Cisco IOS IPS is a core component of the Cisco Self-Defending Network, which helps the network protect itself. This technology uses Cisco IPS Sensor Software and signatures. Because Cisco IOS IPS is inline, it can drop traffic, send an alarm, or reset a connection-facilitating immediate router response to security threats.
for deployment:
http://cisco.com/en/US/products/ps6634/products_white_paper0900aecd80327257.shtml
