ABSTRACT
Today, the word computer network is synonym to Internet or information super-highway and is a household name. Its mass appeal among novices, nerds, and pundits is primarily due to the applications like electronic mail (e-mail), world wide web (www), remote terminal access (telnet), and di¡erent protocols such as ¢le transfer protocol (¥p), network ¢le system (NFS), network news transfer protocol (NNTP), etc. Ÿese applications have made information dissemination easy, timely, and cool. Not long ago, when the Mars Path Finder Lander (nicknamed Sagan Memorial Station) landed on the Mars surface on July 4, 1997 (Independence day for the United States), almost everybody got surprised from the interest of a vast number of people who wanted to know the results and look at the ¢rst-ever high-resolution color images of the Martian surface themselves. Ÿis “get-self-involved” urge took them not in front of TV sets to watch a reporter narrate the story, but to the Internet where they felt satis¢ed by watching the story revealing itself through images that were posted on the Internet almost instantaneously by NASA scientists. More than one million people visited the Jet Propulsion Laboratory web page and its various mirror sites created for this purpose using their web browsers and service providers*; this was a record in itself. Since 1997, the popularity of Internet has grown exponentially. It is a worldwide collection of more than 250,000 networks, public and private, that have agreed to use common protocols and exchange tra«c. An internet (lowercase “i”) or internetwork refers to a set of networks connected by routers and appears to its users as a single network. A network can be taken as a set of machines or hosts linked by repeaters or bridges.
