IT pros and network administrators who look to determine IP address relocation find the CIDR calculator an invaluable asset. The understanding of CIDR notation and how to utilize CIDR notation calculator make the management of IP address distribution effective, and the subnet usage is optimized as well at the same time. The notation of CIDR, as well as the basic understanding of the principles of CIDR blocks and network ranges are all explored here.

Understanding the importance of CIDR

CIDR stands for Classless Inter-Domain Routing. The protocol was first introduced with the purpose of replacing the old class based system in which many IP addresses were simply being wasted. CIDR blocks enabled networks to be divided into separate networks, while sparing them from the rigidity of the class system. This is done via a CIDR calculator that makes the processes of determining network masks, subnet masks and network prefixes simpler, no matter how many IP addresses are involved.

How to Calculate CIDR

The network prefix which determines how many bits from the IP addresses are used for the network address is the first thing to determine when you want to calculate CIDR. By doing so you will also determine how many bits are left available for host addresses. The tool that helps you do that is called a CIDR notation calculation.

The CIDR notation is done based on the following method:

• The IP address is converted into a binary format
• The number of bits used for the network portion is determined – a slash followed by the prefix length is used to mark that in the notation
• The number of available host addresses is determined by the formula 2^(host bits) – 2 (e.g. network address + broadcast address)

The Significance of CIDR blocks

The group of IP addresses sharing the same network prefix is what we call a CIDR block. The blocks enable more efficient network management via flexible subnet division. The CIDR calculator determines the division of larger networks into much smaller, thus more manageable and traffic flow friendly, subnets. The CIDR calculator uses the concepts of network prefix, network mask, subnet mask, broadcast address and available host addresses.

• Network prefix is what denotes the size of the network
• The network mask determines the bits used for the network
• The subnet mask denotes the host identifier inside the network, while the broadcast address is the last IP address in the CIDR range. The available host addresses are the IP addresses that can be used by the host.

CIDR of an IP Address – what is it

The prefix length is what is typically referred to as CIDR of an IP address. It is the number of IPs in a given range. Let’s say we have the following CIDR notation – 192.168.1.0/24. This means there are 24 bits that are assigned to the network, which leave 8 bits for host addressed.

So, a CIDR notation of 24 means there are 8 bits left for host addressed. The number of these addressed can be calculated using the standard formula – 2^8 – 2 = 254 host addresses.

These host addresses are within the range from 192.168.1.1 to 192.168.1.254 – 192.168.1.0 as the network address and 192.168.1.255 as the broadcast address.

What does 255.255.255.0 mean in CIDR Notation

This is basically a subnet mask that corresponds to the CIDR notation of 24. Thus, it means the same thing as the one described above – that the first 24 bits are used for networks, while the remaining 8 bits are host addresses.

CIDR IP Range – the takeaways

The CIDR IP range is what defines the amount of IP addresses that are part of a particular CIDR block. Let’s say that a CIDR of 22 provides a range of 1024 IP addresses. All of these can be assigned by the network administrators for various host addresses in a much more efficient manner once calculated accurately.

How to Use the CIDR Calculator

It isn’t necessary to make all calculations manually, especially when you have a useful CIDR calculator at hand. Calculating the host identifiers, subnet masks and network masks using it is much faster and you will eliminate the possibilities of unpleasant errors that will hinder your workflow. Just:

• Enter an IP address
• Set the prefix length
• Review the results, including the subnet mask, broadcast addresses and the network range
• View the number of available host addresses

A tool like this is an integral part of the process of designing networks, managing access control lists for security reasons and even setting up routers.

Final words

An CIRD Calculator makes the network segmentation and division easier, thus enabling faster and more secure management of routers and gateways. This, in turn, enhances the security of the whole network via proper IP address allocation. Using a CIDR calculator to reduce the risk of errors inherent in manual calculations not only makes the process more efficient, but it speeds it up considerably.