Computer Network

References : Heathcote & Richards (PassECDL4, European Computer Driving Licence Version 4), http://en.wikipedia.org

In this section student should have a capability in

• Describing types of networks, their characteristics and their uses.
• Identifying the differences between LAN and WAN.
• Identifying the problems and issues associated with networked data.

Descriptions :
A computer network is a group of two or more computers connected to each other.
A computer network is composed of multiple computers connected together using a telecommunication system for the purpose of sharing data, resources and communication.

Classification of Computer Networks :
There are many way to classify the computer networks, for example : by scale, connection method, functional relationship, network topology, ect. However, we will learn 3 kind of classification.

1. Classification by Scale
2. Classification by Functional Relationship
3. Classification by Network Topology

By Scale :
Computer networks may be classified according to the scale or extent of reach of the network, for example as a Personal area network (PAN), Local area network (LAN), Metropolitan area network (MAN), or Wide area network(WAN)

By Functional Relationship :
Computer networks may be classified according to the functional relationships which exist between the elements of the network, for example Client-server and Peer-to-peer (workgroup) architectures.

By Network Topology :
Computer networks may be classified according to the network topology upon which the network is based, such as Bus network, Star network, Ring network, Mesh network.

Advantages of Networks :

• Sharing resources among the connected computers. This is cheaper than buying hardware resources, e.g. printer for every workstation.
• Users can save their work centrally on the network server. They can then retrieve their work from any workstation on the network.
• Users can communicate with each other and transfer data between workstations very easily.
• One copy of each application program can be loaded onto the file server and shared by all users.
  

Disadvantages of Networks :

• Special security measures are needed to stop users from using program and data that they shouldn't have access to.
• Networks are complicated to set up and be maintained by skilled ICT technicians.
• If the file server develops a serious fault all the users are affected.
• If a virus enters the network all the users may be affected.