- [Instructor] So let's jump right in to IPv6 addresses
and take a look at the different types
of addresses in this section.
First, we have some comparisons with IP version four
just to make you feel comfortable.
Link-local is used though with IPv6
unlike in IP version four.
This is equivalent to what's called
the APIPA addresses we discussed,
automatic private IP addressing from Microsoft.
This is a terrible thing to see in IP version four.
This means your DHCP host didn't get an address.
However, in IPv6, link-local is used
specifically for your host to talk to your router,
or for routers to communicate with routing protocols.
So we actually get an address called
a link-local on every interface.
Now we also have something called
unique local unicast addresses,
you know, or site-specific.
These are equivalent to our private addresses
in IP version four.
And then lastly, for us to get on to the internet though,
we're going to also have a global address.
These are referred to as global unicast addresses.
The IP4 equivalent is also called a global address
and this is our non-RFC 1918 addresses, right?
Anything that's not the 10 address and so on.
So we're going to have on our interfaces,
unlike with IP version four
where you could only have one address,
with IP version six, you're gonna have
a half a dozen or more different types of IPv6 addresses.
So let's go ahead and talk a little more about this,
because we know that IP version four
uses broadcasts a lot, causing a bunch of problems,
the worst of which is of course the dreaded broadcast storm.
Now this is an uncontrolled deluge
of forwarded broadcast traffic
that can bring an entire network to its knees
and devour every last bit of bandwidth.
Now when broadcasts are sent out,
every machine has to stop what it's doing and respond.
So nicely, we no longer have broadcasts with IP version six.
But wait, that doesn't mean your LAN is that much better.
We still have a lot of traffic or the same traffic
or even more with IP version six.
However we use something just called multicast addresses,
which have the same definition as IP version four,
which is a one-to-many.
Where broadcast was a one-to-all definition,
now we just do one-to-many.
This stops hosts from having to process
every packet that seems to come their way.
With multicast, we only process
the packets that are meant for us.
Now we still also have unicast, which is a one-to-one.
This is our address on our interface
and we have multiple types
of unicast addresses with IP version six.
But wait, there's another one for our interfaces
that we haven't used before.
Now anycast has been used with IP version four,
but not on our hosts.
So there's no such thing as broadcasts in IPv6
because it uses the multicasts, as we said.
However, anycast communication allows the same address
to be placed on more than one device.
So this allows us to have say content servers
and load balancing between servers automatically.
It's very easy to configure this.
We just put the same address on each interface.
Now let's go ahead and take a look
at our address types and expressions.
First it's very important to understand
that there are eight fields of 16 bits each,
and they're in hexadecimal.
Now at first, it looks a little daunting
but you'll totally get used to it.
But what's really nice about this
is the first four fields are my network.
The last four fields are my host, and that never changes.
So this is really easy to see
once you play with it for a little bit.
In this case here, this is my prefix,
2001 oh D B eight oh one zero F.
And then my subnet, uh-oh.
There's subnetting with IPv6?
This is gonna get hard.
No it's not, it's super easy.
So there's no block sizes or broadcast addresses
or you have to worry about valid hosts or anything.
But we do have to have a different number
in this fourth field for each router interface.
Pretty simple.
Now the leading zeros in a field are optional.
So in this case here,
if I'm looking at this top address here,
notice I did 2001 DB eight.
And in addition, I can reference
a group of zeros with a double colon.
So when I look at this address now,
look at how small it looks compared to what it was
when it was completely written out.
2001 D B eight one zero F colon one,
all leading zeros gone,
colon colon, which took care of
more than three fields of zeros.
And then A C D.
Now it's important to understand
you cannot have two double colons in an address,
because IPv6 would not know where the zeros start and end.