# Combination of NAT and BGP

**URL:** <https://forum.networklessons.com/t/combination-of-nat-and-bgp/6827>\
**Category:** BGP\
**Created:** [April 15, 2019, 3:13pm UTC](https://forum.networklessons.com/t/combination-of-nat-and-bgp/6827 "2019-04-15T15:13:54Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![abhishekinfo](https://cdn-forum.networklessons.com/letter_avatar_proxy/v4/letter/a/ee7513/32.png) [@abhishekinfo](https://forum.networklessons.com/u/abhishekinfo)\
**Post date:** [April 15, 2019, 3:13pm UTC](https://forum.networklessons.com/t/combination-of-nat-and-bgp/6827/1 "2019-04-15T15:13:54Z")

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Consider the following figure:

 ![image](https://cdn-forum.networklessons.com/uploads/default/original/2X/4/4cd594f79573697f2c91c6e4a13b1fe1c695def8.png)  
In this setup, how when the GW3 learns route from GW1 and GW2 and does translation via NAT, what is the impact on the updates to next hop routers (GW4 and GW5) ?  
Please provide some sample configurations also.

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**Author:** ![ReneMolenaar](https://cdn-forum.networklessons.com/user_avatar/forum.networklessons.com/renemolenaar/32/488_2.png) [@ReneMolenaar](https://forum.networklessons.com/u/ReneMolenaar)\
**Post date:** [April 24, 2019, 9:18am UTC](https://forum.networklessons.com/t/combination-of-nat-and-bgp/6827/2 "2019-04-24T09:18:50Z")

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Hi Abhishek,

What neighbor adjacencies do you want to use between your routers? BGP between GW1-GW3, GW2-GW3, GW3-GW4, and GW3-GW5?

Rene

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**Author:** ![abhishekinfo](https://cdn-forum.networklessons.com/letter_avatar_proxy/v4/letter/a/ee7513/32.png) [@abhishekinfo](https://forum.networklessons.com/u/abhishekinfo)\
**Post date:** [May 23, 2019, 4:08pm UTC](https://forum.networklessons.com/t/combination-of-nat-and-bgp/6827/3 "2019-05-23T16:08:24Z")

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Hi Rene  
The BGP is used between GW1-GW3, GW2-GW3, GW3-GW4, and GW3-GW5. The requirement is, GW3 is a CGNAT box. Please suggest your opinion on this query.  
Abhishek

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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:** [May 30, 2019, 6:46am UTC](https://forum.networklessons.com/t/combination-of-nat-and-bgp/6827/4 "2019-05-30T06:46:01Z")

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Hello Abhishek

> Hi Laz  
> I was looking for the CGN (Carrier Grade NAT) configuration for BGP based router, but was unable to locate it. Idea is, we have a CGN box that is connected with different VRFs [In this figure A, B, D and E are routers in their respective AS. They are connected with CGN via the VRFs] .  
> Now, how the configuration should be to make the CGN work ?
> 
> ![image](https://cdn-forum.networklessons.com/uploads/default/original/2X/c/cb290ef3f9a3e60d0eb790b16b85e8a878f33114.png)
> 
> Thanks and regards  
> Abhishek

We currently don’t have an example of such a configuration on the site, however, you can find some useful information at the following Cisco links:

> **[Cisco IOS XR Software (End-of-Sale) - Support](https://www.cisco.com/c/en/us/support/ios-nx-os-software/ios-xr-software-end-of-sale/series.html)**
>
> Introduction

[https://community.cisco.com/t5/xr-os-and-platforms/cgn-configuration-for-bgp-router/td-p/2252269](https://community.cisco.com/t5/xr-os-and-platforms/cgn-configuration-for-bgp-router/td-p/2252269)

I hope this has been helpful!

Laz

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<div class="post-metadata">

**Author:** ![abhishekinfo](https://cdn-forum.networklessons.com/letter_avatar_proxy/v4/letter/a/ee7513/32.png) [@abhishekinfo](https://forum.networklessons.com/u/abhishekinfo)\
**Post date:** [June 10, 2019, 5:06pm UTC](https://forum.networklessons.com/t/combination-of-nat-and-bgp/6827/5 "2019-06-10T17:06:03Z")

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Thanks Laz for the help