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Design question for VLAN and firewall

I am planning on vlanning several semi-trusted networks. I want the Vlans to pass through a firewall before being routed to their appropriate destinations (either another VLAN or the internet).

The problem is I am using a Sidewinder G2 firewall with limited ports. They support sub-interfaces (burbs) so I want to use sub interfaces to send all my traffic out one physical ethernet port.

The problem is, how do I keep the router with the subinterface from routing directly from one VLAN to another withhout first passing the traffic out to the firewall while allowing the traffic BACK from the firewall to be routed.

Remember the traffic goes and comes on the same sub interface.

This is kind of difficult to explain, it amounts to a firewall on a stick (or a one armed firewall) if you will.

I can provide a visio diagram to make this clearer if you think you can help.


Dan Sichel

Ponderosa Telephone


Re: Design question for VLAN and firewall

Yeah please email me the visio. Click my profile for my email.

New Member

Re: Design question for VLAN and firewall

Thanks for your response. I have just now emailed you the picture that represents our dilemna. I guess basically I want a firewall on the end of a router on a stick. Anyhow, hopefully the picture with its notes makes it clear.


Dan Sichel

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