Subnetting in computer networking.

What is subnetting

Subnetting is a technique used in computer networking to divide a single large network into smaller subnetworks, called subnets. This is done by borrowing bits from the host portion of an IP address and using them to create a new network prefix for the subnets.

Subnetting provides a way to efficiently use IP addresses by creating smaller, more manageable networks within a larger network. It also helps to improve network security by limiting the number of hosts that can communicate with each other.

Subnetting is commonly used in large organizations or enterprises that have a large number of devices connected to their network. By dividing the network into smaller subnets, it becomes easier to manage and troubleshoot network issues, as well as allocate IP addresses to devices in a more efficient manner.


Type of subnetting

There are two types of subnetting:

Variable Length Subnet Masking (VLSM): In VLSM, different subnets within a network can have different subnet mask lengths, allowing for more efficient use of IP address space. This means that different subnets within the same network can have different sizes and numbers of hosts.

Fixed Length Subnet Masking (FLSM): In FLSM, all subnets within a network have the same subnet mask length, which means that all subnets have the same number of hosts. This makes it easier to manage and configure the network, but can lead to inefficient use of IP address space if some subnets have more hosts than others.



How we do sunetting

Subnetting can be done using the following steps:

Determine the number of subnets needed: This can be based on the number of departments, floors, or geographical locations within the organization.

Determine the number of hosts needed per subnet: This can be based on the number of devices that will be connected to each subnet, including computers, servers, printers, and other network devices.

Choose an appropriate subnet mask: The subnet mask determines the network and host portions of the IP address. The subnet mask must be chosen based on the number of subnets and hosts needed.

Calculate the subnet address range: This involves dividing the network address into subnets and determining the range of IP addresses that can be used in each subnet.

Assign IP addresses to devices: Once the subnet address range has been calculated, IP addresses can be assigned to devices within each subnet.

It is important to note that subnetting requires careful planning and management to ensure that IP addresses are used efficiently and that the network is secure and manageable. It is also recommended to use a subnet calculator or an online subnetting tool to simplify the subnetting process.


Example of subnetting

 here is an example of subnetting:

Let's say we have a network with the IP address 192.168.0.0 and we want to create subnets for three different departments: Sales, Marketing, and Engineering. We also know that Sales requires 50 hosts, Marketing requires 30 hosts, and Engineering requires 20 hosts.

Determine the number of subnets needed: We need three subnets, one for each department.

Determine the number of hosts needed per subnet: Sales needs 50 hosts, Marketing needs 30 hosts, and Engineering needs 20 hosts.

Choose an appropriate subnet mask: Based on the number of subnets and hosts needed, we can use a subnet mask of 255.255.255.192 (/26) which provides 64 addresses per subnet.

Calculate the subnet address range: To calculate the subnet address range, we can use the following formula:

Subnet address = (Network address) + (Subnet number * Subnet size)

For Sales: Subnet address = 192.168.0.0 + (1 * 64) = 192.168.0.64
For Marketing: Subnet address = 192.168.0.0 + (2 * 64) = 192.168.0.128
For Engineering: Subnet address = 192.168.0.0 + (3 * 64) = 192.168.0.192

The subnet address range for each department would be as follows:

Sales: 192.168.0.64 - 192.168.0.127
Marketing: 192.168.0.128 - 192.168.0.191
Engineering: 192.168.0.192 - 192.168.0.255
Assign IP addresses to devices: Once the subnet address range has been calculated, we can assign IP addresses to devices within each subnet. For example, the first host in the Sales subnet would be 192.168.0.65, and the last host would be 192.168.0.126. Similarly, the first host in the Marketing subnet would be 192.168.0.129, and the last host would be 192.168.0.190.

This is just one example of subnetting, and there are many different ways to create subnets based on the specific needs of a network.