37 research outputs found
The heterogeneity of inter-contact time distributions: its importance for routing in delay tolerant networks
Prior work on routing in delay tolerant networks (DTNs) has commonly made the
assumption that each pair of nodes shares the same inter-contact time
distribution as every other pair. The main argument in this paper is that
researchers should also be looking at heterogeneous inter-contact time
distributions. We demonstrate the presence of such heterogeneity in the
often-used Dartmouth Wi-Fi data set. We also show that DTN routing can benefit
from knowing these distributions. We first introduce a new stochastic model
focusing on the inter-contact time distributions between all pairs of nodes,
which we validate on real connectivity patterns. We then analytically derive
the mean delivery time for a bundle of information traversing the network for
simple single copy routing schemes. The purpose is to examine the theoretic
impact of heterogeneous inter-contact time distributions. Finally, we show that
we can exploit this user diversity to improve routing performance.Comment: 6 page
Evaluating Mobility Pattern Space Routing for DTNs
Because a delay tolerant network (DTN) can often be partitioned, the problem
of routing is very challenging. However, routing benefits considerably if one
can take advantage of knowledge concerning node mobility. This paper addresses
this problem with a generic algorithm based on the use of a high-dimensional
Euclidean space, that we call MobySpace, constructed upon nodes' mobility
patterns. We provide here an analysis and the large scale evaluation of this
routing scheme in the context of ambient networking by replaying real mobility
traces. The specific MobySpace evaluated is based on the frequency of visit of
nodes for each possible location. We show that the MobySpace can achieve good
performance compared to that of the other algorithms we implemented, especially
when we perform routing on the nodes that have a high connection time. We
determine that the degree of homogeneity of mobility patterns of nodes has a
high impact on routing. And finally, we study the ability of nodes to learn
their own mobility patterns.Comment: IEEE INFOCOM 2006 preprin
Adaptive Robust Traffic Engineering in Software Defined Networks
One of the key advantages of Software-Defined Networks (SDN) is the
opportunity to integrate traffic engineering modules able to optimize network
configuration according to traffic. Ideally, network should be dynamically
reconfigured as traffic evolves, so as to achieve remarkable gains in the
efficient use of resources with respect to traditional static approaches.
Unfortunately, reconfigurations cannot be too frequent due to a number of
reasons related to route stability, forwarding rules instantiation, individual
flows dynamics, traffic monitoring overhead, etc.
In this paper, we focus on the fundamental problem of deciding whether, when
and how to reconfigure the network during traffic evolution. We propose a new
approach to cluster relevant points in the multi-dimensional traffic space
taking into account similarities in optimal routing and not only in traffic
values. Moreover, to provide more flexibility to the online decisions on when
applying a reconfiguration, we allow some overlap between clusters that can
guarantee a good-quality routing regardless of the transition instant.
We compare our algorithm with state-of-the-art approaches in realistic
network scenarios. Results show that our method significantly reduces the
number of reconfigurations with a negligible deviation of the network
performance with respect to the continuous update of the network configuration.Comment: 10 pages, 8 figures, submitted to IFIP Networking 201
MakeSense: Managing Reproducible WSNs Experiments
International audienceWireless Sensor Networks (WSN) users often use simulation campaigns before real deployment to evaluate performance and to fine- tune application and network parameters. This process requires repeating the same experiments under similar conditions and to collect, parse and present data efficiently. This paper introduces MakeSense: a tool that automates this workflow and that allows reproducing simulations easily by defining the whole experiment and post-processing steps in a single JSON configuration file, easy to share and to modify. MakeSense also provides interfaces to interact with a running simulation, allowing to send external stimuli and to collect data in real time. MakeSense currently runs over the COOJA simulator, but has been built to be easily adapted to other architectures, including real testbeds
Modèle de propagation opportuniste pour soulager l'infrastructure 3G
International audienceNous étudions la diffusion massive de contenus en déplaçant une partie du trafic du réseau d'infrastructure 3G vers un réseau opportuniste sans pour autant sacrifier la fiabilité. Dans ce papier, nous étudions un modèle de propagation de messages dans un réseau opportuniste afin de pouvoir prédire l'évolution de la prochaine propagation et calculer le nombre optimal de copies à injecter dans le réseau au début d'une diffusion
Fair Coflow Scheduling via Controlled Slowdown
The average coflow completion time (CCT) is the
standard performance metric in coflow scheduling. However,
standard CCT minimization may introduce unfairness between
the data transfer phase of different computing jobs. Thus, while
progress guarantees have been introduced in the literature to
mitigate this fairness issue, the trade-off between fairness and
efficiency of data transfer is hard to control.
This paper introduces a fairness framework for coflow scheduling based on the concept of slowdown, i.e., the performance loss
of a coflow compared to isolation. By controlling the slowdown it
is possible to enforce a target coflow progress while minimizing
the average CCT. In the proposed framework, the minimum
slowdown for a batch of coflows can be determined in polynomial
time. By showing the equivalence with Gaussian elimination,
slowdown constraints are introduced into primal-dual iterations
of the CoFair algorithm. The algorithm extends the class of the
σ-order schedulers to solve the fair coflow scheduling problem
in polynomial time. It provides a 4-approximation of the average
CCT w.r.t. an optimal scheduler. Extensive numerical results
demonstrate that this approach can trade off average CCT
for slowdown more efficiently than existing state of the art
schedulers