Armando Ferro

Internet QoS regulation in future networks: a user-centric approach

In the NGN environment, networks are designed to be multiservice, supporting a wide range of premium services. Each of these services may have different QoS requirements based on the overall end users perception. New QoS policies are required that adapt the traditional QoS regulatory model to this emerging context. This article presents a user-centric approach to identify key factors contributing to the development of QoS regulation for future networks. A case study shows the application of our user-centric QoS model to Internet QoS regulation in Spain. The results of the study demonstrate the need to adapt current regulatory frameworks to ensure competition, pluralism, and diversity in the new network environment.

Network Traffic Sensor for Multiprocessor Architectures: Design Improvement Proposals

This document describes several design proposals to enhance net-work sensor performance on multiprocessor architectures. Our main contributions are related to the design of an autonomous sensor and to the idea of per-forming some parallelization of the analysis. These proposals can be implemented in network sensors such as intrusion detection systems, network antivirus appliances, QoS monitors and any other device based on network traffic analysing. Taking a certain model of traffic analysis as our starting point, we look deeply into some design proposals to address the difficulties involved in the parallelization. In this work, we propose a series of resources that can help us to solve these difficulties. Later, we study the prototypes developed in order to test different design alternatives and, finally, present selected case studies. We finish by quantitatively analysing the results to validate our design proposals.

Dandelion-Encoded Harmony Search Heuristics for Opportunistic Traffic Offloading in Synthetically Modeled Mobile Networks

The high data volumes being managed by and transferred through mobile networks in the last few years are the main rationale for the upsurge of research aimed at finding efficient technical means to offload exceeding traffic to alternative communication infrastructures with higher transmission bandwidths. This idea is solidly buttressed by the proliferation of short-range wireless communication technologies (e.g. mobile devices with multiple radio interfaces), which can be conceived as available opportunistic hotspots to which the operator can reroute exceeding network traffic depending on the contractual clauses of the owner at hand. Furthermore, by offloading to such hotspots a higher effective coverage can be attained by those operators providing both mobile and fixed telecommunication services. In this context, the operator must decide if data generated by its users will be sent over conventional 4G+/4G/3G communication links, or if they will instead be offloaded to nearby opportunistic networks assuming a contractual cost penalty. Mathematically speaking, this problem can be formulated as a spanning tree optimization subject to cost-performance criteria and coverage constraints. This paper will elaborate on the efficient solving of this optimization paradigm by means of the Harmony Search meta-heuristic algorithm and the so-called Dandelion solution encoding, the latter allowing for the use of conventional meta-heuristic operators maximally preserving the locality of tree representations. The manuscript will discuss the obtained simulation results over different synthetically modeled setups of the underlying communication scenario and contractual clauses of the users.

A Kernel-Level Monitor over Multiprocessor Architectures for High-Performance Network Analysis with Commodity Hardware

Traffic monitoring is an increasingly important discipline for nowadays networking, as Accounting, Security and also Quality of Service (QoS) lay on it. Besides, traffic bandwidth has increased exponentially in the last few years, and high-speed network monitoring is a challenging aim. Performance requirements are highly relevant for monitoring systems. A low-level study of the capturing stages on a traffic analysis system (TAS) has shown room for improvement. We provide an architecture able to cope with high-speed traffic monitoring using commodity hardware. Our design is also intended to exploit the parallelism available in up-to-date workstations. This paper presents a kernel-level monitoring system (ksensor) that, keeping the previous requirements, removes some issues from user-level processing, improving the overall performance.

An analytical model for loss estimation in network traffic analysis systems

Simulation models have been developed in order to foresee characteristics of networks, systems or protocols when carrying out tests in laboratories is very expensive or even impossible. This paper presents a simulation model of a multiprocessor network traffic analysis system. The model, which is based on closed networks of queues, evaluates the efficiency of the system depending on the hardware/software platform features. Therefore, this model is able to estimate performance early in the design and development stages simulating a multiprocessor architecture in charge of analysing network traffic. The goodness of the model will be checked by comparing analytical results with practical ones obtained in laboratory using a traffic analysis system that runs on a multiprocessor platform.

