The cisco 5505 firewall is the smallest model in the new 5500 Cisco series of hardware appliances. Although this model is suitable for small businesses, branch offices or even home use, its firewall security capabilities are the same as the biggest models like 5510, 5520, 5540, etc.
The Adaptive Security technology of the ASA firewalls offers solid and reliable firewall protection, advanced application aware security, denial of service attack protection and much more. Moreover, the performance of the asa 5505 ips appliance supports 150Mbps firewall throughput and 4000 firewall connections per second, which is more than enough for small networks.
The difference of the cisco asa 5505 new model from the bigger ASA models is that it has an 8-port 10/100 switch which acts as Layer 2 only. That is, you cannot configure the physical ports as Layer 3 ports, rather you have to create interface VlANs and assign the Layer 2 interfaces in each VLAN.
By default, interface Ethernet0/0 is assigned to VLAN 2 and its the outside interface (the one which connects to the Internet), and the other 7 interfaces (Ethernet0/1 to 0/7) are assigned by default to VLAN 1 and are used for connecting to the internal network.