4,983 research outputs found
CATS: linearizability and partition tolerance in scalable and self-organizing key-value stores
Distributed key-value stores provide scalable, fault-tolerant, and self-organizing
storage services, but fall short of guaranteeing linearizable consistency
in partially synchronous, lossy, partitionable, and dynamic networks, when data
is distributed and replicated automatically by the principle of consistent hashing.
This paper introduces consistent quorums as a solution for achieving atomic
consistency. We present the design and implementation of CATS, a distributed
key-value store which uses consistent quorums to guarantee linearizability and partition tolerance in such adverse and dynamic network conditions. CATS is
scalable, elastic, and self-organizing; key properties for modern cloud storage
middleware. Our system shows that consistency can be achieved with practical
performance and modest throughput overhead (5%) for read-intensive workloads
Measurement Based Reconfigurations in Optical Ring Metro Networks
Single-hop wavelength division multiplexing (WDM) optical ring networks operating in packet mode are one of themost promising architectures for the design of innovative metropolitan network (metro) architectures. They permit a cost-effective design, with a good combination of optical and electronic technologies, while supporting features like restoration and reconfiguration that are essential in any metro scenario. In this article, we address the tunability requirements that lead to an effective resource usage and permit reconfiguration in optical WDM metros.We introduce reconfiguration algorithms that, on the basis of traffic measurements, adapt the network configuration to traffic demands to optimize performance. Using a specific network architecture as a reference case, the paper aims at the broader goal of showing which are the advantages fostered by innovative network designs exploiting the features of optical technologies
Electric Vehicles Charging Control based on Future Internet Generic Enablers
In this paper a rationale for the deployment of Future Internet based
applications in the field of Electric Vehicles (EVs) smart charging is
presented. The focus is on the Connected Device Interface (CDI) Generic Enabler
(GE) and the Network Information and Controller (NetIC) GE, which are
recognized to have a potential impact on the charging control problem and the
configuration of communications networks within reconfigurable clusters of
charging points. The CDI GE can be used for capturing the driver feedback in
terms of Quality of Experience (QoE) in those situations where the charging
power is abruptly limited as a consequence of short term grid needs, like the
shedding action asked by the Transmission System Operator to the Distribution
System Operator aimed at clearing networks contingencies due to the loss of a
transmission line or large wind power fluctuations. The NetIC GE can be used
when a master Electric Vehicle Supply Equipment (EVSE) hosts the Load Area
Controller, responsible for managing simultaneous charging sessions within a
given Load Area (LA); the reconfiguration of distribution grid topology results
in shift of EVSEs among LAs, then reallocation of slave EVSEs is needed.
Involved actors, equipment, communications and processes are identified through
the standardized framework provided by the Smart Grid Architecture Model
(SGAM).Comment: To appear in IEEE International Electric Vehicle Conference (IEEE
IEVC 2014
Joint Energy Efficient and QoS-aware Path Allocation and VNF Placement for Service Function Chaining
Service Function Chaining (SFC) allows the forwarding of a traffic flow along
a chain of Virtual Network Functions (VNFs, e.g., IDS, firewall, and NAT).
Software Defined Networking (SDN) solutions can be used to support SFC reducing
the management complexity and the operational costs. One of the most critical
issues for the service and network providers is the reduction of energy
consumption, which should be achieved without impact to the quality of
services. In this paper, we propose a novel resource (re)allocation
architecture which enables energy-aware SFC for SDN-based networks. To this
end, we model the problems of VNF placement, allocation of VNFs to flows, and
flow routing as optimization problems. Thereafter, heuristic algorithms are
proposed for the different optimization problems, in order find near-optimal
solutions in acceptable times. The performance of the proposed algorithms are
numerically evaluated over a real-world topology and various network traffic
patterns. The results confirm that the proposed heuristic algorithms provide
near optimal solutions while their execution time is applicable for real-life
networks.Comment: Extended version of submitted paper - v7 - July 201
- …