From diversity to convergence : British computer networks and the Internet, 1970-1995

The Internet's success in the 21st century has encouraged analysts to investigate the origin of this network. Much of this literature adopts a teleological approach. Works often begin by discussing the invention of packet switching, describe the design and development of the ARPANET, and then examine how this network evolved into the Internet. Although the ARPANET was a seminal computer network, these accounts usually only briefly consider the many other diverse networks that existed. In addition, apart from momentary asides to alternative internetworking solutions, such as the Open Systems Interconnection (OSI) seven-layer reference model, this literature concentrates exclusively on the ARPANET, the Internet, and the World Wide Web. While focusing on these subjects is important and therefore justified, it can leave the reader with the impression that the world of networking started with the ARPANET and ended with the Internet. This thesis is an attempt to help correct this misconception. This thesis analyses the evolution of British computer networks and the Internet between the years 1970 and 1995. After an introduction in Chapter 1, the thesis analyses several networks. In Chapters 2 and 3, the focus is on academic networks, especially JANET and SuperJANET. Attention moves to videotex networks in Chapter 4, specifically Prestel, and in Chapter 5, the dissertation examines electronic mail networks such as Telecom Gold and Cable & Wireless Easylink. Chapter 6 considers online services, including CompuServe, American Online, and the Microsoft Network, and the thesis ends with a conclusion in Chapter 7. All of the networks discussed used protocols that were incompatible with each other which limited the utility of the networks for their users. Although it was possible that OSI or another solution could have solved this problem, the Internet's protocols achieved this objective. This thesis shows how the networks converged around TCP/IP

From diversity to convergence : British computer networks and the Internet, 1970-1995

The Internet's success in the 21st century has encouraged analysts to investigate the origin of this network. Much of this literature adopts a teleological approach. Works often begin by discussing the invention of packet switching, describe the design and development of the ARPANET, and then examine how this network evolved into the Internet. Although the ARPANET was a seminal computer network, these accounts usually only briefly consider the many other diverse networks that existed. In addition, apart from momentary asides to alternative internetworking solutions, such as the Open Systems Interconnection (OSI) seven-layer reference model, this literature concentrates exclusively on the ARPANET, the Internet, and the World Wide Web. While focusing on these subjects is important and therefore justified, it can leave the reader with the impression that the world of networking started with the ARPANET and ended with the Internet. This thesis is an attempt to help correct this misconception. This thesis analyses the evolution of British computer networks and the Internet between the years 1970 and 1995. After an introduction in Chapter 1, the thesis analyses several networks. In Chapters 2 and 3, the focus is on academic networks, especially JANET and SuperJANET. Attention moves to videotex networks in Chapter 4, specifically Prestel, and in Chapter 5, the dissertation examines electronic mail networks such as Telecom Gold and Cable & Wireless Easylink. Chapter 6 considers online services, including CompuServe, American Online, and the Microsoft Network, and the thesis ends with a conclusion in Chapter 7. All of the networks discussed used protocols that were incompatible with each other which limited the utility of the networks for their users. Although it was possible that OSI or another solution could have solved this problem, the Internet's protocols achieved this objective. This thesis shows how the networks converged around TCP/IP.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

