Importance of nodes and tie strength are
necessary elements to characterize and analyze networks, as
well as to study the processes that occur in their interior. We believe that it is also necessary to know the importance of links to have a better characterization of the networks in the study of those processes. In response to this situation, we propose a method to measure the importance of the links.The method is based on applying the line-graph mathematical concept to the graph representing the network, thus we create a new graph in which we apply centrality metrics to find the importance of network links.
In the current telecommunications market that is reaching high saturation levels, mobile network operators (MNOs) try to position themselves among customers through aggressive marketing campaigns and offers. In this environment where customers have multiple MNOs to choose from, different factors influence customers’ decisions. In addition to this, mobile number portability contributes to a phenomenon called churning where customers migrate from one MNO to another. Churning impacts not only the network design but also the pricing methods adopted by MNOs, and hence their revenue. It is because of this that MNOs try to reduce churn through retention campaigns. The key factor for the success of these campaigns is to detect potential churners before they leave the service. The state of the art has focused on proposing methods to identify churners based on data mining techniques, however these techniques doesn’t always offer clear explanations for churn reasons. Instead, we use a technique called agent-based modeling to model customers in the mobile telecommunication market and assess the effects of customers characteristics and behaviors on such market. We propose a model that includes some relevant demographic and psychographic characteristics and the utilizations of usage profiles to describe customers. We show with simple experiments how different factors lead to churn in different ways. We believe the proposed approach is useful because MNOs can use it for explanatory, exploratory and predictive purposes.
Service Providers (SPs), which offer services based on elastic reservations with a guaranteed Grade of Service (GoS), should be interested in knowing how to price these services, i.e. service-i-, how to calculate the associated benefits to this service or, how to know the time until which the price for service-i-could be maintained, when an evolutionary function of the aggregate demand considered is involved and the established GoS for the elastic service is guaranteed. Thus this paper proposes a method that price elastic services (or elastic reservations) with guaranteed GoS in a scenario of evolutionary function of the aggregate demand. The method obtains: first at all, the average rate of the accepted elastic reservations of class-i with guaranteed GoS. Second, according to the accepted reservations, calculates the price that maximizes the selected revenue function. The considered aggregate demand function depends not only on a demand modulation factor, the mean reserved bandwidth, Bres,i, but on the evolution of this aggregate demand function, according to a Bass diffusion model. Third, in a scenario where not plenty access bandwidth Bi is available, evaluates the optimum value of the elasticity of the reservations that maximizes the revenue function for the obtained price. Finally, it is forecasted the time until the SP does not need to change the price or elasticity calculated when the demand increases and the GoS is guaranteed. The paper applies the method to a class-i- of elastic reservations, analyzes the influence of each one of the parameters and could be extended to multiple classes of independent and guaranteed elastic services.
Service Providers (SPs), which offer services based on elastic reservations with a guaranteed Grade of Service (GoS), should know how to price these services and how to quantify the benefits in different scenarios. This paper analyzes a method for evaluating the price of a service based on elastic reservations with a guaranteed Grade of Service. The method works as follows: First, the SP determines the requirements of the service that wants to offer; Second, the SP evaluates the average rate of the accepted elastic reservations of the service with a guaranteed GoS; Third, the SP calculates the price that guarantees the GoS with an aggregate demand function that depends on a demand modulation factor of the elastic reservations that is the mean reserved bandwidth, Bres; and Finally, the SP obtains the optimum value of the elasticity of the reservations that gives the maximum revenue, and the required access bandwidth in this case. The paper not only applies the method to a class i of elastic reservations when a linear-based demand and a revenue function are selected, but it also analyzes the influence of each one of the considered parameters. This method could be extended to the case of multiple classes of independent and guaranteed elastic services, applying the method to each service with its estimated demand and revenue functions.
The goals of FLAMINGO are (a) to strongly integrate the research of leading European research groups in the area of network and service management, (b) to strengthen the European and worldwide research in this area, and (c) to bridge the gap between scientific research and industrial application. To achieve these goals, FLAMINGO performs a broad range of activities, such as to develop open source software, establish joint labs, exchange researchers, jointly supervise Ph.D. students, develop educational and training material, interact with academia and industry, organize event, and strongly contribute to (IETF and IRTF) standardization.\n\n\nFLAMINGO develops a joint program of research activities to contribute to the development of network management and operation frameworks for the Future Internet (FI). Three major and federating challenges will be investigated:\n1. Network and service monitoring, based on flow-based techniques, enabling scalable monitoring systems to share collected data and feed the knowledge plane and decision algorithms of the FI.\n2. Automated configuration and repair, based on self-* features and frameworks, enabling billions of devices and managed objects to manage themselves in a fully distributed and autonomic way.\n3. Economic, legal, and regulative constraints, which do border management systems and operational solutions of the FI.\n\n\nFLAMINGO provides a unique consortium of leading researchers, with complementary knowledge and strong ties to industry, and covering the entire spectrum of network management core functions and application domains, which are necessary to build, integrate, and disseminate the knowledge of the management plane for the FI.\n\n\nFLAMINGO will strongly impact the European development of network management technologies, the development of standards and open-source software in this area, the organization of interoperability and testing labs, and the training of current and the education of future researchers in this area.
