontier approach was applied in the first stage and in the second stage we have used the Tobit model and GMM model to find out the effects of bank specific and macroeconomic variables. On evaluating the efficiencies it was found out that the fully fledged Islamic banking windows were both cost and profit efficient as compared to the Islamic banking windows of conventional banks. We also found out that the Islamic banks were not affected by the recent financial crises of 2007. This research intends to fill the gap and would create a basis for further study on this topic. It would also prove to be useful for the investors as to which type of Islamic bank to invest i.e. fully-fledged Islamic banks or the Islamic banking windows of conventional banks

Cutting the Electric Bill for Internet-Scale Systems

Energy expenses are becoming an increasingly important fraction of data center operating costs. At the same time, the energy expense per unit of computation can vary significantly between two different locations. In this paper, we characterize the variation due to fluctuating electricity prices and argue that existing distributed systems should be able to exploit this variation for significant economic gains. Electricity prices exhibit both temporal and geographic variation, due to regional demand differences, transmission inefficiencies, and generation diversity. Starting with historical electricity prices, for twenty nine locations in the US, and network traffic data collected on Akamai's CDN, we use simulation to quantify the possible economic gains for a realistic workload. Our results imply that existing systems may be able to save millions of dollars a year in electricity costs, by being cognizant of locational computation cost differences.NokiaNational Science Foundatio

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Inverse multiplexing, or network striping, allows the construction of a high-bandwidth virtual channel from a collection of multiple low-bandwidth network channels. Striping systems usually employ a packet scheduling policy that allows applications to be oblivious of the way in which packets are routed to specific network channels. Though this is appropriate for many applications, many other applications can benefit from an approach that explicitly involves the application in the determination of the striping policy. Horde is middleware that facilitates flexible striping over Wireless Wide Area Network (WWAN) channels. Horde is unusual in that it separates the striping policy from the striping mechanism. It allows applications to describe network Quality-of-Service (QoS) objectives that the striping mechanism attempts to satisfy. Horde can be used by a set of data streams, each with its own QoS policy, to stripe data over a set of WWAN channels. The WWAN QoS variations observed across different channels and in time, provide opportunities to modulate stream QoS through scheduling

PDR in massive geo-distributed systems

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 165-171).There is an increasing trend toward massive, geographically distributed systems. The largest Internet companies operate hundreds of thousands of servers in multiple geographic locations, and are growing at a fast clip. A single system's servers and data centers can consume many megawatts of electricity, as much as tens of thousands of US homes. Two important concerns have arisen: rising electric bills; and growing carbon footprints. Our work develops a new traffic engineering technique that can be used to address both these areas of concern. We introduce Power-Demand Routing (PDR), a technique that redistributes traffic between replicas with the express purpose of spatially redistributing the system's power consumption, in order to reduce operating costs. Cost can be described in monetary terms or in terms of pollution. Within existing Internet services, each client request requires a meaningful amount of marginal energy at the server. Thus, by rerouting requests from a server at one geographic location to another, we can spatially shift the systems marginal power consumption at Internet speeds. We show how PDR can be used to reduce electric bills. We describe how to couple request routing policy to real-time price signals from wholesale electricity markets. In response to price-differentials, PDR skews client load across a system's clusters and pushes server power-demand into the least expensive regions. Our analysis quantifies the potential reduction in energy costs. We use simulations driven by empirical data and models: we collected a real-world request traffic workload in collaboration with Akamai; constructed data center energy models; and compiled a database of historical electricity market prices. We conclude that existing systems can use PDR to cut their annual electric bills by millions of dollars. We also show how PDR can be used to reduce carbon footprints. Not all joules are created equal and in power pools like the grid the environmental impact per joule varies geographically and in time. We show how to construct carbon cost functions that can be used with PDR to dynamically push a system's power-demand toward clean energy.by Asfandyar Qureshi.Ph.D

