TL;DR
IPv6 was standardized in 1995 to replace IPv4 by expanding address space from 32 to 128 bits, but adoption has been slower than expected; under half of users reach the web over IPv6 according to major data sources. The protocol remains important in mobile, broadband and cloud contexts even as NAT, application-level workarounds and new transports like QUIC have reduced pressure to move off IPv4.
What happened
Thirty years after its first formal specification (RFC 1883, December 1995), IPv6 has not supplanted IPv4 across the internet. The core technical shift — moving from 32-bit to 128-bit addresses and thus massively increasing the pool of routable IP numbers — solved the address scarcity problem that worried engineers in the early 1990s. Still, global deployment remains uneven: data from Google, APNIC and Cloudflare show fewer than half of end users access the internet over IPv6. Reasons cited by industry experts include IPv6’s lack of backward compatibility with IPv4, limited incremental features beyond larger address space, the widespread use of NAT to stretch IPv4, inertia in vendor and operator ecosystems, and the cost and complexity of migration. At the same time, IPv6 has enabled scale in several large deployments and remains the preferred option where IPv4 resources are constrained.
Why it matters
- IPv6 provides an effectively limitless address pool, enabling predictable network planning and large-scale deployments.
- Persistent IPv4 use and NAT have shaped modern architectures and reduced immediate pressure to migrate, affecting vendor and operator strategies.
- Transition choices influence costs, performance, and operational complexity for ISPs, enterprises and cloud providers.
- Emerging transports and name-based security models mean addressing choices affect how services are delivered and secured.
Key facts
- The first definition of IPv6 was published as RFC 1883 in December 1995.
- IPv4 uses 32-bit addresses (about 4.3 billion addresses); IPv6 uses 128-bit addresses, expanding the available pool dramatically.
- Less than half of internet users access services over IPv6 according to Google, APNIC and Cloudflare data cited in the source.
- IPv6 is not backward-compatible with IPv4, so many deployments run both protocols (dual-stack) or use transition mechanisms.
- Network Address Translation (NAT) has allowed many devices to share single public IPv4 addresses, reducing urgency to adopt IPv6.
- Some new feature work planned for IPv6 was implemented in IPv4 instead, which lowered incentives to migrate.
- Industry voices differ: registries and operators highlight IPv6’s long-term successes in mobile, broadband and cloud; analysts urge planned migrations.
- Technologies such as QUIC and DNS-based service selection have changed assumptions about the need for public IP addresses.
What to watch next
- Whether cloud providers and carriers introduce pricing or architectural incentives that accelerate IPv6 deployment.
- Adoption trajectories in regions already making gains (the source cites Asia reaching leadership in user numbers and some countries passing 50% capability).
- Industry migration planning: validation of application compatibility, lab pilots with DNS64/NAT64, and gradual dual‑stack rollouts recommended by analysts.
Quick glossary
- IPv4: The fourth version of the Internet Protocol using 32-bit addresses to identify devices on the internet.
- IPv6: The successor to IPv4 that uses 128-bit addresses to provide a vastly larger address space.
- NAT (Network Address Translation): A technique that lets multiple devices share a single public IP address by translating private addresses at a network boundary.
- QUIC: A modern transport protocol that reduces dependence on persistent public IP assignments by operating over UDP with connection multiplexing and encryption.
- Dual‑stack: An approach where systems and networks run both IPv4 and IPv6 simultaneously to provide compatibility during transition.
Reader FAQ
Is IPv6 a failure after 30 years?
Not according to the experts quoted: while it hasn't become universal, IPv6 solved long-term address scarcity and enabled key large-scale deployments, so many view it as a qualified success.
Why hasn’t IPv6 been adopted everywhere?
The source cites several reasons: lack of backward compatibility, limited new functionality beyond address expansion, widespread use of NAT, migration costs, and legacy infrastructure gaps.
Does IPv6 fix security and quality-of-service problems?
Not directly; many security and operational features originally envisioned for IPv6 were later implemented for IPv4, reducing that migration incentive.
Will new protocols make IPv6 irrelevant?
Some experts argue that transports like QUIC and name-based service models lessen the need for public IPs on clients, but IPv6 still matters where large address pools and simpler network planning are required.
NETWORKS IPv6 just turned 30 and still hasn’t taken over the world, but don't call it a failure The world has passed it by in many ways, yet it remains…
Sources
- IPv6 just turned 30 and still hasn’t taken over the world, but don't call it a failure
- The State of IPv6 Adoption in 2025: Progress, Pitfalls, and …
- The IPv6 transition
- IPv6 in 2025 – Transitioning to IPv6
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