Carrier Ethernet "label" scalability

A collection of slides from the authorpsilas seminar presentation is given

Improving Label Space Usage for Ethernet Label Switched Paths

Ethernet is becoming the dominant aggregation technology for carrier transport networks; however, as it is a LAN technology, native bridged ethernet does not fulfill all the carrier requirements. One of the schemes proposed by the research community to make ethernet fulfill carrier requirements is ethernet VLAN-label switching (ELS). ELS allows the creation of label switched data paths using a 12-bit label encoded in the VLAN TAG control information field. Previous label switching technologies such as MPLS use more bits for encoding the label. Hence, they do not suffer from label sparsity issues as ELS might. This paper studies the sparsity issues resulting from the reduced ELS VLAN-label space and proposes the use of the label merging technique to improve label space usage. Experimental results show that label merging considerably improves label space usage

QoS online routing and MPLS multilevel protection: a survey

A survey of MPLS protection methods and their utilization in combination with online routing methods is presented in this article. Usually, fault management methods pre-establish backup paths to recover traffic after a failure. In addition, MPLS allows the creation of different backup types, and hence MPLS is a suitable method to support traffic-engineered networks. In this article, an introduction of several label switch path backup types and their pros and cons are pointed out. The creation of an LSP involves a routing phase, which should include QoS aspects. In a similar way, to achieve a reliable network the LSP backups must also be routed by a QoS routing method. When LSP creation requests arrive one by one (a dynamic network scenario), online routing methods are applied. The relationship between MPLS fault management and QoS online routing methods is unavoidable, in particular during the creation of LSP backups. Both aspects are discussed in this article. Several ideas on how these actual technologies could be applied together are presented and compared

Adding QoS protection in order to enhance MPLS QoS routing

In this paper, a method for enhancing current QoS routing methods by means of QoS protection is presented. In an MPLS network, the segments (links) to be protected are predefined and an LSP request involves, apart from establishing a working path, creating a specific type of backup path (local, reverse or global). Different QoS parameters, such as network load balancing, resource optimization and minimization of LSP request rejection should be considered. QoS protection is defined as a function of QoS parameters, such as packet loss, restoration time, and resource optimization. A framework to add QoS protection to many of the current QoS routing algorithms is introduced. A backup decision module to select the most suitable protection method is formulated and different case studies are analyzed

An improved method for discovering link criticality in transport networks

Quantitatively assessing the importance or criticality of each link in a network is of practical value to operators, as that can help them to increase the network's resilience, provide more efficient services, or improve some other aspect of the service. Betweenness is a graph-theoretical measure of centrality that can be applied to communication networks to evaluate link importance. However, as we illustrate in this paper, the basic definition of betweenness centrality produces inaccurate estimations as it does not take into account some aspects relevant to networking, such as the heterogeneity in link capacity or the difference between node-pairs in their contribution to the total traffic. A new algorithm for discovering link centrality in transport networks is proposed in this paper. It requires only static or semi-static network and topology attributes, and yet produces estimations of good accuracy, as verified through extensive simulations. Its potential value is demonstrated by an example application. In the example, the simple shortest-path routing algorithm is improved in such a way that it outperforms other more advanced algorithms in terms of blocking ratio

Availability analysis of GMPLS connections based on physical network topology

This paper presents a study of connection availability in GMPLS over optical transport networks (OTN) taking into account different network topologies. Two basic path protection schemes are considered and compared with the no protection case. The selected topologies are heterogeneous in geographic coverage, network diameter, link lengths, and average node degree. Connection availability is also computed considering the reliability data of physical components and a well-known network availability model. Results show several correspondences between suitable path protection algorithms and several network topology characteristics

Estimation of the probability of congestion using Monte Carlo method in OPS networks

In networks with small buffers, such as optical packet switching based networks, the convolution approach is presented as one of the most accurate method used for the connection admission control. Admission control and resource management have been addressed in other works oriented to bursty traffic and ATM. This paper focuses on heterogeneous traffic in OPS based networks. Using heterogeneous traffic and bufferless networks the enhanced convolution approach is a good solution. However, both methods (CA and ECA) present a high computational cost for high number of connections. Two new mechanisms (UMCA and ISCA) based on Monte Carlo method are proposed to overcome this drawback. Simulation results show that our proposals achieve lower computational cost compared to enhanced convolution approach with an small stochastic error in the probability estimation

El Paisatge

El paisatge de l’Alta Garrotxa ha sofert canvis radicals al llarg del temps i molt especial a les darreres dècades. Es proporcionen dades estadístiques sobre bosc, bosquina, pastura, conreu, vegetació de cinglera i zona estèril (roca nua, etc.)

