Brokering SLAs for end-to-end QoS in cloud computing

In this paper, we present a brokering logic for providing precise end-to-end QoS levels to cloud applications distributed across a number of different business actors, such as network service providers (NSP) and cloud providers (CSP). The broker composes a number of available offerings from each provider, in a way that respects the QoS application constraints while minimizing costs incurred by cloud consumers. Copyright © 2014 SCITEPRESS - Science and Technology Publications

Data centre optimisation enhanced by software defined networking

Contemporary Cloud Computing infrastructures are being challenged by an increasing demand for evolved cloud services characterised by heterogeneous performance requirements including real-time, data-intensive and highly dynamic workloads. The classical way to deal with dynamicity is to scale computing and network resources horizontally. However, these techniques must be coupled effectively with advanced routing and switching in a multi-path environment, mixed with a high degree of flexibility to support dynamic adaptation and live-migration of virtual machines (VMs). We propose a management strategy to jointly optimise computing and networking resources in cloud infrastructures, where Software Defined Networking (SDN) plays a key enabling role

A multipath routing method for tolerating permanent and non-permanent faults

The intensive and continuous use of high-performance computers for executing computationally intensive applications, coupled with the large number of elements that make them up, dramatically increase the likelihood of failures during their operation. The interconnection network is a critical part of such systems, therefore, network faults have an extremely high impact because most routing algorithms are not designed to tolerate faults. In such algorithms, just a single fault may stall messages in the network, preventing the finalization of applications, or may lead to deadlocked confi gurations. This work focuses on the problem of fault tolerance for high-speed interconnection networks by designing a fault-tolerant routing method to solve an unbounded number of dynamic faults (permanent and non- permanent). To accomplish this task we take advantage of the communication path redundancy, by means of a multipath routing approach. Experiments show that our method allows applications to finalize their execution in the presence of several number of faults, with an average performance value of 97% compared to the fault-free scenarios.Presentado en el IX Workshop Procesamiento Distribuido y Paralelo (WPDP)Red de Universidades con Carreras en Informática (RedUNCI

FlexState: Flexible State Management of Network Functions

Network function (NF) developers have traditionally prioritized performance when creating new packet processing capabilities. This was usually driven by a market demand for highly available solutions with differentiating features running at line rate, even at the expense of flexibility and tightly-coupled monolithic designs. Today, however, the market advantage is achieved by providing more features in shorter development cycles and quickly deploying them in different operating environments. In fact, network operators are increasingly adopting continuous software delivery practices as well as new architectural styles (e.g., microservices) to decouple functionality and accelerate development. A key challenge in revisiting NF design is state management, which is usually highly optimized for a deployment by carefully selecting the underlying data store. Therefore, migrating to a data store that suits a different use case is time-consuming as it requires code refactoring and adaptation to new application programming interfaces, APIs. As a result, refactoring NF software for different environments can take up to months, reducing the pace at which new features and upgrades can be deployed in production networks. In this paper, we demonstrate experimentally that it is feasible to introduce an abstraction layer to decouple NF state management from the data store adopted while still approaching line-rate performance. We present FlexState, a state management system that exposes data store functionality as configuration options, which reduces code refactoring efforts. Experiments show that FlexState achieves significant flexibility in optimizing the state management, and accelerates deployment on new scenarios while preserving performance and scalability.Peer reviewe

Balanceo distribuido del encaminamiento para el control de congestión en redes infiniband

El uso de recursos compartidos en las redes de interconexión de alta performance puede provocar situaciones de congestión de mensajes que degradan notablemente las prestaciones, aumentando la latencia de trasporte y disminuyendo la utilización de la red. Hasta el momento las técnicas que intentan solucionar este problema utilizan la regulación de la inyección de mensajes. Esta limitación de la inyección traslada la contención de mensajes desde los conmutadores hacia los nodos fuente, incrementando el valor de la latencia promedio global, pudiendo alcanzar valores muy elevados. En este artículo, proponemos una técnica de control de congestión para redes InfiniBand basada en un mecanismo de encaminamiento adaptativo que distribuye el volumen de comunicaciones entre diversas trayectorias alternativas quitando carga de la zona de congestión, lo que permite eliminarla. La experimentación realizada muestra la mejora obtenida en latencia y throughput, respecto al mecanismo de control de congestión original de InfiniBand basado en la regulación de la inyección. El mecanismo propuesto es totalmente compatible y no requiere que se modifique ningún aspecto de la especificación, debido a que se utilizan componentes de gestión definidos en el estándar InfiniBand.Communications requirements in High Performance Computing (HPC) demand the use of Interconnections Networks to connect processing nodes. Sharing resources in high performance interconnection networks leads to message congestion. Congestion spreading increases latency and reduces network throughput causing important performance degradation. Nowadays most current techniques use message throttling to prevent injection of new messages in network congested region. Message throttling moves contention from switches to sources nodes in order to eliminate congestion, however global latency is highly incremented because of the time that packets must wait in the source node. In this paper, we propose a congestion control mechanism for InfiniBand networks based in an adaptive routing algorithm that perform a communication load balancing over several alternative paths, in order to take load away of the congested network zone, eliminating congestion and maintaining injection rate. Our mechanism’s experimentation results show latency, throughput and dynamic behaviour improvement over InfiniBand original congestion control mechanism which is based in message throttling. The proposed mechanism use the management model defined in InfiniBand specs, thus full compatibility is provided.VIII Workshop de Procesamiento Distribuido y ParaleloRed de Universidades con Carreras en Informática (RedUNCI

