K-core decomposition of Internet graphs: hierarchies, self-similarity and measurement biases

We consider the $k$-core decomposition of network models and Internet graphs at the autonomous system (AS) level. The $k$-core analysis allows to characterize networks beyond the degree distribution and uncover structural properties and hierarchies due to the specific architecture of the system. We compare the $k$-core structure obtained for AS graphs with those of several network models and discuss the differences and similarities with the real Internet architecture. The presence of biases and the incompleteness of the real maps are discussed and their effect on the $k$-core analysis is assessed with numerical experiments simulating biased exploration on a wide range of network models. We find that the $k$-core analysis provides an interesting characterization of the fluctuations and incompleteness of maps as well as information helping to discriminate the original underlying structure

El triple juego de las comunicaciones bidireccionales

Fil: Alvarez-Hamelin, J. Ignacio. Universidad de Buenos Aires. Facultad de Ingeniería; ArgentinaTelefonía, televisión e Internet son actualmente servicios requeridos en la sociedad. Este nuevo paradigma crea intereses entre las empresas que brindan alguno de estos servicios, y el desafío de proveerlos conjuntamente. Sin embargo, la ola de Internet parece cubrirlo todo ya que esta tecnología permite implementar cualquier servicio donde la clave es la propiedad de la bidireccionalidad de las comunicaciones. Internet se inició en los 70 y Argentina comenzó a conectarse a mediados de los 90. En 2000, la red estaba ampliamente difundida y aceptada en el mundo. Este hecho fue observado por las compañías involucradas en el negocio de Internet y en otro tipo de tecnologías de comunicaciones. Surgió entonces el término "triple-play"

Architectural Considerations for a Self-Configuring Routing Scheme for Spontaneous Networks

Decoupling the permanent identifier of a node from the node's topology-dependent address is a promising approach toward completely scalable self-organizing networks. A group of proposals that have adopted such an approach use the same structure to: address nodes, perform routing, and implement location service. In this way, the consistency of the routing protocol relies on the coherent sharing of the addressing space among all nodes in the network. Such proposals use a logical tree-like structure where routes in this space correspond to routes in the physical level. The advantage of tree-like spaces is that it allows for simple address assignment and management. Nevertheless, it has low route selection flexibility, which results in low routing performance and poor resilience to failures. In this paper, we propose to increase the number of paths using incomplete hypercubes. The design of more complex structures, like multi-dimensional Cartesian spaces, improves the resilience and routing performance due to the flexibility in route selection. We present a framework for using hypercubes to implement indirect routing. This framework allows to give a solution adapted to the dynamics of the network, providing a proactive and reactive routing protocols, our major contributions. We show that, contrary to traditional approaches, our proposal supports more dynamic networks and is more robust to node failures