I'm about to puchase two 515E units to build our firewall infrastructure - and include a DMZ for our web server, dns, etc. I was wondering if anyone knew of a link, book, or white paper that could fill in some of the questions I have? I understand how the structure works but I'm little cloudy on how the one PIX concentrator deals with the other internal PIX concetrator. Also, we have a cisco 3005 vpn concentrator and I'm not sure how that is going to fit into the puzzle? Any help would be appreciated