Issues in designing transport layer multicast facilities

Multicasting denotes a facility in a communications system for providing efficient delivery from a message's source to some well-defined set of locations using a single logical address. While modem network hardware supports multidestination delivery, first generation Transport Layer protocols (e.g., the DoD Transmission Control Protocol (TCP) (15) and ISO TP-4 (41)) did not anticipate the changes over the past decade in underlying network hardware, transmission speeds, and communication patterns that have enabled and driven the interest in reliable multicast. Much recent research has focused on integrating the underlying hardware multicast capability with the reliable services of Transport Layer protocols. Here, we explore the communication issues surrounding the design of such a reliable multicast mechanism. Approaches and solutions from the literature are discussed, and four experimental Transport Layer protocols that incorporate reliable multicast are examined

Auditing in common computer environments; Auditing procedure study;

https://egrove.olemiss.edu/aicpa_guides/1039/thumbnail.jp

Beyond swarm intelligence: The Ultraswarm

This paper explores the idea that it may be possible to combine two ideas – UAV flocking, and wireless cluster computing – in a single system, the UltraSwarm. The possible advantages of such a system are considered, and solutions to some of the technical problems are identified. Initial work on constructing such a system based around miniature electric helicopters is described

Implementation and maintenance of telephony network through Avaya s8720: practice application in Fabrics Division at Barcelona

La empresa W.L. GORE and Asociados es una empresa multinacional con sede en Barcelona dedicada a la fabricación y venta de membranas de PTFE (Politetrafluoroetileno), un material transpirable e impermeable con múltiples aplicaciones en el mercado. Una de dichas aplicaciones consiste en insertar dicha membrana en prendas de ciclismo y running, lo que confiere cualidades extras al tejido y mejora el rendimiento del deportista. Aprovechando esta línea de negocio, se ha creado un departamento internacional de atención al cliente compuesto por seis personas, mediante el cual se pretende dar servicio tanto a tiendas como al cliente final para la solicitud de pedidos y cambios. Una vez aprobado el proyecto en Barcelona, se encarga al Departamento de Telecomunicaciones de la empresa su puesta en marcha. Para ello, se parte de los medios de los que dispone la empresa, fundamentalmente un servidor de telefonía Avaya S8700 y un customer service de productos médicos en activo. En este contexto, se ha utilizado una tecnología IP para las conexiones lógicas de los teléfonos y la centralita de tecnología PSTN. De este modo, utilizaremos telefonía IP en el recorrido entre los teléfonos y la centralita, y pasaremos a modo analógico una vez se haya determinado la gestión de las llamadas, tanto internas como externas. La parte más importante del proyecto, una vez asegurada la conexión entre los dispositivos, es la programación de los grupos de llamada. En nuestro proyecto, aplicaremos unas determinadas secuencias de encaminamiento para derivar la llamada a la persona más indicada en cada caso. En este escenario, se considerará la procedencia de la llamada (entorno europeo) y la persona que ha de atenderla, que deberá tener un determinado nivel de conocimiento de la lengua de origen de la llamada. Para dotar al sistema de robustez, deberemos determinar un encaminamiento especial o backup para aquellos casos en que no haya personas disponibles para atender la llamada, la llamada se realice fuera de horario de oficina, haya que enviar mensajes de voz especiales, etc. Una vez completada la parte de instalación e implementación, y una vez terminada la programación del sistema, deberán efectuarse las pruebas correspondientes para depurar errores, así como los cambios propios del mantenimiento de las líneas. Igualmente, se han llevado a cabo otras operaciones secundarias como la configuración del sistema en cintas redundantes, la implementación de buzones de voz, la posibilidad de desviar las líneas locales a internacionales, COS y COR y otras opciones adicionales en vectores y skills

Experience and Lessons learnt from running High Availability Databases on Network Attached Storage

The Database and Engineering Services Group of CERN's Information Technology Department supplies the Oracle Central Database services used in many activities at CERN. In order to provide High Availability and ease management for those services, a NAS (Network Attached Storage) based infrastructure has been setup. It runs several instances of the Oracle RAC (Real Application Cluster) using NFS (Network File System) as shared disk space for RAC purposes and Data hosting. It is composed of two private LANs (Local Area Network), one to provide access to the NAS filers and a second to implement the Oracle RAC private interconnect, both using Network Bonding. NAS filers are configured in partnership to prevent having single points of failure and to provide automatic NAS filer fail-over

The Design of a System Architecture for Mobile Multimedia Computers

This chapter discusses the system architecture of a portable computer, called Mobile Digital Companion, which provides support for handling multimedia applications energy efficiently. Because battery life is limited and battery weight is an important factor for the size and the weight of the Mobile Digital Companion, energy management plays a crucial role in the architecture. As the Companion must remain usable in a variety of environments, it has to be flexible and adaptable to various operating conditions. The Mobile Digital Companion has an unconventional architecture that saves energy by using system decomposition at different levels of the architecture and exploits locality of reference with dedicated, optimised modules. The approach is based on dedicated functionality and the extensive use of energy reduction techniques at all levels of system design. The system has an architecture with a general-purpose processor accompanied by a set of heterogeneous autonomous programmable modules, each providing an energy efficient implementation of dedicated tasks. A reconfigurable internal communication network switch exploits locality of reference and eliminates wasteful data copies

Tunneling Horizontal IEC 61850 Traffic through Audio Video Bridging Streams for Flexible Microgrid Control and Protection

In this paper, it is argued that some low-level aspects of the usual IEC 61850 mapping to Ethernet are not well suited to microgrids due to their dynamic nature and geographical distribution as compared to substations. It is proposed that the integration of IEEE time-sensitive networking (TSN) concepts (which are currently implemented as audio video bridging (AVB) technologies) within an IEC 61850 / Manufacturing Message Specification framework provides a flexible and reconfigurable platform capable of overcoming such issues. A prototype test platform and bump-in-the-wire device for tunneling horizontal traffic through AVB are described. Experimental results are presented for sending IEC 61850 GOOSE (generic object oriented substation events) and SV (sampled values) messages through AVB tunnels. The obtained results verify that IEC 61850 event and sampled data may be reliably transported within the proposed framework with very low latency, even over a congested network. It is argued that since AVB streams can be flexibly configured from one or more central locations, and bandwidth reserved for their data ensuring predictability of delivery, this gives a solution which seems significantly more reliable than a pure MMS-based solution