The technological advancement and information overload in recent years increased the popularity of Distributed Storage Systems where the data is replicated and maintained at multiple disks or servers residing at different network locations. While replication is sufficient to ensure data survivability, it raises an important question: "How can we efficiently maintain consistency among the replicas, despite system asynchrony and failures?"
 

As wireless ad hoc networking becomes more and more popular and ad hoc networks are used for an increasing number of applications, the integration of these networks in today's Internet, still mostly organized as a set of interconnected fixed and wired networks, becomes a key research field in the computer networking domain.

The Madrid Audiovisual Cluster is a member of the steering committee of BROADCAST, the professional forum for audiovisual technology, which this year is adopting a new approach: the event will experience a quantum leap from the traditional exhibition of products to the proposal of emerging solutions and contents. In this manner, BROADCAST aims to adapt to the specificities of the audiovisual technology industry today.

Inter-domain traffic engineering is an important aspect of network operation both technically and economically. Traffic engineering the outbound direction is less problematic as routers under the control of the network operator are responsible for the way traffic leaves the network. The inbound direction is considerably harder as the way traffic enters a network is based on routing decisions in other networks.

It is notoriously difficult to make distributed systems reliable. This becomes even harder in the case of the widely-deployed systems that are heterogeneous (multiple implementations) and federated (multiple administrative entities). The set of routers in charge of the Internet's inter-domain routing is a prime example of such a system.

In this paper we design, characterize in closed-form, and evaluate a new index rule for Markovian time-varying channels, which gives rise to a simple opportunistic scheduling rule for flow-level scheduling in wireless downlink systems. For user channels we employ the Gilbert-Elliot model with a flow-level interpretation: the channel condition follows a general two-state Markov chain with distinct probabilities of finishing the flow transmission.

Sleep modes are emerging as a promising technique for energy-efficient networking: by adequately putting to sleep and waking up network resources according to traffic demands, proportionality between energy consumption and network utilization can be approached, with important reductions in energy consumption. Previous studies have investigated and evaluated sleep modes for wireless access networks, computing variable percentages of energy savings.

Distributed Opportunistic Scheduling (DOS) techniques have been recently proposed to improve the throughput performance of wireless networks. With DOS, each station contends for the channel with a certain access probability. If a contention is successful, the station measures the channel conditions and transmits in case the channel quality is above a certain threshold.

A majority of ISPs (Internet Service Providers) support connectivity to the entire Internet by transiting their traffic via other providers. Although the transit prices per Mbps decline steadily, the overall transit costs of these ISPs remain high or even increase, due to the traffic growth. The discontent of the ISPs with the high transit costs has yielded notable innovations such as peering, content distribution networks, multicast, and peer-to-peer localization.

The injection of artificially fragmented prefixes through BGP is a widely used traffic engineering technique. In this paper we examine one particular economic side-effect of deaggregation, namely the impact on the transit traffic bill. We show that the use of more-specific prefixes has a traffic stabilization side-effect which translates into a decrease of the transit traffic bill. We propose an analytical model in order to quantify the impact of deaggregation on the transit costs. We validate our results by means of simulations and through the extensive analysis of real BGP routing information data.