Genet: A Quickly Scalable Fat-Tree Overlay for Personal Volunteer Computing using WebRTC

WebRTC enables browsers to exchange data directly but the number of possible concurrent connections to a single source is limited. We overcome the limitation by organizing participants in a fat-tree overlay: when the maximum number of connections of a tree node is reached, the new participants connect to the node's children. Our design quickly scales when a large number of participants join in a short amount of time, by relying on a novel scheme that only requires local information to route connection messages: the destination is derived from the hash value of the combined identifiers of the message's source and of the node that is holding the message. The scheme provides deterministic routing of a sequence of connection messages from a single source and probabilistic balancing of newer connections among the leaves. We show that this design puts at least 83% of nodes at the same depth as a deterministic algorithm, can connect a thousand browser windows in 21-55 seconds in a local network, and can be deployed for volunteer computing to tap into 320 cores in less than 30 seconds on a local network to increase the total throughput on the Collatz application by two orders of magnitude compared to a single core

Low-Memory Techniques for Routing and Fault-Tolerance on the Fat-Tree Topology

Actualmente, los clústeres de PCs están considerados como una alternativa eficiente a la hora de construir supercomputadores en los que miles de nodos de computación se conectan mediante una red de interconexión. La red de interconexión tiene que ser diseñada cuidadosamente, puesto que tiene una gran influencia sobre las prestaciones globales del sistema. Dos de los principales parámetros de diseño de las redes de interconexión son la topología y el encaminamiento. La topología define la interconexión de los elementos de la red entre sí, y entre éstos y los nodos de computación. Por su parte, el encaminamiento define los caminos que siguen los paquetes a través de la red. Las prestaciones han sido tradicionalmente la principal métrica a la hora de evaluar las redes de interconexión. Sin embargo, hoy en día hay que considerar dos métricas adicionales: el coste y la tolerancia a fallos. Las redes de interconexión además de escalar en prestaciones también deben hacerlo en coste. Es decir, no sólo tienen que mantener su productividad conforme aumenta el tamaño de la red, sino que tienen que hacerlo sin incrementar sobremanera su coste. Por otra parte, conforme se incrementa el número de nodos en las máquinas de tipo clúster, la red de interconexión debe crecer en concordancia. Este incremento en el número de elementos de la red de interconexión aumenta la probabilidad de aparición de fallos, y por lo tanto, la tolerancia a fallos es prácticamente obligatoria para las redes de interconexión actuales. Esta tesis se centra en la topología fat-tree, ya que es una de las topologías más comúnmente usadas en los clústeres. El objetivo de esta tesis es aprovechar sus características particulares para proporcionar tolerancia a fallos y un algoritmo de encaminamiento capaz de equilibrar la carga de la red proporcionando una buena solución de compromiso entre las prestaciones y el coste.Gómez Requena, C. (2010). Low-Memory Techniques for Routing and Fault-Tolerance on the Fat-Tree Topology [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/8856Palanci

A Family of Fault-Tolerant Efficient Indirect Topologies

© 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.On the one hand, performance and fault-tolerance of interconnection networks are key design issues for high performance computing (HPC) systems. On the other hand, cost should be also considered. Indirect topologies are often chosen in the design of HPC systems. Among them, the most commonly used topology is the fat-tree. In this work, we focus on getting the maximum benefits from the network resources by designing a simple indirect topology with very good performance and fault-tolerance properties, while keeping the hardware cost as low as possible. To do that, we propose some extensions to the fat-tree topology to take full advantage of the hardware resources consumed by the topology. In particular, we propose three new topologies with different properties in terms of cost, performance and fault-tolerance. All of them are able to achieve a similar or better performance results than the fat-tree, providing also a good level of fault-tolerance and, contrary to most of the available topologies, these proposals are able to tolerate also faults in the links that connect to end nodes.This work was supported by the Spanish Ministerio de Economia y Competitividad (MINECO) and by FEDER funds under Grant TIN2012-38341-C04-01.Bermúdez Garzón, DF.; Gómez Requena, C.; Gómez Requena, ME.; López Rodríguez, PJ.; Duato Marín, JF. (2016). A Family of Fault-Tolerant Efficient Indirect Topologies. IEEE Transactions on Parallel and Distributed Systems. 27(4):927-940. https://doi.org/10.1109/TPDS.2015.2430863S92794027

Management of fault tolerance and traffic congestion in cloud data center

In this era of ubiquitous computing, coupled with the emergence of big data and internet of things, there have been constant changes in every aspect of cloud data center communications - its network connectivity, data storage, data transfer, and architectural design. As a result of this, the amount of data transferable, and the frequency of data transfer have tremendously increased; causing device failures and traffic congestions. To cope with these changes so that performance can be sustained amidst device failures and traffic congestion, the design of fault tolerant cloud data center is important. A fault tolerant cloud data center network should be able to provide alternative paths from source to destination during failures so that there will not be abrupt fall in performance. But still with the ongoing researches in this regard, there has not been a robust cloud data center design that can boast of being suitable for alleviating the poor fault tolerance of cloud data center. In this paper, we proposed the improved versions of fat-tree interconnection hybrid designs derived from the structure called Z-fat tree; to address the issues of fault tolerance. Then, we compared these designs with single fat tree architecture with the same amount of resources for client server communication pattern such as Email application in a cloud data center. The simulation results obtained based on failed switches and links, show that our proposed hybrid designs outperformed the single fat tree design as the inter arrival time of the packets reduces