Many delay-based congestion protocols have been proposed. Some recent studies have questioned the validity of congestion prediction at end hosts Based on measurement studies. In this talk, we show that end-host based delay prediction can be more accurate than previously characterized. We propose PERT (Probabilistic Early Response TCP) to mitigate the uncertainties in end-host based congestion prediction. PERT emulates the behavior of AQM/ECN in the end hosts' response to congestion.

This talk addresses the problem of providing throughput guarantees in heterogeneous wireless mesh networks. As a first step, it proposes a novel model to represent the capacity region of a wireless link that, by linearizing this region, has the fundamental property of being very simple while providing a good approximation to the entire region. In a second step, this model is mapped to two of the most prominent wireless technologies nowadays, namely Wireless LAN and WiMAX. The last step addresses the issue of finding optimal routing strategies, which is done by solving an optimization problem subject to the constraints imposed by the linearized capacity region. The performance of the proposed approach has been compared against traditional routing metrics in mesh networks, such as ETT and ETX, and shown to overperform them by approximately a factor of 2.

A substantial amount of work has recently gone into localizing BitTorrent traffic within an ISP in order to avoid excessive and often times unnecessary transit costs. Several architectures and systems have been proposed and the initial results from specific ISPs and a few torrents have been encouraging. In this work we attempt to deepen and scale our understanding of locality and its potential. Looking at specific ISPs, we consider tens of thousands of concurrent torrents, and thus capture ISP-wide implications that cannot be appreciated by looking at only a handful of torrents. Secondly, we go beyond individual case studies and present results for the top 100 ISPs in terms of number of users represented in our dataset of up to 40K torrents involving more than 3.9M concurrent peers and more than 20M in the course of a day spread in 11K ASes. We develop scalable methodologies hat permit us to process this huge dataset and answer questions such as: What is the minimum and the maximum transit traffic reduction across hundreds of ISPs? What are the win-win boundaries for ISPs and their users? What is the maximum amount of transit traffic that can be localized without requiring fine-grained control of inter-AS overlay connections? What is the impact to transit traffic from upgrades of residential broadband speeds?

Existing Swarm-based Peer-to-Peer Streaming (SPS) applications rely on a randomly connected overlays among peers, which tend to generate a significant amount of costly inter-ISP traffic. To reduce such traffic, localization of overlay connectivity within each ISP has received a great deal of attention as a promising approach for reducing the volume of inter-ISP traffic.  

Dr. Sergey Gorinsky (Senior Researcher, IMDEA Networks) Prof. Dr. Arturo Azcorra (Director General for Technology Transfer and Entrepreneurial Development (Spanish Ministry of Science and Innovation) Paul Patras (Research Assistant, IMDEA Networks) Dr. Mary Luz Mouronte (Division Manager, Telefonica Research, Madrid) Dr. Albert Banchs (Deputy Director, IMDEA Networks; Associate Professor, UC3M) Prof. Dr. Narasimha Reddy (Cátedra de Excelencia, University Carlos III of Madrid; Visiting Researcher, IMDEA Networks, Madrid; Texas A&M University, USA) Alejandro Javier Tosina González (Spanish Representative in ICT Committee – EU Framework Programme; CDTI – Ministry of Science and Innovation) Location: Basement Floor, “Sala de Audiovisuales”, Room 3.1.S08, Building: Rey Pastor (Library), University Carlos III of Madrid, Avda. Universidad, 30, 28911 Leganes – Madrid Date: November 11th, 2009, 15:00 – 18:00 Organization: IMDEA Networks in collaboration with the Higher Polytechnic School, University Carlos III of Madrid, Leganes Campus The conference will be conducted in English Advanced registration: rebeca.demiguel imdea.org

The way the Internet works today is that routing protocols select a single path through the network, and transport protocols like TCP then adapt to the properties of that path. So the situation where there are unused paths that remain idle is quite common. The idea behind multipath TCP is to modify TCP so it can send packets over multiple paths at the same time, moving traffic from more congested paths to less congested paths and thus optimizing network utilization and performance.

This talk gives an overview on how different overlay networks can share information among them and some recent results based on an implementation tested on an emulation environment are given.

Interest in underwater acoustic networking research has grown rapidly in the past few years. Fundamental differences between underwater acoustic propagation and terrestrial radio propagation call for new criteria for the design of communications systems and networking protocols. In this talk, we will provide an overview of the main challenges posed by the underwater acoustic propagation environment, with special emphasis on networking and protocol design issues, and provide novel insights that are useful in guiding both protocol design and network deployment. We will then address in more detail some specific examples of how the unique features of underwater propagation and acoustic modems affect protocol design. In particular, we will (1) focus on the energy consumption profile of acoustic modems and its impact on the design of topology control mechanisms and on the trade-off between sleep cycles and wake-up modes, and (2) present a novel energy-efficient routing protocol for underwater networks that explicitly accounts for the relationship between hop distance, bandwidth, and energy consumption.

The peer-to-peer paradigm shows the potential to provide the same functionality like client/server based systems, but with much lower costs. One substantial limitation of p2p systems are missing guarantees on the quality of service, as the whole infrastructure is based on unreliable peers. In order to control the quality of peer-to-peer systems, monitoring and management mechanisms need to be applied. Both tasks are challenging in large-scale networks with autonomous, unreliable nodes.

According to most technology pundits, progress in wireless and sensor networks will lead us into a world of ubiquitous computing, in which myriads of tiny, untethered sensors and actuators will communicate with each other. Information technology will thus deliver its most encompassing and pervasive accomplishment to mankind, promptly taking care of the needs and wishes of everyone.