The encyclopedia · Software & IT · Technical decision · 1995–2017
IPv6 solved address exhaustion with 128 bits, and eventually became the internet
When IPv4 ran out, IPv6's stateless autoconfiguration and huge address space were the only way forward
IETF · Google
the move
By the mid-1990s the internet's 32-bit address space was visibly finite. The IETF's IPng working group designed IPv6 to solve exhaustion: 128-bit addresses, a simpler fixed header, built-in security, and stateless autoconfiguration so devices join networks without a DHCP server.
The design restored end-to-end addressing that NAT had broken and made address assignment automatic — the pieces that would later matter enormously for mobile phones, sensors, and the internet of things. Google's IPv6 statistics page has tracked the transition since 2008, charting the share of users who reach Google over IPv6.
But NAT had already made IPv4 survivable, and every upgrade touched routers, OSes, and applications, so deployment lagged the spec by two decades. The move accelerated only as address exhaustion became acute and mobile networks, which could not stretch IPv4 forever, were built IPv6-first.
why it works
- 128-bit addressing ended the rationing game that NAT, address reuse, and black markets had created
- Stateless autoconfiguration made billions of devices network-ready with zero administration
- A simpler header sped routing and removed the checksum work that constrained IPv4
- The transition mechanisms (dual stack, tunneling) let networks move incrementally
what transfers
A right design can wait decades when workarounds dull the pain: NAT made IPv4 survivable, so IPv6 won only when exhaustion became acute enough to force the move.
what came after
IPv6 now carries a majority of traffic on major mobile networks and a large share of the fixed web, with Google reporting ongoing worldwide adoption; new networks are routinely built IPv6-first with IPv4 as the legacy overlay. It is the long-run standard, won by the arithmetic of exhaustion rather than by persuasion.
references
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