Cost and Profit Efficiencies of Fully-Fledged Islamic Banks and Islamic Windows of Conventional Banks in Pakistan

Pakistan is an emerging and an important country in banking and finance. A lot of emphasis has been made on the Islamic banking sector of Pakistan and its growth in the past decade is plausible. It is opening up the market for international investors. This makes the Islamic banking sector of Pakistan interesting and worth analysing. Furthermore, it has not been taken up widely in the academic literature. The purpose of this research is to present a new perspective on the evaluation of x-efficiencies in Pakistani Islamic banking system. As per the knowledge of the author this is the first time such a study has been conducted for Pakistani banks where a comparison has been made between the cost and profit efficiencies of fully-fledged Islamic banks and the Islamic banking windows of the conventional Banks. We have taken up a sample of four fully fledged Islamic Banks and thirteen conventional banks Islamic banking windows. Stochastic frontier approach was applied in the first stage and in the second stage we have used the Tobit model and GMM model to find out the effects of bank specific and macroeconomic variables. On evaluating the efficiencies it was found out that the fully fledged Islamic banking windows were both cost and profit efficient as compared to the Islamic banking windows of conventional banks. We also found out that the Islamic banks were not affected by the recent financial crises of 2007. This research intends to fill the gap and would create a basis for further study on this topic. It would also prove to be useful for the investors as to which type of Islamic bank to invest i.e. fully-fledged Islamic banks or the Islamic banking windows of conventional banks

Exploring Proximity Based Peer Selection in a BitTorrent-like Protocol

BitTorrent [1] is popular file-sharing tool, accounting for a significant proportion of Internet traffic. Files are divided into fragments and transferred out of order among nodes trying to download them. Individual nodes penalize and reward other nodes, adjacent in the BitTorrent overlay, depending on how willing others are to share data. This incentives scheme and the subsequent enforcement of sharing is credited with making BitTorrent outperform other contemporary file-sharing systems. Nonetheless, BitTorrent builds its overlays by randomly selecting peers, a fact that has the potential to seriously handicap both individual performance and waste global network resources. This paper investigates a scheme which attempts to build a more intelligent overlay network, particularly using synthetic network coordinates to select overlay peers that are close by in the underlying network. We evaluate our techniques both from the network’s perspective (resources used) and from the individual’s perspective (average time to complete a download). In both cases, our results show that better peer selection can lead to improved performance with no major changes to the basic BitTorrent protocol. Our evaluation is based on real-world experiments performed over Planet-Lab [2]

Cost and Profit Efficiencies of Fully-Fledged Islamic Banks and Islamic Windows of Conventional Banks in Pakistan

Pakistan is an emerging and an important country in banking and finance. A lot of emphasis has been made on the Islamic banking sector of Pakistan and its growth in the past decade is plausible. It is opening up the market for international investors. This makes the Islamic banking sector of Pakistan interesting and worth analysing. Furthermore, it has not been taken up widely in the academic literature. The purpose of this research is to present a new perspective on the evaluation of x-efficiencies in Pakistani Islamic banking system. As per the knowledge of the author this is the first time such a study has been conducted for Pakistani banks where a comparison has been made between the cost and profit efficiencies of fully-fledged Islamic banks and the Islamic banking windows of the conventional Banks. We have taken up a sample of four fully fledged Islamic Banks and thirteen conventional banks Islamic banking windows. Stochastic frontier approach was applied in the first stage and in the second stage we have used the Tobit model and GMM model to find out the effects of bank specific and macroeconomic variables. On evaluating the efficiencies it was found out that the fully fledged Islamic banking windows were both cost and profit efficient as compared to the Islamic banking windows of conventional banks. We also found out that the Islamic banks were not affected by the recent financial crises of 2007. This research intends to fill the gap and would create a basis for further study on this topic. It would also prove to be useful for the investors as to which type of Islamic bank to invest i.e. fully-fledged Islamic banks or the Islamic banking windows of conventional banks