4,254 research outputs found
Reliable and timely event notification for publish/subscribe services over the internet
The publish/subscribe paradigm is gaining attention for the development of several applications in wide area networks (WANs) due to its intrinsic time, space, and synchronization decoupling properties that meet the scalability and asynchrony requirements of those applications. However, while the communication in a WAN may be affected by the unpredictable behavior of the network, with messages that can be dropped or delayed, existing publish/subscribe solutions pay just a little attention to addressing these issues. On the contrary, applications such as business intelligence, critical infrastructures, and financial services require delivery guarantees with strict temporal deadlines. In this paper, we propose a framework that enforces both reliability and timeliness for publish/subscribe services over WAN. Specifically, we combine two different approaches: gossiping, to retrieve missing packets in case of incomplete information, and network coding, to reduce the number of retransmissions and, consequently, the latency. We provide an analytical model that describes the information recovery capabilities of our algorithm and a simulation-based study, taking into account a real workload from the Air Traffic Control domain, which evidences how the proposed solution is able to ensure reliable event notification over a WAN within a reasonable bounded time window. © 2013 IEEE
Searching in Unstructured Overlays Using Local Knowledge and Gossip
This paper analyzes a class of dissemination algorithms for the discovery of
distributed contents in Peer-to-Peer unstructured overlay networks. The
algorithms are a mix of protocols employing local knowledge of peers'
neighborhood and gossip. By tuning the gossip probability and the depth k of
the k-neighborhood of which nodes have information, we obtain different
dissemination protocols employed in literature over unstructured P2P overlays.
The provided analysis and simulation results confirm that, when properly
configured, these schemes represent a viable approach to build effective P2P
resource discovery in large-scale, dynamic distributed systems.Comment: A revised version of the paper appears in Proc. of the 5th
International Workshop on Complex Networks (CompleNet 2014) - Studies in
Computational Intelligence Series, Springer-Verlag, Bologna (Italy), March
201
Highly intensive data dissemination in complex networks
This paper presents a study on data dissemination in unstructured
Peer-to-Peer (P2P) network overlays. The absence of a structure in unstructured
overlays eases the network management, at the cost of non-optimal mechanisms to
spread messages in the network. Thus, dissemination schemes must be employed
that allow covering a large portion of the network with a high probability
(e.g.~gossip based approaches). We identify principal metrics, provide a
theoretical model and perform the assessment evaluation using a high
performance simulator that is based on a parallel and distributed architecture.
A main point of this study is that our simulation model considers
implementation technical details, such as the use of caching and Time To Live
(TTL) in message dissemination, that are usually neglected in simulations, due
to the additional overhead they cause. Outcomes confirm that these technical
details have an important influence on the performance of dissemination schemes
and that the studied schemes are quite effective to spread information in P2P
overlay networks, whatever their topology. Moreover, the practical usage of
such dissemination mechanisms requires a fine tuning of many parameters, the
choice between different network topologies and the assessment of behaviors
such as free riding. All this can be done only using efficient simulation tools
to support both the network design phase and, in some cases, at runtime
Mobile Conductance in Sparse Networks and Mobility-Connectivity Tradeoff
In this paper, our recently proposed mobile-conductance based analytical
framework is extended to the sparse settings, thus offering a unified tool for
analyzing information spreading in mobile networks. A penalty factor is
identified for information spreading in sparse networks as compared to the
connected scenario, which is then intuitively interpreted and verified by
simulations. With the analytical results obtained, the mobility-connectivity
tradeoff is quantitatively analyzed to determine how much mobility may be
exploited to make up for network connectivity deficiency.Comment: Accepted to ISIT 201
Data Dissemination in Wireless Networks with Network Coding
We investigate the use of network coding for information dissemination over a
wireless network. Using network coding allows for a simple, distributed and
robust algorithm where nodes do not need any information from their neighbors.
In this paper, we analyze the time needed to diffuse information throughout a
network when network coding is implemented at all nodes. We then provide an
upper bound for the dissemination time for ad-hoc networks with general
topology. Moreover, we derive a relation between dissemination time and the
size of the wireless network. It is shown that for a wireless network with N
nodes, the dissemination latency is between O(N) and O(N^2), depending on the
reception probabilities of the nodes. These observations are validated by the
simulation results
Gossiping with Multiple Messages
This paper investigates the dissemination of multiple pieces of information
in large networks where users contact each other in a random uncoordinated
manner, and users upload one piece per unit time. The underlying motivation is
the design and analysis of piece selection protocols for peer-to-peer networks
which disseminate files by dividing them into pieces. We first investigate
one-sided protocols, where piece selection is based on the states of either the
transmitter or the receiver. We show that any such protocol relying only on
pushes, or alternatively only on pulls, is inefficient in disseminating all
pieces to all users. We propose a hybrid one-sided piece selection protocol --
INTERLEAVE -- and show that by using both pushes and pulls it disseminates
pieces from a single source to users in time, while obeying
the constraint that each user can upload at most one piece in one unit of time,
with high probability for large . An optimal, unrealistic centralized
protocol would take time in this setting. Moreover, efficient
dissemination is also possible if the source implements forward erasure coding,
and users push the latest-released coded pieces (but do not pull). We also
investigate two-sided protocols where piece selection is based on the states of
both the transmitter and the receiver. We show that it is possible to
disseminate pieces to users in time, starting from an
initial state where each user has a unique piece.Comment: Accepted to IEEE INFOCOM 200
Neighbour coverage: a dynamic probabilistic route discovery for mobile ad hoc networks
Blind flooding is extensively use in ad hoc routing protocols for on-demand route discovery, where a mobile node blindly rebroadcasts received route request (RREQ) packets until a route to a particular destination is established. This can potentially lead to high channel contention, causing redundant retransmissions and thus excessive packet collisions in the network. Such a phenomenon induces what is known as broadcast storm problem, which has been shown to greatly increase the network communication overhead and end-to-end delay. In this paper, we show that the deleterious impact of such a problem can be reduced if measures are taken during the dissemination of RREQ packets. We propose a generic probabilistic method for route discovery, that is simple to implement and can significantly reduce the overhead associated with the dissemination of RREQs. Our analysis reveals that equipping AODV with probabilistic route discovery can result in significant reduction of routing control overhead while achieving good throughput
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