The Experts below are selected from a list of 447318 Experts worldwide ranked by ideXlab platform
Anja Feldmann - One of the best experts on this subject based on the ideXlab platform.
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exploring edns client subnet adopters in your free time
Internet Measurement Conference, 2013Co-Authors: Florian Streibelt, Georgios Smaragdakis, Jan Bottger, Nikolaos Chatzis, Anja FeldmannAbstract:The recently proposed DNS extension, EDNS-Client-Subnet (ECS), has been quickly adopted by major Internet companies such as Google to better assign user requests to their servers and improve end-user experience. In this paper, we show that the adoption of ECS also offers unique, but likely unintended, opportunities to uncover details about these companies' operational practices at almost no cost. A key observation is that ECS allows to resolve domain names of ECS adopters on behalf of any arbitrary IP/prefix in the Internet. In fact, by utilizing only a single residential vantage point and relying solely on publicly available information, we are able to (i) uncover the global footprint of ECS adopters with very little effort, (ii) infer the DNS response cacheability and end-user clustering of ECS adopters for an arbitrary network in the Internet, and (iii) capture snapshots of user to server mappings as practiced by major ECS adopters. While pointing out such new measurement opportunities, our work is also intended to make current and future ECS adopters aware of which operational information gets exposed when utilizing this recent DNS extension.
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enabling content aware traffic engineering
ACM Special Interest Group on Data Communication, 2012Co-Authors: Ingmar Poese, Georgios Smaragdakis, Anja Feldmann, Benjamin Frank, Steve Uhlig, Bruce M MaggsAbstract: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 within an Internet Service Provider (ISP) or the end-user location. On the other hand, ISPs struggle to cope with rapid traffic shifts caused by the dynamic server selection policies of the CDNs. The challenges that CDNs and ISPs face separately can be turned into an opportunity for collaboration. We argue that it is sufficient for CDNs and ISPs to coordinate only in server selection, not routing, in order to perform traffic engineering. To this end, we propose Content-aware Traffic Engineering (CaTE), which dynamically adapts server selection for content hosted by CDNs using ISP recommendations on small time scales. CaTE relies on the observation that by selecting an appropriate server among those available to deliver the content, the path of the traffic in the network can be influenced in a desired way. We present the design and implementation of a prototype to realize CaTE, and show how CDNs and ISPs can jointly take advantage of the already deployed distributed hosting infrastructures and path diversity, as well as the ISP detailed view of the network status without revealing sensitive operational information. By relying on tier-1 ISP traces, we show that CaTE allows CDNs to enhance the end-user experience while enabling an ISP to achieve several traffic engineering goals.
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Energy trade-offs among content delivery architectures
2010 9th Conference of Telecommunication Media and Internet CTTE 2010, 2010Co-Authors: Anja Feldmann, Georgios Smaragdakis, Andreas Gladisch, Mario Kind, Christoph Lange, F.-j. WestphalAbstract:It is envogue to consider how to incorporate various home devices such as set-top boxes into content delivery architectures using the Peer-to-Peer (P2P) paradigm. The hope is to enhance the efficiency of content delivery, e.g., in terms of reliability, availability, throughput, or to reduce the cost of the content delivery platform or to improve the end user experience. While it is easy to point out the benefit of such proposals they usually do not consider the implications with regards to the energy costs. In this paper we explore the energy trade-offs of such P2P architectures, data center architectures, and content distribution networks (CDNs) by building upon an energy consumption model of the transport network and datacenters developed in the context of Internet TV (IPTV). Our results show that a CDN within an ISP is able to minimize the overall power consumption. While a P2P architecture may reduce the power consumption of the service provider it increases the overall energy consumption.
Pablo Rodriguez - One of the best experts on this subject based on the ideXlab platform.
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should internet service providers fear peer assisted content distribution
Internet Measurement Conference, 2005Co-Authors: Thomas Karagiannis, Pablo Rodriguez, Konstantina PapagiannakiAbstract:Recently, peer-to-peer (P2P) networks have emerged as an attractive solution to enable large-scale content distribution without requiring major infrastructure investments. While such P2P solutions appear highly beneficial for content providers and end-users, there seems to be a growing concern among Internet Service Providers (ISPs) that now need to support the distribution cost. In this work, we explore the potential impact of future P2P file delivery mechanisms as seen from three different perspectives: i) the content provider, ii) the ISPs, and iii) individual content consumers. Using a diverse set of measurements including Bit-Torrent tracker logs and payload packet traces collected at the edge of a 20,000 user access network, we quantify the impact of peer-assisted file delivery on end-user experience and resource consumption. We further compare it with the performance expected from traditional distribution mechanisms based on large server farms and Content Distribution Networks (CDNs). While existing P2P content distribution solutions may provide significant benefits for content providers and end-consumers in terms of cost and performance, our results demonstrate that they have an adverse impact on ISPs' costs by shifting the associated capacity requirements from the content providers and CDNs to the ISPs themselves. Further, we highlight how simple "locality-aware" P2P delivery solutions can significantly alleviate the induced cost at the ISPs, while providing an overall performance that approximates that of a perfect world-wide caching infrastructure.
