ECHO Facts for Users 2/93

ECHO = European Community Humanitarian Offic

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

Applications of satellite technology to broadband ISDN networks

Two satellite architectures for delivering broadband integrated services digital network (B-ISDN) service are evaluated. The first is assumed integral to an existing terrestrial network, and provides complementary services such as interconnects to remote nodes as well as high-rate multicast and broadcast service. The interconnects are at a 155 Mbs rate and are shown as being met with a nonregenerative multibeam satellite having 10-1.5 degree spots. The second satellite architecture focuses on providing private B-ISDN networks as well as acting as a gateway to the public network. This is conceived as being provided by a regenerative multibeam satellite with on-board ATM (asynchronous transfer mode) processing payload. With up to 800 Mbs offered, higher satellite EIRP is required. This is accomplished with 12-0.4 degree hopping beams, covering a total of 110 dwell positions. It is estimated the space segment capital cost for architecture one would be about $190M whereas the second architecture would be about$250M. The net user cost is given for a variety of scenarios, but the cost for 155 Mbs services is shown to be about $15-22/minute for 25 percent system utilization