DSpace Repository :: Browsing by Author "Aracil Rico, Javier"

Browsing by Author "Aracil Rico, Javier"

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Open Access
A-priori flow bandwidth estimates for dynamic bandwidth allocation in ISP access links
(2001) Aracil Rico, Javier; Morató Osés, Daniel; Automática y Computación; Automatika eta Konputazioa
In this paper we study a-priori bandwidth estimation algorithms for TCP flows. An RTT-based bandwidth allocator is proposed, which outperforms a broad class of peak-rate and static allocation flow switching solutions. Our findings suggest that a-priori bandwidth estimation (i.e, before the TCP data transfer phase takes place) is indeed feasible and serves to design simple, yet efficient, dynamic bandwidth allocation rules for ISP access links.
Open Access
Analysis and stochastic characterization of TCP flows
(Springer, 2000) Aracil Rico, Javier; Morató Osés, Daniel; Izal Azcárate, Mikel; Automática y Computación; Automatika eta Konputazioa
Since the most Internet services use TCP as a transport protocol there is a growing interest in the characterization of TCP flows. However, the flow characteristics depend on a large number of factors, due to the complexity of the TCP. As a result, the TCS characteristics are normally studies by means of simulations or controlled network setups. In this paper we propose a TCP characterization based on a generic model based of stochastic flow with burstiness and throughput (((σ, ρ)-constraints), which is useful in order to characterize flows in ATM and other flow-switched networks. The model is obtained through extensive analysis of a real traffic trace, comprising an approximate number of 1,500 hosts and 1,700,000 TCP connections. The results suggests that TCP connections in the wide area Internet have low throughput while the packet bursts do not suffer an exponential increase, as indicated by the slow-start behavior. On the other hand, the impact of the connection establishment phase is striking. We note that the throughput of the TCP flow is approximately half the throughput which is obtained in the data transfer phase, namely after the connection has been established.
Open Access
Analysis of Internet services in IP over ATM networks
(IEEE, 1999) Aracil Rico, Javier; Morató Osés, Daniel; Izal Azcárate, Mikel; Automática y Computación; Automatika eta Konputazioa
This paper presents a trace-driven analysis of IP over ATM services from a user-perceived quality of service standpoint. QoS parameters such as the sustained throughput for transactional services and other ATM layer parameters such as the burstiness (MBS) per connection are derived. On the other hand, a macroscopic analysis that comprises percentage of flows and bytes per service, TCP transaction duration and mean bytes transferred in both ways is also presented. The traffic trace is obtained with a novel measurement equipment that combines a header extraction hardware and a high end UNIX workstation capable of providing a timestamp accuracy in the order of microseconds. The ATM link under analysis concentrates traffic from a large population of 1,500 hosts from Public University of Navarra campus network, that produce 1,700,000 TCP connections approximately in the measurement period of one week. The results obtained from such a wealth of data suggest that QoS is primarily determined by transport protocols and not by ATM bandwidth. The sustained throughput of TCP connections never grows beyond 80 Kbps with 70% probability in the data transfer phase (i. e., in the ESTABLISHED state) and we observe a strong influence of the connection establishment phase in the user-perceived throughput. On the other hand, the burstiness of individual TCP connections is rather small, namely TCP connections do not produce bursts according to the geometric law given by slow start and commonly assumed in previously published studies.
