Georgios Smaragdakis

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— We study the impact of heterogeneity of nodes, in terms of their energy, in wireless sensor networks that are hierarchically clustered. In these networks some of the nodes become cluster heads, aggregate the data of their cluster members and transmit it to the sink. We assume that a percentage of the population of sensor nodes is equipped with additional(More)
The Domain Name System (DNS) is a fundamental building block of the Internet. Today, the performance of more and more applications depend not only on the responsiveness of DNS, but also the exact answer returned by the queried DNS resolver, e.g., for Content Distribution Networks (CDN). In this paper, we compare local DNS resolvers against GoogleDNS and(More)
Today a spectrum of solutions are available for istributing content over the Internet, ranging from commercial CDNs to ISP-operated CDNs to content-provider-operated CDNs to peer-to-peer CDNs. Some deploy servers in just a few large data centers while others deploy in thousands of locations or even on millions of desktops. Recently, major CDNs have formed(More)
Many emerging scientific and industrial applications require transferring multiple Tbytes of data on a daily basis. Examples include pushing scientific data from particle accelerators/colliders to laboratories around the world, synchronizing data-centers across continents, and replicating collections of high definition videos from events taking place at(More)
Internet eXchange Points (IXPs) are generally considered to be the successors of the four Network Access Points (NAPs) that were mandated as part of the decommissioning of the National Science Foundation Network (NSFNET) in 1994/95 to facilitate the transition from the NSFNET to the "public Internet" as we know it today. While this popular view does not(More)
In a typical overlay network for routing or content sharing, each node must select a fixed number of immediate overlay neighbors for routing traffic or content queries. A selfish node entering such a network would select neighbors so as to minimize the weighted sum of expected access costs to all its destinations. Previous work on selfish neighbor selection(More)
We introduce an Internet traffic anomaly detection mechanism based on large deviations results for empirical measures. Using past traffic traces we characterize network traffic during various time-of-day intervals, assuming that it is anomaly-free. We present two different approaches to characterize traffic: (i) a model-free approach based on the method of(More)
Today, a large fraction of Internet traffic is originated by Content Delivery Networks (CDNs). To cope with increasing demand for content, CDNs have deployed massively distributed infrastructures. These deployments pose challenges for CDNs as they have to dynamically map end-users to appropriate servers without being full+y aware of the network conditions(More)
Recent studies show that a large fraction of Internet traffic is originated by Content Providers (CPs) such as content distribution networks and hyper-giants. To cope with the increasing demand for content, CPs deploy massively distributed server infrastructures. Thus, content is available in many network locations and can be downloaded by traversing(More)
As the Internet continues to grow both in size and in terms of the volume of traffic it carries, more and more networks in the different parts of the world are relying on an increasing number of distinct ways to exchange traffic with one another. As a result, simple questions such as " What is the application mix in today's Internet? " may produce(More)