The FedSM project aims at formalising IT Service Management (ITSM) and introducing industry-standards-based ITSM processes in Federated e-Infrastructures. In the last decade, Federated e-Infrastructures have evolved from a set of ad-hoc academic services to a European scale resource for the science and technology sector.\n\nITSM approaches (like ITIL or ISO/IEC 20000) provide sets of processes and good practices, widely used in the commercial sector, that are used to build business and service provisioning models, structure business and management activities, and define, agree and operate services based on binding, well-understood agreements (service level agreements, SLAs) or contracts.\n\nFedSM will act in a way analogous to commercial ITSM consultancy, engaging with three 'client organisations': two National Grid Infrastructures and the European Grid Initiative, which are all part of the project consortium and committing to adopting an ITSM approach. FedSM will analyse their specific situations, provide new models for their processes and support them in assessing and implementing this new ITSM approach. To this end, FedSM will focus on (1) supporting the definition and implementation of business models, services, processes and a proto standard for Federated Infrastructure ITSM, (2) building up ITSM knowledge in the 'client organisations' through professional training and internationally recognised certification, and (3) consulting the 'client organisations' in defining their specific requirements for automated solutions and selecting adequate tools.\n\nFedSM will not be limited to supporting the involved 'client organisations' in implementing ITSM. Based on the client-specific ITSM programs and the lessons learned, a generic conceptual framework for implementing ITSM in Federated e-Infrastructures based on different business models in the areas of Grids and federated clouds will be developed.
'The objective of the EVANS project is to increase researchers’ mobility between EU countries and China to obtain better understanding of network virtualisation for future Internet infrastructure. In particular, the knowledge transfer, as a result of researcher’s mobility, will focus on the management aspects of the virtualised network resources rather than the virtualisation techniques themselves. As far as the types of network platforms are concerned, there are not only optical networks and IP networks for the core networks that constitute the Internet backbone but also various broadband wireless network technologies for mobile access. In order to provide an end-to-end service solution to end users, wireless mobile access network technologies have to be considered as an increasing number of users use mobile devices to get access to the Internet. The EVANS project aims to investigation into the creation of a network virtualisation environment over a fully heterogeneous network infrastructure and to provide an integrated network management system across different types of network platforms. The project will investigate into two complementary aspects of such an integrated network resource management system: (1) vertical management of virtualised resource for service heterogeneity, which is performed by infrastructure providers, and (2) horizontal management of virtualised resource for network heterogeneity, which is for the interest of service providers.
This staff exchange programme will also help develop new research links and deepen and strengthen the current research links amongst the partners and help build up long-term, world-class research in future Internet technology.'
This letter proposes a novel and open method for pricing substitute elastic services in a streaming content delivery scenario when their Grade of Service (GoS) is guaranteed. The method forces each Service Provider (SP) to calculate the rate for each substitute service that guarantees the GoS. The price of each service is obtained according to the maximization of a chosen revenue function and the estimation of its demand function. This letter illustrates the method calculating the price of two substitute services with a selected exponential demand function, where the assignation of the prices depend on the maximization of a selected revenue function.
In some guaranteed data delivery scenarios, servers can quickly and carefully allocate the available bandwidth among the requests of the users to reduce rejections. This is
particularly important when reservations are higher than minimum required delivery rate (semi-elastic reservations). As an example, when semi-elastic reservations utilize all the available server bandwidth and a new flow reservation arrives, it is useful to reallocate current reservations to accept the new one. The RSVP protocol is receiver oriented and it is in charge of setting up these reservations. However, in some cases, to reallocate bandwidth in a receiver riented way could delay the required sender reservation adjustments. This paper presents a new extension of the RSVP signaling messages that allows the server to adjust and modify these reservations. The performance evaluation of the extended and the native RSVP signaling protocols when used to manage the access bandwidth
of a semi elastic flows server shows the benefits of the extensions. In particular, the use of resource reservation is
reduced because of a more efficient bandwidth usage. In addition, the blocking probability is also reduced because of a
more flexible bandwidth reallocation situation. The authors believe that this procedure is an intermediate step to improve
the lack of flexibility that RSVP presents.
