Nat + Routed IP

jdinsdale · ‎12-18-2007

Hi Guys

My Client has a Cisco 1721 with an addional 10meg WIC.

They have been assigned a range of 5 public IPS from their ISP.

What Id like to do is use the built in fast ethernet interface to provide access to the LAN using NAT, thats no problem. Id also like to be able to put machines on the ethernet interface with the using public IP addresses.

So what i need to know is how would I configure the router to perform in a NAT/NoNat configuration?

Is it possible to do this without using 1to1 NATs?

Collin Clark · ‎12-18-2007

Depends. On the interface connecting to the ISP is there a /30 address or are the IP's part of the /29 pool?

ekhoo · ‎12-18-2007

Hi jdinsdale,

Since you have 5 public ip addresses, you can either use static NAT (1 to 1) or overload NAT ( 1 to many) which also call PAT - port address translation on your router config.

it is depend on what you try to achieve. You can use static NAT and overload NAT at the same time.

NAT Overview URL with sample config

http://www.cisco.com/en/US/tech/tk648/tk361/technologies_white_paper09186a0080091cb9.shtml