Open Access
Resolución de alias para el cálculo de topologías
(2007) García-Jiménez, Santiago; Magaña Lizarrondo, Eduardo; Izal Azcárate, Mikel; Morató Osés, Daniel; Automática y Computación; Automatika eta Konputazioa
The network topology is a fundamental parameter for managers and researchers. The traditional methodology for discovering the topology of a network is based on the tool traceroute, used from several vantage points in different subnetworks. The result is a set of sink trees where the nodes are the discovered IP addresses from the routers. However, few tools have faced the problem of identifying the nodes in different sink trees as interfaces in the same router. This paper shows a new methodology for this problem of alias resolution. It has been used in the european research network using the ETOMIC platform. It shows that the traditional methodologies are not effective in today’s networking scenario but can be easily improved at least in a factor of 3 in the number of successes.
Open Access
IP addresses distribution in Internet and its application on reduction methods for IP alias resolution
(IEEE, 2009) García-Jiménez, Santiago; Magaña Lizarrondo, Eduardo; Izal Azcárate, Mikel; Morató Osés, Daniel; Automática y Computación; Automatika eta Konputazioa
Discovery of Internet topology is an important and open task. It is difficulted by the high number of networks and internetworking equipments, and even by the dynamic of those interconnections. Mapping Internet at router-level needs to identify IP addresses that belong to the same router. This is called IP address alias resolution and classical methods in the state of the art like Ally need to test IP addresses in pairs. This means a very high cost in traffic generated and time consumption, specially with an increasing topology size. Some methods have been proposed to reduce the number of pairs of IP addresses to compare based on the TTL or IP identifier fields from the IP header. However both need extra traffic and they have problems with the probing distribution between several probing nodes. This paper proposes to use the peculiar distribution of IP addresses in Internet Autonomous Systems in order to reduce the number of IP addresses to compare. The difference between pairs of IP addresses is used to know a priori if they are candidates to be alias with certain probability. Performance evaluation has been made using Planetlab and Etomic measurement platforms. The paper justifies the reduction method, obtaining high reduction ratios without injecting extra traffic in the network and with the possibility to distribute the process for alias resolution.
Open Access
Video over OBS Networks
(2008) Espina Antolín, Félix; Morató Osés, Daniel; Izal Azcárate, Mikel; Magaña Lizarrondo, Eduardo; Automática y Computación; Automatika eta Konputazioa
Open Access
Detección de congestión en la Internet europea
(IEEE, 2007) Hernández, Ana; Magaña Lizarrondo, Eduardo; Izal Azcárate, Mikel; Morató Osés, Daniel; Automática y Computación; Automatika eta Konputazioa
In this paper we present a study about the utilization of one-way delay measurements to detect and characterize network congestion in the european Internet. The experiments have been made using the ETOMIC platfom that allows one-way delay measurement with high precision timestamps. We have found a peculiar router behaviour in which the bottleneck is not the available bandwidth but it is the packet processing power of the router (backplane and CPU constraints). This router has been characterized with several network parameters. Some of them are the dependency of this limitation with the input data rate in packets per second, the size of burst packet losses measured in packets or time and the absence of specific scheduling algorithms in the router that could affect to larger flows.
Open Access
Internet mapping at IP level
(2009) García-Jiménez, Santiago; Magaña Lizarrondo, Eduardo; Automática y Computación; Automatika eta Konputazioa
The final objective of our research is to develop new techniques and ideas to create topology maps at IP level, representing Internet as a graph where nodes were routes. This means closer to reality.
Open Access
Mejoras en la identificación de tráfico de aplicación basado en firmas
(2008) Santolaya Bea, Néstor; Magaña Lizarrondo, Eduardo; Izal Azcárate, Mikel; Morató Osés, Daniel; Automática y Computación; Automatika eta Konputazioa
Traffic identification has been based traditionally on transport protocol ports, associating always the same ports with the same applications. Nowadays that assumption is not true and new methods like signature identification or statistical techniques are applied. This work presents a method based on signature identification with some improvements. The use of regular expressions for typical applications has been studied deeply and its use has been improved in the aspects of percentage identification and resources consumption. On the other hand, a flows-record structure has been applied in order to classify those packets that do not verify any regular expression. Results are compared with the opensource related project L7-filter, and the improvements are presented. Finally, detailed regular expressions for analyzed applications are included in the paper, especially P2P applications.
Open Access
Techniques for better alias resolution in Internet topology discovery
(IEEE, 2009) García-Jiménez, Santiago; Magaña Lizarrondo, Eduardo; Morató Osés, Daniel; Izal Azcárate, Mikel; Automática y Computación; Automatika eta Konputazioa
One of the challenging problems related with network topology discovery in Internet is the process of IP address alias identification. Topology information is usually obtained from a set of traceroutes that provide IP addresses of routers in the path from a source to a destination. If these traceroutes are repeated between several source/destination pairs we can get a sampling of all IP addresses for crossed routers. In order to generate the topology graph in which each router is a node, it is needed to identify all IP addresses that belong to the same router. In this work we propose improvements over existing methods to obtain alias identification related mainly with the types and options in probing packets.
Open Access
Improving efﬁciency of IP alias resolution based on offsets between IP addresses
(IEEE, 2009) García-Jiménez, Santiago; Magaña Lizarrondo, Eduardo; Morató Osés, Daniel; Izal Azcárate, Mikel; Automática y Computación; Automatika eta Konputazioa
In order to get a router-level topology in Internet, IP address alias resolution techniques allow to identify IP addresses that belong to the same router. There are several proposals to make this identification, some based on active measurements and others based on inference studies. The former provides more accuracy and completeness, however efficiency is very low because of the high number of probes needed. These methods probe IP addresses in pairs. With thousands or even more IP addresses to check for aliases, the number of tests gets too high. In order to reduce the number of probes, we propose to select the pairs of IP addresses to test for aliasing using information available a priori. This selection will be based on the offset (numerical distance) between the IP addresses to test. We will show that we can improve efficiency of active alias identification with almost no loss on completeness and without generating probing traffic. The technique is also adaptable to a distributed measurement scenario.
Open Access
Arquitectura y diseño de un modelo de red OBS para simulación
(2009) Espina Antolín, Félix; Armendáriz Silva, Javier; Izal Azcárate, Mikel; Morató Osés, Daniel; Magaña Lizarrondo, Eduardo; Automática y Computación; Automatika eta Konputazioa
Optical Burst Switching (OBS) es una nueva tecnología de conmutación óptica capaz de soportar una gran demanda de ancho de banda en backbones ópticos con Wavelength Division Multiplexing (WDM). Muchos investigadores están interesados en el estudio de esta propuesta emergente y la búsqueda de sus parámetros y entornos de funcionamiento óptimos. Sin embargo se encuentran con el gran handicap de que no existen muchas testbed para su estudio físico, ni tampoco herramientas de software óptimas para su estudio mediante simulaciones. En este trabajo se presenta un modelo de simulación de OBS para el simulador de eventos discretos OMNeT++. Este modelo permite estudiar tanto los nodos frontera, como los nodos del core, así como enlazar la red OBS con otras redes de datos soportadas en OMNeT++, principalmente IP. Además, el diseño presenta una gran modularidad lo que permite modificar fácilmente el modelo OBS para incluir futuras propuestas que se hagan sobre esta tecnología.