21,547 research outputs found
CLON: overlay networks and gossip protocols for cloud environments
Although epidemic or gossip-based multicast is a robust and scalable approach to reliable data dissemination, its inherent redundancy results in high resource consumption on both links and nodes. This problem is aggravated in settings that have costlier or resource constrained links as happens in Cloud Computing infrastructures composed by several interconnected data centers across the globe.
The goal of this work is therefore to improve the efficiency of gossip-based reliable multicast by reducing the load imposed on those constrained links. In detail, the proposed clon protocol combines an overlay that gives preference to local links and a dissemination strategy that takes into account locality. Extensive experimental evaluation using a very large number of simulated nodes shows that this results in a reduction of traffic in constrained links by an order of magnitude, while at the same time preserving the resilience properties that make gossip-based protocols so attractive.HP Labs Innovation Research Award, project DC2MS (IRA/CW118736
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
AcTinG: Accurate Freerider Tracking in Gossip
Abstract-Gossip-based content dissemination protocols are a scalable and cheap alternative to centralised content sharing systems. However, it is well known that these protocols suffer from rational nodes, i.e., nodes that aim at downloading the content without contributing their fair share to the system. While the problem of rational nodes that act individually has been well addressed in the literature, colluding rational nodes is still an open issue. Indeed, LiFTinG, the only existing gossip protocol addressing this issue, yields a high ratio of false positive accusations of correct nodes. In this paper, we propose AcTinG, a protocol that prevents rational collusions in gossip-based content dissemination protocols, while guaranteeing zero false positive accusations. We assess the performance of AcTinG on a testbed comprising 400 nodes running on 100 physical machines, and compare its behaviour in the presence of colluders against two state-of-the-art protocols: BAR Gossip that is the most robust protocol handling non-colluding rational nodes, and LiFTinG, the only existing gossip protocol that handles colluding nodes. The performance evaluation shows that AcTinG is able to deliver all messages despite the presence of colluders, whereas both LiFTinG and BAR Gossip suffer heavy message loss. It also shows that AcTinG is resilient to massive churn. Finally, using simulations involving up to a million nodes, we show that AcTinG exhibits similar scalability properties as standard gossip-based dissemination protocols
Hybrid Dissemination: Adding Determinism to Probabilistic Multicasting in Large-Scale P2P Systems
Abstract. Epidemic protocols have demonstrated remarkable scalability and robustness in disseminating information on internet-scale, dynamic P2P systems. However, popular instances of such protocols suffer from a number of significant drawbacks, such as increased message overhead in push-based systems, or low dissemination speed in pull-based ones. In this paper we study push-based epidemic dissemination algorithms, in terms of hit ratio, communication overhead, dissemination speed, and resilience to failures and node churn. We devise a hybrid push-based dissemination algorithm, combining probabilistic with deterministic properties, which limits message overhead to an order of magnitude lower than that of the purely probabilistic dissemination model, while retaining strong probabilistic guarantees for complete dissemination of messages. Our extensive experimentation shows that our proposed algorithm outperforms that model both in static and dynamic network scenarios, as well as in the face of large-scale catastrophic failures. Moreover, the proposed algorithm distributes the dissemination load uniformly on all participating nodes. Keywords: Epidemic/Gossip protocols, Information Dissemination, Peer-to-Peer
On the Inherent Anonymity of Gossiping
Detecting the source of a gossip is a critical issue, related to identifying
patient zero in an epidemic, or the origin of a rumor in a social network.
Although it is widely acknowledged that random and local gossip communications
make source identification difficult, there exists no general quantification of
the level of anonymity provided to the source. This paper presents a principled
method based on -differential privacy to analyze the inherent
source anonymity of gossiping for a large class of graphs. First, we quantify
the fundamental limit of source anonymity any gossip protocol can guarantee in
an arbitrary communication graph. In particular, our result indicates that when
the graph has poor connectivity, no gossip protocol can guarantee any
meaningful level of differential privacy. This prompted us to further analyze
graphs with controlled connectivity. We prove on these graphs that a large
class of gossip protocols, namely cobra walks, offers tangible differential
privacy guarantees to the source. In doing so, we introduce an original proof
technique based on the reduction of a gossip protocol to what we call a random
walk with probabilistic die out. This proof technique is of independent
interest to the gossip community and readily extends to other protocols
inherited from the security community, such as the Dandelion protocol.
Interestingly, our tight analysis precisely captures the trade-off between
dissemination time of a gossip protocol and its source anonymity.Comment: Full version of DISC2023 pape
Collusions and Privacy in Rational-Resilient Gossip
Gossip-based content dissemination protocols are a scalable and cheap alternative to
centralized content sharing systems. However, it is well known that these protocols
suffer from rational nodes, i.e., nodes that aim at downloading the content without
contributing their fair share to the system. While the problem of rational nodes that act
individually has been well addressed in the literature, colluding rational nodes is still
an open issue. In addition, previous rational-resilient gossip-based solutions require
nodes to log their interactions with others, and disclose the content of their logs, which
may disclose sensitive information. Nowadays, a consensus exists on the necessity
of reinforcing the control of users on their personal information. Nonetheless, to the
best of our knowledge no privacy-preserving rational-resilient gossip-based content
dissemination system exists.
The contributions of this thesis are twofold.
First, we present AcTinG, a protocol that prevents rational collusions in gossip-based
content dissemination protocols, while guaranteeing zero false positive accusations.
AcTing makes nodes maintain secure logs and mutually check each others’ correctness
thanks to verifiable but non predictable audits. As a consequence of its design, it is
shown to be a Nash-equilibrium. A performance evaluation shows that AcTinG is able
to deliver all messages despite the presence of colluders, and exhibits similar scalability
properties as standard gossip-based dissemination protocols.
Second, we describe P AG, the first accountable and privacy-preserving gossip pro-
tocol. P AG builds on a monitoring infrastructure, and homomorphic cryptographic
procedures to provide privacy to nodes while making sure that nodes forward the
content they receive. The theoretical evaluation of P AG shows that breaking the
privacy of interactions is difficult, even in presence of a global and active opponent.
We assess this protocol both in terms of privacy and performance using a deployment
performed on a cluster of machines, simulations involving up to a million of nodes, and
theoretical proofs. The bandwidth overhead is much lower than existing anonymous
communication protocols, while still being practical in terms of CPU usage
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