MCTS 70-680: Internet Protocol Version 6 (IPv6)


Uploaded by itfreetraining on 20.10.2011

Transcript:
Welcome back to your free Windows 7 training. In this video I will look
at the IP version 6 protocol that will one day replace the IP version 4 protocol.
There are lots of reasons to change to IP version 6. IP version 6 offers many improvements
to IP version 4. Things like multicast have been improved. Multicast allows one computer
to send a packet to many destinations. Encryption has been improved. IPSec is now
integrated in the protocol rather than being a tacked on add on. The IP version 4 network
grew as demand grew and thus the network is not laid out as well as it could be. With
IP version 6 more thought has gone into the geographical lay out of the network then the
IP version 4 network which grew as demand grew.
The most noticeable difference between the two protocols is that the IP version 6 protocol
uses a much larger address space. There are many different ways that people have used
to describe how many addresses are available in IP version 6. The number of addresses is
2 to power of 128 or 340 trillion, trillion, trillion addresses.
To put it in prospect, IP version 4 has over 4 billion addresses. Using IP version 4 you
could not even allocate a single IP address for every person on the planet. With IP version
6, you could allocate 2 to power of 95 IP addresses for every person on the planet.
With this many IP address available you cannot imagine that you would ever run out.
The larger IP address space also allows you to have better and more efficient routing.
IP version 4 was not designed around efficient routing. It was expanded and allocated based
on the need at the time. Because of this, internet back bones routers have 1000’s
of routes on them. IP version 6 backbone routers in comparison have a smaller amount of routes.
To understand IP version 6 better, let’s have a look at how IP version 6 addresses
are configured. IP version 6 uses a 128 bit address which
is in 8 blocks of 4 hex decimals values. For example the following addresses. IP version
6 addresses are not the easiest addresses to look at and definitely hard to remember.
To make the addresses easier to read, there are some rules that you can use to reduce
the size of the address. Firstly you can remove any leading zeros down to a single number.
Given this example, all the leading zeros can be removed from the groups of 4 digits.
Remove the leading zeros makes the address a little easier to read. Notice that in this
case I did not remove all the zeros as there always needs to be at least one digit in each
group of 4. If you have consecutive blocks of zeros these can be reduced. Given the example
the first set of zeros can be reduce to a double Colin like this.
Also given this example the last set of zeros in the IP version 6 addresses can be reduced.
For example it can be reduced to this. Both of these addresses are valid, however reducing
an address down to a double colon can only be done once per address, thus the following
address is not valid. Once you understand how an IP version 6 address
is represented, the next thing to look at is the different types of IP version 6 addresses.
There are many different types of IP version 6 addresses. If an address is determine to
be a unicast address, this results in one to one communication. The network data travels
directly from one host to the other. The host can be on the same network or on the other
side of the world or somewhere in between. Unicast is used for most network communication
as most network communication is between a host and a server for example when you request
a web page from a web server. The next type of address is multicast. This
is when one packet is sent to multiple computers. For example if you needed to install windows
7 on a number of computers at the same time. If you used unicast and were installing windows
7 on 100 computers at once, every packet would need to duplicated on the network 100 times.
Multicast can sent 1 packet to 100 computers at once. Assuming your network and software
can support it, multicast can save you a lot of bandwidth. You can tell a Multicast address
because they start with FF. The last type of address is any cast. Any
cast is when one packet is sent to one of many destinations. For example, if you had
the same service installed on many servers throughout your network you would want the
client to be directed to the nearest one. Using any cast you can use the same destination
IP address on each host and your routers will direct the client to the nearest server. To
use any cast your network needs to be configured to support it.
Looking closer at unicast addresses these can be divided down into 3 types of addresses.
First there is the global unicast address. This is like the public IP address used in
IP version 4. Global unicast are centrally managed and routable on the internet. You
can tell a global unicast because the IP address starts with 2000 or 2001. When you received
a registered global IP version 6 uni cast address you can be assured that your IP address
is unique and that any one on the internet will be able to contact you using it.
Next you have the address link local. This is simpler to APIPA addresses used in IP version
4. The big different is that a link local address is always present on your network
card. This is because they are used for essential services like neighbor discovery.
In IP version 4, if your computer attempts to communicate with anther computer on the
same network and the computer does not known the MAC address of the other computer. The
MAC address is a unique address assigned to every network card and is guarantee to be
unique. It is used so network adapters can communicate directly with each other.
To find out this MAC address, the IP version 4 computer would then sent out a broadcast
message that all computers on that subnet would receive. This is a waste of bandwidth
since only one computer on a network with possibly hundreds of computers would response
to the broadcast but all computers on the network would receive it.
Neighbor discovery helps eliminate the need for broadcasts.
It performs functions like finding other hosts MAC addresses, finding
routers and used for auto configuration. All this is done without the use of broadcasts.
Since it is used in so many functions critical to network communication, this is why every
network adapter has one of these address even if you manually configure an IP address or
an IP address is obtained from a DHCP server.
Link local addresses always start with FE80.
If I was to run Ipconfig from the command line, you can see the link local address that
have been assigned to the adapter even though this adapter has an IP version 4 address assigned
to it and no IP version 6 address. If I were to configure a IP version 6 address on this
the link local address would still be present. Link local addresses are
IP addresses that will be configured automatically and can communication only on your local network.
They are not routable. The next address is unique local address.
Sometimes you will see this referred to as site local but this is an old term. These
addresses are like IP version 4 private addresses. You can allocate these IP addresses any way
you want but these addresses are not routable on the internet. You can however route these
addresses any way you want inside your network. Unique local addressees start with FC00
or FD00. They can also start with FEC0 but this is the old standard which is being
depreciated. There is one more IP address you may come
across and this is the look back address. In IP version 6 this is represented as colin
colin 1. If you attempt to connect to this address or sent data to this address it will
be redirected back to the local network card.
The loop back address is primarily used to
check if your network card and its software are running. This will not test if you can
send data on the network because the loop back address will still work even if the network
cable is not plugged in. Each day more and more devices support IP
version 6. In the real world IP version 6 deployment has been slow. It is surprising that
few ISP even support IP version 6 meaning that going out and buying an IP version 6
device may be a waste of time. If you want to start using the IP version
6 network and don’t want to wait, consider downloading the go go client from go go 6
available from their web site. This client allows you to connect up to the IP 6 network
without having to upgrade your equipment.
This conclude IP version 6. In the next video I will look at how to trouble shoot the IP
protocol. For more free videos, exam questions and study guide make sure you check out our
web site.