1. COMPUTER NETWORKING

 

• A Network is a way of connecting different computers to allow data and message passing, and resource sharing.

 

• Early communication techniques included telegraphs (with morris code), telephones and teletypes.

 

• Advantages

- allows shared computers and peripherals

- provides communication and cooperation tools for people and computers

- increases reliability by having alternate computers available

- decreases isolation of many computers

 

• Applications,

- allows remote access to databases and libraries

- electronic mail

- distributed computational facilities

- remote control of applications

 

• The relationship between various network types is shown below

 

• The Star Network topology uses many connections to a central server

 

• When all computers are connected to the same network cable, there are a number of structures which may be used. The bus topology below is simpler, and the tree topology is more flexible and versatile. This approach uses a single cable which is easy to add to

 

• The ring topology below shows a closed loop of cable which can be simple to implement, but limited in capabilities

 

• An enhanced ring topology is pictured below

 

• The figure below shows two ring networks, with a few possible devices hooked to them.

 

1.1 OSI NETWORK MODEL

1.2 OPEN SYSTEMS

1.3 NETWORKING HARDWARE