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Unit 1: Introduction to Computer Networks

Person-to-person communication: The 21st Century’s answer to the 19th Century’s telephone. Notes
Electronic mails or emails for everyone. Emails may contain digitized voice, pictures,
moving TV and video images (and even smell!).

Worldwide newsgroups for the population at large, and cover every conceivable topics.
Real-time CSCW systems, such as videoconferencing and virtual meeting environments,
allow remote users to communicate with no delay, possibly seeing and hearing each
others as well.
It is sometime said that transportation and communication are having a race, and whichever one
wins will make the other obsolete.
Interactive entertainment is a huge and growing industry.
(i) Video on demand (the killer application): The user can select any movie or TV program
ever made, in any country, and have it displayed on his screen instantly.
(ii) Interactive films: The user may choose alternative scenarios for the story direction.
(iii) Live and interactive TV: Audience may participate in quiz shows and so on.
(iv) Multiperson real-time games (maybe the alternative killer application): Hide-and-seek,
flight simulators, etc.
If done with goggles and 3-dimensional real-time, photographic-quality moving images, we
have a kind of worldwide shared virtual reality.
The ability to merge information, communication and entertainment will surely give rise to a
massive new industry based on computer networking.

The information revolution may change society as much as the Industrial Revolution did.

Task List the main difference between LAN, WAN and MAN networks in a tabular
format.

1.7 Network Topologies

A network topology is the basic design of a computer network. It is very much like a map of a
road. It details how key network components such as nodes and links are interconnected.
A network’s topology is comparable to the blueprints of a new home in which components such
as the electrical system, heating and air conditioning system, and plumbing are integrated into
the overall design. Taken from the Greek work “Topos” meaning “Place,” Topology, in relation
to networking, describes the configuration of the network; including the location of the
workstations and wiring connections. Basically it provides a definition of the components of a
Local Area Network (LAN). A topology, which is a pattern of interconnections among nodes,
influences a network’s cost and performance. There are three primary types of network topologies
which refer to the physical and logical layout of the Network cabling. They are:
1. Star Topology: All devices connected with a Star setup communicate through a central
Hub by cable segments. Signals are transmitted and received through the Hub. It is the
simplest and the oldest and all the telephone switches are based on this. In a star topology,
each network device has a home run of cabling back to a network hub, giving each device
a separate connection to the network. So, there can be multiple connections in parallel.

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