IPv6 Address Planning

Foreword

Cricket Liu

Chief Infrastructure Officer, Infoblox

If you’ve picked up this book and are reading the foreword, of all things, then I’m going to assume you don’t need to be persuaded that IPv6 is important. Vitally important, in fact. Downright critical.

In fact, it’s so important that even though you’re already convinced, I’m going to take a few sentences to try to really galvanize that conviction.

Most of the world is effectively out of IPv4 addresses. Of the five Regional Internet Registries that cover the world’s population, only one, AFRINIC, still has any substantial stock of IPv4 addresses. That means that the rest of the world’s population, about 85% of us, are going to have to get by without. And this couldn’t have come at a worse time, when movements such as cloud computing, Bring Your Own Device, and the Internet of Things are consuming IP addresses faster and faster. Why, Asia alone is home to about 60% of the world’s population, or over four billion people, and Internet penetration there is estimated at only about 25%! That leaves three billion people without IP addresses—and poor IPv4 only had 4.3 billion to start with.

Luckily, prescient Internet engineers knew this day was coming and designed a successor to your father’s version of the Internet Protocol. This protocol, IP version 6, replaces its predecessor’s 32-bit addresses with 128-bit IP addresses, for an address space that is about 8x10²⁸ times bigger. A standard IPv6 subnet can contain more IP addresses than the entire IPv4 Internet—squared!

What can you do with all that space? Lots of things. You can forget about trying to allocate subnets that are just big enough to accommodate the hosts on a LAN. You can devote groups of bits in the address to signify important attributes of your networks, like region, country, city, and department. You can design your address space so that it makes route summarization and access controls easier. That’s a lot to look forward to.

But you can’t just apply the principles you’ve learned in IPv4 to designing your IPv6 address plan. IPv6’s enormous address space is so large that it requires an entirely different way of thinking, dispensing with the practice of trying to allocate subnets just large enough to accommodate the expected population of hosts. But who can lead us out of IPv4’s Valley of Despair, with its scarcity and guesstimating and gut-churning doubt? Well, I know a guy.

Tom Coffeen cut his teeth on Limelight Networks’ IPv6 rollout, and he’s been talking about the protocol ever since, even when we begged him for a break. At Infoblox, he’s advised dozens of our customers on IPv6 address planning. And he’s whip-smart, a nonpareil wordsmith, and always ready with an amusing-but-relevant quote.

For all those reasons, I think you’ll really enjoy this.