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Webcast-Catalyst9k
New Member

Configure NAT and a routable IP on same interface?

I tried to ask this yesterday and I think I fumbled the question ... let's try again:

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.

5 REPLIES
New Member

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

Hi Dave,

Do you want some machines on your ethernet to be

natted to the serial ip and some to use a assigned address?

Jacques

New Member

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

Hi Jacques,

Yes, that is exactly what I'd like. Is this possible?

Thanks!

-Dave H.

New Member

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

Dave, yes, if understand your scenario, it is possible in fairly recent versions of IOS.

Check this out:

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

good luck,

Mason

New Member

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

Mason, thank you very much -- that looks like the configuration we need. Hopefully, our IOS version 12.0 will provide the required support.

-Dave H.

New Member

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

Hi Dave,

Good Day! :-)

As far as I know the 'ip nat' command was introduced in 11.2 you may refer to the link below.

http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/12cgcr/np1_r/1rprt2/1ripadr.htm#1019011

Another thing you may use this tool to see if the software support a particular feature.

http://www.cisco.com/cgi-bin/Support/CompNav/Index.pl?&SoftwareType=True

I hope these helps.

Have a wonderful weekend! ;-)

Best Regards,

Ansley R. Verzosa

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