The Internet reached a milestone moment in its growth this week, when the last unallocated block of addresses in the IPv4 space were handed out to APNIC - the Asia-Pacific Network Information Centre.
The final two /8 blocks - 39/8 and 106/8 - were delegated by the Internet Assigned Numbers Authority, IANA, late last night - and while the news doesn't really mean that the Internet is 'full,' it's a momentous occasion nevertheless.
The two blocks, which represented the last unallocated /8s available, are now the responsibility of APNIC, which will hand them out - in significantly smaller chunks - to those who can prove a need for a last parcel of IPv4 space.
While it may seem crazy to many that the Internet can 'run out' of space, given that it isn't restricted by physicality, the problem harkens back to January 1980 when Internet Protocol version 4, or IPv4, was put forward in a Request For Comments document.
RFC 760, which was replaced in September 1981 by an update RFC 791, describes a 32-bit address space offering 4,294,967,296 possible unique addresses for Internet-connected machines. While large swathes of that space were earmarked for special uses, including around 18 million addresses for privately-routed networks and a further 270 million for multicast use, the space was considered large enough in the eighties.
Since then, however, the Internet has grown - and continues to do so. When every smartphone, Internet-connected TV, and games console has its own IP address, that space rapidly becomes restrictive - with the result that it eventually runs out.
As with other limiting decisions made back in the early days of computing, such as the inability for 32-bit operating systems to properly address more than 4GB of RAM, there's a solution: make the address space bigger. Enter IPv6.
First officially documented in 1998, IPv6 increases the address space from the 32-bit size available in IPv4 to 128-bit - meaning there are 3.4×10³⁸ possible addresses - more than enough for the foreseeable future.
With the IPv4 allocations on their last legs, the previously slow adoption of IPv6 is likely to increase rapidly in the near future - and while the use of both addressing schemes will result in compatibility issues in the short term, it's a necessary evil if the Internet is to keep on growing.