NAT question

[royalblues]

Hi all

I have a strange NAT situation

My router fastethernet IP is 172.16.24.1/22

I want to PAT 172.16.25.0, 26.0 & 27.0 to 172.16.24.2

Can this be done as the netmask length overlaps

Narayan

[spremkumar]

Hi

Is that ip configured on any of the interfaces of your router ?

regds

[royalblues]

it is not configured on any of the interfaces but since i would be doing this on a production router just wanted to make sure

Narayan

[mark.edwards]

yes it can be done.

ip nat pool TEST 172.16.24.2 172.16.24.2 netmask 255.255.255.0

ip nat inside source list 10 pool TEST overload

access-list 10 permit 172.16.25.0 0.0.0.255

access-list 10 permit 172.16.26.0 0.0.0.255

access-list 10 permit 172.16.27.0 0.0.0.255

[royalblues]

Mark

thanks for the reply, but i know the configurations

what i wanted to know was since the netmask would be a /22 subnet and the pool falls within this range, whether the router accepts it.

Narayan

[mark.edwards · Accepted solution]

Apologies. I've tested the config with 22 & /24 and there is no issue, the router will accept either. This is with an up/up interface configured with a /22 as in your case.

(see below extract from CCO).

netmask - Network mask that indicates which address bits belong to the network and subnetwork fields and which bits belong to the host field. Specify the netmask of the network to which the pool addresses belong.

[royalblues]

Thanks Mark.

Let me configure the same on my router.

Will revert back once done

[royalblues]

I used the /24 netmask and it worked

Thanks everyone

Narayan