Now, before we configure our tunnels, we need to make sure that the tunnel endpoints have connectivity
to each other.
So router two should be able to ping, right a for and vice versa.
In this example, I'm going to set up the tunnel from the serial interfaces.
So logically it looks like we have this separate tunnel interface, but the tunnel is actually configured
from serial 020 to serial 020.
So rather two.
Can we ping for to one to 2 to 2?
Yes, we can.
And en route of four, can we ping for one, two, one, two, one.
Yes, we can.
Now, ping uses a different protocol to go.
So you need to confirm that you have connectivity using geo re from this interface to this interface.
But for the moment, we've used Ping as our initial test to ensure that we have basic connectivity.
So to configure a tunnel, you go to interface tunnel and you specify a number.
I'm going to choose zero to keep it simple.
But as you see, there's a wide range of tunnel numbers that you can choose from.
Tunnel zero in this example has gone down.
The tunnel interface will only come up if we have IP connectivity to the tunnel destination, which
we still need to configure.
But first, let's configure an IP address on the tunnel and I'm going to configure this as a slash 30
network.
And once again, we're going to use a private IP address.
So we're going to be sending traffic across the Internet using private IP addresses.
But it'll work because router three is going to route traffic based on the outer header.
Or as described in the RFC is the delivery header.
So the header and payload packet is not going to be read.
By the Internet routers, they simply going to route traffic based on the delivery header.
We need to specify the tunnel mode.
Notice multiple options are available, but we're going to use JIRA.
And IP version for that is actually the default.
So when we look at the tunnel interface, you'll notice that command doesn't display because that is
once again the default tunnel mode.
We now need to specify the tunnel source.
Notice the tunnel command gives you multiple options.
We've already chosen mode, but now we'll select the source of the tunnel.
You can choose a physical interface or an IP address.
In this example, I'm simply going to choose IP address.
And he'd enter the tunnel is going to originate from this IP address and it's going to go to a destination
afforded 1 to 2.2.
In other words, rather a four.
As you can see, the tunnel has now come up and that's because we have IP connectivity from this router
to the destination of the tunnel.
The tunnel, however, is not going to work because we have to configure the other side.
So kind of t interface tunnel zero on router four IP Address ten .1.3.2.
Keep it in the same subnet.
So this site is once again ten .1.3.1.
And the side is 10.1.
3.2.
So back on route of four tunnel mode, geo IP, you don't have to specify that command because it's
the default, but I'll do it here for completeness.
Tunnel sources.
4 to 1 or 2 to 2.
Tunnel destination.
It's four, two, one, two, one, two, one.
And hopefully what we should see is that that tunnel comes up and there it does show IP interface brief
shows us that we now have a tunnel interface that's up up on the side.
And en route to.
The tunnel is up on a two.
So in order to, we should be able to ping, right.
A force tunnel interface, which we can.
So notice we pinging 10.1 or 3.2, but rather three has no visibility of that route.
And that shows quite nicely that rather three is able to route traffic from this IP address to this
IP address without actually reading those IP addresses.
It's simply routing traffic based on the source to the destination.
So let's prove that I'll start a CAPTCHA here.
I'm going to start a CAPTCHA using LC because the default encapsulation is hdl-c.
On Cisco serial links on interface serial 2/1 on router three.
So at the moment we see CDP, we see some of the messages.
But what I'll do is to a ping from router two to router four again.
And there you go.
There's our ICMP messages.
So we can see it's an ICMP from ten to 1 to 3 to 1 to 10.
To 1.3 to 2.
The Layer two encapsulation is hdl-c.
The protocol used at layer three is IP version four and notice the source and destination IP addresses
4.1.1 and one destination is 4.12222.
In other words, this router is sending traffic to this router.
Rada three is going to root based on these IP addresses, not on the IP addresses contained in the encapsulated
packet.
At layer four, we can see that it's a generic routing encapsulation using IP version four.
And inside there we can see the source tendered.
One, two, three, two, one.
And destination of ten .1.3.2.
In other words, we've encapsulated.
An IP version for packet within an IP version for packet.
The original traffic was a ICMP ping.
So there's the ping.
And if we go to the next packet, we can see the ping reply encapsulated in IP version for within JURI,
within IP version for within Hdl-c.
So we've now successfully configured a tunnel from rather 2 to 2 out of four.
I'll stop that capture.
In the next video will check whether rudder one can ping root of five and do some more.
Wireshark captures and do some other tests.