Improving Real-Time Data Dissemination Performance by Multi Path Data Scheduling in Data Grids

The performance of data grids for data intensive, real-time applications is highly dependent on the data dissemination algorithm employed in the system. Motivated by this fact, this study first formally defines the real-time splittable data dissemination problem (RTS/DDP) where data transfer requests can be routed over multiple paths to maximize the number of data transfers to be completed before their deadlines. Since RTS/DDP is proved to be NP-hard, four different heuristic algorithms, namely kSP/ESMP, kSP/BSMP, kDP/ESMP, and kDP/BSMP are proposed. The performance of these heuristic algorithms is analyzed through an extensive set of data grid system simulation scenarios. The simulation results reveal that a performance increase up to 8 % as compared to a very competitive single path data dissemination algorithm is possible

QoS Provisioning in Converged Satellite and Terrestrial Networks: A Survey of the State-of-the-Art

It has been widely acknowledged that future networks will need to provide significantly more capacity than current ones in order to deal with the increasing traffic demands of the users. Particularly in regions where optical fibers are unlikely to be deployed due to economical constraints, this is a major challenge. One option to address this issue is to complement existing narrow-band terrestrial networks with additional satellite connections. Satellites cover huge areas, and recent developments have considerably increased the available capacity while decreasing the cost. However, geostationary satellite links have significantly different link characteristics than most terrestrial links, mainly due to the higher signal propagation time, which often renders them not suitable for delay intolerant traffic. This paper surveys the current state-of-the-art of satellite and terrestrial network convergence. We mainly focus on scenarios in which satellite networks complement existing terrestrial infrastructures, i.e., parallel satellite and terrestrial links exist, in order to provide high bandwidth connections while ideally achieving a similar end user quality-of-experience as in high bandwidth terrestrial networks. Thus, we identify the technical challenges associated with the convergence of satellite and terrestrial networks and analyze the related work. Based on this, we identify four key functional building blocks, which are essential to distribute traffic optimally between the terrestrial and the satellite networks. These are the traffic requirement identification function, the link characteristics identification function, as well as the traffic engineering function and the execution function. Afterwards, we survey current network architectures with respect to these key functional building blocks and perform a gap analysis, which shows that all analyzed network architectures require adaptations to effectively support converged satellite and terrestrial networks. Hence, we conclude by formulating several open research questions with respect to satellite and terrestrial network convergence.This work was supported by the BATS Research Project through the European Union Seventh Framework Programme under Contract 317533

Qualidade de serviço dinâmico para diferentes tipos de fluxos em SDN

Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Exatas, Departamento de Ciência da Computação, 2019.A estrutura de redes de computadores atual dificulta a implementação de Qualidade de Serviço (Quality of Service (QoS)) em fluxos distintos e nas aplicações em geral (ex: tráfego de vídeos streaming). Uma vez que a maioria das tecnologias de rede são proprietárias, o administrador de rede não detém o conhecimento técnico suficiente para configurar a qualidade de serviço nos equipamentos de rede com tecnologia proprietária. O paradigma das Redes Definidas por Software (SDN) surgiu para poder remover essas restrições separando o plano de controle do plano de dados. Essa separação proporciona aos administradores de rede o uso eficiente de recursos de rede e a facilidade de provisionamento de diversos serviços e novas aplicações desenvolvidas de acordo com a necessidade da rede (ex: QoS ou firewall). Porém, a própria tecnologia SDN ainda sofre com pouca documentação e a limitação de mecanismos sólidos para aplicação de QoS, principalmente em fluxos do tipo elefantes (tráfegos com volume de dados excessivos), guepardo (tráfegos que geram alta taxa de transferência na rede) e alfa (tráfego que geram diversas rajadas no tráfego). Visando preencher esta lacuna, este trabalho propõe um novo serviço que consegue trabalhar com o plano de controle e o plano de dados em SDN, chamado de QoS-Flux. Este serviço tem o objetivo de aplicar filtros para priorizar aplicativos sensíveis e executar algoritmos de QoS em diferentes fluxos em uma rede SDN. Resultados preliminares mostram que o QoS-Flux melhora significativamente o QoS em uma rede SDN nos parâmetros de atraso, jitter, perda de pacotes e largura de banda.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).The current computer network structure makes it difficult to implement Quality of Service (QoS) in distinct streams and in general applications (eg. streaming video traffic). Since most network technologies are proprietary, the network administrator does not have sufficient technical knowledge to configure quality of service on proprietary technology network equipment. The Software Defined Networks (SDN) paradigm has emerged in order to remove these constraints by separating the control plane from the data plane. This separation provides network administrators with the efficient use of network resources and the ease of provisioning of various services and new applications developed according to the need of the network (eg QoS or firewall). However, SDN technology itself still suffers from poor documentation and limited solid mechanisms for QoS application, especially in elephant type flows (traffic with excessive data volume), cheetah (traffic that generates high throughput in the network) and alpha (traffic that generates several bursts of traffic). In order to fill this gap, this work proposes a new service that can work with the control plan and data plan in SDN, called QoS-Flux. This service aims to apply filters to prioritize sensitive applications and execute QoS algorithms on different flows in an SDN network. Preliminary results show that QoS-Flux significantly improves the QoS in an SDN network in the parameters of delay, jitter, packet loss and bandwidth

