Running IPv6

Hi, welcome on my website dedicated to my book Running IPv6 as well as actually running the IPv6 protocol. Have a look around and don't hesitate to email me your questions or remarks.

- Iljitsch van Beijnum

2013-08-21: I wrote a blog post about the when and how of turning off IPv4: When do we turn off IPv4?

Is the book still up-to-date?

I sometimes get the question whether my book "Running IPv6" is still current. Since publication in 2005, not much has changed with regard to the core IPv6 protocols. I may go over what's new in this regard at some point in the future. Howevern what has changed significantly are the operating systems and other software mentioned in the book. The main things to be aware of are:


In Windows XP, IPv6 is a protocol separate from IPv4 that must be installed explicitly. In Windows Vista and Windows 7, IPv6 support is integrated with IPv4 and enabled by default. Vista/7 use something other than the system's MAC address as the interface identifier in link local addresses and stateless autoconfiguration. Unlike XP, Windows Vista and Windows 7 support DHCPv6 for both address configuration and to learn DNS resolver addresses.


In MacOS 10.7 Apple enabled privacy addresses with stateless autoconfig by default and added DHCPv6 support for address configuration and to learn DNS resolver addresses. Also, the system tries looks at the round trip time towards a destination over IPv6 and IPv4, and will use the protocol that has the lowest RTT. So MacOS 10.7 will often connect over IPv4 to destinations that have both IPv4 and IPv6 in the DNS. This makes things harder to debug, but the upside is that it avoids timeouts with broken IPv6 setups. As of 10.6.5 MacOS will prefer IPv4 over IPv6 if it has 6to4 connectivity.


The iPhone, iPod touch and iPad didn't exist yet in 2005. IPv6 support was added for these devices in iOS 4 and is relatively mature in iOS 5, with stateless autoconfig and privacy addresses as well as DHCPv6 support. It looks like iOS 5 also uses the RTT-based IPv4/IPv6 selection mechanism present in MacOS 10.7.


The DHCP software mentioned in the book is quite bad. A much better option is the ISC dhcpd, which now also supports IPv6.

Some classic Ars Technica IPv6 stories:

IPv6 is the next generation Internet Protocol that has been developed over the past decade by the Internet Engineering Task Force (IETF) as a replacement for the current IP (IPv4 or TCP/IP) protocol. TCP/IP was never designed for a network as large as today's internet. The main problem is that the address length is only 32 bits, which allows for about 3.7 billion usable addresses. That doesn't even allow for a single address per person on the planet. In IPv6, addresses are 128 bits in size, which gives us more addresses than we can reasonably count (3.4x10^38).

My book "Running IPv6":

Running IPv6 book cover

Some reviews:

More information about the book is available at:

The book was published in the second half of November 2005 by Apress. As you can guess from the title, it's about running IPv6. Most of the prior books about IPv6 focus on how the different parts of the protocol fit together, so they end up describing the theory of IPv6. In my book, I wanted to show what you can do with IPv6 today, on common operating systems such as Windows XP, MacOS X, Linux and FreeBSD, as well as discuss the Cisco or Juniper router configurations necessary to move IPv6 packets around the network.

An ebook version is available directly from the Apress website. Apress ebooks are in DRM-free PDF format for easy reading and searching. The ebook version costs $38.49.

The Internet Protocol Journal has published the article IPv6 Internals, adapted from the chapter with the same name in the book.

I've also written a book about the Border Gateway Protocol and I have a website about BGP (also some IPv6 information) and a website about me.

You are visiting over IPv4. Your address is
You can always find your IPv6 address (if you have one) on the what's my IPv6 address? page.

Last update: February 20, 2012.