With the evolution of the online advertisement and tracking ecosystem, content-blockers have become the reference tool for improving the security, privacy and browsing experience when surfing the Internet. It is also commonly believed that using content-blockers to stop unsolicited content decreases the time needed for loading websites. In this work, we perform a large-scale study on the actual improvements of using content-blockers in terms of performance and quality of experience. For measuring it, we analyze the page size and loading times of the 100K most popular websites, as well as the most relevant QoE metrics, such as the Speed Index, Time to Interactive or the Cumulative Layout Shift, for the subset of the top 10K of them. Our experiments show that using content-blockers results in small improvements in terms of performance. However, contrary to popular belief, this has a negligible impact in terms of loading time and quality of experience. Moreover, in the case of small and lightweight websites, the overhead introduced by content-blockers can even result in decreased performance. Finally, we evaluate the improvement in terms of QoE based on the Mean Opinion Score (MOS) and find that two of the three studied content-blockers present an overall decrease between 3% and 5% instead of the expected improvement.

Current web tracking practices pose a constant threat to the privacy of Internet users. As a result, the research community has recently proposed different tools to combat well-known tracking methods. However, the early detection of new, previously unseen tracking systems is still an open research problem. In this paper, we present TrackSign, a novel approach to discover new web tracking methods. The main idea behind TrackSign is the use of code fingerprinting to identify common pieces of code shared across multiple domains. To detect tracking fingerprints, TrackSign builds a novel 3-mode network graph that captures the relationship between fingerprints, resources and domains. We evaluated TrackSign with the top-100K most popular Internet domains, including almost 1M web resources from more than 5M HTTP requests. Our results show that our method can detect new web tracking resources with high precision (over 92%). TrackSign was able to detect 30K new trackers, more than 10K new tracking resources and 270K new tracking URLs, not yet detected by most popular blacklists. Finally, we also validate the effectiveness of TrackSign with more than 20 years of historical data from the Internet Archive.

With the evolution of the online advertisement and tracking ecosystem, content-filtering has become the reference tool for improving the security, privacy and browsing experience when surfing the Internet. It is also commonly believed that using content-blockers to stop unsolicited content decreases the time needed for loading websites. In this work, we perform a large-scale study with the 100K most popular websites on the actual performance improvements of using content-blockers. We focus our study on two relevant metrics for measuring the browsing performance; page size and loading time. Our results show that using such tools results in small improvements in terms of page size but, contrary to popular belief, it has a negligible impact in terms of loading time. We also find that, in the case of small and lightweight websites, the use of content-blockers can even result in increased loading times.

Graphene is a promising material which has been proposed to build graphene plasmonic miniaturized antennas, or graphennas, which show excellent conditions for the propagation of Surface Plasmon Polariton (SPP) waves in the terahertz band. Due to their small size of just a few micrometers, graphennas allow the implementation of wireless communications among nanosystems, leading to a novel paradigm known as Graphene-enabled Wireless Communications (GWC). In this paper, an analytical framework is developed to evaluate how the channel capacity of a GWC system scales as its dimensions shrink. In particular, we study how the unique propagation of SPP waves in graphennas will impact the channel capacity. Next, we further compare these results with respect to the case when metallic antennas are used, in which these plasmonic effects do not appear. In addition, asymptotic expressions for the channel capacity are derived in the limit when the system dimensions tend to zero. In this scenario, necessary conditions to ensure the feasibility of GWC networks are found. Finally, using these conditions, new guidelines are derived to explore the scalability of various parameters, such as transmission range and transmitted power. These results may be helpful for designers of future GWC systems and networks.

Rigid fixed-grid wavelength division multiplexing (WDM) optical networks can no longer keep up with the emerging bandwidth-hungry and highly dynamic services in an efficient manner. As the available spectrum in optical fibers becomes occupied and is approaching fundamental limits, the research community has focused on seeking more advanced optical transmission and networking solutions that utilize the available bandwidth more effectively. To this end, the flexible/elastic optical networking paradigm has emerged as a way to offer efficient use of the available optical resources. In this work, we provide a comprehensive view of the different pieces composing the “flexible networking puzzle” with special attention given to capturing the occurring interactions between different research fields. Only when these interrelations are clearly defined, an optimal network-wide solution can be offered. Physical layer technological aspects, network optimization for flexible networks, and control plane aspects are examined. Furthermore, future research directions and open issues are discussed.

The problem of testing whether a packet belongs to a set of filtered addresses has been traditionally addressed using Bloom filters. They have a small memory footprint and require few memory accesses per query and insertion, while presenting a small probability of false positive. The problem of automatic eviction of filtered addresses after a pre-configured time window is more challenging, since it requires tracking insertion times for later removal. This has been achieved in the literature by replacing the Bloom filter's vector of bits for a vector of timestamps. This approach precisely expires old items from the filter, but has a large memory footprint. We present a novel Bloom filter based data structure that features approximate information expiration. This small extra source of error allows for a more compact filter representation, thus becoming more suitable to fit in more expensive, faster memory. Additionally, our data structure is more flexible in that it allows for balancing the trade-off between filtering and expiration accuracy. Our experiments show that this method can obtain up to orders of magnitude higher overall accuracy than the time-stamp approach using the same amount of memory.