SDN-based traffic engineering in data centers, Interconnects, and Carrier Networks

Server virtualization and cloud computing have escalated the bandwidth and performance demands on the DCN (data center network). The main challenges in DCN are maximizing network utilization and ensuring fault tolerance to address multiple node-and-link failures. A multitenant and highly dynamic virtualized environment consists of a large number of endstations, leading to a very large number of flows that challenge the scalability of a solution to network throughput maximization. The challenges are scalability, in terms of address learning, forwarding decision convergence, and forwarding state size, as well as flexibility for offloading with VM migration. Geographically distributed data centers are inter-connected through service providers’ carrier network. Service providers offer wide-area network (WAN) connection such as private lines and MPLS circuits between edges of data centers. DC sides of network operators try to maximize the utilization of such defined overlay WAN connection i.e. data center interconnection (DCI), which applies to edges of DC networks. Service provider sides of network operators try to optimize the core of carrier network. Along with the increasing adoption of ROADM, OTN, and packet switching technologies, traditional two-layer IP/MPLS-over-WDM network has evolved into three-layer IP/MPLS-over-OTN-over-DWDM network and once defined overlay topology is now transitioning to dynamic topologies based on on-demand traffic demands. Network operations are thus divided into three physical sub-networks: DCN, overlay DCI, and multi-layer carrier network. Server virtualization, cloud computing and evolving multilayer carrier network challenge traffic engineering to maximize utilization on all physical subnetworks. The emerging software-defined networking (SDN) architecture moves path computation towards a centralized controller, which has global visibility. Carriers indicate a strong preference for SDN to be interoperable between multiple vendors in heterogeneous transport networks. SDN is a natural way to create a unified control plane across multiple administrative divisions. This thesis contributes SDN-based traffic engineering techniques for maximizing network utilization of DCN, DCI, and carrier network. The first part of the thesis focuses on DCN traffic engineering. Traditional forwarding mechanisms using a single path are not able to take advantages of available multiple physical paths. The state-of-the-art MPTCP (Multipath Transmission Control Protocol) solution uses multiple randomly selected paths, but cannot give total aggregated capacity. Moreover, it works as a TCP process, and so does not support other protocols like UDP. To address these issues, this thesis presents a solution using adaptive multipath routing in a Layer-2 network with static (capacity and latency) metrics, which adapts link and path failures. This solution provides innetwork aggregated path capacity to individual flows, as well as scalability and multitenancy, by separating end-station services from the provider’s network. The results demonstrate an improvement of 14% in the worst bisection bandwidth utilization, compared to the MPTCP with 5 sub-flows. The second part of the thesis focuses on DCI traffic engineering. The existing approaches to reservation services provide limited reservation capabilities, e.g. limited connections over links returned by the traceroute over traditional IP-based networks. Moreover, most existing approaches do not address fault tolerance in the event of node or link failures. To address these issues, this thesis presents ECMP-like multipath routing algorithm and forwarding assignment scheme that increase reservation acceptance rate compared to state-of-art reservation frameworks in the WAN-links between data centers, and such reservations can be configured with a limited number of static forwarding rules on switches. Our prototype provides the RESTful web service interface for link-fail event management and re-routes paths for all the affected reservations. In the final part of the thesis, we focused on multi-layer carrier network traffic engineering. New dynamic traffic trends in upper layers (e.g. IP routing) require dynamic configuration of the optical transport to re-direct the traffic, and this in turn requires an integration of multiple administrative control layers. When multiple bandwidth path requests come from different nodes in different layers, a distributed sequential computation cannot optimize the entire network. Most prior research has focused on the two-layer problem, and recent three-layer research studies are limited to the capacity dimensioning problem. In this thesis, we present an optimization model with MILP formulation for dynamic traffic in a three-layer network, especially taking into account the unique technological constraints of the distinct OTN layer. Our experimental results show how unit cost values of different layers affect network cost and parameters in the presence of multiple sets of traffic loads. We also demonstrate the effectiveness of our proposed heuristic approach

A survey on the evolution of RSVP

The Resource Reservation Protocol (RSVP) represents one of the most important protocols used for resource reservation in the Internet. Developed initially by the Internet Engineering Task Force (IETF) to be used within the Integrated Services (IntServ) mechanism, this protocol undergoes over time several alterations. These alterations come either to respond to some applicability and functionality problems, or to extend the use of RSVP and to make it compatible with other mechanisms like Differentiated Services (DiffServ) or Multiprotocol Label Switching (MPLS). This work presents a survey on the evolution of RSVP illustrating the different alterations introduced over time for this protocol and explaining how each adaptation affects RSVP in functional terms. © 1998-2012 IEEE.status: publishe