Soriano, M.; Aguilar, M.; Esparza, O.; Fernandez, M.; Forne, J.; Hernández-Serrano, J.; Isabel, M.; Pallares, E.; Pegueroles, J.; Postigo-Boix, M.; Jordi, F. Jornadas de Ingeniería Telemática p. 749-752 Presentació treball a congrés
Los servicios y aplicaciones ofrecidos en Internet demandan, con mayor frecuencia, un determinado nivel de servicio para su correcto funcionamiento. Esto supone el desarrollo de mecanismos que permitan ofrecer calidad de servicio diferenciada entre extremos distantes de la red. En una red con estas características el coste debido al uso de este servicio diferenciado es mayor que el de utilizar el modo tradicional de transferencia best-effort. Ello obliga a los usuarios a realizar un uso responsable de los recursos reservados. Por tanto, será crucial reservar sólo aquellos recursos estrictamente necesarios para lograr un mínimo coste. En este trabajo de Tesis Doctoral, se aborda el problema de minimizar los recursos reservados para una transmisión de un flujo semi-elástico. Este tipo de flujo se caracteriza por necesitar la reserva de más o menos recursos en función del estado de la red, por lo que se plantea el diseño de un sistema cliente-servidor capaz de realizar de forma automática las reservas estrictamente necesarias. Para ello, se propone un mecanismo de control de la ocupación de la memoria del cliente que permite determinar los periodos en que es necesario utilizar un modo de transferencia best-effort (aquellos en los que la ocupación garantiza la disponibilidad de datos en recepción), y los periodos en que se necesita un modo de transferencia con reserva de recursos para garantizar el llenado de dicha memoria. Del análisis de este mecanismo, se deducen expresiones para el coste de transmisión en función de los diversos parámetros que afectan a la ocupación de la memoria del cliente. De estos parámetros destaca especialmente la tasa de llegada de datos, que depende del estado de la red, y el umbral máximo de ocupación que indica cuándo se puede transmitir en modo best-effort. Gracias al correcto dimensionado de este umbral máximo, el cliente es capaz de minimizar los recursos reservados de la red. Para calcular este umbral, uno de los problemas que se plantea es la necesidad de una estimación inicial de la tasa de llegada de datos en modo best-effort. Para ello, se propone el uso de un umbral inicial que permita pasar a modo best-effort y realizar así, la estimación de esta tasa. Por otra parte, se propone también el uso de un mecanismo que mejora la minimización del coste de transmisión cuando la variabilidad de la tasa de llegada de paquetes en modo best-effort es grande, sin incrementar desmesuradamente la cantidad de señalización asociada necesaria. Finalmente, se propone un mecanismo para dar servicio de forma simultánea a varios clientes. Concretamente, se estudia mediante simulación un caso homogéneo, donde todos los clientes presentan los mismos requisitos. El esquema propuesto permite dar servicio simultáneo a un número determinado de clientes reservando recursos, mientras que el resto se sirve en modo best-effort. Del estudio se determina la existencia de un valor óptimo para el número de clientes a los que se da servicio en modo de reserva de recursos, que minimiza la señalización extra necesaria para gestionar el servicio. Asimismo, como complemento adicional para realizar este trabajo, se ha desarrollado una implementación del sistema cliente servidor de flujos semi-elásticos en el simulador ns-2, y además otra implementación real en lenguaje C sobre sistema Linux.
