If a large enterprise was looking to protect its corporate network and if every single packet of data both inbound and outbound needed to be captured, logged, scanned for strange characteristics, and then traced, the network bandwidth hit would be unacceptable and the firewall would cause a bottleneck. While not an ideal solution, SPI can ease the pain while other techniques can be implemented to handle its deficiencies. A benefit of SPI is that it can be utilised as an additional technology to protect a Demilitarised Zone (DMZ) or a network that is required to allow public access to some machines/servers. It can allow specific individual IP addresses or segments on the LAN to have open ports, so the administrator can essentially select from a list -- ports to open/close for any given machine's IP address on the LAN.
The majority of these devices are more than just firewalls but we have kept our focus on firewall considerations for the time being -- see the feature tables for some of the additional extras. 
Mirip Wewe ?
