Tom Coffeen - IPv6 Address Planning: Designing an Address Plan for the Future

If youve picked up this book and are reading the foreword, of all things, then Im going to assume you dont need to be persuaded that IPv6 is important. Vitally important, in fact. Downright critical.

In fact, its so important that even though youre already convinced, Im 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 worlds population, only one, AFRINIC, still has any substantial stock of IPv4 addresses. That means that the rest of the worlds population, about 85% of us, are going to have to get by without. And this couldnt 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 worlds 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 fathers version of the Internet Protocol. This protocol, IP version 6, replaces its predecessors 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. Thats a lot to look forward to.

But you cant just apply the principles youve learned in IPv4 to designing your IPv6 address plan. IPv6s 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 IPv4s 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 hes been talking about the protocol ever since, even when we begged him for a break. At Infoblox, hes advised dozens of our customers on IPv6 address planning. And hes whip-smart, a nonpareil wordsmith, and always ready with an amusing-but-relevant quote.

For all those reasons, I think youll really enjoy this.

This book is dedicated to the memory of my father, Clifford Glenn Coffeen.

Its an exciting and somewhat daunting time to be a network engineer. Were living and working through an era of challenging but essential change in our chosen field. Think of the traditional protocols and operational practices that many of us cut our professional teeth on. Theyve helped deliver the Internet and sustained its initial period of unprecedented growth and success. But now theyre rapidly approaching the limits of their ability to enable the next critical stage of Internet and network evolution.

Virtualization, cloud computing, SDN, mobile devices, the Internet of Things all of these trends are laying bare the weaknesses of traditional networking technology. Such trends would seem to simultaneously promise and demand limitless network scale and unprecedented business agility, but from the same old tubes and wires and the quaint rules that bind them together. You can almost hear Scotty inveighing, She canna take anymore, Captain!

Unless youre Rip (or, perhaps, rIP ) Van Winkle, none of these weaknesses is as familiar as the limited and rapidly dwindling supply of IPv4 addresses. Likely just as familiar is the remedy for this shortage, IPv6.