The Quest for Bandwidth Estimation Techniques for large-scale Distributed Systems

In recent years the research community has developed many techniques to estimate the end-to-end available bandwidth of an Internet path. This important metric has been proposed for use in several distributed systems and, more recently, has even been considered to improve the congestion control mechanism of TCP. Thus, it has been suggested that some existing estimation techniques could be used for this purpose. However, existing tools were not designed for large-scale deployments and were mostly validated in controlled settings, considering only one measurement running at a time. In this paper, we argue that current tools, while offering good estimates when used alone, might not work in large-scale systems where several estimations severely interfere with each other. We analyze the properties of the measurement paradigms employed today and discuss their functioning, study their overhead and analyze their interference. Our testbed results show that current techniques are insufficient as they are. Finally, we will discuss and propose some principles that should be taken into account for including available bandwidth measurements in large-scale distributed systems. 1

Stepping stones and access holidays: the fallacies of regulatory micro-management

Good intentions are no substitute for sound economic regulation. Using the ‘in-vestment ladder’ as the stick and access holidays as the carrot is hardly an ef-fective way to generate competition. On the contrary, this approach creates a regulatory spiral. What regulators plead for today is in effect an obligatory shar-ing regime for nearly all network elements. However, this splitting up of net-works into their elements by ad hoc regulatory interventions is destroying con-sumer welfare. Instead, rule-based regulation of network-specific market power should be implemented by means of a disaggregated regulatory mandate, limit-ing incentive regulation to essential facilities as a whole. --

Pedestrian, Crowd, and Evacuation Dynamics

This contribution describes efforts to model the behavior of individual pedestrians and their interactions in crowds, which generate certain kinds of self-organized patterns of motion. Moreover, this article focusses on the dynamics of crowds in panic or evacuation situations, methods to optimize building designs for egress, and factors potentially causing the breakdown of orderly motion.Comment: This is a review paper. For related work see http://www.soms.ethz.c

A Lesson in Scaling 6LoWPAN -- Minimal Fragment Forwarding in Lossy Networks

This paper evaluates two forwarding strategies for fragmented datagrams in the IoT: hop-wise reassembly and a minimal approach to directly forward fragments. Minimal fragment forwarding is challenged by the lack of forwarding information at subsequent fragments in 6LoWPAN and thus requires additional data at nodes. We compared the two approaches in extensive experiments evaluating reliability, end-to-end latency, and memory consumption. In contrast to previous work and due to our alternate setup, we obtained different results and conclusions. Our findings indicate that direct fragment forwarding should be deployed only with care, since higher packet transmission rates on the link-layer can significantly reduce its reliability, which in turn can even further reduce end-to-end latency because of highly increased link-layer retransmissions.Comment: If you cite this paper, please use the LCN reference: M. S. Lenders, T. C. Schmidt, M. W\"ahlisch. "A Lesson in Scaling 6LoWPAN - Minimal Fragment Forwarding in Lossy Networks." in Proc. of IEEE LCN, 201

Assessing the potential for knowledge-based development in transition countries. Bruegel Working Paper 2010/01, May 2010

This Working Paper by Bruegel Senior Fellow Reinhilde Veugelers examines the potential for a knowledge-based growth path in transition countries of central and eastern Europe, the Caucasus and Central Asia. The paper looks closely at how total-factor productivity, a residual growth factor commonly interpreted as reflecting technological progress, drives growth rates in these economies which exhibit a much lower GDP per capita compared to the EU15 or the United States. By analysing the prerequisites for knowledge-based growth, the author explains why transition countries are at a systemic disadvantage relative to the EU15, US and Japan and have limited potential for knowledge-based growth

DiPerF: an automated DIstributed PERformance testing Framework

We present DiPerF, a distributed performance testing framework, aimed at simplifying and automating service performance evaluation. DiPerF coordinates a pool of machines that test a target service, collects and aggregates performance metrics, and generates performance statistics. The aggregate data collected provide information on service throughput, on service "fairness" when serving multiple clients concurrently, and on the impact of network latency on service performance. Furthermore, using this data, it is possible to build predictive models that estimate a service performance given the service load. We have tested DiPerF on 100+ machines on two testbeds, Grid3 and PlanetLab, and explored the performance of job submission services (pre WS GRAM and WS GRAM) included with Globus Toolkit 3.2.Comment: 8 pages, 8 figures, will appear in IEEE/ACM Grid2004, November 200

Studies in Trade and Investment: The Development Impact of Information Technology in Trade Facilitation

It is important to lay out a framework for understanding how trade facilitation (TF) affects the movement of goods, and where information (IT) fits in. This relationship, in turn, sets the stage for locating small and medium-sized enterprises (SMEs) in international transactions. There is an increasing amount of substantial literature on TF and equally wide knowledge of IT. While it is not the intent of this chapter to survey these materials, to the extent that they are relevant to the following discussion, they will be referred to appropriately. Section A of this chapter elaborates on TF and the wide range of instruments that have been used and analyzed while section B details some actual experiences in the use of IT in TF. Section C examines small and medium-sized enterprises and IT in TF. Section D summarizes this chapter and considers the implications for inclusive growth.Trade facilitation, ICT, IT, SMEs,