Cisco ASA 5505's had a bunch of ports on the back of them configured as a switch. This was great for small sites as you could plug everything into it without needed a separate switch.
Then the 5506 came along and this functionality was removed. All the ports were separate layer 3 ports. Suddenly people needing to add in extra switches.
The BVI functionality will allow all the 5506 ports to get back the functionality that they did in a 5505, by allowing a group of them to be put into a single layer 2 domain again.
