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Two FWSMs on the same 7609 chasis sharing the same dmz vlan

I have DHCP/DNS servers in vlan X in a 7609 and I have two FWSMs in that same chasis. Is it possible that both FWSMs could share that vlan X for a DMZ in each FWSM in order to share those DHCP/DNS servers for the clients in both FWSMs??

Cisco Employee

Re: Two FWSMs on the same 7609 chasis sharing the same dmz vlan

Yes that's fine, the only issue you'll run into is that you can't configure the same VLAN in two separate vlan-groups on the MSFC side of things.

For example (assuming vlan20 is your DMZ):

SV4-10(config)#firewall vlan-group 2 20,30,35

SV4-10(config)#firewall vlan-group 3 20,40,45

Vlan 20 is already tied to group 2

So you need to create a separate vlan-group just for vlan20, then assign each firewall module to that vlan-group separately as follows:

firewall vlan-group 2 30,35

firewall vlan-group 3 40,45

firewall vlan-group 100 20

firewall module 7 vlan-group 2,100

firewall module 8 vlan-group 3,100

Other than that it should be fine to share the vlan amongst the modules. Just make sure that you PAT or NAT traffic going to vlan 20 from each module to a different IP address, that way the return traffic will know which of the two FWSM's to go back to.

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