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Four years since World IPv6 Launch: entering the mainstream

It has now been five years since World IPv6 Day and four years since World IPv6 Launch. The long-term global Internet transition to IPv6 is well underway and increasingly entering the mainstream. The American Registry for Internet Numbers (ARIN) exhausted its free pool of IPv4 addresses in September 2015, following all of the other registries except for Africa's AFRINIC (which is on track to exhaust its IPv4 free pool in 2018). The result is that businesses and service providers needing Internet addresses for their mobile users, broadband users, business offices, servers, or cloud infrastructure now need to purchase IPv4 addresses on a transfer market, use IPv4 NAT (network address translation) with corresponding costs and complexity, or make a strategic decision to leverage IPv6.

Akamai continues to see major movements in deploying IPv6, especially by many of the top networks and content providers in the world. We are also starting to see areas, such as mobile networks in the US, where IPv6 is starting to both be widely deployed and also out-perform IPv4. Taken together, IPv6 deployment is moving out of its infancy and into a stage where increased network and content deployments will reinforce each other. While IPv4 will persist  for many years, we are now in a stage where it makes sense to routinely deploy IPv6 alongside IPv4 (called "dual-stacking"). There are even scenarios now where deploying IPv6-only is a viable option for infrastructure simplification.

Moving to dual-stack by default

Akamai has been helping customers deliver content over IPv6 for five years now. While dual-stacking web properties with IPv6+IPv4 has remained opt-in for most Akamai products, we've seen significant numbers of customers dual-stack content, especially for some of our highest request-volume sites. With IPv6 now mainstream for many end-user networks, we are switching to dual-stack being the default for client-to-edge delivery for new sites provisioned onto most of our Web products (Ion, Dynamic Site Accelerator, Dynamic Site Delivery, and a few others), with additional Media and Security products supporting dual-stack today, and defaulting to this configuration in the coming months. IPv4-only delivery will be an option for customers who opt-out for one reason or another, such as back-end origin infrastructure that handle IP addresses as data and do not yet support IPv6 addresses in request headers or delivered logs. Making more content available over IPv6 now will both improve site performance in some situations (such as mobile networks in the US), reduce load on bottleneck links and infrastructure (such as NATs) that serve users not yet upgraded to IPv6, as well as will reduce the amount of content that needs to be migrated to dual-stack down the road when IPv4 starts to get phased out.

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There is already significant dual-stacked content on Akamai and has been for a few quite some time. Among the hundreds of customer hostnames on Akamai serving over a billion HTTP(S) requests per day, over a quarter of them have already dual-stacked. We also have significant usage of IPv6 in the hundreds of thousands of sites we deliver with under 100k requests per day, with over 10% of those being dual-stacked. The latter is in-part due to a number of delivery partners, resellers, and SaaS providers dual-stacking their content through Akamai by default.

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Having an increasing amount of content available dual-stacked with IPv6 is also likely to motivate even more ISPs and businesses to hasten IPv6 deployment, especially when doing so can help offload their IPv4 NAT infrastructure.

Deployment Growth

We continue to see growth in end-user IPv6 deployment worldwide, especially by some of the largest ISPs in the world. A primary way we measure end-user IPv6 adoption is by looking at the percentage of requests that arrive at dual-stacked Akamai customer sites over IPv6, also as reported in our State of the Internet IPv6 adoption visualization. By this metric, IPv6 adoption in many countries is growing steadily, with the United States, Germany, Belgium, Switzerland, and Greece all above 20%, and a number of others such as Malaysia, Ecuador, Portugal, and Peru nearing this. Significant IPv6 deployments by large network operators in Brazil, Australia, the United Kingdom, and Canada have also started or accelerated in the past year, with all of them now being above 5%. Japan and France have seen continued growth and are both nearing 10%. At the other end of the spectrum (and within top world economies) we still see very limited end-user usage of IPv6 from India, China, Russia, Italy, Spain, and Mexico, with all of them remaining well below 2%.

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The country and regional adoption continues to be driven heavily by the efforts of individual networks, with some of the largest network providers being farthest along in their IPv6 deployments. Of Akamai's top five network providers by traffic volume, all but one have IPv6 adoption over 20% and the remaining network has announced that they will be starting their roll-out later this year. Of Akamai's top 25 networks by volume, 14 have IPv6 adoption over 10% and a few more have started or are planning roll-outs in the near future. Looking at our top 100 networks by volume, around a third have started rolling out IPv6 and are past 2% and a quarter are past 10%.

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Note that this way of measuring IPv6 adoption (by looking at the percentage of requests arriving at dual-stacked sites over IPv6) is highly sensitive to the mixture of content and client devices. In particular, we have noticed that our IPv6 adoption measurements in some countries and networks (including the United States) are being pulled down by some consumer electronics such as streaming media consoles and smart TVs that are not IPv6-ready, as well as older operating systems. For example, IPv6 adoption in the United States has a country-wide average around 20% but is over 28% when measured across Windows 10 and Mac OS X El Capitan clients and 33% when measured across iOS 9 and Android 5/6.

