AKQUI, a tool for passive network traffic measurement, consists of dedicated hardware measurement equipment and a software framework for traffic analysis. The purpose of AKQUI is to gather network traffic over a long ...
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AKQUI, a tool for passive network traffic measurement, consists of dedicated hardware measurement equipment and a software framework for traffic analysis. The purpose of AKQUI is to gather network traffic over a long period of time and to extensively analyze the recorded traffic. It is well suited for the use in telecom network laboratories. An overview of the hardware and software of AKQUI is given, and then some measurement results obtained from recording the traffic of a multimedia (audio and video) teleteaching lecture are presented.
We present a token-based accounting mechanism that alleviates the free riding problem in P2P networks. The approach is complemented by distributed pricing as a flexible and viable scheme to incite users to share valua...
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We present a token-based accounting mechanism that alleviates the free riding problem in P2P networks. The approach is complemented by distributed pricing as a flexible and viable scheme to incite users to share valuable content and to efficiently balance requests among all peers based on economic decisions.
SHARK is a novel concept and middleware service for search in peer-to-peer (P2P) networks. Rather than flooding a network like Gnutella or imposing numerical IDs on objects like distributed hash tables, it is based on...
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SHARK is a novel concept and middleware service for search in peer-to-peer (P2P) networks. Rather than flooding a network like Gnutella or imposing numerical IDs on objects like distributed hash tables, it is based on directed routing of keywords in a multidimensional redundant metadata hierarchy. SHARK arranges nodes and objects in the network and in semantic clusters. In spite of its rich keyword search capabilities, it achieves a high degree of scalability, outperforming random networks by several orders of magnitude. It can easily be adopted for applications as diverse as file sharing, P2P trading, or distributed expert and knowledge market places.
There is an emerging need for content management systems (CMS) enabling collaborative development, administration, and distribution of content over the Internet. Many CMS solutions are currently based on a client/serv...
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There is an emerging need for content management systems (CMS) enabling collaborative development, administration, and distribution of content over the Internet. Many CMS solutions are currently based on a client/server architecture with a central server for storage and management. While such centralized systems simplify management with respect to data consistency, security, and accountability, they lack scalability and reliability. Pure peer-to-peer (P2P) network architectures are based on the assumption that no central server exists and has to be relied on, since peers collaboratively provide content and core system functionality that would be provided otherwise by a single server. A P2P-based CMS scales much better, since available system resources increase linearly with the number of participating peers. In addition, the availability of the system can be raised without much effort, by increasing the redundancy of content across the peer.
We consider the version of broadcast scheduling where a server can transmit one message of a given set at each time-step, answering previously made requests for that message. The goal is to minimize the average respon...
ISBN:
(纸本)9780898715132
We consider the version of broadcast scheduling where a server can transmit one message of a given set at each time-step, answering previously made requests for that message. The goal is to minimize the average response time if the amount of requests is known in advance for each time-step and message. We prove that this problem is NP-hard, thus answering an open question stated by Kalyanasundaram, Pruhs and Velauthapillai (Proceedings of ESA 2000, LNCS 1879, 2000, pp. 290-301). Furthermore, we present an approximation algorithm that is allowed to send several messages at once. Using 6 channels for transmissions, the algorithm achieves an average response time that is at least as good as the optimal solution using one channel. The best previous approximation algorithm achieved ratio 1.5 with 6 channels and reached ratio 1 only in the case where there are as many channels as *** the NP-hardness of broadcast scheduling we derive a new inapproximability result of (2-ε, 1) for the (congestion,cost) bicriteria version of the single source unsplittable min-cost flow problem, for arbitrary ε > 0. The result holds even in the often considered case where the maximum demand is less than or equal to the minimum edge capacity (dmax ≤ umin), a case for which an algorithm with ratio (3, 1) was presented by Skutella.
Distributed denial-of-service attacks are still a big threat to the Internet. Several proposals for coping with the attacks have been made, but none are successful by themselves. In this paper, we present a system tha...
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Distributed denial-of-service attacks are still a big threat to the Internet. Several proposals for coping with the attacks have been made, but none are successful by themselves. In this paper, we present a system that helps to defend a network from DDoS attacks. In addition to state of the art active and passive security defences, we propose a honeypot for such attacks. The goal is to simulate convincingly success of the compromise of a system to a potential DDoS attacker. Thereby, we can implement lessons learned by the honeypot in other systems to strengthen them against such attacks. On the other hand, we protect the rest of our network infrastructure from the impact of such an attack.
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