COMPUTER NETWORK ANALYSIS AND OPTIMISATION

This thesis presents a study and analysis of the major influences on network cost and their related performance. New methods have been devised to find solutions to network optimisation problems particular to the AT&T ISTEL networks in Europe and these are presented together with examples of their successful commercial application. Network performance is seen by the user in terms of network availability and traffic delay times. The network performance is influenced by many parameters, the dominating influences typically being the number of users accessing the network, the type of traffic demands they place upon it and the particular network configuration itself. The number of possible network configurations available to a network designer is vast if the full range of currently available equipment is taken into account. The aim of this research has been to assist in the selection of most suitable network designs for optimum performance and cost. This thesis looks at the current differing network technologies, their performance characteristics and the issues pertinent to any network design and optimisation procedures. A distinction is made between the network equipment providing user 'access' and that which constitutes the cross country, or *core\ data transport medium. This partitioning of the problem is exploited with the analysis concentrating on each section separately. The access side of the AT&T ISTEL - UK network is used as a basis for an analysis of the general access network. The aim is to allow network providers to analyse the root cause of excessive delay problems and find where small adjustments to access configurations might lead to real performance improvements from a user point of view. A method is developed to allow statistical estimates of performance and quality of service for typical access network configurations. From this a general method for the optimisation of cost expenditure and performance improvement is proposed. The optimisation of both circuit switched and packet switched computer networks is shown to be difficult and is normally tackled by the use of complex procedures on mainframe computers. The new work carried out in this study takes a fresh look at the basic properties of networks in order to develop a new heuristic method for the design and optimisation of circuit switched core networks on a personal computer platform. A fully functional design system was developed that implements time division multiplexed core network design. The system uses both a new heuristic method for improving the quality of the designs and a new 'speed up' algorithm for reducing times to find feasible routes, thereby dramatically improving overall design times. The completed system has since been used extensively to assist in the design of commercial networks across Europe.AT&T ISTEL Ltd., Redditch, Englan

Managing the Transition from SNMP to NETCONF: Comparing Dual-Stack and Protocol Gateway Hybrid Approaches

As industries become increasingly automated and stressed to seek business advantages, they often have operational constraints that make modernization and security more challenging. Constraints exist such as low operating budgets, long operational lifetimes and infeasible network/device upgrade/modification paths. In order to bypass these constraints with minimal risk of disruption and perform ``no harm'', network administrators have come to rely on using dual-stack approaches, which allow legacy protocols to co-exist with modern ones. For example, if SNMP is required for managing legacy devices, and a newer protocol (NETCONF) is required for modern devices, then administrators simply modify firewall Access Control Lists (ACLs) to allow passage of both protocols. In today's networks, firewalls are ubiquitous, relatively inexpensive, and able to support multiple protocols (hence dual-stack) while providing network security. While investigating securing legacy devices in heterogeneous networks, it was determined that dual-stack firewall approaches do not provide adequate protection beyond layer three filtering of the IP stack. Therefore, the NETCONF/SNMP Protocol Gateway hybrid (NSPG) was developed as an alternative in environments where security is necessary, but legacy devices are infeasible to upgrade, replace, and modify. The NSPG allows network administrators to utilize only a single modern protocol (NETCONF) instead of both NETCONF and SNMP, and enforce additional security controls without modifying existing deployments. It has been demonstrated that legacy devices can be securely managed in a protocol-agnostic manner using low-cost commodity hardware (e.g., the RaspberryPi platform) with administrator-derived XML-based configuration policies

Proceedings of the Second International Mobile Satellite Conference (IMSC 1990)

Presented here are the proceedings of the Second International Mobile Satellite Conference (IMSC), held June 17-20, 1990 in Ottawa, Canada. Topics covered include future mobile satellite communications concepts, aeronautical applications, modulation and coding, propagation and experimental systems, mobile terminal equipment, network architecture and control, regulatory and policy considerations, vehicle antennas, and speech compression

Информатика от абака до интернета. Введение в специальность

Указ.: с. 466-48

Jornalismo na internet: interatividade na prática jornalística dos veículos Folha de S. Paulo (Brasil) e El País (Espanha)

A presente pesquisa analisa como a interatividade tem contribuído para modificar a produção do conteúdo noticioso nas redações dos veículos tradicionais Folha de S.Paulo, do Brasil, e El País, da Espanha, a partir da etapa pauta do processo produtivo. A base teórica está ancorada em três eixos: 1) interatividade e jornalismo, 2) interatividade e audiência hiperativa e, por último, 2) jornalismo, organizações jornalísticas capitalistas e etapas da produção noticiosa. A metodologia de investigação utilizou o método do estudo de caso múltiplo incorporado/comparativo com a realização de observação não-participante, entrevistas em profundidade semi-abertas, análise documental e tipificação das opções de interatividade. Entre os resultados, identificou-se nos dois veículos que a interatividade era então aplicada sem uma estratégia clara de objetivos nem investimento em recursos humanos para torná-la efetiva e consistente