The Evolving National Information Network
Notes
1. This paper focuses on the network, but the network is itself imbedded in the larger organizational structure of the standards-based computing world. The international information technology community is emerging as a non-hierarchical and rapidly evolving set of inter-dependent organizations based on a commonly held set of values about open architectures, distributed management, and the importance of standards.
2. Written during the spring of 1993, this report can, at best, provide only a snapshot of an extraordinarily rapidly changing environment. While background is provided and some prognostications are attempted, the background will soon become ancient history and the prognostications will rapidly be supplanted by the future reality.
3. A fuller discussion of protocols than possible for this paper can be found in John S. Quarterman The Matrix, Computer Networks and Conferencing Systems Worldwide, Digital Press, Bedford, MA, 1990. Quarterman provides a very extensive survey of the computer networking world, and his work is an extraordinarily useful reference.
4. The higher protocol layers are the transport, session, presentation, and application layers. The transport layer provides for the integrity of the message being transported as opposed to the packets making up that message. The session layer establishes the environment in which a group of messages are combined into a session. The presentation layer is concerned with defining the meaning of the data transmitted, and includes the various codes by which characters are mapped to numbers and more complicated schemes such as that defining the format of an electronic mail message. The application layer provides services to the user, be it a human being or computer. Examples include electronic mail, information bases, etc.
5. These services often use “spread-spectrum” technology. It allows multiple stations to simultaneously transmit on a frequency range without the usual problems of allocating separate channels to each transmitter. These systems therefore do not generally need to be licensed as many transmitters can coexist on the same frequency band. Spread spectrum works by assigning a “spreading algorithm” to each transmitter. This algorithm is analogous to a person’s individual voice. The receiver then uses another algorithm to decode only the desired sender’s code in much the way that people at a party can listen to a specific conversation in a crowded room and perceive every other conversation as noise. Wireless LANs can be configured like Ethernet without the expense of wiring but with the flexibility to support mobile workstations. Spread spectrum is also being tested for public wide area data and voice services so that ubiquitous untethered communications can be offered as a service.
6. The service is called Advanced Radio Data Information Service (ARDIS). It covers 8000 cities and towns in the U. S. and operates at about 00 characters per second. Another service that has been announced and is just becoming operational is Ram Mobile Data.
7. Perhaps the most notable of the international networks is the High Energy Physics Network HEPnet). Another example is the Space Physics Analysis Network (SPAN), a U.S.-based network with extensions to Japan, Canada, and Europe.
8. See discussion in Preservation and Access Technology,A Report of the Technology Assessment Advisory Committee to the Commission on Preservation and Access, August 1990, pp. 45-46.
