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Attention: The Cisco Support Community site will be in read only mode on Dec14, 2017 from 12:01am PST to 11:30am for standard maintenance. Sorry for the inconvenience.

New Member

Dual ISP w/static IP on 1812

I have a 1812 router configured with 2 different ISP connections. I was able to get a static IP range from both ISPs now and want to configure my router to use OER/SLA to do load-balancing using this example (

The problem is that I will have inbound traffic on both lines, so I will need to do static mappings for both.

Will the mappings work properly so that if traffic comes into a server on ISP 1, the reply will go back out the same like? Or will I need to set it up so that things are limited to one connection or the other?

Hall of Fame Super Gold

Re: Dual ISP w/static IP on 1812

Worry not, nat mapping will do so that replies will be sent back on the link that are received.

Hope this helps, please rate post if it does!

New Member

Re: Dual ISP w/static IP on 1812

That is what I thought, but it isn't working quite right. Currently, my DNS entries point the my DSL, which will be the secondary connection. If I enable the cable/primary connection, I do not receive incoming email. As soon as I shutdown the primary connection, email begins arriving again.

I am attaching the relevant part of my config (only stripped out the vpn parts) with the public IPs changed. Any suggestions or help would be greatly appreciated.

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