An experiment in high-speed international packet switching

Abstract

The high-speed international packet switching experiment (HIPS) provides a test bed for development efforts currently underway within both COMSAT Laboratories and the German Aerospace Research Establishment (DFVLR) in high-speed computer-to-computer communications, link control and networking protocols, interface processors, and multiple service applications. The system configuration is based on a high-speed (1.544 Mbit/s) satellite link established between earth terminals located at COMSAT Laboratories in Clarksburg, Maryland, and at DFVLR Headquarters in Oberpfaffenhofen, Federal Republic of Germany. The space segment is provided by a 14/11-GHz transponder in the Atlantic spare (INTELSAT V ) satellite. The interface between the data processing system and the communications system is a special high-speed version of the programmable interface processor (PIP) being developed by COMSAT Laboratories. Interfaces are provided to a number of data processing devices to demonstrate that a data com:nunications network with intelligent interfaces is capable of sirnultaneously supporting a wide diversity of user demands on the network. These include supporting interactive terainals requiring short response times, and file and data base transfer applications requiring high throughputs. COMSAT Laboratories and the DFVLR have ongoing research and development programs to investigate the technologies and system architectures suitable for international high-speed packet networks. Services provided by such networks would include computer communications, facsimile and electronic mail, and video teleconferencing. To further these programs, an international experiment in packet communications is being conducted jointly by these organizations. The HIPS experiment serves as a vehicle to investigate the performance of both the equipment and protocols, and to de~nonstrate selected applications for a high-speed international packet switched service via satellite. International satellite cornmunications services currently are limited to leased voice-grade channels, although a limited number of demand-assigned voice/ data (SPADE) and video channels are also available. With the growth of national and regional packet switched networks, especially in North America, Europe, and Japan, the volume of packet data traffic across international borders is also increasin9.l This growth, along with the availability of more powerful and lower cost data terminal equipment, is responsible for a rapid increase in the number of new business applications, which in turn pose new requirements for communications services in general. Communications satellites may more efficiently accommodate growth in international data communications traffic, and the specific requirements of new services supporting the international business community, by offering an international highspeed packet network service in addition to the basic telecommunications services currently offered. Data presented in standardized packet format (X.25 or X.75) to this network would be delivered to the appropriate international destination. A high-speed international packet switched network could offer individual users and national and private networks a high connectivity to international destinations, and lower cost service (achieved by statistical multiplexing of multiple users into common destination channels), and could meet future high bandwidth require-