So rather one ping.
Ten 112.
That works right?
A one can ping rather to write a one has a static root.
In this case, it's a default route, sending all traffic to router two.
So can router one ping.
Eight one.
One, two, rather three.
The pings are coming out on router three show IP route.
Shows us that the router doesn't have any routing enabled.
It doesn't have a static route.
All it knows about is this network.
So debug ip icmp do that ping again on router three we can see that the traffic is arriving.
So router three is receiving the pings from router one, but it's receiving them from ten 111.
So router three is trying to reply back to the ICMP echo message using the source 8.1.122 going to ten
111.
But the router doesn't have a route back and we can see that by doing debug IP packet we can see that
the packets are unreadable.
Router three doesn't know how to send the traffic back to router one.
So let's configure dynamic nat on router two to allow both router four and right one to send traffic
to router three.
So show run pipe include net.
At the moment, no net has been configured.
The first thing I'm going to do is go onto the Fost Ethernet zero one interface and make that to the
outside interface.
So this interface is now deemed to be outside from the routers point of view.
Go onto Foster Ethernet zero zero IP net insight.
So those commands are very similar to static Nat.
What we need to do now, however, is specify a pool and an access list.
So we'll start with the access list.
So access list one permit.
And who are we going to allow to be netted?
In this example?
I'll allow anyone in the ten 110 network so anyone in this network will be permitted or allowed to have
their addresses translated.
So that'll affect right of one and right of four.
Now I can use the command IP net.
And rather than choosing static, I'm going to use the option pool to define a pool of addresses and
then we need to create a name.
So I'm just going to call this net pool.
What's going to be the first IP address in the pool?
So I need to specify a range of IP addresses on this interface.
So I'm going to say 81152811 ten.
And then I need to specify the network mask.
So the network mask will be a slash 24 in our example.
And lastly, I need to specify IP net inside source list access list one which we created is determining
who's going to be netted or who's going to be allowed to be netted.
And we're going to net them to a pool of addresses which we called net pool.
It's a show run pipe, including that will allow me to see the commands that I configured.
We specify the inside and outside interfaces, which would be on these two interfaces.
We created a pool of addresses.
This net command is allowing.
Anyone in access list one.
So anyone in this range based on that entry to be netted to an address in this pool.
And the pool contains these addresses 5 to 10.
So I've added six addresses to the pool.
So debug IP net to allow us to see things in real time.
Rather one wasn't able to ping rather three previously.
Let's see if it works now.
Notice after a while it started working.
And we can see that this address ten 111 translated to 8115 for traffic going to 8112 so we can see.
Traffic's being netted and then the reply came back.
These ping time outs are probably due to the OP taking place between rather two and rather three.
So they're on the third attempt.
The reply came back, so 8115 was translated to ten 111 and that continues.
Can write a four ping 8112.
See the nets taking place.
Ping started succeeding in the output.
We can see that ten 114 was translated to the second address in the pool.
81164 traffic going to 8112.
That means that both writer one and writer Falk can send traffic to Writer three and rather two will
dynamically do the net between the addresses.
So there's write of four.
He has wrote a two being netted.
Show IP net translation.
Now in this example, every ping is going to get a new dynamic net entry.
So to keep it simple, I'm going to use telnet.
So I'll enable the V lines on router three.
And I'll telnet to router three from router one and I'll do that from router four as well.
En route a t show IP net translation we can see the dynamic net entries created for those two hosts
accessing router three.
You can see that this address ten 111 was netted to 8115 and ten 114 was netted to 8116.
And then the actual traffic for that telnet session is shown as a dynamic net entry here with the port
numbers if we exit.
Out of both of those Telnet sessions.
After a period of time, these dynamic entries will disappear.
I can remove them by typing clear IP net translation star.
So at the moment notice there are no net translations.
As soon as I send traffic.
A net translation is created for that host entry.
If I leave it long enough.
Those net translations will time out and be removed.
That's very different to a static net translation where the static net translation stays permanently
in the net table.
As you can see here, the net entry is coming out.
So show IP net translations shows me that that net entry has been removed from the table.
Now, one of the problems with this way of doing network address translation is there is a 1 to 1 mapping
between the inside and outside IP addresses in our pool.
We only created a few addresses.
So short run pipe include net we can see that we've got addresses 8.1, 1.5 up to ten.
So there are only six addresses in the pool.
What happens if we have 100 hosts that need to be netted onto the Internet?
That's not going to work well with dynamic net or static net, and that's where overloading comes in.
In the next demonstration, I'll show you how to set up net overloading.