Towards a scalability model for wireless mesh networks

Zenzeleni mesh network is a wireless ad-hoc mesh network that provides voice services using public analogue telephones to the Mankosi community in the Eastern Cape Province. We would like to improve on the network infrastructure by upgrading the mesh routers and introducing low-end smartphones onto the network; and offer both data and voice over Internet protocol services. However, before deploying resources, it is imperative to identify the maximum number of mesh nodes, clients and simultaneous voice over internet protocol calls that can be supported by the mesh network while maintaining acceptable quality of service levels. Absence of such data might lead to financial risk and time depletion when setting up an optimal network. Bolstering the claim are investigations that report drop in quality levels as network density and hop count escalate. As current investigations mostly yield capacity models to predict per-node throughput with increasing hop count, we propose experiments to devise a scalability model to quantify scalability of mesh networks in this paper. We recommend experimental implementations at simulation level in Network Simulator-3 moving on to testbeds built using WiBed, and then finally take results to the field.Telkom, Cisco, Aria Technologies, THRIP, CONFINEDepartment of HE and Training approved lis

Evaluación del Enrutamiento y Acceso al Medio en Redes Mesh Auto-Configurables

Las redes comunitarias de tipo Mesh mediante la utilización de la tecnología inalámbrica (802.11b/g/n) permiten el acceso libre a la red a través de la colaboración de los propietarios que dejan abiertos sus puntos de acceso a cada nodo. Son particularmente útiles en aquellos lugares que no cuentan con una infraestructura de comunicaciones comercial. En este proyecto se pretende estudiar el problema de escalabilidad en estas redes, utilizando simuladores especialmente diseñados para ello. Se ahondará en el problema de contención en el acceso al medio que degrada la perfomance de estas redes brindando soluciones a través de diversos protocolos.Eje: Arquitecturas, Redes y Sistemas OperativosRed de Universidades con Carreras en Informática (RedUNCI

Advances in wireless community networks with the community-lab testbed

Beyond traditional telecom providers, citizens and organizations pool their own resources and coordinate in order to build local network infrastructures to address the digital divide in many parts of the world. These crowdsourced network infrastructures can be self-organized and shared by a community for the collective benefit of its members. Several of these networks have developed open, free, and neutral agreements, and are governed as a common-pool resource: community networks. These are built using a variety of commodity wireless hardware (e.g., Wi-Fi long-range point-to-point links, Wi-Fi and GSM access points, and mesh networks), sometimes optical fiber links, heterogeneous nodes, routing protocols, and applications. A group of researchers, developers, and community networks developed the Community-Lab testbed, and for the last five years have worked together to overcome obstacles, improve the technologies, tools, and operational models being used, as well as model best practices for more effective and sustainable community networks. This article presents the challenges for experimentation, the testbeds built, results, lessons learned, and the impact of that work to place wireless community networks as one sustainable way toward an Internet accessible to all.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

