In this video from ITFreeTraining, I will have a look at IPv6 transition protocols.
IPv6 will one day replace IPv4. However, until that occurs, you may be in a situation where
you have an IPv4 network attempting to connect to an IPv6 network or vice versa. When this
occurs, a transition protocol can provide the bridge between the 2 networks.
In this video I will take a quick look at 3 different IPv6 transition protocols. This
will give you an introduction into how these protocols work and how you may use them in
your organization. In later videos, I will go into these protocols in more detail and
look at how to configure them.
The first protocol that I will look at is ISATAP. This stands for Intra-Site Automatic
Tunnel Address Protocol. The most important point to remember is that it is for internal
use only. If you see an exam question on this, you can straight away eliminate any answers
that involve external networks or accessing the internet. ISATAP provides a bridge between
IPv4 network and IPv6 networks.
For example, your company network has an IPv4 network and an IPv6 network. There is no common
network protocol between the two. In order to bridge the two networks, an ISATAP router
is installed to provide the bridge between the two networks. It does this by allowing
IPv6 packets to be transferred over the IPv4 network. This means it provides a common protocol
of IPv6 between both networks. Remember however, ISATAP is designed to be used on an internal
network.
The next network transition protocol that I will look at is Teredo. Teredo allows IPv4
clients to access IPv6 clients. Unlike ISATAP, the IPv6 clients can be on the internet. Teredo
is designed to temporarily allow IPv4 clients to access IPv6 clients until the internet
is upgraded to IPv6. For this reason, Teredo can travel over NAT. So essentially it is
designed to allow home and business IPv4 networks to access IPv6 networks on the internet.
To understand this better, I will look at an example. Consider that there is a computer
on an IPv4 network. This could be in the home or the work place. This network is connected
to the internet using NAT.
The Teredo protocol will locate a Teredo server on the internet. This will work as a router
between the IPv4 network and the IPv6 network. The idea behind Teredo is that it is a temporary
system to allow a computer to access IPv6 networks until the internet has been upgraded
to IPv6. Once all or most of the internet has been upgraded to IPv6, it is expected
that Teredo servers on the internet will be shut down, as they will no longer be required.
The next transition protocol that I will look at is 6to4. This transition protocol allows
an IPv6 network to communicate with other IPv6 networks when there is no native IPv6
internet between the networks.
This is especially important during the initial deployment of IPv6 on the internet, when only
small parts of the internet support IPv6. Your ISP may support IPv6; however, there
is no physical path across the internet that supports IPv6 to get your data to the destination.
Let’s consider an example of when you may use 6to4. Consider that your company has an
IPv6 network. The computers on this network want to communicate with computers on another
IPv6 network. The problem with this is that in between the networks is an IPv4 internet.
So essentially you need a transition protocol that will route IPv6 packets on the IPv4 internet.
If the internet between the two networks becomes IPv6 ready, 6to4 will no longer be required.
To make this possible, a 6to4 router needs to be placed between each network. The 6to4
router will place the IPv6 packet inside an IPv4 packet so it may be transferred over
the IPv4 internet to the IPv6 destination.
6to4 is different from other transition protocols in that it does not require tunnels to be
set up. So the question is, how does the protocol know how to route traffic to its destination.
All nodes on the IPv6 network require an IPv6 and IPv4 address. The IPv6 address that is
used starts with 2002. The IPv4 address that is used for the node has this address encapsulated
in the IPv6 address.
This may sound a little confusing as to how it works. So let’s consider how you would
use it in the real world. Consider the left and right IPv6 networks. A computer on these
networks was allocated an IPv4 address. This is a publically registered IP address. So
any computer on the IPv4 internet can communicate to these computers directly. This is an important
fact to remember with 6to4, you require a publically registered IPv4 address for it
to work. Because of this, NAT will not work with 6to4.
The company now wants to use IPv6, but there is an IPv4 network in between. To do this,
the computers are allocated an IPv6 6to4 address. Notice that the address starts with 2002.
This means it is a publically registered IPv6 address and thus can be routed on the IPv6
public internet. Notice that the IPv4 address is encased in the IPv6 address. The administrator
does not need to register this IPv6 address on the internet, they only need to ensure
that it is the same as the IPv4 address that they have registered on the internet.
Once the IPv6 address packet reaches the 6to4 router, the 6to4 router will place the IPv6
packet in an IPv4 packet. The 6to4 router looks at the IPv6 address and can remove the
IPv4 address. It then uses this address to route the packet across the internet like
it would any other packet. When the packets reach the next 6to4 router, the IPv4 packet
is removed and the IPv6 packet inside is routed like any other packet.
Remember that 6to4 is designed to be used only while IPv6 support on the internet is
not present. Once the two networks can be connected using IPv6, 6to4 should no longer
be used.
That covers it for the basics of IPv6 transition protocols. In later videos I will look at
these protocols in more depth and how to configure them. Until then thanks for watching.