World IPv6 Day: 8th June 2011
It has long been forecast that the number of IP addresses available in the current Internet Protocol format (IPv4) is insufficient to cope with the spectacular growth of the internet and consequent number of devices that need their own IP address.
This has come into sharp relief this year, with the last remaining blocks of IPv4 addresses being allocated by the Internet Assigned Numbers Authority (IANA). These addresses pass down to the Regional Internet Registries (the one that applies to the UK is RIPE NCC), which then allocate them to ISPs and other companies that need them.
The internet won't stop working on the day that the last IPv4 address is allocated, but a solution is required to allow the internet to continue to expand.
That solution is IPv6.
IPv6 provides a mind-boggling number of addresses (3.4 x 10^38). It's hard to find a meaningful analogy for a number this large, but if every man, woman and child on Earth had a billion devices each with an IPv6 address, you haven't even come close to scratching the surface of the number of addresses available.
Unfortunately, IPv6 is not backwards compatible with IPv4, so there's a lot of work required before end-to-end IPv6 operation becomes the norm. In practice, this means that IPv4 and IPv6 will have to co-exist with each other for a long time. As content providers, content distribution networks, network operators and equipment manufacturers introduce IPv6 there are plenty of opportunities for problems to appear that interfere with a user's experience of using the internet.
And that's where World IPv6 Day comes in - it's a 24 hour "test flight" intended to motivate relevant companies to "prepare their services for IPv6 to ensure a successful transition as IPv4 addresses run out".
In the spirit of this, the BBC is also making BBC Online available over IPv6. We're doing it in two ways:
1) We've created a new address: http://ipv6.bbc.co.uk. When you try to access this address over an IPv4 network, it simply won't work (your browser will produce an error saying something like "The requested URL could not be retrieved"). However, if you access this address over a network that supports both IPv4 and IPv6 you will see the home page as normal.
2) We've also, just for today, made the usual BBC Online address (http://www.bbc.co.uk) enabled for both IPv4 and IPv6. You shouldn't notice the difference, with the site working as normal for you. In fact, unless you're a bit of an expert, you won't be able to tell whether you're accessing the site over IPv4 or IPv6.
Very few of you will have an IPv6-capable network. If you want to try accessing the BBC's site (or any of the sites participating in World IPv6 Day), you may find that the only way, today, is to set up an IPv6 tunnel (which allows you to make an IPv6 connection over an IPv4 network). There are a number of companies that provide this service, some of which are listed here.
Under the hood, we still have a lot of work to do at the BBC to make BBC Online fully IPv6 capable.
To make the site available over IPv6 to the extent that we have, we've added a separate (much smaller) network that is both IPv6 and IPv4 enabled, and connected it to the site through a pair of load balancers that we normally use for testing purposes. The host name ipv6.bbc.co.uk only has an IPv6 address registered on it, and this is the IPv6 address of the load balancers. Through this you can access pages on the BBC Online site, but note that most objects referenced by these pages are on other domains that are IPv4 only (so to see the pages correctly you must be on a both IPv6 and IPv4 enabled network). Our DNS is IPv4 only, as is our IP geolocation system that we use to serve different editions of the site as appropriate to your country, and restrict access where we only have content rights for the UK.
We'll be upgrading the site to be fully IPv6 enabled as part of our normal technology refresh programme, and we expect that will be complete sometime next year.
Meanwhile, what we've done for today allows you to see if you can make an IPv6 connection, and for us to see the problems that we have to solve and determine the work remaining for us to do to be fully IPv6 enabled.
Many thanks go to colleagues in Future Media, R&D and Siemens who pulled this all together.
Richard Cooper is Controller, Digital Distribution, BBC Future Media