Advanced TCP/IP
The original design for the Internet required every organization to have one or more unique IP network numbers. In the early to mid-1990s, it became apparent that the Internet was growing so fast that all IP network numbers would be used. One solution to this problem was to increase the size of the IP address by developing IP Version 6 (IPv6). IPv6 has a much larger address structure than IPv4, allowing for trillions of IPv6 networks.
Three other IP functions have been introduced to reduce the need for IPv4 registered network numbers. These include Network Address Translation (NAT), along with a feature called private IP addressing, which allows organizations to use unregistered IP network numbers internally and still communicate well with the Internet; and Classless Interdomain Routing (CIDR), which allows Internet service providers (ISPs) to reduce the wasting of IP addresses by assigning a company a subset of a network number rather than the entire network.