Les cartes privades d’un historiador [Ressenya del llibre Epistolari de Jaume Vicens]

Ressenya del llibre Epistolari de Jaume Vicens. Els editors d’aquesta obra exposen un epistolari de la seva correspondència particular, amb el propòsit d’aportar dades sobre la història quotidiana que ajudin a perfilar la imatge de Vicens Vives

Segmentació de teixit i lesions en imatges de MRI de malalts d'esclerosi múltiple

Actualment, en l'àmbit mèdic, la ressonància magnètica, MRI Magnetic Resonance Imaging, és un dels sistemes més utilitzats per a la realització de diagnòstics i el seguiment de l'evolució de malalties com l'esclerosi múltiple (EM). No obstant, la gran quantitat d'informació que proporciona aquesta modalitat té com a conseqüència una tasca feixuga d'anàlisi i d'interpretació per part dels radiòlegs i neuròlegs. L'objectiu general d'aquest projecte és desenvolupar un sistema per ajudar als metges a segmentar les imatges de MRI del cervell. S'ha implementat amb MATLAB. Durant tot el procés s'han utilitzat dades sintètiques, de la base de dades simulada BrainWeb, i reals, proporcionades pels grup de metges col•laboradors amb el grup VICOROB. El projecte s'emmarca dins d'un projecte de recerca del grup de Visió per Computador i Robòtica de la Universitat de Girona

Entorn de suport al diagnòstic dels aneurismes

L’objectiu d’aquest projecte es dissenyar i implementar un entorn de suport al diagnòstic dels aneurismes. Aquest entorn s’haurà d’integrar en la plataforma Starviewer. La plataforma Starviewer és un entorn de processament i visualització de dades mèdiques desenvolupat conjuntament entre el Laboratori de Gràfics i Imatge de la UdG i l’ Institut de Diagnòstic per la Imatge de l’Hospital Josep Trueta de Girona. Aquesta plataforma ofereix les funcionalitats bàsiques per diagnosticar a partir d’imatges. Tot i les funcionalitats de la plataforma, en la versió actual no es suporta el processament avançat d’imatge d’angiografia. En aquest projecte ens proposem ampliar aquesta plataforma integrant els mòduls necessaris que permetin el processament d’angiografies usades en el diagnòstic dels aneurismes

Abstracting qualitative information for process supervision

Supervisory systems evolution makes the obtaining of significant information from processes more important in the way that the supervision systems' particular tasks are simplified. So, having signal treatment tools capable of obtaining elaborate information from the process data is important. In this paper, a tool that obtains qualitative data about the trends and oscillation of signals is presented. An application of this tool is presented as well. In this case, the tool, implemented in a computer-aided control systems design (CACSD) environment, is used in order to give to an expert system for fault detection in a laboratory plant

Transmission delays in residual computation

The design of control, estimation or diagnosis algorithms most often assumes that all available process variables represent the system state at the same instant of time. However, this is never true in current network systems, because of the unknown deterministic or stochastic transmission delays introduced by the communication network. During the diagnosing stage, this will often generate false alarms. Under nominal operation, the different transmission delays associated with the variables that appear in the computation form produce discrepancies of the residuals from zero. A technique aiming at the minimisation of the resulting false alarms rate, that is based on the explicit modelling of communication delays and on their best-case estimation is proposed

Un diluvio de datos: realidades,tendencias y e-iniciativas en América Latina

Primera conferencia. Bibliotecas y Repositorios Digitales: Gestión del Conocimiento, Acceso Abierto y Visibilidad Latinoamericana. (BIREDIAL) Mayo 9 al 11 de 2011. Bogotá, Colombia.

Escoletes de Menorca : qu?? ho ha fet i ho fa possible?. 'Escuelas infantiles de Menorca : ??qu?? lo ha hecho y lo hace posible?''

Resumen tomado de la publicaci??n. Incluye gr??ficas y tablas de datos