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We present an attack to locate hidden servers in anonymous common networks. The attack is based on correlating the flow of messages that arrives to a certain server with the flow that is created by the attacker client. The fingerprint is constructed by sending requests, each request determines one interval. To improve the performance a prediction of the time of arrival is done for each request. We...
Implications of implementing a local storage within Passive Optical Networks to enhance Video-on-Demand delivery are critically examined in this work. We conduct packet level simulations in order to study enhancements of Quality of Service attributes. Two architectures where the Passive Optical Network is equipped with and without a local storage server are simulated to study the behavior of packet...
Several approaches for fault-tolerance in distributed systems were introduced; however, they require prior knowledge of the environment's operating conditions and/or constant monitoring of these conditions at run time. That allows the applications to adjust the load and redistribute the tasks when failures occur. These techniques work well when there is no high communication delay. Yet, this is not...
Cloud computing has been a revolutionary force in changing the way organizations deploy web applications and services. However, many of cloud computing's core design tenets, such as consolidating resources into a small number of datacenters and fine-grain partitioning of general purpose computing resources, conflict with an emerging class of multimedia applications that is highly latency sensitive...
Base station (BS) sleep mode operation is one of the effective ways to save energy, but it may lead to longer delay to the customers. In order to evaluate the tradeoffs between energy consumption and customer delay, we model the BS sleep mode operation as an N-policy M/G/1 vacation queue with setup and close-down times, where the BS enters sleep mode if no customers arrive during the close-down time...
Streaming services have grown rapidly in the last few years and providers of video on-demand, such as Netflix or YouTube, are increasing the number of users even more quickly. The majority of these companies implement their services using huge Content Delivery Networks that are as much powerful as expensive, e.g. Amazon and Akamai. In this paper we propose a hybrid CDN/P2P solution that aims at reducing...
In high bandwidth, low latency data center networks, when multiple data senders simultaneously communicate with a single receiver, namely in many-to-one communication pattern, the burst data overload the receiver's switch buffers, which leads to TCP throughput collapse. That is so-called TCP In cast problem. It has become a new hot research topic in recent years. And, many proposals have been put...
This paper investigates and compares the performance of the popular VoIP codecs G.711, G.723.1 and G.729A over an IP network based on SIP architecture, using RTP as a transport protocol. This is based on different simulations in order to evaluate the performance of each codec and to find the optimal codec. For this objective this paper analyzes Quality of service (QoS) parameters, principally delay,...
Architectures for information-centric networks (ICNs), like CCN, propose simple on-path caching with LRU cache management for caching of data items in the network. We propose alternative strategies, based on off-path caching, which try to avoid redundant caching of data items to use cache space more efficiently. Based on a mathematical model for LRU and LFU cache management and a simulation, we analyze...
Cloud computing is a consolidation environment that hosts heterogeneous applications. Currently, clouds use virtualization technologies to provide an isolated execution environment and agile resource provisioning. Furthermore, live migration is widely exploited to achieve energy saving. However, consolidation and live migration can cause resource contention and utilization overhead that influence...
The goal of this work is to characterize scientific data transfers and to determine the suitability of dynamic virtual circuit service for these transfers instead of the currently used IP-routed service. Specifically, logs collected by servers executing a commonly used scientific data transfer application, GridFTP, are obtained from three US super-computing/scientific research centers, NERSC, SLAC,...
Replication techniques that tolerate byzantine failures have been applied in distributed computing to cope with hostile environments in which system components may fail due to malicious or natural causes (e.g., intrusions). From the seminal work of Lamport, Pease and Shostak on Byzantine Generals, in 1982, Castro and Liskov proposed in 1999 a successful solution, named PBFT, which overcomes performance...
To alleviate the growing concern of energy waste in networked devices, we propose an energy saving strategy in the ``server-centric" data center network. Focusing on servers, we introduce a basic scheme based on the transition of automata. By changing efficiently from sleeping state to active state in different network traffic, servers save the energy. This scheme is self-adaptive and simple...
Live streaming distribution services have spread as one of the most popular services. The technique of creating contents has been developed, and users can use it easily. Accordingly, the number of contents rapidly increased. In the existing content distribution system, users must select an interesting content from a large amount of contents in the Internet. It takes long time to find out the most...
In distributed systems, a group of multiple processes are required to cooperate with each other to achieve some objectives. In this paper, we consider a distributed system where there is o centralized coordinator. Each member process is peer, i.e. each peer has to autonomously make a decision by itself through communicating with other peers in a group. Each peer sends a message to every peer and every...
Bandwidth aggregation of heterogeneous wireless links faces numerous challenges in maximizing available connectivity services for mobile applications. One serious issue is the out-of-sequence arrival of packets at receiver that is amplified by distribution of packets of a flow over multiple paths. These packets experience asymmetric path characteristics that results in diverse congestion states for...
Content delivery networks have been widely used for many years providing service for millions of users. Lately, many of these networks are migrating to the cloud for its numerous advantages such as lower costs, increased performance, availability and flexibility in installing new resources. This paper introduces a new approach towards load balancing as well as power reduction in cloud-based content...
This paper explores possible advantages of the Information Centric Networking (ICN) paradigm in a geostationary satellite network. We find out that, with respect to plain HTTP services, ICN makes possible to reduce the downstream bandwidth consumed for Internet access by better exploiting the temporal locality of references within requested streams of Web contents. We present an ICN satellite architecture,...
VoIP (Voice over Internet) provides delivery of voice information over unsecured IP-based networks like the Internet. VoIP data, signaling and voice, needs to be secured in such an environment. Security mechanisms take their toll on VoIP system performance. SIP is dominant signaling protocol for VoIP. This paper measures relative decrease in VoIP performance of system with secured SIP signaling over...
In a scenario where service reliability is achieved through multiple providers, it is crucial to detect faulty equipment. Such a scenario is the IP Multimedia Core Network Subsystem (IMS). where service is provided by multiple instances of the Application Server (AS). These servers may reside on remote locations, and network link between the Call Session Control Function (CSCF) and AS may become broken...
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