Survey of traffic control schemes and error control schemes for ATM networks

Among the techniques proposed for B-ISDN transfer mode, ATM concept is considered to be the most promising transfer technique because of its flexibility and efficiency. This paper surveys and reviews a number of topics related to ATM networks. Those topics cover congestion control, provision of multiple classes of traffic, and error control. Due to the nature of ATM networks, those issues are far more challenging than in conventional networks. Sorne of the more promising solutions to those issues are surveyed, and the corresponding results on performance are summarized. Future research problems in ATM protocol aspect are also presented

QoSatAr: a cross-layer architecture for E2E QoS provisioning over DVB-S2 broadband satellite systems

This article presents QoSatAr, a cross-layer architecture developed to provide end-to-end quality of service (QoS) guarantees for Internet protocol (IP) traffic over the Digital Video Broadcasting-Second generation (DVB-S2) satellite systems. The architecture design is based on a cross-layer optimization between the physical layer and the network layer to provide QoS provisioning based on the bandwidth availability present in the DVB-S2 satellite channel. Our design is developed at the satellite-independent layers, being in compliance with the ETSI-BSM-QoS standards. The architecture is set up inside the gateway, it includes a Re-Queuing Mechanism (RQM) to enhance the goodput of the EF and AF traffic classes and an adaptive IP scheduler to guarantee the high-priority traffic classes taking into account the channel conditions affected by rain events. One of the most important aspect of the architecture design is that QoSatAr is able to guarantee the QoS requirements for specific traffic flows considering a single parameter: the bandwidth availability which is set at the physical layer (considering adaptive code and modulation adaptation) and sent to the network layer by means of a cross-layer optimization. The architecture has been evaluated using the NS-2 simulator. In this article, we present evaluation metrics, extensive simulations results and conclusions about the performance of the proposed QoSatAr when it is evaluated over a DVB-S2 satellite scenario. The key results show that the implementation of this architecture enables to keep control of the satellite system load while guaranteeing the QoS levels for the high-priority traffic classes even when bandwidth variations due to rain events are experienced. Moreover, using the RQM mechanism the user’s quality of experience is improved while keeping lower delay and jitter values for the high-priority traffic classes. In particular, the AF goodput is enhanced around 33% over the drop tail scheme (on average)

A methodological approach to BISDN signalling performance

Sophisticated signalling protocols are required to properly handle the complex multimedia, multiparty services supported by the forthcoming BISDN. The implementation feasibility of these protocols should be evaluated during their design phase, so that possible performance bottlenecks are identified and removed. In this paper we present a methodology for evaluating the performance of BISDN signalling systems under design. New performance parameters are introduced and their network-dependent values are extracted through a message flow model which has the capability to describe the impact of call and bearer control separation on the signalling performance. Signalling protocols are modelled through a modular decomposition of the seven OSI layers including the service user to three submodels. The workload model is user descriptive in the sense that it does not approximate the direct input traffic required for evaluating the performance of a layer protocol; instead, through a multi-level approach, it describes the actual implications of user signalling activity for the general signalling traffic. The signalling protocol model is derived from the global functional model of the signalling protocols and information flows using a network of queues incorporating synchronization and dependency functions. The same queueing approach is followed for the signalling transfer network which is used to define processing speed and signalling bandwidth requirements and to identify possible performance bottlenecks stemming from the realization of the related protocols

Contributions based on cross-layer design for quality-of-service provisioning over DVB-S2/RCS broadband satellite system

