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NAT with Route-Maps and secondary IP Addresses

Hi all,

I am a newbie with VLANs, so this question may be a little basic!

I am about to implement NAT with Route-Maps to allow traffic with some ports to be translated to source address x1, and traffic with other ports to be translated to source address x2 on the public side of the router.

On the private side (NAT inside) I also have multiple subnets with only one physical port, so I was looking at configuring subinterfaces on the private side. However between the router and the various hosts we have an unmanaged switch that does not support VLANs. Therefore I am assuming that if the router were to VLAN tag (e.g 802.1Q) the frame, the switch would not remove the tag and it would arrive at the host which wouldn't recognise the frame.

Hence I am looking at secondary addressing on the router to get around this. My question: having a secondary address on the router (which will not require NAT) will still allow the same source address to be translated to different public source address dependent on the port number, if my Route-Map configuration is correct - there won't be any failure on the secondary address to not NAT if it isn't configured in the Route-Map?

I think logically there will be no problem, but I just want to check in case someone is aware of an issue.

TIA,

Matthew.

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1 REPLY
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Re: NAT with Route-Maps and secondary IP Addresses

I believe your logic is right. The NATting should work, secondary or no secondary address. The important thing is that NATting changes the address on a packet as it transverse the router.

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