On Reconfiguring 5G Network Slices

The virtual resources of 5G networks are expected to scale and support migration to other locations within the substrate. In this context, a configuration for 5G network slices details the instantaneous mapping of the virtual resources across all slices on the substrate, and a feasible configuration satisfies the Service-Level Objectives (SLOs) without overloading the substrate. Reconfiguring a network from a given source configuration to the desired target configuration involves identifying an ordered sequence of feasible configurations from the source to the target. The proposed solutions for finding such a sequence are optimized for data centers and cannot be used as-is for reconfiguring 5G network slices. We present Matryoshka, our divide-and-conquer approach for finding a sequence of feasible configurations that can be used to reconfigure 5G network slices. Unlike previous approaches, Matryoshka also considers the bandwidth and latency constraints between the network functions of network slices. Evaluating Matryoshka required a dataset of pairs of source and target configurations. Because such a dataset is currently unavailable, we analyze proof of concept roll-outs, trends in standardization bodies, and research sources to compile an input dataset. On using Matryoshka on our dataset, we observe that it yields close-to-optimal reconfiguration sequences 10X faster than existing approaches.Peer reviewe

Dynamic routing balancing on InfiniBand network

InfiniBand (IBA) technology was developed to address the performance issues associated with messages movement among Endnodes and computer I/O devices. However, InfiniBand is also widely deployed within high performance computing (HPC) clusters due to the high bandwidth and low message latency attributes it offers to inter-processor communication systems. An interconnection-network efficient design is mandatory because its great impact on the parallel computer performance. Therefore, a high speed routing scheme that minimizes congestion and avoids hot-spot areas should be included in the network components. We have developed Dynamic Routing Balancing (DRB), an adaptive routing mechanism that balances the communication traffic over the interconnection network. It is based on limited and load-controlled multipath expansion in order to maintain low and bounded network latency. In this work, we propose using DRB as the congestion control mechanism for InfiniBand networks. Experimentation shows that our method achieves significant performance improvement over the original InfiniBand technique which is based on message throttling. An improvement up to 66% for latency and 35% for throughput is achieved for the networks under analysis. Finally, the proposed mechanism use the management model defined in InfiniBand specs, thus full compatibility is provided.Facultad de Informátic

Balanceo distribuido del encaminamiento para el control de congestión en redes infiniband

El uso de recursos compartidos en las redes de interconexión de alta performance puede provocar situaciones de congestión de mensajes que degradan notablemente las prestaciones, aumentando la latencia de trasporte y disminuyendo la utilización de la red. Hasta el momento las técnicas que intentan solucionar este problema utilizan la regulación de la inyección de mensajes. Esta limitación de la inyección traslada la contención de mensajes desde los conmutadores hacia los nodos fuente, incrementando el valor de la latencia promedio global, pudiendo alcanzar valores muy elevados. En este artículo, proponemos una técnica de control de congestión para redes InfiniBand basada en un mecanismo de encaminamiento adaptativo que distribuye el volumen de comunicaciones entre diversas trayectorias alternativas quitando carga de la zona de congestión, lo que permite eliminarla. La experimentación realizada muestra la mejora obtenida en latencia y throughput, respecto al mecanismo de control de congestión original de InfiniBand basado en la regulación de la inyección. El mecanismo propuesto es totalmente compatible y no requiere que se modifique ningún aspecto de la especificación, debido a que se utilizan componentes de gestión definidos en el estándar InfiniBand.Communications requirements in High Performance Computing (HPC) demand the use of Interconnections Networks to connect processing nodes. Sharing resources in high performance interconnection networks leads to message congestion. Congestion spreading increases latency and reduces network throughput causing important performance degradation. Nowadays most current techniques use message throttling to prevent injection of new messages in network congested region. Message throttling moves contention from switches to sources nodes in order to eliminate congestion, however global latency is highly incremented because of the time that packets must wait in the source node. In this paper, we propose a congestion control mechanism for InfiniBand networks based in an adaptive routing algorithm that perform a communication load balancing over several alternative paths, in order to take load away of the congested network zone, eliminating congestion and maintaining injection rate. Our mechanism’s experimentation results show latency, throughput and dynamic behaviour improvement over InfiniBand original congestion control mechanism which is based in message throttling. The proposed mechanism use the management model defined in InfiniBand specs, thus full compatibility is provided.VIII Workshop de Procesamiento Distribuido y ParaleloRed de Universidades con Carreras en Informática (RedUNCI

Env2Vec: accelerating VNF testing with deep learning

The adoption of fast-paced practices for developing virtual network functions (VNFs) allows for continuous software delivery and creates a market advantage for network operators. This adoption, however, is problematic for testing engineers that need to assure, in shorter development cycles, certain quality of highly-configurable product releases running on heterogeneous clouds. Machine learning (ML) can accelerate testing workflows by detecting performance issues in new software builds. However, the overhead of maintaining several models for all combinations of build types, network configurations, and other stack parameters, can quickly become prohibitive and make the application of ML infeasible. We propose Env2Vec, a deep learning architecture that combines contextual features with historical resource usage, and characterizes the various stack parameters that influence the test execution within an embedding space, which allows it to generalize model predictions to previously unseen environments. We integrate a single ML model in the testing workflow to automatically debug errors and pinpoint performance bottlenecks. Results obtained with real testing data show an accuracy between 86.2%-100%, while reducing the false alarm rate by 20.9%-38.1% when reporting performance issues compared to state-of-the-art approaches