IPv6 in 2025 – Where Are We?

janeiro 29, 2025

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The first in a series of blogs throughout 2025 highlighting the state of IPv6 across the industry, best practices to consider, and how Cisco is helping customers on their journeys with its products and services.

The complex history of IPv6

IPv6: a protocol with a long and winding history, and one that is sure to evoke a wide range of reactions upon mention – from skepticism to curiosity, from dismissal to openness, from indifference to fear, and everything in between. Most of the time, the first things I hear are either “It’s never going to happen” or “What’s going on with IPv6 anyway?” The first is quite easy to address – it is happening. The progress may not be uniform around the world nor across market segments, but the data is there, and it may come as a surprise to many.

The rise of IPv6 traffic

The percentage of global IPv6 traffic Google sees across all its properties from users did not cross the 1% threshold until 2013. Since then, it has risen dramatically, hitting around 48% at the end of 2024. Going by country, the United States is at 53%, while France, Germany, and India are at 78%, 76% and 72%, respectively. As of 2022, Akamai saw 52% of their US traffic as IPv6 and Facebook was seeing over 61% in the US. And yet when one digs into the data, you find that Residential and Mobile segments have driven a lot of these numbers, with Enterprise and Public Sector lagging.

Delayed adoption despite early promise

Given these prominent levels of adoption, it is natural to wonder why it has taken so long to deploy a protocol that is 30 years old (!). Many people have memories of the 1995-2015 time period where there was a lot of talk and hype around IPv6, but nothing ever seemed to materialize. Network professionals got rounds of training, it was incorporated into exam material, and we even had previous government mandates, but nothing ever seemed to get deployed.

Around the same time as the creation of IPv6, the industry also developed some life extenders for IPv4 – CIDR, VLSM, NAT and RFC 1918 private address space – that turned out to be so effective they delayed the need for IPv6 not just by a couple years, but by several decades. But as successful as they were, they still could not overcome the fact that 32 bits simply isn’t enough space for today’s global Internet. We ran out of new public IPv4 addresses to hand out in the mid 2010’s and are still feeling the consequences: Prices have skyrocketed on the secondary markets. ISP’s have had to increasingly deploy Carrier Grade NAT and shoulder the operational issues that accompany it. Enterprises have had to constantly re-address their networks to squeeze every last bit out of each subnet. Furthermore, many have had to deal with the pain of overlapping private address space, as different parts of their network started using the same address blocks independently. This forces more and more NAT just to achieve internal communication, let alone external connectivity.

The shift towards IPv6

The good news is we had a solution ready to go – it had just been in hibernation. However, it was going to require a team effort, an endeavor that has been working well in some areas, but that we still struggle with in others. Service Providers, both mobile and terrestrial, have IPv6-enabled many of their networks (with some choosing to run a single-stacked IPv6 core), large content providers have turned on dual-stack to serve as many potential customers as possible, and major operating systems vendors have ramped up their support. Combine these with developments like Happy Eyeballs (an algorithm built into most endpoints that will attempt IPv6 first, but quickly fail over to IPv4 without any noticeable delay to the user) and you begin to see why adoption has significantly increased.

However, more work is needed within Enterprises. There are a whole set of middleboxes, software suites, monitoring and management tools, identity and policy products, and other operational considerations that present challenges not faced by mobile and home users.

Governmental support and IPv6 moving forward

Many governments around the world, including the United States with OMB M-21-07, have seen this and are putting more emphasis behind closing these gaps [1]. They foresee an IPv6-only future and know that remaining in a dual-stack state indefinitely is the worst situation to be in, even though it is almost certainly required in the short-term. This future is not just about overcoming address exhaustion, but also presents new and exciting opportunities around architecture and operations that simply were not possible in a constrained IPv4 world. While Cisco has published a bit on this previously [2], my colleagues and I are going to use the rest of 2025 to lay out a series of blogs that will help you on that journey: how to think about and plan your new (nearly infinite) address space, how to transition from IPv4-only to IPv6-only, considerations for security and operations, the role of fabrics and other architectural designs, and what management and monitoring looks like in an IPv6 world. Stay tuned!