Overlapping Networks with Tunnel GRE/IPsec and NAT

[teschweizer]

Has anyone experience with NATing on a GRE tunnel interface? I need to NAT between two private networks because they are overlapping. I tried to NAT directly on the tunnel interface.

e.g.

Ethernet 0/0

ip nat inside

Tunnel0 (GRE with CryptoMap)

ip nat outside

However I didn't succeed this way. What's the best way to achive my goal?

[umedryk]

NAT such that it translates the inside device to an address from the pool and the outside device to an address from the corresponding pool .

You can check the following link for more details.

http://www.cisco.com/warp/public/556/3.html

[teschweizer]

Thanks. I already checked this paper. The problem is that it only talks about IPsec and not about GRE/Ipsec and nating on a Tunnel interface.

However I made some tests in the lab and it worked fine. So I went back to the customer-site and I had to reboot the small 836 to get it working.

What I learnedis : "ip nat outside" on a tunnel interface on a Cisco 836 is no problem. This is good news if you have to add partners companies with GRE/IPsec and they don't have IP ranges you like, so you just NAT them and give them IP addresses of your choice.

[Mubasher Sultan - 2x CCIE # 20149 (R&S | Sec)]

Hi,

Could you please send me the working config, if possible? I am in the same situation.

Looking for your prompt response.

Thanks,

Regards,

Mubasher Sultan

[khaled alodat]

Hi , 

have you solved the problem, i have the same issue and the only solution is the GRE/ipsec .

Could you provide me with configs please ?

Thanks,