48,449 research outputs found
Self-Modeling Based Diagnosis of Software-Defined Networks
Networks built using SDN (Software-Defined Networks) and NFV (Network
Functions Virtualization) approaches are expected to face several challenges
such as scalability, robustness and resiliency. In this paper, we propose a
self-modeling based diagnosis to enable resilient networks in the context of
SDN and NFV. We focus on solving two major problems: On the one hand, we lack
today of a model or template that describes the managed elements in the context
of SDN and NFV. On the other hand, the highly dynamic networks enabled by the
softwarisation require the generation at runtime of a diagnosis model from
which the root causes can be identified. In this paper, we propose finer
granular templates that do not only model network nodes but also their
sub-components for a more detailed diagnosis suitable in the SDN and NFV
context. In addition, we specify and validate a self-modeling based diagnosis
using Bayesian Networks. This approach differs from the state of the art in the
discovery of network and service dependencies at run-time and the building of
the diagnosis model of any SDN infrastructure using our templates
Self-Healing Protocols for Connectivity Maintenance in Unstructured Overlays
In this paper, we discuss on the use of self-organizing protocols to improve
the reliability of dynamic Peer-to-Peer (P2P) overlay networks. Two similar
approaches are studied, which are based on local knowledge of the nodes' 2nd
neighborhood. The first scheme is a simple protocol requiring interactions
among nodes and their direct neighbors. The second scheme adds a check on the
Edge Clustering Coefficient (ECC), a local measure that allows determining
edges connecting different clusters in the network. The performed simulation
assessment evaluates these protocols over uniform networks, clustered networks
and scale-free networks. Different failure modes are considered. Results
demonstrate the effectiveness of the proposal.Comment: The paper has been accepted to the journal Peer-to-Peer Networking
and Applications. The final publication is available at Springer via
http://dx.doi.org/10.1007/s12083-015-0384-
Path-Fault-Tolerant Approximate Shortest-Path Trees
Let be an -nodes non-negatively real-weighted undirected graph.
In this paper we show how to enrich a {\em single-source shortest-path tree}
(SPT) of with a \emph{sparse} set of \emph{auxiliary} edges selected from
, in order to create a structure which tolerates effectively a \emph{path
failure} in the SPT. This consists of a simultaneous fault of a set of at
most adjacent edges along a shortest path emanating from the source, and it
is recognized as one of the most frequent disruption in an SPT. We show that,
for any integer parameter , it is possible to provide a very sparse
(i.e., of size ) auxiliary structure that carefully
approximates (i.e., within a stretch factor of ) the true
shortest paths from the source during the lifetime of the failure. Moreover, we
show that our construction can be further refined to get a stretch factor of
and a size of for the special case , and that it can be
converted into a very efficient \emph{approximate-distance sensitivity oracle},
that allows to quickly (even in optimal time, if ) reconstruct the
shortest paths (w.r.t. our structure) from the source after a path failure,
thus permitting to perform promptly the needed rerouting operations. Our
structure compares favorably with previous known solutions, as we discuss in
the paper, and moreover it is also very effective in practice, as we assess
through a large set of experiments.Comment: 21 pages, 3 figures, SIROCCO 201
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