Advances in optical transmission technology are driving the evolution from legacy opaque toward transparent backbone networks. Aiming at reducing the costs and energy consumption, transparent networks allow the data to be kept optical end to end and thus removing the majority of the expensive optical-electrical-optical (OEO) devices. Nonetheless, physical impairments accumulate on the signal along optical transparent paths, therefore limiting the system reach and the overall network performance. Furthermore, failures propagate in a transparent network environment and they cannot be easily localized and isolated. So then, transparent networks need to deal with a number of challenges impacting both planning and operation phases. Such challenges require the use of cross-layer approaches, which involve dynamic interactions between the physical layer and the network layer to enable the compensation for mismatching of requirements and resources. In this paper, we aim to provide an overview of such challenges, reporting comparative analysis with a selection of existing solutions and to cast a glance at the open issues for future research.

Diffusion-based molecular communication is a promising bio-inspired paradigm to implement nanonetworks, i.e., the interconnection of nanomachines. The peculiarities of the physical channel in diffusion-based molecular communication require the development of novel models, architectures and protocols for this new scenario, which need to be validated by simulation. With this purpose, we present N3Sim, a simulation framework for diffusion-based molecular communication. N3Sim allows to simulate scenarios where transmitters encode the information by releasing molecules into the medium, thus varying their local concentration. N3Sim models the movement of these molecules according to Brownian dynamics, and it also takes into account their inertia and the interactions among them. Receivers decode the information by sensing the particle concentration in their neighborhood. The benefits of N3Sim are multiple: the validation of channel models for molecular communication and the evaluation of novel modulation schemes are just a few examples.

In this paper, we deal with the physical layer impairments (PLIs) in optical burst switching (OBS). In particular we present a formulation of the routing and regenerator placement and dimensioning (RRPD) problem for a feasible translucent OBS (T-OBS) network architecture. Since addressing the joint RRPD problem results in an extremely complex undertaking, we decouple the problem, and hence, we eventually provide formal models to solve routing and RPD separately in the socalled R+RPD problem. Thus, making use of mixed integer linear programming (MILP) formulations, we first address the routing problem with the aim of minimizing congestion in bottleneck network links, and second, we tackle the issue of performing a sparse placement of electrical regenerators in the network. Since the RPD formulation requires high computational effort for large problem instances, we also propose two alternative heuristic strategies that provide good near-optimal solutions within reasonable time limits. To be precise, we evaluate the trade-off between optimality and complexity provided by these methods. Finally, we conduct a series of simulation experiments on the T-OBS network that prove that the R+RPD strategies effectively deal with burst losses caused by the impact of PLIs, and therefore, ensure that the overall T-OBS network performance remains unaffected.

This paper introduces a Generalized Multi-Protocol Label Switching (GMPLS)-enabled Optical Burst Switched (OBS) network architecture featuring end-to-end QoS-aware burst transport services. The proposed GMPLS/OBS architecture guarantees specific burst loss probability requirements, independently of the offered network load. This is achieved through the configuration of burst Label Switched Paths (LSPs) over the network which are set-up at the GMPLS control plane level only, while it is the OBS node controller the responsible for eventually committing data plane resources upon burst arrival. In such a way, statistical multiplexing feature is preserved and, at the same time, the end-user QoS demands are met by tightly dimensioning the LSPs. A Mixed Integer Linear Programming (MILP) model is devised to provide the optimal burst LSPs dimensioning according to the offered network load and QoS requirements. Moreover, GMPLS-driven capacity reconfigurations are dynamically triggered whenever unfavorable network conditions are detected. The performance of the proposed architecture is extensively assessed on several network scenarios. Future work on the topic is finally outlined.

Energy consumption and the concomitant Green House Gases (GHG) emissions of network infrastructures are becoming major issues in the Information and Communication Society (ICS). Current optical network infrastructures (routers, switches, line cards, signal regenerators, optical amplifiers, etc.) have reached huge bandwidth capacity but the development has not been compensated adequately as for their energy consumption. Renewable energy sources (e.g. solar, wind, tide, etc.) are emerging as a promising solution both to achieve drastically reduction in GHG emissions and to cope with the growing power requirements of network infrastructures. The main contribution of this paper is the formulation and the comparison of several energy-aware static routing and wavelength assignment (RWA) strategies for wavelength division multiplexed (WDM) networks where optical devices can be powered either by renewable or legacy energy sources. The objectives of such formulations are the minimization of either the GHG emissions or the overall network power consumption. The solutions of all these formulations, based on integer linear programming (ILP), have been observed to obtain a complete perspective and estimate a lower bound for the energy consumption and the GHG emissions attainable through any feasible dynamic energy-aware RWA strategy and hence can be considered as a reference for evaluating optimal energy consumption and GHG emissions within the RWA context. Optimal results of the ILP formulations show remarkable savings both on the overall power consumption and on the GHG emissions with just 25% of green energy sources.

