Posted on June 7, 2021 4:15 pm
 |  Asked by Christopher Vickers
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I regularly use GNS3 to create and test configs and commands before using them in production. I have an instance where I need to test Network Address Translation with overloading (one public IP address to multiple internal addresses). When trying the commands with vEOS, the NAT commands do not work, as it is not supported on that hardware device.

Is there any way to run NAT on a virtual appliance? I have tried vEOS, Router and Cloud in GNS3 but all do not support NAT.

Posted by Aniket Bhowmick
Answered on June 7, 2021 4:36 pm

Hi Christopher

We do support overload NAT on CloudEOS/vEOS-router. However it is not supported on "vEOS-LAB" images.

Can you confirm whether you are using CloudEOS or vEOS-LAB image ? Also what is the image version you are using (show version) ?

If you are using CloudEOS and facing the error:  can you share the error output that you are observing? Also are you facing issue only with "overloading" or with NAT in general? Does Static Source/Destination NAT works ?



Answered on June 10, 2021 10:31 am

Having looked into this further, the syntax has changed. The below is the new syntax. I was trying to use the old one.


Many-to-One NAT ( overload )

Dynamic NAT where multiple local addresses are mapped to single global address (many-to-one) using different source ports.

Also called as NAT Overloading, NAPT (Network and Port address translation) and Masquerade ( (PAT).

Source IP of inside hosts translated to IP of interface on which NAT overload is configured


This is also referred to as NAPT (many to one mapping) or IP Masquerade. The overload keyword provides the masquerade capability.


switch(config)#ip nat profile <profilename>

switch(config-nat-profile-<profilename>)#ip nat source dynamic acl <access-list-id> overload


switch(config-if-ethernet<x>)#ip nat service-profile <profilename>

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