Internet services and applications are increasingly demanding appropriate levels of service for their adequate operation. That supposes the development of new mechanisms to allow end-to-end differentiated quality of service. In these networks, the cost of using this differentiated service is consequently higher than the employment of the well-known best-effort delivery mode, which requires users to make a responsible use of the reserved resources. Therefore, it is essential to reserve only those resources strictly necessary to achieve the minimum cost. This Thesis work deals with the problem of minimizing reserved resources in a semi-elastic flow transmission. This type of flow is characterized for requiring the reservation of more or less resources depending on network conditions, and for this reason, it is considered the design of a client-server system to reserve automatically the required demanded resources. Hence, it is proposed a method to control the client memory occupancy that determines when it is necessary to use a best-effort delivery mode (those periods when occupancy guarantees data availability in the client side), and when to use a resource reservation delivery mode to guarantee enough data entering into the client memory. From the analysis of this method, it is deduced the transmission cost, which depends on several parameters directly involved with client memory occupancy. Among these parameters, the delivery data rate and the maximum occupancy threshold, that indicates when it is possible to send data using best-effort mode, are the most significant ones. Thanks to the correct dimensioning of this maximum threshold, the client is able to minimize reserved network resources. To calculate this threshold, it is necessary to acquire an initial estimate for the best-effort delivery rate. To achieve this, it is proposed the use of an initial threshold to force a change to best-effort mode to obtain this estimate. In addition, it is proposed the use of a mechanism to improve the minimization cost for high delivery rate variability, without excessively increasing the signalling associated to the switching of transmission modes. Finally, it is proposed a method to serve simultaneously various clients. A homogeneous case is studied by simulation, in which all clients have the same requirements. This method allows a particular number of clients to be served by reserving resources, while the rest use best-effort mode. From this study, it is determined the existence of an optimum value for the number of simultaneous clients to be served by using resource reservation, that minimizes extra signalling to manage this service. Furthermore, as an aid to complement this research work, it has been developed an implementation of a client-server system for semi-elastic flows using ns-2, and additionally, a real implementation using C programming language in a Linux system.
The growing demand of network bandwidth indicates that user access to high speed (i.e. ATM)
networks is a key issue. The Inverse Multiplexing for ATM (IMA) is a technology that combines multiple
T1/E1 links to support the transparent transmission of ATM cells over one single logical data trunk whose
bandwidth is the aggregate of the T1/E1 capacities, minus a small amount due to overhead. That is, it
provides high bandwidth by using already deployed WAN infrastructure and at a reasonable cost. Employing
this technology, it is possible to dispose of ATM connections with data rates between the T1/E1 (an
economical but sometimes too slow option) and T3/E3 ones (with high bandwidth, but expensive for the
mass market of users). In this framework, and facing a new technology, it is crucial to have tools (analytical
and simulation ones) easy to manipulate that help telecommunication engineers and network planners on
the performance evaluation and dimensioning of these systems. In this paper, the fundamentals and major
applications of IMA technology are described. Also, the behavior of IMA multiplexers is carefully analyzed
and a method to dimension them proposed. An estimate for the Cell Loss Ratio (CLR) and the mean
waiting time measured in the IMUX devices are obtained. The analytical study is based on the comparison
with a M/D/1 queue system. Even though, we are aware of some weakness of our assumptions, especially
concerning the Poisson input traffic, the model is compact, easy to understand and to manipulate, therefore
it can be valuable to validate simulation models developed to evaluate IMUX devices under more realistic
input traffic patterns.
The growing demand of network bandwidth indicates that user access to high speed (i.e. ATM) networks is a key issue. The Inverse Multiplexing for ATM (IMA) is a technology that combines multiple T1/E1 links to support the transparent transmission of ATM cells over one single logical data trunk whose bandwidth is the aggregate of the T1/E1 capacities, minus a small amount due to overhead. That is, it provides high bandwidth by using already deployed WAN infrastructure and at a reasonable cost. Employing this technology, it is possible to dispose of ATM connections with data rates between the T1/E1 (an economical but sometimes too slow option) and T3/E3 ones (with high bandwidth, but expensive for the mass market of users). In this framework, and facing a new technology, it is crucial to have tools (analytical and simulation ones) easy to manipulate that help telecommunication engineers and network planners on the performance evaluation and dimensioning of these systems. In this paper, the fundamentals and major applications of IMA technology are described. Also, the behavior of IMA multiplexers is carefully analyzed and a method to dimension them proposed. An estimate for the Cell Loss Ratio (CLR) and the mean waiting time measured in the IMUX devices are obtained. The analytical study is based on the comparison with a M/D/1 queue system. Even though, we are aware of some weakness of our assumptions, especially concerning the Poisson input traffic, the model is compact, easy to understand and to manipulate, therefore it can be valuable to validate simulation models developed to evaluate IMUX devices under more realistic input traffic patterns.
Postigo-Boix, M.; García-Haro, J.; Aguilar, M. 2001 IEEE Pacific Rim Conference on Communications, Computers and Signals Processing (PACRIM 2001) p. 188-191 Data de presentació: 2001-08 Presentació treball a congrés
Postigo-Boix, M.; Garcia-Haro, J.; Garcia, J.; Aguilar, M. 2000 Symposium on Performance Evaluation of Computer and Telecommunication Systems p. 52-56 Data de presentació: 2000-07 Presentació treball a congrés