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network_user
Beginner

NAT with dynamic routing

Hello,

Is there a way I can track interface status and use this tracking to do NAT for LAN subnet?

I have three WAN interfaces and only one of them is going to be active at any given time. I would like to NAT my LAN traffic to whichever  WAN interface is up at that time of the day. How can I acomplish this on a cisco router?

Thank you.

1 ACCEPTED SOLUTION

Accepted Solutions
Edwin Summers
Participant

Replying to "tag" this because I'm curious as well.

According to the Order of Operations (this may be out of date), NAT occurs after routing so I'd think  you could configure all interfaces for NAT and the router would handle the rest.  The traffic would only undergo NAT after it was routed to the egress interface.

Your question got me curious to do some research, and I found a good post indicating use of route-maps for multiple-exit NATs by marwanshawi here.

-Ed

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3 REPLIES 3
Edwin Summers
Participant

Replying to "tag" this because I'm curious as well.

According to the Order of Operations (this may be out of date), NAT occurs after routing so I'd think  you could configure all interfaces for NAT and the router would handle the rest.  The traffic would only undergo NAT after it was routed to the egress interface.

Your question got me curious to do some research, and I found a good post indicating use of route-maps for multiple-exit NATs by marwanshawi here.

-Ed

Hello Ed,

Thanks for providing the link to multiple-exit NAT. Seesm like this is what I needed, I was under the impression that "match interface" looks at the traffic sourec interface. But it actually looks at the next hop which is exactly what I wanted. I will doi some more testing with this config and see if there is anything else I need relating to this.

Thanks!!

Edwin Summers
Participant

Let me know if it works out. Not sure if I'll be able to lab it this week b/c of family commitments, and very curious to see the final working config.

Best of luck!
-Ed

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