Some time ago, I wrote an article giving an overview of how to configure VLANs on a Cisco Catalyst 3550. I did not go into detail on firewall configuration because this was not necessary for me at the time using a PIX 515e. However, things have changed on my network as they often do and we are now utilizing an Untangle firewall which does not currently support the use of VLANs. I have however found a workaround that functions perfectly in my environment without compromising security or efficiency.
One solution would be to revert back to a single subnet; however, we would lose the benefits of network segmentation that reduces collisions and optimizes our network performance. For the sake of this discussion, I am going to build upon the discussion in the previous article located here and only focus on the configuration of Untangle to meet the needs of the network designed in that article. It would be wise to review that article before continuing with this discussion.