• It is the ability of the network to carry out the desired operation through a network such as communication through a network.
• In network functionality it plays a significant role.
• The network monitoring systems and devices are the essential requirements for making the network reliable.
• The network devices ensure that data should reach the appropriate destination while network monitoring system identifies the problems that are occurred in the network.
• The reliability of a network can be measured by three following factors, they are:

Downtime

• It is defined as the required time to recover.

Failure Frequency

• It is defined as the frequency when it fails to work the way it is intended.

Catastrophe

• It indicates that the network has been attacked by some unexpected event such as earthquake, fire.