In this section I will look at configuring ip version 6. IP version 6 has been around
since the late 1990’s and since than the adoption of the protocol has been slow. Why
the need for IP version 6, well since ip version 4 was first developed the world has changed.
When Ip version 4 was first introduced there has been significant increases in bandwidth
and the need for greater security just to name two of the new challenges facing computing.
In this video I will first look at the improvements that IP version 6 has to offer over IP version
4. There are quite a few good reasons to use the new protocol if you are able to. Next
I will look at the ip version 6 address. The IP version 6 address uses a 128 bit address
which is 4 times larger than the ip version 4 address.
The first address I will look at is the Global unicast address. This is simpler to the IP
version 4 public address. Next I will look the Link local address. This address is a
special address used by IP version 6 to communicate on a local network. The last address I will
look at this the unqiue local address which is the equivalent of the private address used
in ip version 4. Lastly I will look at the states of ip version
6 addresses. IP version 6 addresses have a life cycle they follow. Depending on where
the ip address is in it’s life cycle you may or may not be able to use it. IP version
6 can look at little daunting at first, but once you learn the basis it becomes a lot
easier to understand and use. With IP version 6, there are a lot of improvements
over IP version 4. Firstly there is a larger address space. One of the problems with IP
version 4 is that we are running out of IP addresses. There have been some studies done
that have concluded that we will run out of free IP addresses by the end of 2010.
This does not sound good at all, but also consider that a lot of IP addresses in the
old days were handed out very wastefully. Since than a number of systems have been developed
to reduce the number of IP addresses that any organisation needs will have help converse
free ip addresses. You may find that in the future a lot of these
wasted IP addresses are reclaimed and handed back delaying the day when there are no more
free IP version 4 addresses. It is difficult to predicate what is going to happen, but
rest assured, if you already have an ip v 4 address registered, you will be able to
keep using it even after all the ip addresses are allocated. Also even if there are no more
ip addresses left for sale, a lot of ISP’s will have a lot of free IP addresses that
they will continue to hand out until they are all gone.
To give you an idea how many more addresses IP version 6 has think of this way. If all
the Ip addresses were grains of sand than all the ip version 4 addresses would fill
a dump truck. On the other hand, if all the ip version 6 addresses were grains of sand
they would fill the sun. This as you can imagine is a hugh increase of ip addresses.
IP version 6 also offers more efficient routing. The IP version 4 network grew as the need
grew and thus the network was not organised in a well thought out manner. IP version 6
addresses are based on a hierarchical and geographical approach. Because of this, the
number of the routes in a back bone router on the internet can significantly be reduced.
Currently an internet backbone router can have some thing like 85000 routes in it. As
you could image this is difficult to mange. IP version 6 significantly reduces the number
of routes require on a backbone router making routing faster and improves efficiency.
With IP version 6, the protocols allow simple automatic configuration. Plug in a device
and it will automatically allocate itself and IP address without the need for a DHCP
server. This address will only work on the local network. For routerable addresses, you
can use a DHCP server or a router to allocate an ip address to the client or even manually
assign one. IP version 6 offers built in security using
IPSec. IP version 4 can use IPSec, but there is no native support. IP version 6 can use
IPSec without the need for significant configuration and infrastructure. Having native support
ensure that all hosts can used encrypted transmissions. IP version 6 offers greater quality of service
features. In IP version 4 these features were limited to particular ports. With IP version
6, you can place priority information inside the header. This means that IPSec packets
can also use quality of service features. As you can see, IP version 6 has a lot of
great features, but in the real world it will take a long time before IP version 6 becomes
the default protocol used on the internet. One of the most noticeable changes between
IP version 4 and IP version 6 is the size of the address. IP version 6 use a 128 bit
address. To give you an idea how many addresses that is, with roughly 6.5 billion people on
the earth there would be 5 times 10 to the power of 28 addresses for each person on earth.
The 128 bits is broken down in two parts. The first part is the 64bit network id or
in IP version 6 terminology is known as the network prefix. The second part is the 64
bit host id or in ip version 6 terminology known as the interface identifier.
Since one host can have multiple interfaces, IP version 6 uses the term interface ID rather
than host id. The interface id is generated from the 48 bit MAC address of the network
card or randomly generated. With the change in address size also comes a change in the
way the ip address are formatted. The 128 bit address is broken down into two
parts. As stated the first 64-bits is the network prefix and the second 64 bits is the
interface identifier. The network address is divided up into 3 parts. First the prefix.
