- [Male Narrator] In this video,
we want to take a look at a static NAT configuration.
Notice that we've got PC1 on the inside of our network,
it's got an IP address of 192.168.1.100,
and it's going to be going somewhere on the internet.
And when we go out to the internet,
we want to be translated into an inside global address.
Remember, it's inside because we're referring to a device
on the inside of our network,
but it's going to be a global address
because it's going to be globally routable.
We're going to translate PC1 into an inside global address of
192
.0
.2 .101.
Notice that's not the IP address
of the interface on R1,
we're assuming that we've got a pool of addressees.
Maybe we're able to hand out 192.0.2.101 through 199.
So we're going to hand out 192.0.2.101
as the inside global address when PC1 wants
to go out to the internet.
Here's how we configure that.
On router R1, step #1 is, we identify
who is the inside interface
and who is the outside interface.
We can see looking at the deepology
but we need to tell router R1.
Let's go into interface gigabit 0/1
and I'll explicitly say,
IP nat inside to say you are an inside nat address.
And sometimes when you do that
you'll get a little processor hit, that will calm down,
that's not going to be an issue for us.
And now I need to say who's the outside interface.
I'll say interface gigabit 0/2 IP nat
outside.
I've now done step 1.
I've said who's the inside and who's the outside.
Now, we just give a static nat configuration statement.
We do that from global configuration mode.
I'm going to say IP nat inside and I'll say who's the source,
and the source is going to be a static IP address.
It's not going to be an access control list
and we're matching anybody from that ECL,
no it's going to be a single address
and I'm going to statically configure here.
And it's the IP address of PC1.
And it's 192.168
.1.100.
And now I say into what do I want
to translate that static address.
And we said we want to translate
that into 192.0
.2
.101
And that's it.
We're done.
Let's do some verification though.
Let's go over to our PC and let's do a ping
to an address out on the "internet".
Notice I've got an address of 1.1.1.1
that I'm saying is available
in our lab topology out on the Internet.
So can I ping 1.1.1.1?
Now don't be surprised if the first ping packet fails,
let's see if it does.
Yeah, the first ping packet is going to fail, but that's okay.
That's because we were doing an ARP lookup, that's normal.
If I do a subsequent ping, it's going
to be all successful, as we can see here.
But now that I've created some ping traffic,
going out to the Internet,
let's see if that translation really happened.
Let's go back to router R1
and let's do a show IP nat translations command
and we can see, for those two pings I did,
we see those ICMP flows, that's what ping is using
and notice the inside local address
is the address of PC1,
192.168.1.100,
and we're translating into an inside global address
of 192.0.2.101, and we were destined
for an outside global address of 1.1.1.1.
Now, don't be thrown by this column,
remember I said in our previous video
that we would maybe never use outside local addresses,
and this kind of violates the definition
that I gave you, but if you're not truly pointing
to a locally significant address
at a site that's outside of your network,
then the outside local address in this output
is going to be the same as your outside global address.
So don't be thrown by that, just typically try
to ignore that column because
that column is not meaningful to me in this scenario.
What I do want you to notice though,
is the inside local address, PC1,
the inside global address, the address
into which PC1 was translated, and our destination,
the outside global address.
And that's a look at a static nap configuration.