Fish Eye OLSR Scaling Properties

International audienceScalability is one of the toughest challenges in ad hoc networking. Recent work outlines theoretical bounds on how well routing protocols could scale in this environment. However, none of the popular routing solutions really scales to large networks, by coming close enough to these bounds. In this paper, we study the case of link state routing and OLSR, one of the strongest candidate for standardization. We analyze how these bounds are not reached in this case, and we study how much the scalability is enhanced with the use of Fish Eye techniques in addition to the link state routing framework. We show that with this enhancement, the theoretical scalability bounds are reached

Towards Scalable MANETs

International audienceIn the near-future, self-organized networking is expected to become an important component in ITS, and in the Internet architecture in general. An essential challenge concerning the integration of this new component is the accomplishment of scalable and efficient mobile ad hoc routing. This paper overviews considerations relative to the design of such MANET protocols inside the framework provided by the IETF, stating the need for new hybrid protocols and architecture which offer a gradual transition from "traditional" MANET routing towards scalable MANET routing integrated in the Internet. This paper also proposes a tentative solution in this domain: DHT-OLSR, based on OLSR enhanced with dynamic clustering and distributed hash table routing

DHT-OLSR

L'auto-organisation est considérée comme un élément important de l'architecture Internet dans un futur proche. Un défi majeur concernant l'intégration de cet élément est l'accomplissement du routage mobile ad hoc à grande échelle. Ce rapport propose une nouvelle solution dans ce domaine, DHT-OLSR

Using Relative Neighborhood Graphs for Reliable Database Synchronization in MANETs

International audienceAchieving reliable communication of critical data on mobile ad hoc networks is a must before MANETs can be considered practical for standard mobile and vehicular commu- nications. This paper thus focuses on schemes that complement existing ad hoc broadcast mechanisms (inherently unreliable), which can guarantee the full diffusion of critical messages, when necessary. An interesting approach in this domain is the use of an overlay network, over which critical messages are acknowledged peer to peer, in order to verify the actual dissemination. This paper elaborates on the problem of performance, related to the discovery and the maintenance of such an overlay network, in a mobile ad hoc context. We present an analysis of a novel algorithm, SLOT (Synchronized Link Overlay - Triangular), an overlay selected based on a Relative Neighborhood Graph (RNG) scheme, and we compare its performance with that of other existing algorithms, in the context of the industry-standard IP routing protocol OSPF, which uses alternative overlay algorithms to synchronize link state databases of routers. The results presented in this paper show that SLOT outperforms other existing overlays by necessitating drastically less control traffic in order to function, enabling OSPF to scale to larger mobile ad hoc topologies

A Bioinspired Adaptive Congestion-Avoidance Routing for Mobile Ad Hoc Networks

Traditional mobile Ad Hoc network routing protocols are mainly based on the Shortest Path, which possibly results in many congestion nodes that incur routing instability and rerouting. To mitigate the side-efforts, this paper proposed a new bioinspired adaptive routing protocol (ATAR) based on a mathematics biology model ARAS. This paper improved the ARAS by reducing the randomness and by introducing a new routing-decision metric "the next-hop fitness" which was denoted as the congestion level of node and the length of routing path. In the route maintenance, the nodes decide to forward the data to next node according to a threshold value of the fitness. In the recovery phase, the node will adopt random manner to select the neighbor as the next hop by calculation of the improved ARAS. With this route mechanism, the ATAR could adaptively circumvent the congestion nodes and the rerouting action is taken in advance. Theoretical analysis and numerical simulation results show that the ATAR protocol outperforms AODV and MARAS in terms of delivery ratio, ETE delay, and the complexity. In particular, ATAR can efficiently mitigate the congestion

Evaluation of mesh routing protocols for wireless community networks

In recent years, we have witnessed the exponential growth of wireless community networks as a response to the clear necessity of Internet access for participation in society. For wireless mesh networks that can scale up to thousands of nodes, which are owned and managed in a decentralized way, it is imperative for their survival to provide the network with self-management mechanisms that reduce the requirements of human intervention and technological knowledge in the operation of a community network. In this paper, we focus on one important self-management mechanism, routing, and we study the scalability, performance, and stability of three proactive mesh routing protocols: BMX6, OLSR, and Babel. We study different metrics on an emulation framework and on the W-ILab.T testbed at iMinds, making the most of the two worlds. Emulation allows us to have more control over the topology and more systematically repeat the experiments, whereas a testbed provides a realistic wireless medium and more reliable measurements, especially in terms of interference and CPU consumption. Results show the relative merits, costs, and limitations of the three protocols.Peer ReviewedPostprint (author's final draft

