Introduction to Computer Networks

 Introduction to Computer Networks:

A set of devices often mentioned as nodes connected by media link is called a Network.
 A node can be a device which is capable of sending or receiving data generated by other nodes on the network like a computer, printer etc. These links connecting the devices are called Communication channels. 
 Computer network is a telecommunication channel using which we can share data with other computers or devices, connected to the same network. It is also called Data Network. The best example of computer network is Internet. 
 Computer network does not mean a system with one Control Unit connected to multiple other systems as its slave. That is Distributed system, not Computer Network. 
 A network must be able to meet certain criterias, these are mentioned below: 
  •  Performance 
  •  Reliability 
  •  Security  

Performance:

It can be measured in the following ways: 
  • Transit time : It is the time taken to travel a message from one device to another. 
  • Response time : It is defined as the time elapsed between enquiry and response. 
Other ways to measure performance are

Efficiency of software 

Number of users 

Capability of connected hardware 

Reliability:

 It decides the frequency at which network failure take place. More the failures are, less is the network's reliability. 

Security:

 It refers to the protection of data from any unauthorised user or access. While travelling through network, data passes many layers of network, and data can be traced if attempted. Hence security is also a very important characteristic for Networks.  


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