Open Access
Aproximación al modelado y predicción de tráfico de Internet como múltiplex de conexión de transporte
(2001) Morató Osés, Daniel; Aracil Rico, Javier; Automática y Computación; Automatika eta Konputazioa
El tráfico de datos en la Internet actual presenta un nuevo reto de caracterización y modelado para el correcto dimensionamiento de los equipos y enlaces que conforman la llamada “red de redes”. En este trabajo presentamos una revisión de los modelos propuestos hasta la fecha, lo cual nos lleva desde los límites de la telefonía clásica hasta los conceptos de dependencia a largo plazo y autosimilitud. A partir de estos modelos abordamos la caracterización de una gran población de usuarios de Internet. Para ello nos hemos basado en trazas del tráfico del enlace IP sobre ATM para acceso a Internet en la Universidad Pública de Navarra. Dichas trazas han sido obtenidas mediante una novedosa herramienta de monitorización de enlaces ATM. Con estas trazas presentamos un análisis macroscópico de protocolos y servicios en el enlace que nos muestra a TCP como principal protocolo y al Web como el servicio más utilizado al suponer más de tres cuartas partes del tráfico generado. A la vista de la predominancia de estas conexiones TCP realizamos una caracterización en base a procesos estocásticos para el múltiples de flujos TCP. Dicha caracterización se fundamenta en varias características observadas del tráfico, concretamente que la tasa de las conexiones TCP depende fuertemente del retardo extremo a extremo (RTT) de la conexión y que la intermitencia de las mismas no sigue la progresión exponencial que se esperaría del algoritmo slow-start. Esto nos lleva a un modelo mediante restricciones (σ, ρ) que permite el empleo de tecnologías de conmutación de circuitos para la reserva de ancho de banda por flujo. Con el conocimiento obtenido del funcionamiento de los flujos TCP en la red actual realizamos una revisión del modelo M/G/∞ de flujos. Este es uno de los modelos más empleados tanto para generación de tráfico sintético de datos como en el estudio analítico de las características del mismo. Confirmamos dos de las hipótesis en que se basa (proceso de llegadas de Poisson y duraciones de flujos con varianza infinita), pero vemos que la hipótesis de tasa constante de transferencia dista de lo observado en el tráfico real. Por ello proponemos una alteración del modelo mediante la incorporación de una variable aleatoria de Weibull para la tasa de flujos. Esta modificación permite que el tráfico resultante ajuste mejor la variabilidad de la marginal del mismo. El modelo M/G/∞ clásico subestima la variabilidad del tráfico aunque modele correctamente su dependencia a largo plazo. Mostramos, sin embargo, que en futuras redes de alta velocidad que formarán la próxima generación de internet el efecto de dependencia a largo plazo tenderá a desaparecer a costa de un aumento en la variabilidad del tráfico, que pasará a ser el factor que condicione las prestaciones de la red. Esto último es un fuerte apoyo para aceptar modificaciones del modelo en la línea de la propuesta. Finalmente, empleamos la caracterización de flujos TCP obtenida para proponer un algoritmo de estimación de ancho de banda basado en el RTT de las conexiones. La estimación está orientada a la reserva de ancho de banda en enlaces de proveedores de acceso a Internet. Los resultados muestran que la estimación en base a parámetros conocidos a priori es realizable y mejora los resultados obtenidos con asignadores basados en tasa de pico, asignaciones estáticas o best-effort. Esto abre numerosas posibilidades de estudio de algoritmos de asignación así como de cálculo dinámico de los parámetros de los mismos.
Open Access
Blocking time analysis of OBS routers with arbitrary burst size distribution
(IEEE, 2003) Morató Osés, Daniel; Izal Azcárate, Mikel; Aracil Rico, Javier; Magaña Lizarrondo, Eduardo; Miqueleiz Alamos, J.; Automática y Computación; Automatika eta Konputazioa
The blocking time distribution for an OBS router is obtained, under the assumption of Poisson-arriving bursts with Pareto, Gaussian and Exponential burst size distributions. Analytical expressions are provided as a function of number of wavelengths per port. Such expressions can be used to dimension Fiber Delay Lines (FDLs) and to perform end-to-end delay estimation. On the other hand, we show that the blocking time distribution becomes exponential as the number of wavelengths increases, regardless of the burst size distribution. Since the burst size distribution is determined by the burst assembly algorithm at the network edges, we conclude that the burst assembly algorithm will have no influence on both burst blocking probability and burst blocking time in future DWDM networks.
Open Access
Characterizing Internet load as a non-regular multiplex of TCP streams
(IEEE, 2000) Aracil Rico, Javier; Morató Osés, Daniel; Automática y Computación; Automatika eta Konputazioa
A commonly accepted traffic model for a large population of Internet users consists of a multiplex of Poisson-arriving heavy-tailed streams with the same constant rate (M/G//spl infin/). We show that even though such a regular model provides an accurate description of long-range dependence, the marginal distribution variance is underestimated, resulting in erroneous calculation of overflow probability in network simulations. On the other hand, we show that the traffic variability due to the marginal distribution variance can be the limiting factor for performance in the gigabit-speed next-generation Internet, rather than the long-range dependence features present in today's traffic.
