Network Address Translation and its Role in IPv4 Conservation

By Timothy Boyer, Smart City‘s Data Operations Manager at the San Diego Convention Center


Since the development of the Internet in the 1980’s, 2^32 or about 4.2 billion unique Internet Protocol version 4 (IPv4) addresses were created. Of those 4.2 billion only 3.2 billion were made available, the others being reserved for multicasting, testing and other uses. Since the 1980’s, the volume of available IPv4 addresses has significantly dwindled with the Internet exploding with computers, smart phones, smart appliances and other mobile devices. With demand for IP addresses outpacing supply there are two ways to delay the IPv4 apocalypse and the rise of the IP black market. The first solution is through IPv4 conservation with Network Address Translation (NAT). The other solution is to increase the supply of existing IP addresses by adopting IPv6.

NAT is the process where a piece of hardware or software acts like an agent between the Internet (public network) and a local network (private network). NAT functionality is usually found on routers and other gateway devices at the network boundary. It has the ability of translating a private non-globally unique IP addresses arrange from to, to, or to into a public IP address required to access Internet.*

Gateway devices on a network boundary, such as a router contributes to IPv4 address conservation by reducing consumption through consolidation. Historically, if a household has eight devices connected to the Internet, eight IPv4 addresses will be assigned and consumed. By using a NAT router, a household with eight devices will now consume only one IPv4 globally-routable IP address instead. Similar to a traditional telephone switchboard operator the router tracks the ports and packet orders within the private network, communicates to the public network, and redirects the request to the requesting location.

IPv4 exhaustion is inevitable. The only sustainable method to support the continuous growth of the Internet is for businesses, institutions and countries to adopt IPv6. Until then, NAT will maintain its conservation efforts with the remaining volume of IP address. Through the use of household routers, switches, and carrier grade NAT, the Internet community will continue to stave off the IPv4 apocalypse and the threat of IP black market.

*For more information on NAT and address allocation, visit “RFC 1918 Address Allocation for Private Internets” article.

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