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Double NAT

Hi,

I'm struck with a situation where in our management wants to extend a WAN Link to one of our customer sites, and since there is a conflicting IP Addressing Scheme (we both have 10.120.X.X).

Hence, a solution has been suggested by using NAT on the Router with a Proxy Address (or NATted IP Address of 192.168.5.55).

Could anyone please point out a URL which describes my situation with a solution.

Kind Regards,

Wilson Samuel

  • WAN Routing and Switching
3 REPLIES

Re: Double NAT

and what about the subnetmask... it is also identical or what?

and will you please give me the more detail for the same issue?

regards

Devang

Re: Double NAT

Hi Devang,

Thanks for the response.

Infact the situation is something like this:

1. Our Subnet is 10.120.x.x and our client's subnet is also of the same range.

2. There is one server at our end which is of 10.120.11.15/16 and there is a Server at the other end which is of 10.120.14.15/16

3. Both the Servers should be able to talk to each other in order to make the things work.

4. Now we want to translate their Server 10.120.14.15 = 192.168.12.15/28 and Our Server to be translated as 192.168.14.15/28 so that there is no confusion in our exisiting Routing infrastructure.

Now the issue is that on our Border Router this translation should take place:

1. The Server at our end neednt know the actual IP Address of the SErver at our client side i.e. 10.120.14.15/16 but would be configured to use the Destination IP as 192.168.14.15/28.

Similarly the Server at the client side needn't to know our Server's actual address ie.10.120.11.15/16 but should be configured to use 192.168.12.15/28 as the destination address.

Any help would be great.

Regards,

Wilson Samuel

Gold

Re: Double NAT

Try this document to start.

It has some examples of how to do this this.

http://www.cisco.com/en/US/tech/tk648/tk361/technologies_configuration_example09186a0080093f30.shtml

Now if there was not a exact duplication you might get by putting /32 static routes in. The router since it has a /32 will respond to a arp (proxy arp) and then send the traffic to the other interface. This is not the best thing to do but is useful as you migrate address ranges.

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