what is benefit of CIDR?

Question

Hi,

What is the basic usage of CIDR in networking and also give me the benefit over SubNetting.

Answer 1

CIDR was developed as a replacement for class based allocation of IP addresses. The purpose was to eliminate wastefulness and to provide mechanisms for route aggregation. Sub-netting is the process of taking a given network and dividing it into parts that are a subset of the original.

Here is 192.168.128.0 /24 sub-netted:

Network           Net Broadcast     CIDR Mask           
192.168.128.0     192.168.128.127   25   255.255.255.128
192.168.128.128   192.168.128.191   26   255.255.255.192
192.168.128.192   192.168.128.223   27   255.255.255.224
192.168.128.224   192.168.128.239   28   255.255.255.240
192.168.128.240   192.168.128.243   30   255.255.255.252
192.168.128.244   192.168.128.247   30   255.255.255.252
192.168.128.248   192.168.128.251   30   255.255.255.252
192.168.128.252   192.168.128.255   30   255.255.255.252