In our last post on CircleID—Networks Announcing IPv6 - One Year Later—we showed encouraging growth in the number of IPv6-enabled networks.

But announcing an IPv6 prefix is only one of the first steps a network operator should take when deploying IPv6. For a full IPv6 deployment, IPv6 needs to be enabled on network infrastructure and made available to end users. One key piece of infrastructure for which we can measure IPv6 capabilities are DNS resolvers. These are typically (in around 80% of cases) located in the same network as the end users who are using them.

We’ve been tracking the IPv6 capabilities of the DNS resolvers that are used by visitors to www.ripe.net since early 2010. See Measuring IPv6 at Clients and Caching Resolvers for earlier results (March 2010). Two key metrics used here are the IPv6 preference of end users and the IPv6 capability of the DNS resolvers used by these end users. The IPv6 preference of end users measured here indicates the percentage of clients that connect over IPv6 to www.ripe.net, which is dual-stacked. The IPv6-capable resolvers measured here indicate the percentage of clients that use a DNS resolver that is capable of using IPv6 for DNS resolution. The intuition here is that network operators will first enable IPv6 on their caching DNS resolvers and in later steps of IPv6 deployment roll it out to end users.

Recently, we saw noticeable increases in the IPv6 capabilities of DNS resolvers, as indicated by the blue line in the image below.*

As you can see, over 25% of end users that visit www.ripe.net currently use a resolver that is IPv6-capable. This is far more then the 2-3% of end users that really use IPv6 to visit www.ripe.net (as indicated by the red line in Figure 1).

The gap between the IPv6 capabilities of end users and the resolvers they use is widening over time. I think this is indicative of a frequently mentioned problem with deploying IPv6 to end users: the lack of IPv6 capabilities in many (older) customer-premises equipment (CPE) and/or the economics of replacing old CPE. (see also the IPv6 CPE Survey on RIPE Labs). However, it does show operators extending the IPv6 capabilities of their networks, and why would they do that, other then to eventually provide this to their end-users?

The growth curves of both the IPv6-enabled networks and IPv6-enabled DNS resolvers show broad progress towards full IPv6 adoption. We’re getting there ... slowly.

For more details, please refer to the background article on RIPE Labs: Growth in IPv6-Capable DNS Infrastructure.

* Note that the www.ripe.net audience is biased towards network operators. That means the IPv6 capability of typical end users is probably lower than what we measure here.