IP NAT outside

From: <Keegan.Holley_at_sungard.com>
Date: Sun, 26 Jul 2009 13:55:54 -0400

Can someone answer a quick question about outside NAT please? Cisco's
config guide was once again inadequate. See below:

Cloud1 --- Cloud2

Say you have two clouds both representing companies that have recently
merged. They both use the exact same address space, /24 subnets of
10.1/16. There is routers connecting the two companies together using
/30's in an unused block. The following is configured on the edge router
for cloud1.

hostname cloud1router
Gigabitethernet0/0
description to cloud2
ip address 172.1.2.2 255.255.255.252
ip nat outside

int gigabitethernet0/1
description toCore
ip address 10.1.254.1 255.255.255.252
ip nat inside

ip nat pool merge 11.1.0.1 11.1.255.254
access-list 12 permit 10.1.0.0 0.0.255.255

ip nat outside source list 12 pool merge

So my question is (I think) traffic from cloud1's 10.1/16 will be nat'd to
11.1/16 when sent to cloud2. However, will this cover traffic in the
other direction or would you have to do the same thing on the cloud2
router? Can you just do "ip nat destination ..." on the cloud1 router to
nat in the other direction or does that do something different entirely?

Thanks all,

Keegan

Blogs and organic groups at http://www.ccie.net
Received on Sun Jul 26 2009 - 13:55:54 ART

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