IPv4 address exhaustion and solutions

IPv4 exhaustion

The Internet Protocol version 4 or IPv4 was deployed for ARPANET in 1983. Internet Assigned Numbers Authority (IANA) and five regional Internet registers (RIRs) are responsible for managing and assigning IP addresses. IPv4 addresses are 32-bit and provide 4,294,967,296 unique addresses. Special address blocks are reserved for private networks and multicast addresses. 

Such a number of addresses has become insufficient for the current number of worldwide devices connected to the Internet. However, IPv4 is still the Internet Protocol that routes most of the Internet traffic, as IPv6 adoption is taking place at a slow pace.

The exhaustion of IPv4 addresses has been a concern for more than a decade. The Internet Protocol (IP) is a communications protocol used to transfer data between IP addresses (IPv4 or IPv6) through a network. IP addresses are numerical addresses used to identify the different devices that are connected to the Internet. They allow delivering data packets from one host to another.

IPv4 address exhaustion

During the 1980s, the future exhaustion of IPv4 addresses was already apparent; since they were exhausting at a faster rate than anticipated. The rapidly growing number of Internet users and the increase in mobile devices accelerated the depletion. So, new technologies were developed and adopted to slow it down. For instance:

IANA’s global stock of available IPv4 addresses was depleted in 2011. RIRs ran out of IPv4 addresses as follows (except for addresses destined to IPv6 transition):

  • The Asia Pacific Network Information Centre (APNIC): April 2011.
  • The Latin America and Caribbean Network Information Centre (LACNIC): June 2014.
  • The American Registry for Internet Numbers (ARIN): September 2015.
  • The African Network Information Centre (AFRINIC): April 2017.
  • The Réseaux IP Européens Network Coordination Center (RIPE NCC): November 2019.

The version 6 of the protocol was developed as the long-term solution to this problem; as it would provide a significantly higher number of unique IP addresses. However, previously to IPv6, other technologies were implemented to slow down IPv4 exhaustion.

Classless Inter-Domain Routing (CIDR)

The Internet Engineering Task Force implemented the CIDR method to slow down the fast exhaustion of IPv4 addresses in 1993. This new method introduced the CIDR notation, a new, compact method for representing IP addresses.

In the CIDR notation, addresses are written with a suffix, introduced by a slash (/), that indicates the number of bits of the prefix. For instance, the suffix /16 means that the first 16 bits out of the 32 bits of an IPv4 address are defined by the network and the other 16 bits left are defined by the host.

From classful network architecture to CIDR

The classful IP addressing architecture was used from 1981 until 1993, when the CIDR was introduced. This method divided the IP address space for IPv4 into five classes (from A to E), based on the leading 4 bits of the address. Transitioning from classful network addressing to the CIDR method considerably delayed the exhaustion of IPv4 addresses.

Network Address Translation (NAT)

NAT or IP masquerading allows ISPs and companies to use special private IP addresses to connect computer networks to the Internet using a single public IP address. This way, they can use an IPv4 for an entire private network instead of an IP address per network device. NAT has also been key for slowing down IPv4 exhaustion.

Internet Protocol Version 6 (IPv6)

As we explain in our article about IPv6 and its adoption, the transition from IPv4 to IPv6 is necessary for technological advance. IPv6 is the long-term solution to the exhaustion of the former protocol. That is why, from the beginning, Stackscale has been a leader in the adoption and implementation of IPv6 on its network. All Stackscale customers can deploy services on this new protocol, which should end up replacing IPv4.

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