566 research outputs found
Bridging the Network Reservation Gap Using Overlays
We propose the concept of Overlay-linked IntServ (OLIntServ), a system architecture that combines network overlays with intra-domain QoS to provide assured communications over the Internet, while allowing ISPs to extend the reach of their currently under-utilized IntServ services. We describe our system prototype, and provide some preliminary experimental results on its efficacy
The Virtual Block Interface: A Flexible Alternative to the Conventional Virtual Memory Framework
Computers continue to diversify with respect to system designs, emerging
memory technologies, and application memory demands. Unfortunately, continually
adapting the conventional virtual memory framework to each possible system
configuration is challenging, and often results in performance loss or requires
non-trivial workarounds. To address these challenges, we propose a new virtual
memory framework, the Virtual Block Interface (VBI). We design VBI based on the
key idea that delegating memory management duties to hardware can reduce the
overheads and software complexity associated with virtual memory. VBI
introduces a set of variable-sized virtual blocks (VBs) to applications. Each
VB is a contiguous region of the globally-visible VBI address space, and an
application can allocate each semantically meaningful unit of information
(e.g., a data structure) in a separate VB. VBI decouples access protection from
memory allocation and address translation. While the OS controls which programs
have access to which VBs, dedicated hardware in the memory controller manages
the physical memory allocation and address translation of the VBs. This
approach enables several architectural optimizations to (1) efficiently and
flexibly cater to different and increasingly diverse system configurations, and
(2) eliminate key inefficiencies of conventional virtual memory. We demonstrate
the benefits of VBI with two important use cases: (1) reducing the overheads of
address translation (for both native execution and virtual machine
environments), as VBI reduces the number of translation requests and associated
memory accesses; and (2) two heterogeneous main memory architectures, where VBI
increases the effectiveness of managing fast memory regions. For both cases,
VBI significanttly improves performance over conventional virtual memory
A proposal for secured, efficient and scalable layer 2 network virtualisation mechanism
El contenidos de los capítulos 3 y 4 está sujeto a confidencialidad.
291 p.La Internet del Futuro ha emergido como un esfuerzo investigador para superar estas limitaciones identificadas en la actual Internet. Para ello es necesario investigar en arquitecturas y soluciones novedosas (evolutivas o rompedoras), y las plataformas de experimentación surgen para proporcionar un entorno realista para validar estas nuevas propuestas a gran escala.Debido a la necesidad de compartir la misma infraestructura y recursos para testear simultáneamente diversas propuestas de red, la virtualización de red es la clave del éxito. Se propone una nueva taxonomía para poder analizar y comparar las diferentes propuestas. Se identifican tres tipos: el Nodo Virtual (vNode), la Virtualización posibilitada por SDN (SDNeV) y el overlay.Además, se presentan las plataformas experimentales más relevantes, con un foco especial en la forma en la que cada una de ellas permite la investigación en propuestas de red, las cuales no cumplen todos estos requisitos impuestos: aislamiento, seguridad, flexibilidad, escalabilidad, estabilidad, transparencia, soporte para la investigación en propuestas de red. Por lo tanto, una nueva plataforma de experimentación ortogonal a la experimentación es necesaria.Las principales contribuciones de esta tesis, sustentadas sobre tecnología SDN y NFV, son también los elementos clave para construir la plataforma de experimentación: la Virtualización de Red basada en Prefijos de Nivel 2 (Layer 2 Prefix-based Network Virtualisation, L2PNV), un Protocolo para la Configuración de Direcciones MAC (MAC Address Configuration Protocol, MACP), y un sistema de Control de Acceso a Red basado en Flujos (Flow-based Network Access Control, FlowNAC).Como resultado, se ha desplegado en la Universidad del Pais Vasco (UPV/EHU) una nueva plataforma experimental, la Plataforma Activada por OpenFlow de EHU (EHU OpenFlow Enabled Facility, EHU-OEF), para experimentar y validar estas propuestas realizadas
PROMOTING CSET OUTREACH ACTIVITIES THROUGH SAFETY DATA MANAGEMENT AND ANALYSIS IN RITI COMMUNITIES
Traffic crashes are one of the leading causes of death among all people in the United States, but the rates among American Indian and Alaska Native (AIAN) populations are significantly higher than other groups. In fact, rural areas in general are disadvantaged from a traffic safety perspective due to the lack of funding and challenges in safety improvement decisions. This may contribute to the much higher fatality rate on rural roadways than on urban roadways. Additionally, there is a known issue of underreporting of fatal crashes of tribal members. Thus, an increased focus on rural, isolated, tribal, and indigenous (RITI) community traffic safety is necessary in order to progress towards zero fatalities. The need for quality data is recognized, and even included in many tribal transportation plans, but implementation and collection of the data varies. Quality data enables better safety analysis and enables greater support for traffic safety improvements. An easy-to-use and multisource database would enable tribes throughout the state and other rural communities to more readily manage data and apply for improvement funding. In order to reach this point, it is necessary to have agreements with tribes on crash data collection and usage, and understand local customs, needs, and current practices. This research aimed to form trusting and lasting relationships with tribal leaders in Washington State in order to facilitate crash database management and traffic safety analysis in their communities. The outreach activities included meetings with local tribal leaders, interviews, and attendance and presentations at tribal conferences. Ultimately a formal research agreement was signed with one tribe in Washington State granting access to the fatal and serious injury crash data they had collected
A proposal for secured, efficient and scalable layer 2 network virtualisation mechanism
El contenidos de los capítulos 3 y 4 está sujeto a confidencialidad.
