This article only explains some of the benefits of subnets, not how to implement a subnet.
1. It provides security.
In larger companies, employees must be able to communicate with other employees from that department. Subnetting allows for the department to have its own subnetwork. Depending on how many departments the company has, each one can have its own private and secure subnetwork, independent from the other networks.
2. It allows organization of resources.
A company has several departments or types of resources: sales, customer care, IT, executive, research. With subnetting, these resources can be organized within the larger network. For example:
192.168.130.x - Executive
192.168.131.x - Research
192.168.132.x - IT
192.168.133.x - Sales
192.168.134.x - Customer Care
3. It speeds up the network.
Using subnets will decrease the size of the broadcast domain, allowing data to reach its destination much faster. For example, a network without subnetting:
There are 255 possible values for x, and for each x there are 255 possible values for y.
This means that there are 255*255 possible recipients in the network broadcast domain.
Having such a large network broadcast domain means the signal must go through each possible recipient until it finds the correct one. To decrease the number of possible recipients, we use subnets. For example:
Here, there are 255 possible values for y within the 132 subnet. The network broadcast domain only contains 255 possible recipients, thus making the network much faster.