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mar a commuter router infrastructure for the mobile internet
International Conference on Mobile Systems Applications and Services, 2004Co-Authors: Pablo Rodriguez, Rajiv Chakravorty, Julian Chesterfield, Ian Pratt, Suman BanerjeeAbstract:We introduce MAR, a commuter mobile access router infrastructure that exploits wireless diversity (e.g. channel diversity, network diversity, and technology diversity) to provide improved data performance for wireless data users. Our system design stems from the observation that rather than choosing a single wireless service provider (e.g. Sprint, AT&T, BT, Vodafone), a single technology (e.g. GPRS, UMTS, CDMA, 802.11), or a single wireless channel, users can obtain significant benefits by using the multiplicity of choices available. MAR is a wireless multi-homed device that can be placed in moving vehicles (e.g. car, bus, train) to enable high-speed data access. MAR dynamically instantiates new channels based on traffic demand, aggregates the bandwidth and dynamically shifts load from poor quality to better quality channels. MAR, thus, provides a faster, more stable, and reliable communication channel to mobile users.We have implemented and tested the MAR system in our testbed which spans the networks of three different cellular providers. Through our experiments we have performed a detailed evaluation to quantify the benefits of MAR for different protocols and applications. For example, even in highly mobile environments, MAR, on average, improves the end-user experience of web-browsing and streaming applications by a factor of 2.8 and 4.4 respectively. Our results show that significant benefits can be obtained by exploiting the diversity in coverage offered by many cellular operators, different technology networks (e.g. GPRS, CDMA), and diverse wireless channels.
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dynamic parallel access to replicated content in the internet
IEEE ACM Transactions on Networking, 2002Co-Authors: Pablo Rodriguez, Ernst W BiersackAbstract:Popular content is frequently replicated in multiple servers or caches in the Internet to offload origin servers and improve end-user experience. However, choosing the best server is a nontrivial task and a bad choice may provide poor end user experience. In contrast to retrieving a file from a single server, we propose a parallel-access scheme where end users access multiple servers at the same time, fetching different portions of that file from different servers and reassembling them locally. The amount of data retrieved from a particular server depends on the resources available at that server or along the path from the user to the server. Faster servers will deliver bigger portions of a file while slower servers will deliver smaller portions. If the available resources at a server or along the path change during the download of a file, a dynamic parallel access will automatically shift the load from congested locations to less loaded parts (server and links) of the Internet. The end result is that users experience significant speedups and very consistent response times. Moreover, there is no need for complicated server selection algorithms and load is dynamically shared among all servers. The dynamic parallel-access scheme presented in this paper does not require any modifications to servers or content and can be easily included in browsers, peer-to-peer applications or content distribution networks to speed up delivery of popular content.
Srikumar Venugopal - One of the best experts on this subject based on the ideXlab platform.
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Anomaly Detection in Complex Real World Application Systems
IEEE Transactions on Network and Service Management, 2018Co-Authors: Fethi A. Rabhi, Srikumar VenugopalAbstract:The ability to understand application performance and pro-actively manage system state is becoming increasingly important as infrastructure services move toward commodisation models such as cloud computing. The complexity of systems being monitored in large corporations means that detailed component-by-component analysis and/or simulation of behaviour can be impractical. The key problem is to find practical systems management approaches that enable behavioural profiling and detection of anomalous events in complex real world systems. This paper details a system performance measurement method that enables slowdown event detection and characterisation of application behaviour. These measurement techniques can underpin IT service management frameworks such as the IT Infrastructure Library. This enables business to manage the stability and performance of the end-user experience in order to support productivity and effectiveness of business processes. This paper examines anomaly detection efficiency in two case studies using six detection models in a large Australian financial services organisation. The whole of service anomaly detection methodology proposed in this paper was found to be more efficient than alternative individual transaction and whole of service models.
Georgios Smaragdakis - One of the best experts on this subject based on the ideXlab platform.