We propose a predictive resource management scheme for network monitoring systems that can proactively shed excess load while maintaining the accuracy of monitoring applications within bounds defined by the operator. The main novelty of our scheme is that it considers monitoring applications as black boxes, with arbitrary (and highly variable) input traffic and processing cost. This way, the monitoring system preserves a high degree of flexibility, increasing the range of applications and network scenarios where it can be used. We implemented our load-shedding-based resource management scheme in an existing network monitoring system and deployed it in a large research and educational network. We present experimental evidence of the performance and robustness of our system with multiple concurrent monitoring applications during long-lived executions and using real-world traffic traces.

Most research works in optical burst switching (OBS) networks do not take into account the impact of physical layer impairments (PLIs) either by considering fully transparent (i.e., using optical 3R regeneration) or opaque (i.e., electrical 3R regeneration) networks. However, both solutions are not feasible for different reasons. In this paper, we propose a novel translucent OBS network architecture which aims at bridging the gap between the transparent and opaque solutions. In order to evaluate its performance, two different joint regenerator placement and routing heuristics are provided. Simulation results show that our translucent network model achieves performance results as good as those obtained with an opaque solution but with considerably less regenerators.

Optical burst switching architectures without buffering capabilities are sensitive to burst congestion. The existence of a few highly congested links may seriously aggravate the network throughput. Proper network routing may help in congestion reduction. The authors focus on adaptive routing strategies to be applied in labelled OBS networks, that is, with explicit routing paths. In particular, two isolated alternative routing algorithms that aim at network performance improvement because of reactive route selection are studied. Moreover, a nonlinear optimisation method for multi-path source-based routing, which aims at proactive congestion reduction is proposed. Comparative performance results are provided and some implementation issues are discussed.

This paper focuses on the problem of quality of service (QoS) provisioning in optical burst switching (OBS) networks. OBS is a promising photonic network technology aiming at efficient transport of IP traffic by means of statistical multiplexing. The lack of optical memories, however, makes this operation quite complicated. Problems such as unfairness in access to the shared transmission resources, facility in adopting alternative and backup routing, scheduling complexity and so on arise in the conventional OBS architecture. In this paper we proposed the offset-time emulated OBS (E-OBS) architecture, which overcomes all these drawbacks by means of distributed provisioning of the offset time in core nodes. Nonetheless it is still difficult to guarantee a certain level of service quality. Burst preemption mechanism, which, alongside with offset-time differentiation, was proven to be the most effective technique for QoS provisioning in OBS networks. The general drawback of any burst preemption-based mechanism is that, in case of successful preemption, either the resources reserved for the preempted bursts on outgoing path are wasted or an additional signaling procedure should be carried out in order to release them. In order to avoid wasted resources reservation, we also proposed the preemption Window (PW) mechanism which enhances the E-OBS for efficient QoS support. In this paper we evaluate exhaustively the performance of the resulting architecture showing all its advantageous with respect to other solutions.

This paper reports the main results achieved in the development of a prototype for demonstrating communication services, based on the principles autonomic self-organisation. In particular, the prototype has been designed and developed as a distributed adaptable complex system, realized by means of a population of lightweight autonomic components interacting with each other through self-organizing algorithms. A demonstration prototype to show the collaborative ambient of a rescue team in a critical situation with limited connectivity, such as mobility, data distribution and high probability of disconnection, has been simulated. This prototype show both how these factors represent strong challenges for current software architecture and how the distributed lightweight components can self-organize themselves in order to face these challenges.

Network monitoring is becoming a necessity for network operators, who usually deploy several monitoring applications that aid in tasks such as traffic engineering, capacity planning and the detection of attacks or other anomalies. There is also an increasing interest in large-scale network monitoring infrastructures that can run multiple applications in several network viewpoints [4].

This paper presents a RWA strategy based on the stochastic estimation of the effective number of available wavelengths (ENAW) along interdomain paths. We propose an approximate model to roughly estimate the ENAW on the paths across multiple domains, and then refine this estimation by means of observations and an adaptive prediction-correction Kalman filtering process. Unlike traditional Kalman filters, which use noisy measurements as their observations, we use the information contained in the routing updates as noisy measurements of the existent wavelength occupancy along the paths. Based on these observations, we estimate the ENAW on the candidate paths, and use this information to influence the RWA decision when the number of available wavelengths makes a lightpath request prone to be blocked. The approximate model we are proposing in this paper is based on a noisy extension of a simplified model derived for two domains. Our results validate the usefulness of the model, and confirm that by estimating the wavelength occupancy prior to the RWA decision the blocking ratio can be considerably reduced.