Open Access
Delay-throughput curves for timer-based OBS burstifiers with light load
(IEEE, 2006) Izal Azcárate, Mikel; Aracil Rico, Javier; Morató Osés, Daniel; Magaña Lizarrondo, Eduardo; Automática y Computación; Automatika eta Konputazioa
The OBS burstifier delay-throughput curves are analyzed in this paper. The burstifier incorporates a timer-based scheme with minimum burst size, i. e., bursts are subject to padding in light-load scenarios. Precisely, due to this padding effect, the burstifier normalized throughput may not be equal to unity. Conversely, in a high-load scenario, padding will seldom occur. For the interesting light-load scenario, the throughput delay curves are derived and the obtained results are assessed against those obtained by trace-driven simulation. The influence of long-range dependence and instantaneous variability is analyzed to conclude that there is a threshold timeout value that makes the throughput curves flatten out to unity. This result motivates the introduction of adaptive burstification algorithms, that provide a timeout value that minimizes delay, yet keeping the throughput very close to unity. The dependence of such optimum timeout value with traffic long-range dependence and instantaneous burstiness is discussed. Finally, three different adaptive timeout algorithms are proposed, that tradeoff complexity versus accuracy.
Open Access
The ETOMIC active probing infrastructure: demo proposal
(2006) Csabai, István; Hága, Péter; Simon, Gábor; Stéger, József; Vattay, Gábor; Magaña Lizarrondo, Eduardo; Morató Osés, Daniel; Izal Azcárate, Mikel; Aracil Rico, Javier; Automática y Computación; Automatika eta Konputazioa
ETOMIC (www.etomic.org) is a European Union sponsored effort, that aims at providing a Paneuropean traffic measurement infrastructure. This infrastructure contains 15 PC based active probing nodes equipped with high-precision, sending capable DAG cards and GPS receivers to achieve time synchronization. Such cards are specifically designed to transmit packet trains with strict timing, in the range of nanoseconds. Every kind of active probing techniques can be applied on the nodes, from the quite simple ping application to the complex network tomography methods which are based on the synchronized sending capability of the DAG cards. The measurement nodes are centrally managed via a web platform, where the new arbitrary measurement jobs can be uploaded to and handled. The management system schedules the jobs and does the maintenance tasks. Now, the infrastructure is opened to the networking community. This paper describes the node architectures, the management system, and the proposed conference demonstration.
Open Access
ETOMIC advanced network monitoring system for future Internet experimentation
(Springer-Verlag Berlin Heidelberg, 2010) Csabai, István; Fekete, Attila; Hága, Péter; Hullár, Béla; Kurucz, Gábor; Laki, Sándor; Mátray, Péter; Stéger, József; Vattay, Gábor; Espina Antolín, Félix; García-Jiménez, Santiago; Izal Azcárate, Mikel; Magaña Lizarrondo, Eduardo; Morató Osés, Daniel; Aracil Rico, Javier; Gómez, Francisco; González, Iván; López Buedo, Sergio; Moreno, Víctor; Ramos, Javier; Automática y Computación; Automatika eta Konputazioa
ETOMIC is a network traffic measurement platform with high precision GPS-synchronized monitoring nodes. The infrastructure is publicly available to the network research community, supporting advanced experimental techniques by providing high precision hardware equipments and a Central Management System. Researchers can deploy their own active measurement codes to perform experiments on the public Internet. Recently, the functionalities of the original system were significantly extended and new generation measurement nodes were deployed. The system now also includes well structured data repositories to archive and share raw and evaluated data. These features make ETOMIC as one of the experimental facilities that support the design, development and validation of novel experimental techniques for the future Internet. In this paper we focus on the improved capabilities of the management system, the recent extensions of the node architecture and the accompanying database solutions.
Open Access
The European Traffic Observatory Measurement Infraestructure (ETOMIC)
(IEEE, 2004) Morató Osés, Daniel; Magaña Lizarrondo, Eduardo; Izal Azcárate, Mikel; Aracil Rico, Javier; Naranjo Abad, Francisco José; Astiz Saldaña, Francisco Javier; Simon, Gábor; Stéger, József; Automática y Computación; Automatika eta Konputazioa
The European Traffic Observatory is a European Union VI Framework Program sponsored effort, within the Integrated Project EVERGROW, that aims at providing an paneuropean traffic measurement infrastructure with high-precision, GPS-synchronized monitoring nodes. This paper describes the system and node architectures, together with the management system.