Next you have a 45bit global routing prefix. This part is unique to the network it is on.
The last 16 bits can be allocated by the ISP or individual how they like for subnetting.
In other words, for each public IP version 6 address, there are 16 bit of networks or
over 65000 networks available. You may also notice that by having a fix subnet like this,
you no long have to worry about doing those binary converting to work out subnetting like
you did in IP version 4. Before we look at the different types of IP addresses first
of all it help to look how IP address version 6 addresses are formatted.
Slide 5 Ip version 6 addresses are displayed as a
group of 8 4 digit hexadecimal numbers. If you have any leading zeros in any group of
4 digits they can be dropped. For example all the zeros displayed in red can be removed
giving us the following address. Notice that if there are four zero’s in a group the
address gets reduced to one zero, they must be at least one number in each group of four.
IPv6 can be reduced down even further, if you have multiple groups of 0 together, they
can be reduced down to a double Colin. Notice the original 8 zero in the address has been
reduced down to a single double colin. Notice however that the group of zeros at the end
of the address can not be reduced. You can only perform this step once per IP address.
I could reduce the other set of zeros like this. This address is still valid, however
reducing the first set of zeros makes the address shorter. If I were to reduce all zeros
to double colins the address would be invalid. Remember this fact when you studying for your
exam, it will help you remove a few wrong answers.
As stated the host ID and network ID are both 64 bit. There is always a subnet section of
64 bits and unlike IP version 4 you don’t need to worry about subnetting on the binary
level. You will sometimes see the syntax is the ip version 6 addresses followed by a slash
and the number of bits used. Unlike IP version 4 ip address, this value is used by routing
or to represent a range of ip address. Because of this reason this value normally only gets
set on routers and not on the client computer. If you are confused about this, always set
this value to 64 the half way point in the address. Once you get your head around the
syntax of IP version 6 addresses they do become less confusing.
Slide 6 The first type of address that IP version
6 offers is global Unicast addresses. These are equivalent to IP version 4 public addresses.
These are issued by the Internet Assigned Numbers Authority so you are guaranteed the
address will be unique and routable on the internet. Global Unicast addresses are hierarchal
based and thus greatly reduces the route tables on internet backbone routers on of the goal
of IP version 6. You can tell a Global Unicast address as the address always starts with
the bits 001. Or to think of it anther way, they always start with a value between 2000
and 3FFF. If you have a closer look at the bit layout
of a global unicast address, you see the first 3 bits are 001, followed by the global routing
prefix which is assigned by Internet assigned numbers authority. The next 16 bits allocated
to a subnet. The subnet part is assigned by your ISP or your company independent of the
internet assigned numbers authority. The last 64 bits are allocated to the interface ID.
This taken from the mac address, manually assigned or randomly generated.
As you can see, even just 1 ip version 6 network address gives you 64bits of client computers.
This is more than enough for any company. You could have one IP address for the whole
company and use it world wide. To help with routing you simply set the subnet part of
the ip address for which network it is in. You no longer have to plan how many or how
few clients to will need have in each network. The next address is the Link local addresses.
Link local addresses are automatically configured and applied to your adapter. They always begin
with f e 8 0. The host part, or the last 64 bits is randomly assigned. In some literacy
you may see that the mac address of the network card is supposed to be part of the interface
id. This is true, but will find that a lot of operating systems like windows will use
a randomly assigned value rather than use the mac address.
The reason the MAC address may not be used is that it raises privacy concerns. If the
mac address is part of the ip address it could be used to identify the computer. For this
reason, even though a lot of literacy states the interface ID should be generated from
the MAC address, you may find in the real world it is often randomly generated.
Link local addresses are equivalent to automatic private IP addressing used in IP version 4.
When using IP version 4 with windows, windows automatic assigns a private ip address which
always started with 169 dot 254 when no DHCP server was available. In IP version 4, if
your adapter received an IP address from DHCP, this would replace this that address.
In IP version 6 the link local address is always present on you adapter even if you
assign a static ip address or have one assigned through dhcp. There is only one valid on the
local network and routers will not forward them. IP version 6 uses link local address
for neighbour discovery. For example, if your computer needed to obtain
additional configuration from DHCP it would use the link local address to communicate
with the DHCP server. This helps to eliminate the needs for broadcasts on your network.
