COMPUTER NETWORK
A computer network is a communications system connecting two or more computers that work
to exchange information and share resources (hardware, software and data). A network may
consist of microcomputers, or it may integrate microcomputers or other devices with larger
computers. Networks may be controlled by all nodes working together equally or by specialized
nodes coordinating and supplying all resources. Networks may be simple or complex, self-
contained or dispersed over a large geographical area.
Network architecture is a description of how a computer is set-up (configured) and what
strategies are used in the design. The interconnection of PCs over a network is becoming more
important especially as more hardware is accessed remotely and PCs intercommunicate with
each other.
3.1 Terms used to describe computer networks
Node – any device connected to a network such as a computer, printer, or data storage
device.
Client – a node that requests and uses resources available from other nodes. Typically a
microcomputer.
Server – a node that shares resources with other nodes. May be called a file server, printer
server, communication server, web server, or database server.
Network Operating System (NOS) – the operating system of the network that controls and
coordinates the activities between computers on a network, such as electronic
communication and sharing of information and resources.
Distributed processing – computing power is located and shared at different locations.
Common in decentralized organizations (each office has its own computer system but is
networked to the main computer).
Host computer – a large centralized computer, usually a minicomputer or mainframe.
3.2 Types of computer networks
Different communication channels allow different types of networks to be formed. Telephone
lines may connect communications equipment within the same building. Coaxial cable or fiber-
optic cable can be installed on building walls to form communication networks. You can also
create your own network in your home or apartment. Communication networks also differ in
geographical size.
Three important networks according to geographical size are LAN, MAN and WAN.
Local Area Network (LAN)
A LAN is a computer network in which computers and peripheral devices are in close physical
proximity. It is a collection of computers within a single office or building that connect to a
common electronic connection – commonly known as a network backbone. This type of network
typically uses microcomputers in a bus organization linked with telephone, coaxial, or fibre-optic
cable. A LAN allows all users to share hardware, software and data on the network.
Minicomputers, mainframes or optical disk storage devices can be added to the network. A
network bridge device may be used to link a LAN to other networks with the same configuration.
A network gateway device may be used to link a LAN to other networks, even if their
configurations are different.
Metropolitan Area Network (MAN)
