Catálogo de publicaciones - libros

Proactive routing protocols for mobile ad hoc networks currently offer few mechanisms to detect and/or counter malevolent nodes. Stability and performance of most, if not all, emerging standard proactive protocols rely on cooperation between nodes. While cryptographic methods may be a solution to secure control messages, nodes not willing to cooperate may still decide not to forward data packets. In this paper, a method to enable resilience to such malevolent nodes is presented. It is non-intrusive with respect to the packet forwarding mechanisms (e.g. TCP/IP kernel stack) and particularly well suited for integration with proactive routing protocols.

This paper presents a new hybrid traffic engineering routing algorithm for bandwidth guaranteed traffic. Former traffic engineering routing algorithms mainly optimize one of the three objectives: minimizing the hop count, balancing the load and minimizing the interference between source-destination pairs. But usually there is a tradeoff among these three factors. Single objective optimizations can’t get the best performance. The main contribution of this paper is a new hybrid approach to consider the three objectives together. From the simulation results, the proposed algorithm has better performance than former algorithms.

In this article we present a methodology by which an autonomous system (AS) can estimate the stability of their BGP routes without requiring access to restricted BGP data. We demonstrate a novel measurement approach using DNS anycast as an indicator of routing instability. Using this method, even end-users may monitor their ISP’s routing stability, something which was previously infeasible without the continual use of expensive ICMP traceroutes or access to generally restricted routing information. We then perform a case study from within a large ISP in order to quantify and determine the cause of the routing instability. To determine causation, we correlate external and internal BGP events with variations in the final anycast destination. We conclude that anycast is extremely sensitive to anomalous BGP events and that by monitoring anycast it may be possible for large networks to receive early warning of BGP instability.

Mobility models must scale accordingly to the application and reflect real scenarios in which wireless devices are deployed. Typical examples of scenarios requiring precise mobility models are critical situations ( vehicular traffic incident, escaping pedestrians in emergency situations) – for which the ad hoc paradigm was first designed for. In these particular situations, autonomous agents of communicating devices will assist mobile users in their displacements either to avoid traffic jam due to incidents or find the closest emergency exit. But, since the environment conditions (, flow of pedestrians or vehicles and incidents) may change during time in part due to mobility itself, autonomous agents assisting mobile users in their displacements must constantly exchange information and dynamically adapt to the perceived situations. This requires to precisely modeling both mobility (vehicular and pedestrian traffic) and communications systems between agents. Unfortunately, these two areas have been treated separately, although mobility and network simulators should be tightly bound. In this paper, we propose a new modeling approach to mobility, namely Behavioral Mobility models (BM), which decomposes mobility into simple atomic individual behaviors. Combined, these behaviors yield realistic displacement patterns by reproducing the mobility observed at small scales in every day life, in both space and time. We also propose to bind mobility and network simulators to run joint simulations in order to push simulations to more realness. This approach combined to BM models is particularly suited to simulate critical situations where mobility is influenced by the changing environment conditions. We demonstrate the feasibility of our approach with two cases studies.

The study conducted in this paper evaluates the performance of on-demand mobile ad hoc wireless network protocols under varying node densities in a large network. The focus in this study centers on the relationship between the mobility, density and connectivity of ad hoc wireless nodes. Ad hoc wireless node density is often discussed on a single group subnets of nodes. In this study a scenario is proposed to evaluate the ad hoc wireless nodes communicating between different node sub with different densities. A simulation is conducted using the two prominent on demand routing protocol for ad hoc networks namely DSR and AODV. In the simulation each protocol is given 2 different scenarios in terms of node location. The first scenario is a normal ad hoc wireless simulation scenario. The second scenario contains nodes that are partitioned into 7 areas where respective areas have their node density and connection probability. The objective of this study is to look at how on demand ad hoc wireless routing protocols react to environments with non uniform node densities and to seek and understanding for future improvement.

In this paper, we will build a fault-tolerant network using a Multiple Care-of Addresses registration implementation on NEPL (NEMO Platform for Linux) for the GNU/Linux Operating System. As we will explain in a detailed scenario, Multiple Care-of Addresses registration is a very interesting solution for fault recovery when connecting multihomed networks to the Internet with multiple non-reliable access technologies. The feasibility of this scenario will be endorsed by an experiment using the implementation.

In the near future, we expect many mobile networks (ex. vehicle in-side network, personal area network) are connected to the Internet and to the other mobile network to support rich applications for user’s daliy life. There are several technology to connect these mobile networks to network and the Internet such as Mobile IP, Network Mobility (NEMO) and Mobile Ad-hoc Network (MANET). We specially investigate the use of both NEMO and MANET for efficient communication for an in-vehicle network. This paper proposes Mobile Gateway supporting policy based routing. It manages both NEMO connectivity and MANET connectivity and switches path to a destination according to application requirements and network environment. Our results shows this approach is efficient for vehicle network.