The big difference with link local address is that they have a zone id. The zone ID identifies
the link the data will be sent over. Each adapter gets one Link local address and a
unique zone id. To identity which network to sent the data over the zone id is used.
The syntax is ip address percentage size and that zone id.
Link local addresses are a bit confusing, to better understand I will go through pinging
anther computer using it’s link local address. First of all from the command prompt I will
run ipconfig to show the adapters on this computer and their ip addresses. This computer
has two different network adapters connected to two different networks.
Notice that both address end with a percentage sign and a number. The number is the zone
id. Both IP addresses are on different networks, however both have the same network ID of fe80.
Since all link local addresses have the same network address routing is impossible between
networks. You will also notice that the network adapter has a static ip address assigned to
it. Even though the adapters has a static ip address the link local address is still
present. The link local address is still used for local neighbour discovery and other functions
even with the present of a static or dynamic ip address.
If I now try to ping anther computer on my network, you will notice the request times
out. This is because the ping request was sent out the wrong adapter. Since all link
local addresses have the same network ID windows did not known which adapter was the correct
adapter to sent the request out of. If I now add %10 to the end of the ping command, in
other words, sent the ping out of the adapter with the zone ID of 10, I now get a response
back from the other computer. Remember this important fact about zone ID’s.
The zone ID only determines which local interface to sent the data out of, it has nothing to
do with the remote computers ip address and nothing to do with subnetting. In the real
world, windows should determine the correct interface to sent data out of. In some rare
troubleshooting scenarios you may need to use a zone id.
The last type of IP version 6 address is unique local address. These addresses are equivalent
to the private address ranges in IP version 4. These addresses are for private network
use only and thus not routable on the internet. All unique local addresses start with FD so
they are easy to identify. The format of the addresses are as follows. You will notice
the format is very simpler to Global addresses. The address scheme gives you 40 bits to define
your network with and 16 bits to define your subnets with.
Each private address gives you 64bits of client address which is more than enough for any
network. Using the global ID and subnet ID you are free to divide you network up into
a simple and logical network. There are three additional addresses with
IP version 6. The first is the loopback address. This is used to test the network stack to
make sure it is loaded and working. It is simply colon colon 1. To test the network
stack from the command line run the command ping colon colon 1.
If you receive a response back the network stack is working. This test only tests the
software is loaded and working. If your network card is not plugged into the network you will
still get a response back. The next address is anycast. The anycast address allows many
hosts or interfaces to have the same IP address. When you attempt to contact one of these hosts
the traffic will be directed to the host that is closest. The address itself uses a standard
unicast address. For this to work however, your network does need to have anycast compatible
routers. Next you have a mulitcast address. Any data
sent to a multicast address is sent to many different hosts. These addresses will start
with FF in the address. Multicast is generally used for data streaming.
With IP version 6 addresses have what is called a state. The terminology is a little confusing,
to make it simpler think of it as a life cycle. The ip address start it life off as tentative.
In this brief period the IP addresses life, the computer will check the network for duplicates.
If no duplicates are found the IP address changes it’s state to preferred. When the
ip addresses is first created, the router, DHCP server or auto configuration will give
the ip address a time to live. The preferred state is used for the lifetime
of the ip address. The IP address state will change to deprecated one the lifetime of the
address has expired. All existing communication will still work, however no new communication
will be allowed to use this ip address. Just remember this, as long as your IP address
says preferred you should not have any problems. At first IP version 6 can be a bit hard to
understand and especially with the longer addresses can be a bit daunting. Ip version
6 has been slow to take off but it is here to stay. Each day more and more devices and
software are supporting it. If you are running Windows XP, the operating system will preference
ip version 4 over ip version 6. If you are running windows server 2008, Windows
Vista or windows 7 it will preference IP version 6. What this means is if the operating system
is not sure what protocol to use, it will used the preferred one. For example if you
attempt to ping anther computer on your network when not using a dns server, don’t be surprised
if you receive a response back from the ip version 6 address.
When windows did not know the ip address of the computer it found it using ip version
6 network discovery. Even if you are only using IP version 4 addresses it is a good
idea to keep ip version 6 enabled and running. Network discovery is only one of the services
that windows will use ip version 6.