History of IPv4.
An Internet Protocol (IP) Address is a numerical label assigned to network devices that use the Internet to communicate, such as a computer, printer or smartphone. IPv4 refers to Internet Protocol Version 4. IPv4 addresses have 9 digits, ex: 172.16.254.1. IPv4 addresses were introduced in 1981 and form the cornerstone of networks and the Internet. Their 32-bit length, though, implies a maximum limit that we have already reached.
Prior to 1997, known as the “Legacy” period, IP addresses were allocated without a contract since ICANN, IANA and the Regional Internet Registry (RIR) system had not yet been created. Legacy addresses comprise approximately 44% of the entire IPv4 address space and were divided up into classes. Class A, B and C are the three classes of addresses used on IP networks in common practice.
• Class A (/8 address range) – 16.7 million addresses per network. Apple, AT&T, Chrysler (Daimler), CSC, DEC (HP), DuPont, Eli Lilly, Ford, GE, Halliburton, HP, IBM, Level 3, Merck, MERIT, MIT, Prudential, Stanford, USPS, Xerox and various governmental agencies were assigned Legacy Class A address blocks.
• Class B (/16 address range) – 65.3 thousand addresses per network. Thousands of address holders (active and defunct) were assigned Class B address blocks.
• Class C (/24 address range) – 256 addresses per network.
Since 1997, IP address space management and allocation has been handled by the Internet Assigned Numbers Authority (IANA) under a contract with ICANN (Internet Corporation for Assigned Names and Number). IANA was originally funded by the U.S. Government under a contract between the Defense Advanced Research Projects Agency (DARPA) and the Information Sciences Institute. The Legacy Registration Services Agreement (LRSA), which guarantees that recipients of addresses during the Legacy period receive services from the American Registry for Internet Numbers (ARIN), was also implemented. Not all Legacy allocation holders have an LRSA in place, though, despite the fact that ARIN originally asked all of them to sign. IANA allocates IP addresses to RIRs, which allocate and assign addresses to Local Internet Registries (LIRs) within their respective geographic regions. To receive assignments, organizations must demonstrate need and document the specific purpose and reason for the addresses. The five RIRs are:
AfriNIC – African Network Information Center
APNIC – Asia Pacific Network Information Centre
LACNIC – Latin American and Caribbean IP Address Regional Registry
RIPE NCC – RIPE Network Coordination Centre