291 p.La Internet del Futuro ha emergido como un esfuerzo investigador para superar estas limitaciones identificadas en la actual Internet. Para ello es necesario investigar en arquitecturas y soluciones novedosas (evolutivas o rompedoras), y las plataformas de experimentación surgen para proporcionar un entorno realista para validar estas nuevas propuestas a gran escala.Debido a la necesidad de compartir la misma infraestructura y recursos para testear simultáneamente diversas propuestas de red, la virtualización de red es la clave del éxito. Se propone una nueva taxonomía para poder analizar y comparar las diferentes propuestas. Se identifican tres tipos: el Nodo Virtual (vNode), la Virtualización posibilitada por SDN (SDNeV) y el overlay.Además, se presentan las plataformas experimentales más relevantes, con un foco especial en la forma en la que cada una de ellas permite la investigación en propuestas de red, las cuales no cumplen todos estos requisitos impuestos: aislamiento, seguridad, flexibilidad, escalabilidad, estabilidad, transparencia, soporte para la investigación en propuestas de red. Por lo tanto, una nueva plataforma de experimentación ortogonal a la experimentación es necesaria.Las principales contribuciones de esta tesis, sustentadas sobre tecnología SDN y NFV, son también los elementos clave para construir la plataforma de experimentación: la Virtualización de Red basada en Prefijos de Nivel 2 (Layer 2 Prefix-based Network Virtualisation, L2PNV), un Protocolo para la Configuración de Direcciones MAC (MAC Address Configuration Protocol, MACP), y un sistema de Control de Acceso a Red basado en Flujos (Flow-based Network Access Control, FlowNAC).Como resultado, se ha desplegado en la Universidad del Pais Vasco (UPV/EHU) una nueva plataforma experimental, la Plataforma Activada por OpenFlow de EHU (EHU OpenFlow Enabled Facility, EHU-OEF), para experimentar y validar estas propuestas realizadas
Bridging the Innovation Divide: An Agenda for Disseminating Technology Innovations within the Nonprofit Sector
Examines technology practices -- such as neighborhood information systems, electronic advocacy, Internet-based micro enterprise support, and digital inclusion initiatives -- that strengthen the capacity of nonprofits and community organizations
Recommended from our members
HARD: Hybrid Adaptive Resource Discovery for Jungle Computing
In recent years, Jungle Computing has emerged as a distributed computing paradigm based on simultaneous combination of various hierarchical and distributed computing environments which are composed by large number of heterogeneous resources. In such a computing environment, the resources and the underlying computation and communication infrastructures are highly-hierarchical and heterogeneous. This creates a lot of difficulty and complexity for finding the proper resources in a precise way in order to run a particular job on the system efficiently. This paper proposes Hybrid Adaptive Resource Discovery (HARD), a novel efficient and highly scalable resource-discovery approach which is built upon a virtual hierarchical overlay based on self-organization and self-adaptation of processing resources in the system, where the computing resources are organized into distributed hierarchies according to a proposed hierarchical multi-layered resource description model. The proposed approach supports distributed query processing within and across hierarchical layers by deploying various distributed resource discovery services and functionalities in the system which are implemented using different adapted algorithms and mechanisms in each level of hierarchy. The proposed approach addresses the requirements for resource discovery in Jungle Computing environments such as high-hierarchy, high-heterogeneity, high-scalability and dynamicity. Simulation results show significant scalability and efficiency of the proposed approach over highly heterogeneous, hierarchical and dynamic computing environments
Incentive-driven QoS in peer-to-peer overlays
A well known problem in peer-to-peer overlays is that no single entity has control over the software,
hardware and configuration of peers. Thus, each peer can selfishly adapt its behaviour to maximise its
benefit from the overlay. This thesis is concerned with the modelling and design of incentive mechanisms
for QoS-overlays: resource allocation protocols that provide strategic peers with participation incentives,
while at the same time optimising the performance of the peer-to-peer distribution overlay.
The contributions of this thesis are as follows. First, we present PledgeRoute, a novel contribution
accounting system that can be used, along with a set of reciprocity policies, as an incentive mechanism
to encourage peers to contribute resources even when users are not actively consuming overlay services.
This mechanism uses a decentralised credit network, is resilient to sybil attacks, and allows peers to
achieve time and space deferred contribution reciprocity. Then, we present a novel, QoS-aware resource
allocation model based on Vickrey auctions that uses PledgeRoute as a substrate. It acts as an incentive
mechanism by providing efficient overlay construction, while at the same time allocating increasing
service quality to those peers that contribute more to the network. The model is then applied to lagsensitive
chunk swarming, and some of its properties are explored for different peer delay distributions.
When considering QoS overlays deployed over the best-effort Internet, the quality received by a
client cannot be adjudicated completely to either its serving peer or the intervening network between
them. By drawing parallels between this situation and well-known hidden action situations in microeconomics,
we propose a novel scheme to ensure adherence to advertised QoS levels. We then apply
it to delay-sensitive chunk distribution overlays and present the optimal contract payments required,
along with a method for QoS contract enforcement through reciprocative strategies. We also present a
probabilistic model for application-layer delay as a function of the prevailing network conditions.
Finally, we address the incentives of managed overlays, and the prediction of their behaviour. We
propose two novel models of multihoming managed overlay incentives in which overlays can freely
allocate their traffic flows between different ISPs. One is obtained by optimising an overlay utility
function with desired properties, while the other is designed for data-driven least-squares fitting of the
cross elasticity of demand. This last model is then used to solve for ISP profit maximisation
- …