Linux :: IP Supernetting or CIDR ::
CIDR stands for "Classless Inter-Domain Routing". It is a new addressing scheme for the Internet, intended to replace the old classful (Class A, B, C) address scheme. CIDR allows a more efficient allocation of IP addresses and uses routing aggregation for minimizing the routing table entries, and is also called supernetting.
If a provider needed 10,000 IP addresses for a project, then it would receive a class B network, and 55,534 IP addresses would not be used. If however, the provider had been assigned 40 class C networks for that 10,000 IP addresses, it could not match its needs (not all the IP addresses would be in the same network) and the routing tables of routers on the Internet would grow with 40 new routes. xxx.xxx.xxx.xxx/n where xxx.xxx.xxx.xxx is the IP address of the network and "n" is the number of '1' bits in the mask. For example, the class C network 192.168.1.0 with the mask 255.255.255.0 is written in CIDR as 192.168.1.0/24.
How the Internet Works Large providers are assigned large IP blocks for them and for their customers. When accessing an IP address outside the provider's network, the data must travel through certain routers to get to the destination IP. The Internet Protocol is responsible for routing the packet to the destination. |
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