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Device: Cisco SR520W-FE

I have added a guest wireless network to this router but I can't seem to get nat overload to work with the new space.

LAN: (VLAN 75) Guest WLAN: (VLAN 50)

Here is the commands I'm using for the NAT overload

interface FastEthernet0
 switchport access vlan 75

interface FastEthernet3
 switchport access vlan 50

 interface FastEthernet4
 ip address x.x.x.x
 ip nat outside
 ip virtual-reassembly

interface Vlan50
 ip address
 ip access-group 120 out
 ip nat inside

interface BVI75
 ip address
 ip nat inside
 ip virtual-reassembly

ip nat inside source list 10 interface FastEthernet3 overload
ip nat inside source route-map SDM_RMAP_1 interface FastEthernet4 overload

route-map SDM_RMAP_1 permit 1
 match ip address 101

access-list 10 remark PAT IP space for the guest WLAN
access-list 10 permit

access-list 101 deny   ip
access-list 101 permit ip any

access-list 120 remark ACL to block guest wireless from LAN
access-list 120 deny   ip
access-list 120 permit ip any
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It's been ages since I've done this, so my apologies if I missed something obvious, but... aren't you missing something like

ip nat pool "address of your external interface" ?

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The LAN nat overload is currently working so I don't think that command is needed. I'm not sure if the "ip nat outside" command is what is making it work or not. – evolvd Mar 14 '12 at 14:47
up vote 0 down vote accepted

The problem was that I was "NATing" the physical interface and not the SVI. Once I did that everything worked.

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