Another way we measure IPv6 deployment is to count the total number of client addresses and networks that touch the Akamai platform on a daily, weekly, and monthly basis. We currently see over 500 million client IPv6 addresses accessing Akamai-delivered web content per day from over five thousand client networks.  Measured over longer periods of time we see nearly 3 billion IPv6 addresses per week and over 10 billion IPv6 addresses per month.  Primarily due to IPv6 privacy addressing features, none of these numbers are an exact measurement of user count, but they do correspond with other measurements that suggest about 10% of worldwide Internet users have IPv6 today.

Akamai continues to work with our network partners to expand our deployment of IPv6 and as of June 2016, we now have IPv6 live on Akamai servers in 105 countries, over 550 cities, and over 700 network providers. 

For more measurements on IPv6 adoption, see:

Using IPv6 to solve business problems

With the highly limited availability of IPv4 address space and the complexity of running IPv4 and IPv6 side-by-side, an increasing number of businesses are looking at ways to accelerate the path to IPv6-only environments. In this way, IPv6 can be used to solve real-world business problems. One challenge here is the number of Internet resources that are still IPv4-only, requiring many IPv6 "only" environments to still provide "IPv4 as a service" over IPv6 while in-parallel looking to drive down the amount of IPv4 traffic.

Hacking around IPv4 exhaustion is challenging. There are only 16.8 million IPv4 addresses in the RFC1918 private address spaces. This means that ISPs and enterprises that have, or plan to have, millions of  subscribers or devices need to reuse the same addresses in different parts of their network, with careful partitioning and NAT between them. This also makes combining multiple networks during acquisitions very challenging. Using IPv6 enables a single flat routable address space across all devices and subscribers and enables much more deterministic ways of managing devices and subscribers. 

Some examples of using IPv6 to solve real-world business problems include:

  • Some ISPs are now using IPv6-only interfaces for managing network devices such as cable modems and VOIP gateways, allowing them to assign unique addresses per device, even for many tens of millions of devices. This also frees up IPv4 addresses for residential users.
  • Some mobile networks are using IPv6-only for Android handsets (and hopefully Apple iOS handsets soon) using NAT64+DNS64 for access to legacy IPv4 content. Access to content over IPv6 is faster than IPv4 in these environments due to being able to bypass the NAT64 gateway. T-Mobile US, one of the leaders in this approach, now sees that for IPv6-enabled handsets between 65% and 73% (off-peak vs. peak) of all bits transferred use native IPv6 and only the remainder uses their NAT64 gateway. With this volume of IPv6 traffic, at least for one mobile operator in the US, it's clear that IPv6 traffic flows are already the clear majority rather than the exception.
  • Some virtual hosting providers have experimented with or already offer lower-cost offerings for IPv6-only virtual machines. This may become increasingly common as cloud service providers run out of IPv4 address space and start moving infrastructure and management interfaces primarily to IPv6-only with IPv4 access being provided as a service or through gateways. 

To help support some of these use-cases, Akamai continues to integrate IPv6 support into an increasing number of areas within our platform. For example:

  • In the near future some products will support going forward to dual-stacked IPv6+IPv4 origin infrastructure. This will allow us to terminate requests from clients over IPv4 (as well as IPv6) and then make connections to origin servers primarily over IPv6. This allows for significantly reducing load on origin IPv4->IPv6 gateway infrastructure. At some point in the future this will also natively support IPv6-only origins, allowing Akamai's edge to be used as the gateway to the "legacy IPv4" Internet. We are already using this at production scale with one customer with over 99% of content from their origin being fetched over IPv6.
  • We are adding IPv6 addresses to the DNS authority records for an increasing number of Akamai zones. While we've supported this for "FastDNS" with akam.net authorities for a few years now, many of Akamai's zones that dynamically map traffic are now getting IPv6 authorities or will be in the coming months. This will soon allow many services hosted on Akamai to be resolved via DNS even if the DNS resolver has no IPv4 connectivity.
  • Akamai's AnswerX DNS resolver can be used by ISPs deploying DNS64 environments and can be deployed in a dual-stacked environment where it can act as a DNS resolver for IPv6-only end-user populations while talking to DNS authorities over IPv6 and IPv4.

What Next

Next year will be the fifth anniversary of World IPv6 Launch and it is almost certain that even then we will still have a long way to go on the path of migrating the Internet from IPv4 to IPv6. However, as IPv6 increasingly enters the mainstream it will be in our best interests to move the migration along as fast as possible to reduce the amount of time where both IPv4 and IPv6 simultaneously exist in the mainstream with the resultant complexity. When building out and deploying new services, sites, and applications it certainly makes sense now to support both IPv4 and IPv6, defaulting to dual-stack. It is even starting to look attractive in some scenarios to ditch IPv4 entirely and to consider building out new infrastructure as IPv6-only from the start.

Thank you to Dave Plonka and others for providing some of the details for this blog post.