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The accuracy provided by traditional sampling-based monitoring approaches, such as NetFlow, is increasingly being considered insufficient to meet the requirements of today's networks. By summarizing all traffic for specific statistics of interest, sketch-based alternatives have been shown to achieve higher levels of accuracy for the same cost. Existing switches, however, lack the necessary capability...
MapReduce is a popular distributed data-processing system for analyzing big data in cloud environments. This platform is often used for critical data processing, e.g., in the context of scientific or financial simulation. Unfortunately, there is accumulating evidence of severe problems - including arbitrary faults and cloud outages - affecting the services that run atop cloud services. Faced with...
MapReduce is a framework for processing large data sets much used in the context of cloud computing. MapReduce implementations like Hadoop can tolerate crashes and file corruptions, but not arbitrary faults. Unfortunately, there is evidence that arbitrary faults do occur and can affect the correctness of MapReduce job executions. Furthermore, many outages of major cloud offerings have been reported,...
Scalable and fault-tolerant distributed Software-Defined Networking (SDN) controllers usually give up strong consistency for the network state, adopting instead the more efficient eventually consistent storage model. This decision is mostly due to the performance overhead of the strongly consistent replication protocols (e.g., Paxos, RAFT), which limits the responsiveness and scalability of network...
Recent SDN-based solutions give cloud providers the opportunity to extend their “as-a-service” model with the offer of complete network virtualization. They provide tenants with the freedom to specify the network topologies and addressing schemes of their choosing, while guaranteeing the required level of isolation among them. These platforms, however, have been targeting the datacenter of a single...
Applications such as web search and social networking have been moving from centralized to decentralized cloud architectures to improve their scalability. MapReduce, a programming framework for processing large amounts of data using thousands of machines in a single cloud, also needs to be scaled out to multiple clouds to adapt to this evolution. The challenge of building a multi-cloud distributed...
The rapid growth of IPTV services and the resulting increase in traffic volumes is raising concerns over energy consumption. In this paper we propose to save energy by shifting particular IPTV traffic from power-hungry electronic routing to greener optical switching. The traffic profile of IPTV results in such a hybrid switching approach to allow both energy and bandwidth efficiencies. To achieve...
The Internet has led to the creation of a digital society, where (almost) everything is connected and is accessible from anywhere. However, despite their widespread adoption, traditional IP networks are complex and very hard to manage. It is both difficult to configure the network according to predefined policies, and to reconfigure it to respond to faults, load, and changes. To make matters even...
One of the major concerns of IPTV network deployment is channel switching (or zapping) delay. This delay can add up to two seconds or more, and its main culprits are synchronisation and buffering. By analysing an extensive dataset - comprising 255 thousand users, 150 TV channels, and covering a 6-month period - we have observed that most channel switching events are linear: it is very common the user...
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