Table Of ContentIPv6 Address Planning
Tom Coffeen
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.
Dedication
This book is dedicated to the memory of my father, Clifford Glenn Coffeen.
Preface
It’s an exciting and somewhat daunting time to be a network engineer. We’re 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. They’ve helped deliver the Internet and sustained its initial period of
unprecedented growth and success. But now they’re 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 you’re 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.
Who Should Read This Book
I’ve written this book with network architects, engineers and administrators for enterprises
in mind. For practical examples, I’ve tried to stick with scenarios and network designs that
will be familiar to enterprise IT personnel. However, much of the material presented
should be suitable to anyone who needs to learn about network address planning using
IPv6. The addressing plan concepts we’ll explore should be relevant and extensible to IP
networks of any purpose or size.
The content of this book is based on the assumption that the reader has a working grasp of
both the theory and practice of designing and operating computer networks. Universally
deployed protocols like TCP/IP, and Ethernet and WAN and LAN architectures should
already be very familiar to the reader, while a general knowledge of more recent trends in
data-center virtualization, cloud computing, mobile networks, SDN, and the IoT may be
helpful as we discuss how IPv6 addressing plan design is likely to be impacted by (and
impact) these rapidly evolving technologies.
I’ve aspired to make IPv6 Address Planning durably useful to network architects and
engineers, whether they are:
Getting started with IPv6 adoption
Ramping up their IPv6 adoption efforts
Iterating or improving their existing IPv6 addressing plans
Adding IPv6 to an existing IPv4 network
Designing and implementing a “green-field” IPv6 network
Whatever your particular situation, this book aims to help you design an addressing plan
that will prove effective for years to come. To do that, you’ll need best-practice design
concepts, principles, and practical examples. This book was conceived and written to help
provide them.
