Note: Many topics at this site are reduced versions of the text in "The Encyclopedia of Networking and Telecommunications." Search results will not be as extensive as a search of the book's CD-ROM.

In radio communication, a broadcast is a one-to-many signal transmission. Transmitters broadcast signals to receivers. In Ethernet networks, stations broadcast packet transmissions on a shared medium. Other stations listen to these broadcasts, but receive only packets addressed to them. This broadcast network metaphor is the opposite of a point-to-point network in which transmissions take place between two systems over a dedicated circuit or virtual circuit.

Applications that produce broadcast messages include ARP (used by hosts to locate IP addresses on a network), routing protocols like RIP, and network applications that "advertise" their services on the network. Some other variations include SLP (Service Locaton Protocol), a relatively new protocol used on the Internet to find services. PIP (Presence Information Protocol) alerts users when other users log on.

A discussion of broadcasting may be found in RFC 791 (Internet Protocol, September 1981) and RFC 919 (Broadcasting Internet Datagrams, October 1984).

A form of broadcasting is used on the Internet in which users choose to subscribe to information that is "published" by various services. These publishers are usually news services that deliver content to users at regular intervals. See "Broadcasting on the Internet" and "Webcasting."

Multicasting is a selective form of broadcasting that is supported on the Internet. It allows broadcasts to be directed to users who request to see the broadcast and limits broadcasts to only those parts of the network where users have requested it, thus controlling traffic where it is not needed.

Copyright (c) 2001 Tom Sheldon and Big Sur Multimedia.
All rights reserved under Pan American and International copyright conventions.