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1.
Daniel M. Batista Luciano J. Chaves Nelson L. S. da Fonseca Artur Ziviani 《The Journal of supercomputing》2010,53(1):103-121
Modern large-scale grid computing systems for processing advanced science and engineering applications rely on geographically
distributed clusters. In such highly distributed environments, estimating the available bandwidth between clusters is a key
issue for efficient task scheduling. We analyze the performance of two well known available bandwidth estimation tools, pathload and abget, with the aim of using them in grid environments. Differently than previous investigations (Jain et al., ; Shriram et al., in Passive and active network measurement: 6th international workshop, PAM 2005. Springer, Berlin, 2005), our experiments consider a series of relevant metrics such as accuracy of the estimation, convergence time, degree of intrusion
in the grid links, and ability to handle multiple simultaneous estimations. No previous work has analyzed the use of available
bandwidth tools for the derivation of efficient grid scheduling. 相似文献
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SDN-based architecture for providing quality of service to high-performance distributed applications
Alexandre T. Oliveira Bruno José C. A. Martins Marcelo F. Moreno Antônio Tadeu A. Gomes Artur Ziviani Alex Borges Vieira 《International Journal of Network Management》2021,31(5):e2078
The specification of quality of service (QoS) requirements in most of the existing networks is still challenging. In part, traditional network environments are limited by their high administrative cost, although software-defined networks (SDNs), a newer network paradigm, simplify the management of the whole network infrastructure. In fact, SDN provides a simple way to effectively develop QoS provisioning mechanisms. In this sense, we explore the SDN model and its flexibility to develop a QoS provisioning architecture. Through the use of our new architecture, network operators are able to specify QoS levels in a simple way. Each individual data flow can be addressed, and the architecture we propose also negotiates the QoS requirements between the network controller and applications. On the other hand, the network controller continuously monitors the network environment. Then, it allocates network elements resources and prioritizes traffic, adjusting the network performance. We evaluate the feasibility of our QoS provisioning mechanism by presenting three experimental setups under realistic scenarios. For example, for a given scenario where we evaluate file transfers, our results indicate that the additional SDN modules present negligible overhead. Moreover, for a given setup, we observe a reduction of up to 82% in the file transfer times. 相似文献
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Pedro H.B. Las-Casas Dorgival Guedes Jussara M. Almeida Artur Ziviani Humberto T. Marques-Neto 《Computer Networks》2013,57(2):526-539
Despite the large variety and wide adoption of different techniques to detect and filter unsolicited messages (spams), the total amount of such messages over the Internet remains very large. Some reports point out that around 80% of all emails are spams. As a consequence, significant amounts of network resources are still wasted as filtering strategies are usually performed only at the email destination server. Moreover, a considerable part of these unsolicited messages is sent by users who are unaware of their spamming activity and may thus inadvertently be classified as spammers. In this case, these oblivious users act as spambots, i.e., members of a spamming botnet. This paper proposes a new method for detecting spammers at the source network, whether they are individual malicious users or oblivious members of a spamming botnet. Our method, called SpaDeS, is based on a supervised classification technique and relies only on network-level metrics, thus not requiring inspection of message content. We evaluate SpaDeS using real datasets collected from a Brazilian broadband ISP. Our results show that our method is quite effective, correctly classifying the vast majority (87%) of the spammers while misclassifying only around 2% of the legitimate users. 相似文献
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The main purpose of this article is to provide researchers or practitioners with greater flexibility to analyze their proposed designs for network, protocol, or video coding of MDC video transmission without being obliged to consider a particular tool set for each kind of video-quality evaluation. Therefore, a generalized simulation and evaluation frame work for video transmission is an important and useful tool to the video-coding of networking was found by research community. On the one hand, for video-coding studies, one can simulate the effects of a more realistic network on video sequences resulting from their coding schemes. On the other hand, in networking analysis, one can evaluate the impact of real video streams on proposed network protocols 相似文献
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We propose an efficient proactive data dissemination approach that allows a mobile sink to effectively gather a representative view of a monitored region covered by n sensor nodes by visiting any m nodes, where m << n. Moreover, the proposed strategy allows the mobile sink to follow any trajectory through the deployment region, thus decoupling the data dissemination management from the mobile sink?s trajectory. Index Terms?Random walks; proactive data 相似文献
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The continually growing Web challenges information retrieval systems to deliver data quickly. The authors' technique combines several data compression features to provide economical storage, faster indexing, and accelerated searches 相似文献
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A hash function is a mapping from a key universe U to a range of integers, i.e., h:U?{0,1,…,m−1}, where m is the range's size. A perfect hash function for some set S⊆U is a hash function that is one-to-one on S , where m≥|S|. A minimal perfect hash function for some set S⊆U is a perfect hash function with a range of minimum size, i.e., m=|S|. This paper presents a construction for (minimal) perfect hash functions that combines theoretical analysis, practical performance, expected linear construction time and nearly optimal space consumption for the data structure. For n keys and m=n the space consumption ranges from 2.62n+o(n) to 3.3n+o(n) bits, and for m=1.23n it ranges from 1.95n+o(n) to 2.7n+o(n) bits. This is within a small constant factor from the theoretical lower bounds of 1.44n bits for m=n and 0.89n bits for m=1.23n. We combine several theoretical results into a practical solution that has turned perfect hashing into a very compact data structure to solve the membership problem when the key set S is static and known in advance. By taking into account the memory hierarchy we can construct (minimal) perfect hash functions for over a billion keys in 46 min using a commodity PC. An open source implementation of the algorithms is available at http://cmph.sf.net under the GNU Lesser General Public License (LGPL). 相似文献
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Geolocation of Internet hosts enables a new class of location-aware applications. Previous measurement-based approaches use reference hosts, called landmarks, with a well-known geographic location to provide the location estimation of a target host. This leads to a discrete space of answers, limiting the number of possible location estimates to the number of adopted landmarks. In contrast, we propose Constraint-Based Geolocation (CBG), which infers the geographic location of Internet hosts using multilateration with distance constraints to establish a continuous space of answers instead of a discrete one. However, to use multilateration in the Internet, the geographic distances from the landmarks to the target host have to be estimated based on delay measurements between these hosts. This is a challenging problem because the relationship between network delay and geographic distance in the Internet is perturbed by many factors, including queueing delays and the absence of great-circle paths between hosts. CBG accurately transforms delay measurements to geographic distance constraints, and then uses multilateration to infer the geolocation of the target host. Our experimental results show that CBG outperforms previous geolocation techniques. Moreover, in contrast to previous approaches, our method is able to assign a confidence region to each given location estimate. This allows a location-aware application to assess whether the location estimate is sufficiently accurate for its needs 相似文献