Internet quality of service measurement tool for both users and providers

This paper offers an approach to the definition of access speed measurements. An ever growing increase of Internet Service Providers (ISP) and different types of technologies in the Internet access, makes it difficult for users to decide which is the best or most suitable connection to satisfy their needs. From these considerations, the possibility for Internet users of obtaining a real and neutral measurement of their access may help them to decide if it is covering their demands or, on the contrary, the provider is not complying with the terms of the contract. To perform this measurement, an Internet speed test has been defined, as well as the way to obtain a measure which can comply with the objective of giving users a proper idea of how their Internet access is working. This project is included in the Quality of Service (QoS) investigation area in our investigation group.

On the heritability of dandelion-encoded harmony search heuristics for tree optimization problems

Tree based optimization problems stand for those paradigms where solutions can be arranged within a tree-like graph whose nodes represent the optimization variables of the problem at hand and their interconnecting edges topological and/or hierarchical relationships between such variables. In this context, a research line of increasing interest during the last decade focuses on the derivation of intelligent solution encoding strategies capable of 1) capturing all topological constraints of this particular class of graphs; and 2) preserving their connectivity properties when they undergo combination/mutation operations within approximative evolutionary solvers. This manuscript takes a step over the state of the art by shedding light on the heri-tability properties of the Dandelion tree encoding approach under avant-garde stochastically-controlled evolutionary operators. In particular we elaborate on the topological heritability of the so-called Harmony Memory Considering Rate (HMCR) exploitative operator of the Harmony Search algorithm, a population-based meta-heuristic algorithm that has so far shown to outperform other evolutionary schemes in a wide range of optimization scenarios. Results from extensive Monte Carlo simulations are discussed in terms of the preserved structural properties of the newly produced solutions with respect to the initial Dandelion-encoded population.

Application of a PQoS Based Quality Management Model to Identify Relative Importance of the Agents

In last years there have been some governmental initiatives aimed at the regulation of quality of service evaluation in telecommunications services. However this has proven to be a complex task especially for Internet services, where it is difficult to objectively assess the quality of a service and to identify whether one or more of the provider agents are responsible of final dissatisfaction of users. This paper affords the cited problem and intends to provide a methodology to asses the quality of service as perceived by end users. The aims of the proposed model are twofold: the evaluation of perceived quality of service (PQoS) based on subjective and objective measurements and the identification of responsibilities of the different agents involved in a service provision

Performance Analysis of a Network Sensor's Packet Processing System using Generalized Stochastic Petri Nets

This paper describes a modeling based on Generalized Stochastic Petri Nets (GSPN) to analyze the performance of a network probing node in terms of throughput. The probing node is part of a distributed monitoring system. In this environment, the use of multiprocessor and multicore systems, as well as the parallelization of applications, is aimed at improving the node performance. Petri nets allow not only to represent the parallelization feature, but also to include the main events identified in the system: the packet arrival and a two-stage processing. The two-stage processing consists of a first stage in which packet capturing functionalities are performed, and a second stage in which a deeper packet treatment is performed. In addition, the Petri net model can reproduce a shared buffer control mechanism to ensure the integrity of the data. After detailing all the model components, the verification and validation of the model are done by using a simulation tool. With this model, it is expected to estimate the efficiency of the probing node early in the design and development stages.

A simulation-based quantitative analysis on the topological heritability of Dandelion-encoded meta-heuristics for tree optimization problems

The solutions to many optimization paradigms arising from different application domains can be modeled as a tree graph, in such a way that nodes represent the variables to be optimized and edges evince topological relationships between such variables. In these problems the goal is to infer an optimal tree graph interconnecting all nodes under a measure of topological fitness, for which a wide portfolio of exact and approximative solvers have hitherto been reported in the related literature. In this context a research line of interest in the last few years has been focused on the derivation of solution encoding strategies suited to deal with the topological constraints imposed by tree graph configurations, particularly when the encoded solution undergoes typical operators from Evolutionary Computation. Almost all contributions within this research area focus on the use of standard crossover and mutation operators from Genetic Algorithms onto the graph topology beneath encoded individuals. However, the pace at which new evolutionary operators have emerged from the community has grown much sharply during the last decade. This manuscript elaborates on the topological heritability of the so-called Dandelion tree encoding approach under non-conventional operators. This experimental application-agnostic-based study gravitates on the topological transmission of Dandelion-encoded solutions under a certain class of multi-parent crossover operators that lie at the core of the family of