Our client has an existing network where all the server farms are behind the firewall. Everything are working fine. Now the client decided to put IDSM-2 the problem is the documentation from Cisco site is not that much helpful. I am confused on what VLAN pair to configure, the VLAN between FWSM and MSFC is VLAN5 and the IP subnet is 172.16.0.0/29. Please see diagram.