Hey what's up guys welcome to CertBros. In this video we're going to be looking
at IP addresses. More specifically IP version 6 addresses. So we've already
looked at IP version 4 addresses in the previous videos
but there's a problem when IP version 4 first came out the people that designed
it sat back in their chairs and said "we've done it. We've created every IP
address that anyone will ever need" how many addresses did they create?
four billion two hundred ninety four million, nine hundred and sixty-seven
thousand, two hundred and ninety six addresses which sounds like a lot right?
But at the time they couldn't have imagined the massive explosion of
devices that would require an IP address if you think about every device you own
like a PC laptop smartphone TV etc it quickly became apparent that we would
soon run out of IP version 4 addresses. The solution is to eventually move over
to the new IP version 6. IP version 6 provides us with, well, I'm not even gonna
try and say that number but it's a lot! Aside from the number of addresses IP version 6
also brings a lot of other improvements that makes it a lot more
efficient and practical
Ok so let's dive into what an IP version 6 address looks like. Let's first
remind ourselves of IP version 4. It's 32 bits in length. Remember bits referred to
the binary digits off the address. It contains four sections called octets which
are separated by dots and in theory each octet can contain any number between 0
and 255 now we're familiar with our good old
friend IP version 4 let's bring in an IP version 6 address
Now at first this address looks pretty scary but don't worry we're gonna break
it down step-by-step. First let's do some comparisons. We know our IP version 4
address is 32 bits long but our IP version 6 address is 128 bits long. This
is where we get our massive IP address space from
IP version 4 has four sections called octets. IP version 6 has eight sections
but these are commonly called hextets
IP version 4 uses dots to separate octet but IP version 6 uses colons to separate
hextets. So let's get rid of our ipv4 address and
go into some more detail. The first thing you probably noticed is
there are letters in this IP address. IP version 6 is hexadecimal, meaning each
character can be between 0 and 9 or A and F. Let's take a look at how IP
version 6 works when it comes to binary. This is especially important when it
comes to subnetting. Each hexadecimal character is made up of four binary bits
These bits can either be a 0 or a 1. Each bit represents a value of 1 2 4 or 8
It doubles with each column from right to left. Wherever we see a 1 that toggles
that column on and wherever we see a 0 that toggles the column off. We then add
up all of the columns that have a 1 and this gives us our number, or letter. So
let's take the first number from the address which is 2 how do you think we
can make the number 2 from our binary bits? We simply add a 1 in the 2 column
all other columns stays 0 because we don't need them. So the binary value for our
first number is 0 0 1 0. We're going to go through a few of these
just to make sure it sticks. The second number in our address is zero how do we
get zero? Well, we simply leave all the columns off. So this gives us a binary
value of 0 0 0 0. Our next number is also zero so it's the same. Now
we have number one. Just like with before, we turn on the column for one and
we leave the rest as zero. our binary value is 0 0 0 1
We have yet another zero so we know our binary value will be, well, all zeros
This next one we do need to look at. How do you think we get the letter D from
our binary chart? Well if you remember I mentioned that each character can either
be 0 to 9 or A to F. Clearly we can make bigger numbers with
our binary chart than nine. In fact we can get up to the number 15 if we turn
on all the columns with a 1. The problem is we can't use double digits so instead
we swap out 10 11 12 13 14 and 15 for A B C D E and F. So now we know that how do
we get the letter D? D has replaced the value 13 so this is the number we need
to get. You should always start with the highest
number you can and in this case that number is 8. Then the second highest
which is 4. This gives us 12 so we only need 1 more
We'll leave the two column off because this would make our number too high and
turn on the 1 column. Add this all up and we get 13. So that means our binary
value for D is 1 1 0 1 Hopefully you get the idea by now. If you
were to continue doing this, you would eventually end up with the full binary value
Ok, so that's our brief binary lesson it's not something you do every
day but it is important to understand especially when looking at some more
in-depth subnetting. Ok so just like IP version 4, IP version 6 has a network
section and a host section. The way ipv4 does this is by using a subnet mask
However, IP version 6 has gotten rid of the subnet mask and instead it just uses
a forward slash and the number of network bits which you should be
familiar with from IP version 4. So in our example /64 is half of our 128
