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We are moving office and our managed service provider has let us down badly. We have a Cisco 4500 stack with 5 VLANS configured of interest. These are:

interface Vlan200 description FLOOR0 Gateway ip address 172.17.0.1 255.255.252.0 ! interface Vlan201 description FLOOR1 Gateway ip address 172.17.4.1 255.255.252.0 ! interface Vlan202 description FLOOR2 Gateway ip address 172.17.8.1 255.255.252.0 ! interface Vlan203 description FLOOR3 Gateway ip address 172.17.12.1 255.255.252.0 ! interface Vlan204 description FLOOR4 Gateway ip address 172.17.16.1 255.255.252.0 

Our old network was 10.0.0.0/8 (inherited it). An example server would be 10.0.0.81. Our entire environment (several thousand devices) cannot be reconfigured to point at our new 172.17.4.81 address as the package deployment for SCCM has just collapsed.

The 10.0.0.0/8 range is not on the 4500's (as it was handled over our MPLS so the MPLS default gateway on the 4500's sent traffic to it anyway).

Is it possible to use static NAT or similar for requests to 10.0.0.81 to point to 172.17.4.81? I became nervy when all examples show applying inside/outside rules to interfaces (I don't have one for 10.0.0.81/8 but could always create a stub VLAN). Also didn't know the consequences of applying it to the VLAN interfaces above (in case I lost access to our production network).

Guessing that adding inside/outside NAT would be harmless but would like to know how you Cisco geniuses would tackle this.

UPDATE:

We've fixed SCCM but for future reference it would still be great to know the best way to handle this.

1 Answer 1

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Translate a whole network range is possible by using static NAT (aka Net Static). Anyway the problem here is that old network is a /8, while the new can be 172.16.0.0/12 at most (you forgot to specify this).

So, unless you want to specify the translation of each IP needed, a good idea could be to select a subnet of 10.0.0.0/8 with the same size of your new network.

Because you're talking about 172.17.4.81, and because the config shows 172.17.4.0/22, these commands can be used to translate 10.0.0.0/22 to 172.17.4.0/22:

int vlan201 ip nat inside int vlanX # Every other VLAN ip nat outside ip nat inside source static network 172.17.4.0 10.0.0.0 255.255.252.0 

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