JITEL

ABSTRACT
Este artículo trata sobre los esquemas de distribución de contenido multimedia a través de Internet, con especial interés en Internet móvil. Tanto la variabilidad de la calidad de los accesos radio como el incremento del tráfico multimedia plantean nuevos retos en relación a la gestión dinámica de los servicios sobre recursos de red compartidos. En primer lugar, el artículo ofrece una revisión del estado de la tecnología relacionada con el transporte multimedia extremo a extremo. A continuación, el artículo se centra en analizar la evolución de los mecanismos de adaptación dinámica, incluyendo desde esquemas extremo a extremo hasta la gestión dinámica de los recursos de red. Se analizan las posibles ventajas asociadas a nuevas arquitecturas como la computación en la nube móvil y las futuras redes 5G. Finalmente, el artículo identifica una serie de retos y desafíos en la gestión adaptativa de los servicios multimedia en el futuro.

ABSTRACT
Radio Resource Management (RRM) function is a critical element in multi-user mobile networks. Nowadays, RRM is implemented at the 4G radio edge in order to enhance channelawareness and thus to optimize the efficiency of radio resources, at the cost of high computational requirements at the radio nodes. Current trends towards Network Function Virtualization aim at enabling software-based networking capabilities at different locations of the radio network architecture. This paper analyzes the impact of moving RRM functions to different Radio Access Network locations and with different channel quality feedback periods. Based on simulation results, the paper analyzes the experienced performance of different channel-aware scheduling strategies in the context of multi-user mobile multimedia scenarios with different radio channel conditions.

ABSTRACT
Packet capturing and analysis in high-speed networks, like 1-10 Gigabit Ethernet, is a challenging task, especially when applications do not permit packet loss. In this environment, the use of multiprocessor and multicore systems, as well as the parallelization of applications, is aimed at improving the performance. However, the monitoring application may even experience performance penalties when adapted to multiprocessor architectures. After observing certain anomalies in a real traffic monitoring system that runs on a multiprocessor platform, this paper presents an analytical model for that type of systems. The model, which is based on generalized stochastic Petri nets, evaluates the efficiency of the traffic capturing and analysis system depending on the hardware/software platform features.

ABSTRACT
Con el aumento de la velocidad en las redes de datos la capacidad computacional de la infraestructura de comunicaciones y de los servidores principales puede verse comprometida. Para poder probar el rendimiento de las redes, de los equipos de interconexión y de los servidores se hace necesario disponer de sistemas de inyección de tráfico, que permitan la generación de tráfico sintético con diferentes características. También es necesario disponer de sistemas de monitorización, que permitan estudiar las características del tráfico. Hacer esto en segmentos de alta capacidad de una forma eficaz no es un asunto trivial. Este artículo propone el diseño de una arquitectura de inyección y monitorización de tráfico sintético que pretende mejorar los rendimientos de las soluciones disponibles utilizando una arquitectura de propósito general como es un sistema Linux sobre un PC con una interfaz de red común. El fundamento en la mejora de los rendimientos se basa principalmente en la introducción de la lógica de inyección y monitorización en el núcleo del sistema operativo.

ABSTRACT
Deployment of quality-of-service (QoS) policies is becoming one of the biggest challenges for today's Internet Service Providers (ISPs). Nowadays, QoS does not only address specific technical standard metrics; it must be concern about other aspects such as user's final perception or regulations mandatory compliments instead. Although some efforts are being made on studying and analysing this new QoS scope, there are not still many advances on defining methodologies to deploy it on real network sceneries. UIT-T Rec. G-1000 makes an approachon this issue and provides a meaningful framework to users, service providers and regulators. Nevertheless, UIT-T G.1000 does not go an step further and remains at the 'theorical stage'. Our research group NQaS (Networking Quality and Security) is carrying out different initiatives focus on solving this new QoS dimension. This paper presents some of the on-going research areas of NQaS on the way to find an appropiate methodology to apply a global QoS policy in an ISP on the basis of the UIT-T G.1000 framework.

ABSTRACT
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 requierements are highly relevant for monitoring systems. A low-level study of the capturing stages on a traffic analysis system 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 in user level monitoring system, improving the overall performance.

