The Cisco Firewall Service Module (FWSM) is a module card installed on 6500 switches or 7600 routers and is based on the Cisco PIX/ASA security software. It integrates security services in the popular 6500/7600 network devices, providing one of the fastest firewall data rates in the industry. With 5 Gbps firewall throughput per module, and four modules per chassis, you can scale your firewall performance to a maximum 20 Gbps throughput in a single chassis. This is an excellent choice for service providers or for large data center environments, since you can integrate firewall security inside your network infrastructure without loosing performance.
As it is installed as a module inside the 6500/7600 platforms, it basically works on the backplane of the switch/router allowing any port of the network device to operate as a firewall port. VLANs of the switch can be assigned as “interface legs” of the FWSM, thus forcing traffic between VLANs to pass through the firewall which applies statefull inspection and control in the traffic flow. Having also an integrated firewall box inside your network infrastructure makes administration easier and lowers your total cost of ownership.