Contributions based on cross-layer design for Quality-of-Service provisioning over DVB-S2/RCS Broadband Satellite Systems Nowadays, geostationary (GEO) satellite infrastructure plays a crucial role for the provisioning of IP services. Such infrastructure can provide ubiquity and broadband access, being feasible to reach disperse populations located worldwide within remote areas where terrestrial infrastructure can not be deployed. Nevertheless, due to the expansion of the World Wide Web (WWW), new IP applications such as Voice over IP (VoIP) and multimedia services requires considering different levels of individual packet treatment through the satellite network. This differentiation must include not only the Quality of Service (QoS) parameters to specify packet transmission priorities across the network nodes, but also the required amount of bandwidth assignment to guarantee its transport. In this context, the provisioning of QoS guarantees over GEO satellite systems becomes one of the main research areas of organizations such as the European Space Agency (ESA). Mainly because, their current infrastructures require continuous exploitation, as launching a new communication satellite is associated with excessive costs. Therefore, the support of IP services with QoS guarantees must be developed on the terrestrial segment to enable using the current assets. In this PhD thesis several contributions to improve the QoS provisioning over DVB-S2/RCS Broadband Satellite Systems have been developed. The contributions are based on cross-layer design, following the layered model standardized in the ETSI TR 102 157 and 462. The proposals take into account the drawbacks posed by GEO satellite systems such as delay, losses and bandwidth variations. The first contribution proposes QoSatArt, an architecture defined to improve QoS provisioning among services classes considering the physical layer variations due to the presence of rain events. The design is developed inside the gateway, including the specification of the main functional blocks to provide QoS guarantees and mechanisms to minimize de delay and jitter values experienced at the application layer. Here, a cross-layer design between the physical and the network layer has been proposed, to enforce the QoS specifications based on the available bandwidth. The proposed QoSatArt architecture is evaluated using the NS-2 simulation tool. In addition, the performance analysis of several standard Transmission Control Protocol (TCP) variants is also performed. This is carry out to find the most suitable TCP variant that enhances TCP transmission over a QoS architecture such as the QoSatArt. The second contribution proposes XPLIT, an architecture developed to enhance TCP transmission with QoS for DVB-S2/RCS satellite systems. Complementary to QoSatArt, XPLIT introduces Performance Enhanced Proxies (PEPs), which breaks the end-to-end semantic of TCP connections. However, it considers a cross-layer design between the network layer and the transport layer to enhance TCP transmission while providing them with QoS guarantees. Here, a modified TCP variant called XPLIT-TCP is proposed to send data through the forward and the return channel. XPLIT-TCP uses two control loops (the buffer occupancy and the service rate to provide optimized congestion control functions. The proposed XPLIT architecture is evaluated using the NS-2 simulation tool. Finally, the third contribution of this thesis consists on the development of a unified architecture to provide QoS guarantees based on cross-layer design over broadband satellite systems. It adopts the enhancements proposed by the QoSatArt architecture working at the network layer, in combination with the enhancements proposed by the XPLIT architecture working at the transport layer.Actualmente, los satélites Geoestacionarios (GEO) juegan un papel muy importante en la provisión de servicios IP. Esta infraestructura permite proveer ubicuidad y acceso de banda ancha, haciendo posible alcanzar poblaciones dispersas en zonas remotas donde la infraestructura terrestre es inexistente. Sin embargo, en la provisión de aplicaciones como Voz sobre IP (VoIP) y servicios multimedia, es importante considerar el tratamiento diferenciado de paquetes a través de la red satelital. Esta diferenciación debe considerar no solo los requerimientos de Calidad de Servicio (QoS) que especifican las prioridades de los paquetes a través de los nodos de red, si no también el ancho de banda asignado para garantizar su transporte. En este contexto, la provisión de garantías de QoS sobre satélites GEO es una de las Principales áreas de investigación de organizaciones como la Agencia Espacial Europea (ESA) persiguen. Esto se debe principalmente ya que dichas organizaciones requieren la explotación continua de sus activos, dado que lanzar un nuevo satélite al espacio representa costos excesivos. Como resultado, el soporte de servicios IP con calidad de servicio sobre la infraestructura satelital actual es de vital importancia. En esta tesis doctoral se presentan varias contribuciones para el soporte a la Calidad de Servicio en redes DVB-S2/RCS satelitales de banda ancha. Las contribuciones propuestas se basan principalmente en el diseño ”cross-layer” siguiendo el modelo de capas definido y estandarizado en las especificaciones ETSI TR 102 157 [ETS03] y 462 [10205]. Las contribuciones propuestas consideran las limitaciones presentes de los sistemas satelitales GEO como lo son el retardo de propagación, la perdida de paquetes y las variaciones de ancho de banda causados por eventos atmosféricos. La primera contribución propone QoSatArt, una arquitectura definida para mejorar el soporte a la QoS. Esta arquitectura considera las variaciones en la capa física debido a la presencia de eventos de lluvia para priorizar los niveles de QoS. El diseño se desarrolla en el gateway e incluye las especificaciones de los principales elementos funcionales y mecanismos para garantizar la QoS y minimizar el retardo presente en la capa de aplicación. Aquí, se propone un diseño ”cross-layer” entre la capa física y la capa de red, con el objetivo de reforzar las especificaciones de QoS considerando el ancho de banda disponible. La arquitectura QoSatArt es simulada y evaluada empleando la herramienta de simulación NS-2. Adicionalmente, un análisis de desempeño de diversas variantes de TCP (Transmission Control Protocol) es realizado con el objetivo de encontrar la variante de TCP más adecuada para trabajar en un ambiente con QoS como QoSatArt. La segunda contribución propone XPLIT, una arquitectura desarrollada para mejorar las transmisiones TCP con QoS en un sistema satelital DVB-S2/RCS. Complementario a QoSatArt, XPLIT emplea PEPs (Performance Enhanced Proxies), afectando la semántica end-to-end de las conexiones TCP. Sin embargo, XPLIT considera un diseño ”cross-layer” entre la capa de red y la capa de transporte con el objetivo de mejorar las transmisiones TCP considerando los parámetros de QoS como la ocupación de la cola y la tasa de transmisión (_i, _i). Aquí, se propone el uso de una nueva variante de TCP es propuesta llamada XPLIT-TCP, que usa dos bucles para proveer funciones mejoradas en el control de congestión. La arquitectura XPLIT es simulada y evaluada empleando la herramienta de simulación NS-2. Finalmente, la tercera contribución de esta tesis consiste en el desarrollo de un arquitectura unificada para el soporte a la QoS en redes satelitales de banda ancha basada en técnicas ”cross-layer”. Esta arquitectura adopta las mejoras propuestas por QoSatArt en la capa de red en combinación con las mejoras propuestas por XPLIT en la capa de transporte

