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NAT ovelap

sivakondalarao
Level 1
Level 1

Hi,

is anybody using nat overlap, if so how to use this practically.

for example i have two 192.168.1.0/24 networks connected by leased line.

after nat overlap configuraton, how to identify particular system on particular system?

is NAT overlap really useful? if so how with one example?

Regards

skrao

3 Replies 3

pkhatri
Level 11
Level 11

Hi,

When you have an overlap NAT situation, both sites would be using a separate address block

to identify systems at the other site. This could be done statically but is a bit

unwieldy. More often, what would happen is that when site A wishes to communicate with a

host in site B (which has an address from the same network), the incoming DNS response is

translated by site A's NAT device so that the Site B address is now from a different

range. When the site A host now sends a packet to this address, it's own source address

will be translated to a different address block. That way, unambiguous connectivity will

result.

There's a good diagram describing this here:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios124/124cg/hiad_c/ch20/ntbaddrs

.htm#wp1070492

Pls do remember to rate posts.

Paresh

hi paresh,

thanks for your response, but the link you have given is not working.

is there any facility to configure NAT like this.

two networks having 192.168.1.0/24 address.

I want to translate like this.

192.168.1.0/24 to 192.168.2.0/24

that means 192.168.1.1 becomes 192.168.2.1

and 192.168.1.2 becomes 192.168.2.2 and so on consecutively................

is there any such one-to-one NAT for ranges mapping facility?

Regards

skrao

Here's that link again:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios124/124cg/hiad_c/ch20/ntbaddrs.htm#wp1070492

To answer your second question: yes, there is such a facility and it's called static network translation. You would configure it as such:

ip nat inside source static network 192.168.1.0 192.168.2.0 /24

With the above config, 192.168.1.1 becomes 192.168.2.1, 192.168.1.2 becomes 192.168.2.2 and so on....

Pls do remember to rate posts.

Paresh

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