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exploring edns client subnet adopters in your free time
Internet Measurement Conference, 2013Co-Authors: Florian Streibelt, Georgios Smaragdakis, Jan Bottger, Nikolaos Chatzis, Anja FeldmannAbstract:The recently proposed DNS extension, EDNS-Client-Subnet (ECS), has been quickly adopted by major Internet companies such as Google to better assign user requests to their servers and improve end-user experience. In this paper, we show that the adoption of ECS also offers unique, but likely unintended, opportunities to uncover details about these companies' operational practices at almost no cost. A key observation is that ECS allows to resolve domain names of ECS adopters on behalf of any arbitrary IP/prefix in the Internet. In fact, by utilizing only a single residential vantage point and relying solely on publicly available information, we are able to (i) uncover the global footprint of ECS adopters with very little effort, (ii) infer the DNS response cacheability and end-user clustering of ECS adopters for an arbitrary network in the Internet, and (iii) capture snapshots of user to server mappings as practiced by major ECS adopters. While pointing out such new measurement opportunities, our work is also intended to make current and future ECS adopters aware of which operational information gets exposed when utilizing this recent DNS extension.
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enabling content aware traffic engineering
ACM Special Interest Group on Data Communication, 2012Co-Authors: Ingmar Poese, Georgios Smaragdakis, Anja Feldmann, Benjamin Frank, Steve Uhlig, Bruce M MaggsAbstract: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 within an Internet Service Provider (ISP) or the end-user location. On the other hand, ISPs struggle to cope with rapid traffic shifts caused by the dynamic server selection policies of the CDNs. The challenges that CDNs and ISPs face separately can be turned into an opportunity for collaboration. We argue that it is sufficient for CDNs and ISPs to coordinate only in server selection, not routing, in order to perform traffic engineering. To this end, we propose Content-aware Traffic Engineering (CaTE), which dynamically adapts server selection for content hosted by CDNs using ISP recommendations on small time scales. CaTE relies on the observation that by selecting an appropriate server among those available to deliver the content, the path of the traffic in the network can be influenced in a desired way. We present the design and implementation of a prototype to realize CaTE, and show how CDNs and ISPs can jointly take advantage of the already deployed distributed hosting infrastructures and path diversity, as well as the ISP detailed view of the network status without revealing sensitive operational information. By relying on tier-1 ISP traces, we show that CaTE allows CDNs to enhance the end-user experience while enabling an ISP to achieve several traffic engineering goals.
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Energy trade-offs among content delivery architectures
2010 9th Conference of Telecommunication Media and Internet CTTE 2010, 2010Co-Authors: Anja Feldmann, Georgios Smaragdakis, Andreas Gladisch, Mario Kind, Christoph Lange, F.-j. WestphalAbstract:It is envogue to consider how to incorporate various home devices such as set-top boxes into content delivery architectures using the Peer-to-Peer (P2P) paradigm. The hope is to enhance the efficiency of content delivery, e.g., in terms of reliability, availability, throughput, or to reduce the cost of the content delivery platform or to improve the end user experience. While it is easy to point out the benefit of such proposals they usually do not consider the implications with regards to the energy costs. In this paper we explore the energy trade-offs of such P2P architectures, data center architectures, and content distribution networks (CDNs) by building upon an energy consumption model of the transport network and datacenters developed in the context of Internet TV (IPTV). Our results show that a CDN within an ISP is able to minimize the overall power consumption. While a P2P architecture may reduce the power consumption of the service provider it increases the overall energy consumption.
Erik Elmroth - One of the best experts on this subject based on the ideXlab platform.
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adaptive anomaly detection in performance metric streams
IEEE Transactions on Network and Service Management, 2018Co-Authors: Olumuyiwa Ibidunmoye, Alireza Rezaie, Erik ElmrothAbstract:Continuous detection of performance anomalies such as service degradations has become critical in cloud and Internet services due to impact on quality of service and end-user experience. However, the volume and fast changing behavior of metric streams have rendered it a challenging task. Many diagnosis frameworks often rely on thresholding with stationarity or normality assumption, or on complex models requiring extensive offline training. Such techniques are known to be prone to spurious false-alarms in online settings as metric streams undergo rapid contextual changes from known baselines. Hence, we propose two unsupervised incremental techniques following a two-step strategy. First, we estimate an underlying temporal property of the stream via adaptive learning and, then we apply statistically robust control charts to recognize deviations. We evaluated our techniques by replaying over 40 time-series streams from the Yahoo! Webscope S5 datasets as well as four other traces of real Web service QoS and ISP traffic measurements. Our methods achieve high detection accuracy and few false-alarms, and better performance in general compared to an open-source package for time-series anomaly detection.