# NAT Virtual Interface

**URL:** https://forum.networklessons.com/t/nat-virtual-interface/1337
**Category:** Lessons Discussion
**Created:** [December 29, 2016, 9:14pm UTC](https://forum.networklessons.com/t/nat-virtual-interface/1337 "2016-12-29T21:14:32Z")
**Posts on this page:** 1
**Showing post:** 6

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### Author: ![lagapidis](https://cdn-forum.networklessons.com/user_avatar/forum.networklessons.com/lagapidis/32/4949_2.png) [@lagapidis](https://forum.networklessons.com/u/lagapidis)
#### Post date: [July 4, 2017, 7:06am UTC](https://forum.networklessons.com/t/nat-virtual-interface/1337/6 "2017-07-04T07:06:08Z")

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Hello Maodo

> [@kayoutoure](#):
>
> Point-1

The command `ping 19.168.12.3 repeat 1` is used to test if a NAT translation without a default route will function correctly.

The command `ping 192.168.23.1 repeat 1` is a completely different test. which is testing the NAT translation between 192.168.23.1 and 192.168.12.1. This can be seen from the words: “Let’s try something else…” before the command as seen below:

 ![](https://cdn-forum.networklessons.com/uploads/default/original/1X/6d0c020b8ef1d033c9bbeda758f898967e8ce214.png)

Secondly:

> [@kayoutoure](#):
>
> Point-2
> 
> Hard to see (in the debug ouptut) the difference between using “add-route” or not-using “add-route” !

There is no difference in the debug output for when the ping goes from R3 to R1. The difference is on the return of the ping. On the return of the ping, with no `add-route` command, there is no indication of a NAT translation, whereas with the `add-route` command, the translation occurs correctly.

> [@kayoutoure](#):
>
> Point-3
> 
> The text below lets suppose that it takes two “ip nat source static” commands for the configuration of NVI.

With these two commands, we are implementing the TWO NAT translations that were implemented in the first section. These are two separate NAT translations creating two separate NVIs.

> [@kayoutoure](#):
>
> In the command below :
> 
> R2(config)#interface range GigabitEthernet 0/1 - 1
> 
> I would say “2” at the place of the last “1”

Yes you are correct, this should read `interface range GigabitEthernet 0/1 - 2` I will inform @ReneMolenaar

> [@kayoutoure](#):
>
> Point-5
> 
> The first NVI configuration example (Static NAT) does not show that the initial issue has been solved. Again, why do the command below is not tried again ?
> 
> R1#ping 192.168.12.3 repeat 1

With the NVI, this problem will have been solved. You can lab it up, test it out and let us know your results!

I hope this has been helpful!

Laz

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