Internet sharing in community networks

Cotutela Universitat Politècnica de Catalunya i Instituto Superior TécnicoThe majority of the world's population does not have any or adequate Internet access. This implies that the Internet cannot provide universal service, reaching everyone without discrimination. Global access to the Internet for all requires the expansion of network infrastructures and a dramatic reduction in Internet access costs especially in less developed geographical regions. Local communities come together to build their own network infrastructures, known as Community Networks, and provide accessible and affordable local and Internet inter-networking. Sharing resources, such as infrastructure or Internet access, is encouraged at all levels, in order to lower the cost of connectivity and services. Communities can develop their own network infrastructures as a commons, using several interconnected sub-networks when the scale requires it, and sharing several Internet gateways among their participants. Shared Internet access is offered through web proxy gateways, where individuals or organisations share the full or spare capacity of their Internet connections with other participants. However, these gateway nodes may be overloaded by the demand, and their Internet capacity may degrade due to lack of regulation. This thesis investigates whether shared Internet access in community networks can be utilized to provide universal Internet access. As a first step in this direction, in this thesis we explored characteristics, limitations and usability of a concrete shared Internet Web proxy service in community networks. Based on our findings we studied and proposed mechanisms to improve the user experience and fairness of Internet sharing Web proxy services in community networks, without introducing significant overhead to the network and other services. More specifically, we proposed a scalable client-side Internet gateway selection mechanism suitable for heterogeneous environments such as community networks. Finally, we studied and proposed techniques for sharing spare Internet capacity without deteriorating the contributors' performance.La mayoría de la población mundial no tiene ningún o un adecuado acceso a Internet. Esto implica que Internet no puede prestar un servicio universal, llegando a todos sin discriminación. El acceso global a Internet para todos requiere una drástica reducción de los costos de acceso a Internet, especialmente en zonas geográficas y poblaciones menos desarrolladas. Las comunidades locales se organizan para construir sus propias infraestructuras de red, conocidas como redes comunitarias, y proporcionan interconexión local y con Internet de forma accesible y asequible. Se fomenta la compartición de recursos, como la infraestructura o el acceso a Internet, para reducir el coste de la conectividad y los servicios. Las comunidades pueden desarrollar sus propias infraestructuras de red como un recurso común, utilizando varias subredes interconectadas dado su tamaño, y compartiendo varias pasarelas de Internet entre sus participantes. El acceso compartido a Internet se ofrece a través de pasarelas que son proxy web, donde los participantes o las organizaciones comparten la capacidad total o excedente de su conexión a Internet con otros participantes. Sin embargo, estas pasarelas pueden saturarse por la demanda, y su capacidad de acceso a Internet se puede degradar debido la falta de regulación. Esta tesis investiga si las redes comunitarias se pueden utilizar para proporcionar acceso universal a Internet. Como primer paso en esta dirección, exploramos las características, limitaciones y usabilidad de un servicio concreto de acceso compartido a Internet con proxies web en una red comunitaria. Sobre la base de nuestros hallazgos, estudiamos y proponemos mecanismos para mejorar la experiencia del usuario y la equitatividad de la compartición, sin introducir una sobrecarga significativa en la red y a otros servicios. Más específicamente, proponemos un mecanismo escalable de selección de pasarela a Internet del lado del cliente, adecuado para entornos heterogéneos como las redes comunitarias. Además, estudiamos y proponemos técnicas para compartir la capacidad de Internet sin deteriorar el desempeño de los participantes que contribuyen.Postprint (published version

UPC CN-A Testbed mesh network deployment, monitoring and validation

[CATALÀ] Aquest projecte presenta WiBed, una solució desenvolupada per obtenir un testbed el més proper possible als entorns reals, a la vegada que aportant les característiques comunes dels entorns virtualitzats.[ANGLÈS] Testbeds are used in computer networking research to perform research experiments. Virtualization is sometimes used to simplify the experiment setup and reduce costs needed for large scale experimental testbeds

WiBed, a platform for commodity wireless testbeds

This paper presents WiBed, a FOSS platform for WiFi testbeds based on OpenWRT Linux made to run on commodity IEEE802.11 WiFi routers part of the Community-lab.net project, a global testbed for Community networks. WiBed has been designed to support realistic low layer network experiments (according to the OSI model). This work recolects the details of the architecture, design and implementation of WiBed consolidated during its operation as a testbed.Este trabajo presenta WiBed, una plataforma de software libre para bancos de pruebas Wi-Fi basada en OpenWRT Linux, hecha para utilizarse en los routers WiFi IEEE802.11 que forman parte del proyecto comunitario lab.net, un banco de pruebas mundial para las redes comunitarias. WiBed ha sido diseñado para apoyar los experimentos de red de capa baja realistas (de acuerdo con el modelo OSI). Este trabajo recolecta los detalles de la arquitectura, el diseño y la implementación de WiBed, consolidado durante su funcionamiento como banco de pruebas.Aquest treball presenta WiBed, una plataforma de programari lliure per a bancs de proves Wi-Fi basada en OpenWRT Linux, feta per utilitzar-se en els routers WiFi IEEE802.11 que formen part del projecte comunitari lab.net, un banc de proves mundial per a les xarxes comunitàries. WiBed ha estat dissenyat per donar suport als experiments de xarxa de capa baixa realistes (d'acord amb el model OSI). Aquest treball recull els detalls de l'arquitectura, el disseny i la implementació de WiBed, consolidat durant el seu funcionament com a banc de proves

WiBed, a platform for commodity wireless testbeds

Testbeds are a stage between the simulation and the production stages. To this end they must be as close as possible to production environments (i.e. real hardware, on the field deployments) while also keeping the traits of experimentation facilities (i.e. fault tolerance, ease of deployment, testing and data collection). This paper presents WiBed, a FOSS platform for WiFi testbeds based on OpenWRT Linux made to run on commodity IEEE802.11 WiFi routers part of the Community-lab. net project, a global testbed for Community networks. WiBed has been designed to support realistic low layer network experiments (according to the OSI model). This work recollects the details of the architecture, design and implementation of WiBed consolidated during its operation as a testbed as well as two deployments where real experiments were performed.Peer Reviewe