Network emulation focusing on QoS-Oriented satellite communication

This chapter proposes network emulation basics and a complete case study of QoS-oriented Satellite Communication

A Survey on the Contributions of Software-Defined Networking to Traffic Engineering

Since the appearance of OpenFlow back in 2008, software-defined networking (SDN) has gained momentum. Although there are some discrepancies between the standards developing organizations working with SDN about what SDN is and how it is defined, they all outline traffic engineering (TE) as a key application. One of the most common objectives of TE is the congestion minimization, where techniques such as traffic splitting among multiple paths or advanced reservation systems are used. In such a scenario, this manuscript surveys the role of a comprehensive list of SDN protocols in TE solutions, in order to assess how these protocols can benefit TE. The SDN protocols have been categorized using the SDN architecture proposed by the open networking foundation, which differentiates among data-controller plane interfaces, application-controller plane interfaces, and management interfaces, in order to state how the interface type in which they operate influences TE. In addition, the impact of the SDN protocols on TE has been evaluated by comparing them with the path computation element (PCE)-based architecture. The PCE-based architecture has been selected to measure the impact of SDN on TE because it is the most novel TE architecture until the date, and because it already defines a set of metrics to measure the performance of TE solutions. We conclude that using the three types of interfaces simultaneously will result in more powerful and enhanced TE solutions, since they benefit TE in complementary ways.European Commission through the Horizon 2020 Research and Innovation Programme (GN4) under Grant 691567 Spanish Ministry of Economy and Competitiveness under the Secure Deployment of Services Over SDN and NFV-based Networks Project S&NSEC under Grant TEC2013-47960-C4-3-

Downstream Bandwidth Management for Emerging DOCSIS-based Networks

In this dissertation, we consider the downstream bandwidth management in the context of emerging DOCSIS-based cable networks. The latest DOCSIS 3.1 standard for cable access networks represents a significant change to cable networks. For downstream, the current 6 MHz channel size is replaced by a much larger 192 MHz channel which potentially can provide data rates up to 10 Gbps. Further, the current standard requires equipment to support a relatively new form of active queue management (AQM) referred to as delay-based AQM. Given that more than 50 million households (and climbing) use cable for Internet access, a clear understanding of the impacts of bandwidth management strategies used in these emerging networks is crucial. Further, given the scope of the change provided by emerging cable systems, now is the time to develop and introduce innovative new methods for managing bandwidth. With this motivation, we address research questions pertaining to next generation of cable access networks. The cable industry has had to deal with the problem of a small number of subscribers who utilize the majority of network resources. This problem will grow as access rates increase to gigabits per second. Fundamentally this is a problem on how to manage data flows in a fair manner and provide protection. A well known performance issue in the Internet, referred to as bufferbloat, has received significant attention recently. High throughput network flows need sufficiently large buffer to keep the pipe full and absorb occasional burstiness. Standard practice however has led to equipment offering very large unmanaged buffers that can result in sustained queue levels increasing packet latency. One reason why these problems continue to plague cable access networks is the desire for low complexity and easily explainable (to access network subscribers and to the Federal Communications Commission) bandwidth management. This research begins by evaluating modern delay-based AQM algorithms in downstream DOCSIS 3.0 environments with a focus on fairness and application performance capabilities of single queue AQMs. We are especially interested in delay-based AQM schemes that have been proposed to combat the bufferbloat problem. Our evaluation involves a variety of scenarios that include tiered services and application workloads. Based on our results, we show that in scenarios involving realistic workloads, modern delay-based AQMs can effectively mitigate bufferbloat. However they do not address the other problem related to managing the fairness. To address the combined problem of fairness and bufferbloat, we propose a novel approach to bandwidth management that provides a compromise among the conflicting requirements. We introduce a flow quantization method referred to as adaptive bandwidth binning where flows that are observed to consume similar levels of bandwidth are grouped together with the system managed through a hierarchical scheduler designed to approximate weighted fairness while addressing bufferbloat. Based on a simulation study that considers many system experimental parameters including workloads and network configurations, we provide evidence of the efficacy of the idea. Our results suggest that the scheme is able to provide long term fairness and low delay with a performance close to that of a reference approach based on fair queueing. A further contribution is our idea for replacing `tiered\u27 levels of service based on service rates with tiering based on weights. The application of our bandwidth binning scheme offers a timely and innovative alternative to broadband service that leverages the potential offered by emerging DOCSIS-based cable systems