Why you need to upgrade to the latest IPS Software 7.0
We have needed this, wanted this, and have lived without it for long enough. Global Correlation (Cisco GC) builds a database of network devices that have a reputation for malicious activities. When a host which is monitored by your Intrusion Prevention System sees a known malicious device it will take action against it based on preconfigured rules.
You have to configure DNS after you upgrade to 7.0 which will allow the IPS global correlation to obtain reputation data. The reputation data contained in the Global Correlation updates is factored in to the analysis of network traffic, which increases IPS efficacy. The participating IPS devices send data back in to the Global Correlation database, which results in a feedback loop that keeps the updates current and global. Naturally one can configure the sensor to participate in the Global Correlation updates and or in sending telemetry data or you can turn both services off.