Open Access
The European Traffic Observatory Measurement Infraestructure (ETOMIC): a testbed for universal active and passive measurements
(IEEE, 2005) Morató Osés, Daniel; Magaña Lizarrondo, Eduardo; Izal Azcárate, Mikel; Aracil Rico, Javier; Naranjo Abad, Francisco José; Alonso Camaró, Ulisses; Astiz Saldaña, Francisco Javier; Vattay, Gábor; Csabai, István; Hága, Péter; Simon, Gábor; Stéger, József; Automática y Computación; Automatika eta Konputazioa
The European Traffic Observatory is a European Union VI Framework Program sponsored effort, within the Integrated Project EVERGROW, that aims at providing a paneuropean traffic measurement infrastructure with highprecision, GPS-synchronized monitoring nodes. This paper describes the system and node architectures, together with the management system. On the other hand, we also present the testing platform that is currently being used for testing ETOMIC nodes before actual deployment.
Open Access
Evaluation of preemption probabilities in OBS networks with burst segmentation
(IEEE, 2005) Magaña Lizarrondo, Eduardo; Morató Osés, Daniel; Izal Azcárate, Mikel; Aracil Rico, Javier; Automática y Computación; Automatika eta Konputazioa
Preemption techniques have been recently proposed for service differentiation in Optical Burst Switching (OBS) networks. According to [1], an incoming burst with the same priority that the burst in service will preempt the wavelength if the residual length of the burst in service is smaller than the incoming burst transmission time. For a network scenario with no wavelength conversion, the preemption probability is evaluated assuming Exponential, Gaussian and Pareto-distributed burst sizes. Knowledge of the preemption dynamics at an OBS switch is a fundamental issue in performance evaluation, since the downstream switches will surely be affected. An analytical upper bound is provided, that shows that the preemption probability depends on the burst size distribution, which in turn depends on the burst assembly technique used at the network edges. On the other hand, not only truncated bursts result from preemption, as reported in other studies, but also the burst size distribution for preempting bursts is shifted to larger values.
Open Access
Herramienta de gestión en tiempo real de redes de área extensa
(1998) Magaña Lizarrondo, Eduardo; Aracil Rico, Javier; Villadangos Alonso, Jesús; Automática y Computación; Automatika eta Konputazioa
This paper presents PROMIS, a new network management tool based on a distributed architecture of traffic probes. It allows network managers to monitor traffic from any wide area network segment in real time using a WWW console or a Tcl/Tk graphic interface.
Open Access
Instrumentation for measuring users' goodputs in dense Wi-Fi deployments and capacity-planning rules
(Springer Nature, 2020-01-11) García-Dorado, José Luis; Ramos, Javier; Gómez-Arribas, Francisco J.; Magaña Lizarrondo, Eduardo; Aracil Rico, Javier; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza
Before a dense Wi-Fi network is deployed, Wi-Fi providers must be careful with the performance promises they made in their way to win a bidding process. After such deployment takes place, Wi-Fi-network owners-such as public institutions-must verify that the QoS agreements are being fulfilled. We have merged both needs into a low-cost measurement system, a report of measurements at diverse scenarios and a performance prediction tool. The measurement system allows measuring the actual goodput that a set of users are receiving, and it has been used in a number of schools on a national scale. From this experience, we report measurements for different scenarios and diverse factors-which may result of interest to practitioners by themselves. Finally, we translate all the learned lessons to a freely-available capacity-planning tool for forecasting performance given a set of input parameters such as frequency, signal strength and number of users-and so, useful for estimating the cost of future deployments.
