CIDR Full Form

CIDR means a Classless Inter-Domain Routing. It is an IP address-assigning method that improves the efficiency of an address distribution. It is also known as superneting which replaces the older system based on classes A, B, and C networks. By using a single CIDR IP address many unique IP addresses can be designated. The CIDR IP address is the same as the normal IP address except that it ends with a slash followed by a number. 172.200.0.0/16 It is called an IP network prefix.

What is CIDR?

CIDR means a Classless Inter-Domain Routing. It is a way to give out the IP addresses on the internet more easily. These IP addresses are like phone numbers for the computers and other devices that connect to the internet. Each device needs its own IP address to connect to the other devices online. CIDR helps big companies and internet providers hand out these addresses in a smart way. It lets them use the available addresses better, so more devices can connect to the internet.

CIDR also helps information move around the internet more quickly. It does this by making it easier for the systems that send data between different parts of the internet to do their job.

What Are The Different IP Address Formats?

In the past IP addresses came in fixed sizes. But now we have the two types.

Classful IP Address

The IPv4 address is made of the 32 bits shown as the four numbers from a 0 to 255 separated by the dots. There are the five classes but only three classes are used to assign to the client and remaining two class are reserved for future purpose.

Class A

• Uses 8 bits for the network part. Example: 44.0.0.1
• Here, 44 is the network, and 0.0.1 is the device.

Class B

• Uses 16 bits for the network part. Example: 128.16.0.2
• Here, 128.16 is the network, and 0.2 is the device.

Class C

• Uses 24 bits for the network part. Example: 192.168.1.100
• Here, 192.168.1 is the network, and 100 is the device.

Classless IP Addresses

These are called the CIDR Classless Inter-Domain Routing addresses. They use a more flexible way to split the network and device parts. This lets network managers create smaller sub networks of different sizes. These CIDR addresses adds the number at the end to show that how many bits are used for the network part. for example a 192.0.2.0/24 means the first 24 bits 192.0.2 is the network address.

What Are The Limitations of Classful IP Addressing That CIDR Overcomes?

The old way of using IP addresses (classful) had some problems that CIDR fixed. Below are the main issues.

Not Flexible Enough

In the old system, IP addresses came in fixed sizes :

• Class A could fit 16,777,214 devices
• Class B could fit 65,534 devices
• Class C could fit 254 devices

This led to a wasting IP addresses. For example, If a company had 300 devices, they couldn't use Class C (too small). They had to use Class B, which was much bigger than they needed. This left many IP addresses unused.

Hard to Design Networks

The old system made it tough to join the networks together. For instance:

• 192.168.1.0
• 192.168.0.0

These are two different Class C networks. In the old system, you couldn't combine them because they had a fixed size. This made it hard for network managers to create the setups they wanted.

Benefits of CIDR

• Saves IP Addresses: CIDR lets you give out just the right number of IP addresses for each network. This means fewer IP addresses are wasted. It also makes routing data between devices easier and faster.
• Sends Data Faster: CIDR helps routers organize IP addresses into smaller groups called subnets. This means data can go straight to where it needs to, without taking long routes.
• Helps Make Private Cloud Spaces: A Virtual Private Cloud (VPC) is a private area in the cloud for a company's work. VPCs use CIDR to send data between devices safely.
• Makes Big Networks Easily: CIDR lets you join smaller networks into bigger ones (called supernets) easily. For example: 192.168.1 /23 and 192.168.0 /23. This joins two networks into one big network. It makes it simpler for routers to send data between devices in these networks.

How Does CIDR work?

CIDR helps routers send data to the right device by looking at the subnet. It doesn't use the old class system. Instead, it uses a special way to show which part of an IP address is for the network and which is for the device. To understand CIDR, you need to know about two things that mentioned below.

CIDR blocks

A CIDR block is a group of IP addresses that share the same start and size. Big blocks have more IP addresses. Big internet groups give out large CIDR blocks to smaller groups. These smaller groups then give them to companies. If you're at home, you get your CIDR block from your internet company.

CIDR notation

CIDR notation shows an IP address with a number at the end. This number tells how much of the address is for the network. For example the 192.168.1.0/22 means the first 22 bits of the address are for a network. This way of writing a IP addresses helps the routers know where to send the data.

How is CIDR Used in IPv6?

IPv6 is a new technology of giving the internet addresses. It is meant to replace the old IPv4 system. The IPv6 uses a longer string of numbers and the letters which means it can create the many more addresses than a IPv4. It is important because more and more devices are connecting to the internet. A IPv6 address looks different from the IPv4 address. It has the 8 groups of numbers and letters separated by the colons. The CIDR works with a IPv6 too.

Just like with a IPv4 you can use CIDR to split IPv6 addresses into network and device parts. For example in a 2001:0db8:/32 the first 32 bits 2001:db8 is the network part. This flexible system helps manage the huge number of addresses in IPv6, making it easier to organize and route internet traffic.

Conclusion

CIDR is a smart way to give out and manage internet addresses. It fixes problems from the old system, where addresses often didn't fit right and were wasted. With CIDR, network managers can give out just the right number of addresses and easily group them. This makes the internet work better and faster. A CIDR works with both of the old IPv4 and a new IPv6 internet address systems. It helps us use the internet addresses more efficiently which is important as the more devices connect to the internet every day.