What is IPv6, and why is adoption taking so long?

Just under 30% of the Alexa Top 1000 websites are currently reachable over IPv6, World IPv6 Launch says, a number that has remained stubbornly stagnant over recent years.

Enterprises are trailing in deployment. For instance, a RIPE Labs report on IPv6 adoption noted that U.S. use of IPv6 actually dropped from 2020 to 2021, and speculated that the reason might be that people who had worked at home early in the COVID-19 pandemic were returning to the office and IPv4-based corporate networks.

Complexity, costs, and time needed to complete a transition are all reasons that corporate IT is gun-shy over migration projects. In addition, many medium-sized and small enterprises outsource their networking needs to service providers, who themselves don’t have a strong incentive to migrate in the absence of a push from their customers.

When will more deployments occur?

Enterprise resistance to large-scale IPv6 migration is slowing adoption overall. Patrick Hunter, Charter Communications’ director of IT enterprise network and telecom, lays out many of the factors in play, noting that while most network administrators know migration is inevitable, nobody wants to necessarily wants to be a pioneer if the risk is causing problems for their own networks and applications.

As he puts it, admins have the attitude of “I’m not going to break things and make life difficult just because some insist everyone should hurry to the new protocol.” Not all companies are resisting—Amazon is migrating its serverless and container AWS workloads to IPv6. But inertia, plus the fact that, as noted, widespread NAT use has staved off an IPv4 apocalypse, have reduced the incentives to make the move. The transition may not be complete until 2030 or later.

Nevertheless, as the price of IPv4 addresses begin to drop, the Internet Society suggests that enterprises sell off their existing IPv4 addresses to help fund IPv6 deployment. The Massachusetts Institute of Technology has done this, according to a note posted on GitHub. The university concluded that 8 million of its IPv4 addresses were “excess” and could be sold without impacting current or future needs since it also holds 20 nonillion IPv6 addresses. (A nonillion is the numeral one followed by 30 zeroes.)

In addition, as more deployments occur, more companies will start charging for the use of IPv4 addresses, while providing IPv6 services for free. UK-based ISP Mythic Beasts says “IPv6 connectivity comes as standard,” while “IPv4 connectivity is an optional extra.”

Pushing for a faster transition will take government action, though many Western governments don’t have this on their to-do list. One country moving to IPv6 in a big way is China. In 2021, the Cyberspace Administration of China unveiled an ambitious roadmap, aiming to have 800 million active IPv6 users by the end of 2025.

When will IPv4 be “shut off”?

Most of the world “ran out” of new IPv4 addresses between 2011 and 2018 – but we won’t completely be out of them as IPv4 addresses get sold and re-used, and any leftover addresses will be used for IPv6 transitions.

There’s no official switch-off date, so people shouldn’t be worried that their internet access will suddenly go away one day. As more networks transition, more content sites support IPv6 and more end users upgrade their equipment for IPv6 capabilities, the world will slowly move away from IPv4.

Why is there no IPv5?

There was an IPv5 that was also known as Internet Stream Protocol, abbreviated simply as ST. It was designed for connection-oriented communications across IP networks with the intent of supporting voice and video.

It was successful at that task, and was used experimentally. One shortcoming that undermined its popular use was its 32-bit address scheme – the same scheme used by IPv4. As a result, it had the same problem that IPv4 had – a limited number of possible IP addresses. That led to the development and eventual adoption of IPv6. Even though IPv5 was never adopted publicly, it had used up the name IPv5.