Open Access
Internet traffic shaping for IP over WDM links with source output buffering or multiple parallel wavelengths
(Kluwer Academic Publishers, 2001) Aracil Rico, Javier; Izal Azcárate, Mikel; Morató Osés, Daniel; Automática y Computación; Automatika eta Konputazioa
Since the number of wavelengths per fiber is growing in an exponential fashion the over- flow traffic can be routed through overflow lightpaths, thus providing an ideal network with near-infinite capacity and almost no-buffering. Such unprecedented bandwidth growth in the network backbone is only limited by the processing speed of the electronic elements. Even though multiple parallel high-speed channels (lightpaths) are provided between IP routers the switching speed of the latter is an order of magnitude below the lightpath transmission speed. As a result, minimizing transfer delay is not only a matter of forwarding traffic as fast as possible but to shape traffic so that the input queues of the destination routers do not over-flow. Even though it is desirable to exploit the WDM capabilities to forward traffic in parallel channels in order to nearly eliminate the router output buffering, it turns out that the extreme burstiness of Internet traffic is even increased by routing part of the traffic through a backup channel. Instead, the use of source output buffering for traffic shaping purposes proves more beneficial. In this paper, we examine the typical scenario of a static WDM network with several wavelengths between IP routers. In a simple configuration of a primary and over flow lightpath the results show that if 3% of the traffic is routed through the over flow lightpath then the packet forwarding speed in the destination router should be increased in 20% in order to obtain the same transfer delay as with the single lightpath configuration with source output buffering.
Open Access
IP traffic prediction and equivalent bandwidth for DAMA TDMA protocols
(IEEE, 2003) Aracil Rico, Javier; Izal Azcárate, Mikel; Morató Osés, Daniel; Magaña Lizarrondo, Eduardo; Automática y Computación; Automatika eta Konputazioa
The use of IP traffic prediction techniques for DAMA TDMA protocols is investigated in this paper. The predicted traffic distribution is derived when the input traffic shows long-range dependence features. Furthermore, an equivalent bandwidth is calculated, which allows the wireless terminal to request a certain amount of bandwidth (slot duration) in terms of a target traffic loss probability. The numerical results indicate very good traffic prediction capabilities, together with moderate bandwidth loss.
Open Access
IPmiser, sistema de monitorización de enlaces ATM a 155Mbps
(1998) Aracil Rico, Javier; Morató Osés, Daniel; Izal Azcárate, Mikel; Solana, Juan Ignacio; Ariste, Teresa; Fillmore, David; Automática y Computación; Automatika eta Konputazioa
Open Access
IPmiser: herramienta de medida and análisis de redes de alta velocidad
(1999) Aracil Rico, Javier; Morató Osés, Daniel; Izal Azcárate, Mikel; Automática y Computación; Automatika eta Konputazioa
Las redes de área extensa IP generan en la actualidad un tráfico difícil de predecir y caracterizar. Así, se hace necesario disponer de herramientas que proporcionen monitorización en tiempo real de los enlaces, sin interrupción y con la máxima fiabilidad y precisión de reloj. La herramienta IPmiser consigue este objetivo mediante un hardware dedicado y una estación de trabajo para el proceso de datos, que es además servidor seguro de información de monitorización. En este artículo se presenta la arquitectura de IPmiser, junto con los resultados más destacables de diversas mediciones en el enlace IP sobre ATM de la Universidad Publica de Navarra.
Open Access
KISS methodologies for network management and anomaly detection
(IEEE, 2018) Vega, Carlos; Aracil Rico, Javier; Magaña Lizarrondo, Eduardo; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
Current networks are increasingly growing in size, complexity and the amount of monitoring data that they produce, which requires complex data analysis pipelines to handle data collection, centralization and analysis tasks. Literature approaches, include the use of custom agents to harvest information and large data centralization systems based on clusters to achieve horizontal scalability, which are expensive and difficult to deploy in real scenarios. In this paper we propose and evaluate a series of methodologies, deployed in real industrial production environments, for network management, from the architecture design to the visualization system as well as for the anomaly detection methodologies, that intend to squeeze the vertical resources and overcome the difficulties of data collection and centralization.
Open Access
Monitorización activa de altas prestaciones mediante la plataforma paneuropa ETOMIC
(2005) Magaña Lizarrondo, Eduardo; Naranjo Abad, Francisco José; Aracil Rico, Javier; Automática y Computación; Automatika eta Konputazioa
In this paper we present the first set of active measurements that we have made using the ETOMIC system. ETOMIC is a paneuropean traffic measurement infrastructure with GPS-synchronized monitoring nodes. Specific hardware is used in order to provide high-precision transmission and reception capabilities. Besides, the system is open and any experiment can be executed. Internet measurements with high infrastructure requirements are now possible like one-way delay, routes and topology changing, congestion detection and virtual path aggregation detection. We will explain the results and how easy is to implement these measurements using the tools provided by ETOMIC, specially the API for using the specific sending and receiving capabilities.