With the VPN 3000 concentrators, how can I differentiate the traffic of different users as it exits the device? I am working on a solution in which traffic from different customers, all of whom will be terminating at a VPN 3000 box, needs to be distinguishable to a non-Cisco firewall sitting off the back end of the concentrator. Can I assign addresses, ports, combinations, something else which will be unique for each customer?