Cisco provides for intrusion detection and prevention in a variety of ways in its current security portfolio. You might add this powerful tool to your network via a dedicated hardware appliance known as a sensor. Or you might add this functionality using a network module inserted into a router or switch. However you decide to implement the technology, the goal is the same—to take some action based on an attack introduced into your network. This action might be to alert the network administrator via an automated notification, or it might be to prevent the attack from dropping the packet at a device.