bit address. / 64 addresses are common when it comes to IP version 6 it
splits a nicely down the middle and ensures we have plenty of networks and
plenty of hosts but be prepared to see different numbers. Remember each
character is 4 bits long and each hextet is 16 bits. We'll now look at how we
compress this address to make it look a little nicer. I'm sure we can all agree
that this is a lengthy address and the thought of typing this out over and over
again is simply horrific.But there are a couple of tricks that we can do to make
this address a bit more bearable.The first trick is to remove continuous zeros
Because we find ourselves with so many
addresses a lot of the time we see multiple hextets next to each other
that contain only zeros. We can simply replace all of these zeros with a double
colon. When the computer sees this address it sees the double colon works
out there are two missing hextets and then fills in the zeros. The rule to this
trick is it can only appear once. For example if we change this address
slightly and add another hextet of zeros, we cannot add another double colon. If a
computer looked at this address it has no way of filling in the missing pieces
How would it know if the address is missing eight zeros from here and four
zeros from there, or four zeros from here and eight zeros from there? So this is
why it can only happen once. But there is another trick we can use
We take all of the leading zeros from each hextet. So where it starts with one
or more zeros. We have one here and three there. Then we simply remove them
So now when the computer looks at db8 it realizes there is a missing character
and it fears in the gap. The same thing happens on this hextet
Note that even though it's all zeros because we already use the double colon
we need to leave the last zero. And this is the address we're left with
Still pretty large but as a big improvement from where we started
Ok so moving on. Just like IP version 4 there are different types of IP version
6 addresses and they serve different purposes. What we see here is called a
global unicast address. You can think of this like a public IP
version 4 address that is routable over the Internet. Unlike IP version 4
because we have such a massive amount of IP addresses, we no longer need to rely
on private addresses. Every device can have its own public IP address. The first
part of this address is known as a global prefix. This is what your ISP will
provide you as a block of IP addresses. This global prefix will be a minimum of
48-bits long. Once we have the global prefix we can then use the next 16-bits
for our subnet ID. 16-bits gives us over 65,000 subnets to play with. And that
leaves us nicely with a 64 bit host or interface ID
Ok so let's look at some other address types. We have global unicast which we
just looked at. This is a publicly routable address like the IP version 4 public IPs.
The prefix to identify these addresses is 2000::/3 this means
the first three bits identify a global unicast address. It will start with either
a 2 or a 3. Next, we have a unique local address. This
globally routable. The prefix to identify a unique local
address is FC00:/7. Using the first seven bits a
unique local address will always start with an F followed by either a C or a D
Link local addresses. Think of these as quick automatic private IP addresses
that are not routable over a network. They are designed to communicate only
within a single area of a network. You may have seen the dreaded 169.254
.something .something address when your computer can't connect. This is
pretty much the IP version 6 replacement. You can identify a link local address
because it has a prefix of fe80:/10. This means the link
local address will always start with FE
Multicast addresses. These are addresses that are sent to a group of computers or
devices listening for that particular multicast address. IP version 4 used to
also use broadcast addresses these were sent to all computers within a network
these have now been scrapped with IP version 6. Multicast addresses are easy
to spot because they always start with FF. Ok last but not least we have
something could in anycast address. Now these are interesting because IP version
6 allows us to assign the same IP address to multiple devices. The data is
then sent to the closest device with that address
There isn't a specific IP range for anycast addresses, they use the same
range as global unicast so as you can see the prefix is the same
Now it's really important to be able to look at an IP version 6 address and
identified the type. So to recap global unicast addresses will start with
either a 2 or a 3. Unique local will start with an F followed by C or D. Link
local will always start with FE and multicast will always start with FF
Ok so I think that's enough for one video. You should now understand the
fundamentals of IP version 6. This video is part of our full CCNA course which
can be found in the description so please feel free to go and check that
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than that, I hope this video helped and thank you for watching