NAT Pool with 2 serials

Unanswered Question
Mar 13th, 2006
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One of the customers owned internet Link from our ISP and another Link from another provider and he need to configure tow NAT pools each of them matches the same customer LAN and but assigning different IPs (POOl1=ISP1 & POOL2=ISP2) and he laso need if one of the providers serial failed the customer using the active provider POOL

Any body did that before

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Overall Rating: 4.5 (2 ratings)
leonvd79 Mon, 03/13/2006 - 01:18
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Hello Mohamed,

To use two different pools you can translate inside local address with a route-map. This is done by eximing the destination address in the IP packet.

Also read the ASK-THE-EXPERT discussion on Network Address Translation (NAT).



* Please rate useful posts.

mounir.mohamed Mon, 03/13/2006 - 01:35
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Yes but what is the address i shall matches on while the customer targeting internet access through both links

Both Serials providing internet access with different ISP ranges IPs and what i need to make the router doesn't use the address range of ISP1 if ISP1 serial go down

pkhatri Mon, 03/13/2006 - 01:41
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Hi Mounir,

This is how you would do it:

ip nat pool ISP1Pool netmask

ip nat pool ISP2Pool netmask

ip nat inside source route-map ISP1-map pool ISP1Pool

ip nat inside source route-map ISP2-map pool ISP2Pool


route-map ISP11-map permit 10

match interface atm1/0.32


route-map ISP12-map permit 10

match interface atm2/0.32

Now, with the above config, when the ISP1 link is used, pool ISP1Pool is used and when the ISP2 link is used, pool ISP2Pool is used. This ensures that the router always uses the correct address.

Hope that helps - pls rate the post if it does.


mounir.mohamed Mon, 03/13/2006 - 01:53
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As usual u r very helful :)

Best Regards,

Mounir Mohamed


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