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Configure NAT and a routable IP on same interface?


We've just installed a 2600 router (IOS 12.0) and been assigned a single IP for the serial interface and an IP block /29 for the ethernet interface. As configured, this works fine and gives us 6 routable addresses. Of course, for firewalling and expanded address space, we need to configure NAT.

The question is: using only the 2600 router (with one serial and 1 ethernet interface) can we configure NAT and also retain the 6 routable addresses? Or, do we have to abandon the assigned IP block, just use the address assigned to our serial interface, and only configure NAT on the ethernet interface?

Thanks in advance!

-Dave H.

Community Member

Re: Configure NAT and a routable IP on same interface?

Hey Dave, I answered this question you posted in the WAN forum as well.....the answer is yes this is quite possible.

In your /29 you designate one IP for your router (usually the lowest IP in the block) and use the remaining addresses for your NAT pool. Use static NAT assignments if you need the outside world to have access to your web servers, mx servers etc.

check this out:

good luck.

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