Cooperation in open, decentralized, and heterogeneous computer networks

Community Networks (CN) are naturally open and decentralized structures, that grow organically with the addition of heterogeneous network devices, contributed and configured as needed by their participants. The continuous growth in popularity and dissemination of CNs in recent years has raised the perception of a mature and sustainable model for the provisioning of networking services. However, because such infrastructures include uncontrolled entities with non delimited responsibilities, every single network entity does indeed represent a potential single-point of failure that can stop the entire network from working, and that no other entity can prevent or even circumvent. Given the open and decentralized nature of CNs, that brings together individuals and organizations with different and even conflicting economic, political, and technical interests, the achievement of no more than basic consensus on the correctness of all network nodes is challenging. In such environment, the lack of self-determination for CN participants in terms of control and security of routing can be regarded as an obstacle for growth or even as a risk of collapse. To address this problem we first consider deployments of existing Wireless CN and we analyze their technology, characteristics, and performance. We perform an experimental evaluation of a production 802.11an Wireless CN, and compare to studies of other Wireless CN deployments in the literature. We compare experimentally obtained throughput traces with path-capacity calculations based on well-known conflict graph models. We observe that in the majority of cases the path chosen by the employed BMX6 routing protocol corresponds with the best identified path in our model. We analyze monitoring and interaction shortcomings of CNs and address these with Network Characterization Tool (NCT), a novel tool that allows users to assess network state and performance, and improve their quality of experience by individually modifying the routing parameters of their devices. We also evaluate performance outcomes when different routing policies are in use. Routing protocols provide self-management mechanisms that allow the continuous operation of a Community Mesh Network (CMN). We focus on three widely used proactive mesh routing protocols and their implementations: BMX6, OLSR, and Babel. We describe the core idea behind these protocols and study the implications of these in terms of scalability, performance, and stability by exposing them to typical but challenging network topologies and scenarios. Our results show the relative merits, costs, and limitations of the three protocols. Built upon the studied characteristics of typical CN deployments, their requirements on open and decentralized cooperation, and the potential controversy on the trustiness of particular components of a network infrastructure, we propose and evaluate SEMTOR, a novel routing-protocol that can satisfy these demands. SEMTOR allows the verifiable and undeniable definition and distributed application of individually trusted topologies for routing traffic towards each node. One unique advantage of SEMTOR is that it does not require a global consensus on the trustiness of any node and thus preserves cooperation among nodes with even oppositional defined trust specification. This gives each node admin the freedom to individually define the subset, and the resulting sub-topology, from the whole set of participating nodes that he considers sufficiently trustworthy to meet their security, data-delivery objectives and concerns. The proposed mechanisms have been realized as a usable and open-source implementation called BMX7, as successor of BMX6. We have evaluated its scalability, contributed robustness, and security. These results show that the usage of SEMTOR for securing trusted routing topologies is feasible, even when executed on real and very cheap (10 Euro, Linux SoC) routers as commonly used in Community Mesh Networks.Las Redes Comunitarias (CNs) son estructuras de naturaleza abierta y descentralizada, que crecen orgánicamente con la adición de dispositivos de red heterogéneos que aportan y configuran sus participantes según sea necesario. Sin embargo, debido a que estas infraestructuras incluyen entidades con responsabilidades poco delimitadas, cada entidad puede representar un punto de fallo que puede impedir que la red funcione y que ninguna otra entidad pueda prevenir o eludir. Dada la naturaleza abierta y descentralizada de las CNs, que agrupa individuos y organizaciones con diferentes e incluso contrapuestos intereses económicos, políticos y técnicos, conseguir poco más que un consenso básico sobre los nodos correctos en la red puede ser un reto. En este entorno, la falta de autodeterminación para los participantes de una CN en cuanto a control y seguridad del encaminamiento puede considerarse un obstáculo para el crecimiento o incluso un riesgo de colapso. Para abordar este problema consideramos las implementaciones de redes comunitarias inalámbricas (WCN) y se analiza su tecnología, características y desempeño. Realizamos una evaluación experimental de una WCN establecida y se compara con estudios de otros despliegues. Comparamos las trazas de rendimiento experimentales con cálculos de la capacidad de los caminos basados en modelos bien conocidos del grafo. Se observa que en la mayoría de los casos el camino elegido por el protocolo de encaminamiento BMX6 corresponde con el mejor camino identificado en nuestro modelo. Analizamos las limitaciones de monitorización e interacción en CNs y los tratamos con NCT, una nueva herramienta que permite evaluar el estado y rendimiento de la red, y mejorar la calidad de experiencia modificando los parámetros de sus dispositivos individuales. También evaluamos el rendimiento resultante para diferentes políticas de encaminamiento. Los protocolos de encaminamiento proporcionan mecanismos de autogestión que hacen posible el funcionamiento continuo de una red comunitaria mesh (CMN). Nos centramos en tres protocolos de encaminamiento proactivos para redes mesh ampliamente utilizados y sus implementaciones: BMX6, OLSR y Babel. Se describe la idea central de estos protocolos y se estudian la implicaciones de éstos en términos de escalabilidad, rendimiento y estabilidad al exponerlos a topologías y escenarios de red típicos pero exigentes. Nuestros resultados muestran los méritos, costes y limitaciones de los tres protocolos. A partir de las características analizadas en despliegues típicos de redes comunitarias, y de las necesidades en cuanto a cooperación abierta y descentralizada, y la esperable divergencia sobre la confiabilidad en ciertos componentes de la infraestructura de red, proponemos y evaluamos SEMTOR, un nuevo protocolo de encaminamiento que puede satisfacer estas necesidades. SEMTOR permite definir de forma verificable e innegable, así como aplicar de forma distribuida, topologías de confianza individualizadas para encaminar tráfico hacia cada nodo. Una ventaja única de SEMTOR es que no precisa de consenso global sobre la confianza en cualquier nodo y por tanto preserva la cooperación entre los nodos, incluso con especificaciones de confianza definidas por oposición. Esto proporciona a cada administrador de nodo la libertad para definir el subconjunto, y la sub-topología resultante, entre el conjunto de todos los nodos participantes que considere dignos de suficiente confianza para cumplir con su objetivo y criterio de seguridad y entrega de datos. Los mecanismos propuestos se han realizado en forma de una implementación utilizable de código abierto llamada BMX7. Se ha evaluado su escalabilidad, robustez y seguridad. Estos resultados demuestran que el uso de SEMTOR para asegurar topologías de encaminamiento de confianza es factible, incluso cuando se ejecuta en routers reales y muy baratos utilizados de forma habitual en WCN.Postprint (published version