The is no statefull failover for the Cisco IPS Sensors. You can set the sensors to fail open, but only the 4260 has a hardware failopen capability. This means that the other sensors have to fail in such a way that they KNOW that they've failed in order to pass traffic around the sensor. In my experience this is not a reasonable assumption to make and you would be better serviced making other failopen arraingements with an eaternal switch.
