NAT Question?

[Kimberly Adams]

Hey Guys,

I am struggling with trying to resolve something that someone else setup.  Here is the scoop:

I have a 2901 router at a remote location routing between two networks 10.41.69.X and 192.168.20.X.  They are already have a NAT setup in the following configuration:

Gi0/0 is on the 10.41.69.X network and was setup with IP NAT INSIDE

Gi0/1 is on the 192.168.20.X network and was setup with IP NAT OUTSIDE

There are two servers on the 10.41.69.X network in access-list 15 and then the IP NAT statement is:

ip nat inside source list 15 interface gigabit0/1 overload

This is working just fine for these two servers to communicate with the 192.168.20.X network.  The problem I am having is with another system that needs a different nat. 

There is a system on the 192 network that needs to NAT into the 10.41.69 network.  That is not difficult, but here is the tricky part:  I can't undo or touch the existing NAT as it is in production.  The system on the 192 network is not going to be initiating the connection, the connection will be coming from our core network through the MPLS into the 10.41.69.X network for this communication.

Dose anyone have any ideas to help me out?  Appreciate any assistance.

Thanks,

Kimberly

[milan.kulik]

Hi,

I'm not 100% sure what's your request indetails.

To configure a NAT translating a source address of packets incoming from the WAN?

Why don't you configure the WAN port as ip nat outside

and configure some kind of

ip nat outside source ...

NAT then?

See

http://www.cisco.com/en/US/customer/tech/tk648/tk361/technologies_configuration_example09186a0080093f8e.shtml

or

http://www.cisco.com/application/pdf/paws/13770/1.pdf

for examples.

Or are the devices in  the 10.41.69.X subnet able to communicate within that subnet only, i.e., you'd need some kind of interface overload NAT as used already?

That would be a true challenge, I'm afraid.

HTH,

Milan

[Antonio Knox]

There is a system on the 192 network that needs to NAT into the 10.41.69 network.  That is not difficult, but here is the tricky part:  I can't undo or touch the existing NAT as it is in production.  The system on the 192 network is not going to be initiating the connection, the connection will be coming from our core network through the MPLS into the 10.41.69.X network for this communication.

The way that I'm reading this is that you need to translate a single 192 address to 10.41.69

In this case why not:

Static NAT (the link is not specific to the 2901, but the concept can be applied nonetheless)

http://www.cisco.com/en/US/tech/tk648/tk361/technologies_tech_note09186a0080093f31.shtml

Hope that helps.