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2 IPs on 1 Interface with NAT inside/outside


here is a prblem I am not sure how to solve.

For some reason, I need to setup a router with NAT. Addresses from our LAN ( /24) would be NATed to a private IP assigned to us by a service provider ( Where things get interesting is that the router from our service provider (IP has to be connected to our LAN as well (because is does some bridging stuff in addition to the IP stuff).

So we are looking at running two IP subnets on the same Vlan.

What I am trying to do is use only 1 ethernet interface on our router to accept packets on, translate them to and send them down the same ethernet interface.

I am not sure how to get there. I was considering using subinterfaces, but it doesn't look like I can do that unless the ethernet iterface becomes a dot1q trunk. Am I understanding that correctly?

Is there a better way to approach this?

Thank you,



Re: 2 IPs on 1 Interface with NAT inside/outside


There's a workaround to this situation. You can create a loopback and make it the nat inside interface and make your physical interface as nat outside int. Configure PBR and apply it on the ethernet interface to make the traffic coming in that has to be NATted to be switched to the loopback. That should do the trick.

Let us know if you have any problems setting it up.



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Re: 2 IPs on 1 Interface with NAT inside/outside

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