This paper considers an optical packet-switched node with limited buffer capabilities and subject to asynchronous, variable-length packets and connection-oriented operation. In such a scenario, we address the problem of providing QoS. While existing solutions focus on applying some form of resources reservation on top of the contention resolution algorithm, here we propose a novel method: given a set of K categories of service to be provided in the network, K different contention resolution algorithms are implemented to cope with the requirements of such service categories. In this paper, we define three different OPS service categories based on three different contention resolution algorithms, we design an ad-hoc pool of fiber delay lines for such a scheme, and evaluate its performance by simulation. The obtained results indicate the merits of our method which opens up future interesting developments for a whole network scenario studies.

A hierarchical network architecture is one of the hard recommendations stated at the automatically switched optical networks (ASON) specifications. This paper focuses on providing ASON with a hierarchical routing in order to ensure the scalability for large worldwide networks, mainly focusing on the functionality expected from GMPLS routing, such as aggregation schemes and routing algorithms, targeting to optimize the global network performance while guaranteeing scalability. Simulation results indeed show the benefits obtained owing to harder overhead reduction without impacting on the blocking probability.

The data and voice integration over dense wavelength-division-multiplexing (DAVID) project proposes a metro network architecture based on several wavelength-division-multiplexing (WDM) rings interconnected via a bufferless optical switch called Hub. The Hub provides a programmable interconnection among rings on the basis of the outcome of a scheduling algorithm. Nodes connected to rings groom traffic from Internet protocol routers and Ethernet switches and share ring resources. In this paper, we address the problem of designing efficient centralized scheduling algorithms for supporting multiclass traffic services in the DAVID metro network. Two traffic classes are considered: a best-effort class, and a high-priority class with bandwidth guarantees. We define the multiclass scheduling problem at the Hub considering two different node architectures: a simpler one that relies on a complete separation between transmission and reception resources (i.e., WDM channels) and a more complex one in which nodes fully share transmission and reception channels using an erasure stage to drop received packets, thereby allowing wavelength reuse. We propose both optimum and heuristic solutions, and evaluate their performance by simulation, showing that heuristic solutions exhibit a behavior very close to the optimum solution.

Multiprotocol label switching and traffic engineering are proposed by the IETF to improve the network performance. Moreover, some QoS routing algorithms must be added in order to optimize the path selection process. However, in highly dynamic large networks, existing QoS routing algorithms suffer from a blocking probability, which in part is due to the existence of inaccuracy in the network state information used to select the path. This paper deals with the BYPASS based routing mechanism, which was introduced in the previous paper to overcome this routing inaccuracy effect in IP/MPLS scenarios. We suggest an enhancement of the BBR mechanism to optimize the bandwidth allocation by balancing the path length and the residual bandwidth, and its performance is evaluated by simulation.

In this paper, promising technologies and a network architecture are presented for future optical packet switched networks. The overall network concept is presented and the major choices are highlighted and compared with alternative solutions. Both long and shorter term approaches are considered, as well as both the wide-area network and multiple-area networks parts of the network. The results presented in this paper were developed in the frame of the research project DAVID (Data And Voice Integration over DWDM) project, funded by the European Commission through the IST-framework.

Multiprotocol label switching (MPLS) is an advanced forwarding scheme, which allows the network to achieve the traffic engineering (TE) objectives. When two or more MPLS nodes are connected via an ATM backbone merely composed of ATM switches, it is necessary to add some mechanisms to allow the label distribution and allocation between both nodes. In this paper a solution is proposed to integrate ATM and MPLS, so that the ATM backbone will be seen as a unique MPLS node from the MPLS domain and as a consequence of that the end-to-end LSP establishment can be carried out.

We address the problem of supporting high performance distributed computing (HPDC) applications running over ATM networks. For this purpose, we consider a logically separate subnetwork for these applications. After presenting an architectural reference model for the HPDC subnetwork and distinguishing which functions should be installed over the ATM network in order to satisfy the needs of HPDC applications, we propose two mechanisms that aim at optimizing communications by taking advantage of both the special properties of HPDC traffic and the cell based nature of ATM. The performance of these mechanisms is evaluated and compared with that achieved by the SSCOP protocol. The results show that when the ATM network experiences high load and the HPDC applications make an intensive use of arrays, cell based mechanisms become more robust than standard SSCOP and provide low latency and efficient cell loss recovery. Since both situations are very likely to occur in HPDC environments, we conclude that the introduction of cell based retransmission mechanisms does contribute to enhance performance of HPDC systems over ATM networks.