You can once again look at RFC 2784 or go to the updated version 2890.
To see some of the extra extensions to go back in to 784.
Notice once again you can see the encapsulated packet with a payload header and delivery header.
You can see what the grey header looks like.
As an example, you can see the protocol type, you can see the version and other fields.
That kind of information is explained in this RFC.
But rather than boring you going through an RFC, I'm going to show you practically with a Wireshark
capture what the actual packets look like.
In our topology.
So we'll capture some packets here.
And we'll also capture them on the Internet to see how the packets are encapsulated and what headers
are used.
You can see the protocol type used by E in RFC 1700.
And in this RFC, you'll see that Joey uses protocol number 47.
Other protocols that you may be more familiar with include TCP, which is Protocol six.
And UDP, which is Protocol 17.
So the point to remember is GRC is a protocol that resides next to UDP and TCP.
In the OSA model, GRC doesn't run on top of UDP or on top of TCP, it's its own protocol type.
You can also see the ether type for Jerry in the Ethernet numbers on the IANA.
But once again, I'm going to be using Wireshark to show you this, even though that kind of information
is contained in the various RF keys.
So let's get started configuring tunnels.
In this example, rather, one and router five are configured as PCs topping the show IP Route Command.
Shows me that no routing is enabled on this router.
A default gateway has been configured to ten 112.
Now I disabled routing on the router using the command.
No IP routing.
So this router doesn't even have a routing table as you would expect from a normal router.
I've turned off routing and essentially turned the router into a PC.
The router can ping its default gateway, which is reported to but cannot ping.
Root of five.
And that's because no routing has been configured on rather three.
Rather three has only been configured with IP addresses.
The command show IP route on router three shows us that it has directly connected interfaces.
It has an interface here and an interface here, but no routing is configured.
The only configuration at the moment is IP addresses on these interfaces, and the interfaces have been
enabled.
Once we've configured this topology.
However, rather, one should be able to ping router five without router three having any visibility
of the ten networks.
Ten is once again in RFC 1918 address.
In other words, it's a private IP address.
I've used Network four, which is part of level three on the Internet.
So this is a public IP address that belongs to an ISP.
So I'm doing that in this topology to emulate the Internet.
And once again, Router three in this example has no visibility of this network or this network, and
we are not going to configure it with any visibility of these private IP addresses.
But when the jury tunnel is configured logically, traffic is going to go across this Ethernet interface,
hit this router, go through the tunnel.
Come out of the tunnel and go across this Ethernet interface and hit four out of five and return back
through the tunnel.
So we should have connectivity between router one and router five.
Now rather to and rather for have static default routes.
Pointing to Rada three.
So in this example, rather two is configured with an Internet facing IP address as well as an internal
IP address on Fost Ethernet zero zero.
And once again, with the default gateway pointing to router three, router four.
Has something similar.
Sure pirate shows default route pointing to ten 121, which is rather three.
We have an Internet facing interface and an internal interface, but at the moment, no tunnels have
been configured on these routers.
So on router four, we see first Ethernet zero zero, we see Serial 2/0, but we don't see a tunnel
interface and on router two.
The same is true.
There's Foster Ethernet zero zero.
Here is serial 2/0.
So that's the initial topology.
Now let's configure the tunnel between router two and router four and prove that we can send traffic
from router one to out of five.