IPv6 Addressing and Expressions
Just as understanding how IP addresses are structured and used is critical with IPv4 addressing,
it’s also vital when it comes to IPv6. You already know that at 128 bits, an IPv6 address is
much larger than an IPv4 address. Because of this, as well as the new ways the addresses can
be used, you’ve probably guessed that IPv6 will be more complicated to manage. But no worries!
As I said, I’ll break down the basics and show you what the address looks like, how you
can write it, and what many of its common uses are. It’s going to be a little weird at first, but
before you know it, you’ll have it nailed!
So let’s take a look at Figure 10.1, which has a sample IPv6 address broken down into
sections.
FIGURE 1 0 . 1
IPv6 address example
So as you can now see, the address is truly much larger—but what else is different? Well,
first, notice that it has eight groups of numbers instead of four and also that those groups are
separated by colons instead of periods. And, hey, wait a second…there are letters in that
address! Yep, the address is expressed in hexadecimal just like a MAC address is, so you could
say this address has eight 16-bit hexadecimal colon-delimited blocks. That’s already quite a
mouthful, and you probably haven’t even tried to say the address out loud yet!
When you use a web browser to make an HTTP connection to an IPv6 device, you have to
type the address into the browser with brackets around the literal address. Why? Well, the
browser is already using a colon for specifying a port number. So basically, if you don’t enclose
the address in brackets, the browser will have no way to identify the information.
Here’s an example of how this looks:
http://[2001:0db8:3c4d:0012:0000:0000:1234:56ab]/default.html
Now obviously, if you can, you would rather use names to specify a destination (such as
www.lammle.com
). However, even though it’s definitely going to be a pain in the rear, we just
have to accept the fact that sometimes we have to type the address number. So, it should be
pretty clear that DNS is going to become extremely important when implementing IPv6.