ABSTRACT
One of the most important tasks of a researcher consists in performing tests to validate the results of the research done. In a network related research work, with complex infrastructure and many configuration parameters, testing our work is usually rather mechanic, tedious and error prone if tests are done manually. In the Networking, Quality and Security Research Group, we have developed a generic test framework to automate this important task, composed of four kind of logical elements: a manager, agents, daemons and formatters. With these four elements, every phase of the process is automated, from test configuration to result formatting. The deployment of this framework has drastically reduced the time needed for the test phase and the number of errors due to mistakes. It has also allowed us to share resources among projects more easily and to schedule test sets when the devices are not being used.

ABSTRACT
This paper presents a comprehensive model intended to analyse quality of service in telecommunications services. Many works have been published in this area, both from a technical viewpoint as well as taking into consideration subjective concerns. However, these works have not resulted in a unique methodology to assess the experienced quality. While most of the studies consider the quality of service from biased perspectives, we try to analyse quality of service as a general gauge of final users’ satisfaction. The proposed model allows us to estimate the quality experienced by end users, while offering detailed analysis regarding the different agents involved in the service provision. Once we overview the most significant elements of the model, an in-depth analytical study is detailed. Finally, we illustrate a practical study for HTTP service in order to validate the theoretical model.

ABSTRACT
Analysis of network traffic has become a really important task for many fields, from IDS to QoS evaluation. The great increase in the speed of networks, much faster than processor's performance increase, is making difficult to handle the processing of all network packets. One way to solve this problem is to move the processing to the hardware elements. This is a very expensive solution and, in some cases, improving the performance of the capturing software may be enough. Although current general purpose operating systems have been improving the performance of network processing, there is still place for improvement. In this paper we present in detail the way followed by a packet through the operating system until it is processed at user level. Some empirical measurements has been made along the packet journey in order to find the bottlenecks of the capturing process as well as discussing some ways to further increase the performance of the capturing process.

ABSTRACT
This paper proposes a service descovery protocol for discovering and advertising services in a proactive ad hoc network. The protocol we have defined is piggybacked into the OLSR (Optimized Link State Routing) routing protocol. We have defined a new message type into OLSR, called Service Discovery Message (SDM), for both advertisement and discovery of services. The advertisement frequency and advertisement lifetime are user-controlled parameters, so that they can be modified depending on the user requirements. Each node mantains a service cache to store information about its own services, and the services each device discovers in the network. We also present simulation results of our protocol and show that the service discovery protocol defined here, achieves much efficiency in discovering services, while it introduces practically no packet overhead compared to the basis OLSR protocol.

ABSTRACT
This paper presents an analytical model based in queueing theory which allows to represent the behavior of an intrusion detection system . Besides, an iterative calculation method based in the mean value method has been developed to obtain the most significant parameters of the system, for example throughput. In the future, the main objective of this work is to extend the analytical model of this intrusion detection system to any generic multiprocessor architecture.

ABSTRACT
During the 90's the exponential growth of the number of Internet users led to the birth of many ISPs and data operators. Nowadays, after the technological bubble, only some of them survive. Since prices have reached the lowest limit, some kind of service quality differentiation between competitors is a must. Unfortunately, QoS measuring methods don’t always agree with users' expectations. Moreover, many times data operators don't know how to improve the quality that users perceive. Any investment on infrastructures seems to result on an improvement, but there are no guarantees. This article describes the effort of a group of Spanish Universities towards the definition of a method to set up and measure the relationships between users' satisfaction and network parameters. The model developed would allow both ISPs and legislators to control the degree of users' satisfaction, as well as how any change in network parameters results on a variation of their perceptions.

ABSTRACT
This paper presents velocimetro.org, the service developed by the Engineering Faculty of Bilbao to provide access speed measurements in Internet. The explosion of Internet Service Providers (ISP) and different types of technologies in Internet access, makes it difficult for Internet users to decide about the best or more acquaint access to cope with their needs. Velocimetro.org offers the possibility to obtain a neutral measurement of the quality of service (QoS) of the access to Internet. In this way, users can evaluate and decide if their ISP is covering their demands or, on the contrary, is not complying with the terms of the contract. From the point of view of an ISP, velocimetro.org allows to make comparisons of their service against their competitors.