We recently downgraded our FWSM from 3.2.2 to 3.1.7 to resolve a HTTP firewall authentication issue. This fixed the Firewall authentication issue, but has introduced a new problem where the FWSM does not map virtual IP addresses into the ARP table dynamically. For instance, if I try a ping of a virtual IP from the FWSM, there is no response and no ARP entry . If I place a static entry in the ARP table for that IP and mac, the connection works. Any idea why the FWSM does not add the virtual IP addresses to the ARP table automatically?