Networking Technology: Subnets & Subnetting

A Subnet is a small part of a network that keeps the overall network functional and efficient. Subnets or subnetworks are like a network inside a network. In a subnet, traffic is able to travel shorter distances without going through unnecessary distances.

Internet is becoming a growing necessity in all parts of the world, so it is more efficient when messages travel as quickly as possible. Data travels through the network in packets, which are decoded once the receiver gets them. These packets travel fast with the help of subnets, and not take an inefficient path towards the receiver.

Understanding IP Address

In order to understand subnets, we must look at the concept of IP addresses. Just like our names, an IP address is given to every unique device connected within a network. An IP address is made up of 32 bits in binary, divided within the network. Each 32 binary bit is broken into 4 octets. 1 octet is equal to 8 bits. Octets are divided into decimal and separated from each other with the help of a dot. This is why IP addresses are seen in dotted decimal format like 192.168.2.1.

Parts of an IP Address

IPv4 addresses are based of four decimal digits separated by dots or periods. Every IP address is made up of two parts:

  • The first part signifies the network to which the address belongs
  • The second part signifies the device on the network

While subnetting applies to both IPv4 and IPv6, we are discussing the IPv4 and its network classes. IPv4 addresses were designed based on classes A t E.

  • Class A uses the initial 8 bits for the network and the remaining 24 bits for the host ID
  • Class B Uses the first 16 bits for the network and the remaining 16 bits for host IDs
  • Class C uses the first 24 bits for network and 8 bits are left to the host IDs

Based on these classes, a computer can look at any address and tell it apart. Host IDs also tell us how many host numbers each network class can support.

Subnetting

Subnetting is the process of creating small networks within a large network by taking bits of the host IDs from an IP address. you can use these bits from any address to create additional networks, leading to small subnets. Imagine we need to split a school into classrooms. We split into classrooms to stop the students from interfering with each other and to create an efficient learning system.

Now, 30 students in each classroom have one desk with a computer on it. when we label each desk and computer, we can get a series of computers and their placement in each class. For example, computer # 34, class 12.

Here is what the labeling will look like: computer 34, class 12. 12-34 or 3412. If we go with 3412, we will instantly know that computer 34 is in classroom 12. Just like the classrooms, IP addresses are also split into two components as mentioned before.

Subnet Masks

A subnet mask is used for internal communication within a network. Routers use these masks to send information to the right receiver. When a data packets arrives at a network, the router in the network checks its routing table. It does binary maths by decoding the subnet mask and calculates where the subnet packet should go. This is how information travels smoothly within a network and subnet.

On an overall basis, the subnet masks help in determining a subnet’s size as well mark the subnet’s end points if a user is given an IP address inside the subnet. It’s called a “mask” because the hosts bits are actually market while the Network ID responsible for starting the subnet is left behind. After a user discovers the starting of the subnet and its approximate size, it can reach the Broadcast ID (aka. the end of the subnet).

Conclusion

When it comes to nailing your subnetting, the old adage “Practice! Practice! Practice! Still applies. Try using 10.0.0.0 and 192.168.0.0 to create IP space form blocks on some kind of a test network. Then grant yourself a range of workers on a department basis and build various departments. The last step is to identify IP space blocks that fit the numbers with space to expand.