A computer network can be seen as a series of (two or more) interconnected computing devices (PCs, Servers and Printers). These devices are connected using some form of communications medium.
It does not matter whether the network is to play games or to facilitate world wide video conferencing, the general purposes of having computing devices networked are to:
- Communicate - people and devices need to talk to each other
- Share Resources - data and printing are two important resources that often need to be shared.
Categories of Networks
There are two main categories of networks: Local Area Networks (LANs) and Wide Area Networks (WANs). Local area networks are localised and confined to a particular location ñ an office or a building, whereas a wide area network is a geographically dispersed network - over cities, countries and continents.
Internet is short for interconnected networks and is a global network of networks linking together LANs, WANs and individual users.
Clients and Servers
On a majority of (but not all) networks today, computers connected to the network are seen as either clients or servers:
- A client is a computer that allows a user, or users, to log on to the network and take advantage of the resources available on the network. The operating system run on the client has networking capabilities that allows the client to log on to the network and take advantage of the resources on the network.
- A server is a much more powerful computer (than a client) and administers the network and its resources. The operating system that is run on the server is a network operating system - an operating system that provides for network administration.
There are two main approaches to networking:
- Peer-to-Peer, and
Deciding what approach to use in which situation is largely dependent on the number of computers (or users) that will be attached to the network, and the nature of the resources to be shared via the network.
A Peer-to-Peer network is a workgroup where all of the connected computers (and users) are seen as peers (equals), and there is no one computer that is used to administer or control the network.
Peer-to-Peer networks are ideal for situations where there are no more than ten (10) computers to be networked, few resources to share (1 printer and a few files), security is not a major issue, and cost is very important.
However, Peer-to-Peer networks are not scalable - they are limited to fewer than ten (10) computers, and if your network grows you would have to change your networking approach.
In a server based network (Client-Server networks), one or more computers act as a server and other computers are connected to this (these) server(s). The server is used to control access to the network and to administer its resources to the clients (users), and the clients connect to the server to access its resources.
Server based networks offer centralised control of the network and its resources - one username (and password) can be used to decide who gets access to what; and flexibility and scalability - you can have servers for different purposes (file servers, data servers, print servers), and from one to several hundred clients.
However, these types of networks can be very expensive to set up and maintain - there are high costs for equipment (specialised servers), licensing fees (associated with the server operating system), and a full time network administrator.