Intrusion Prevention Systems (IPS) on routers come in two flavors: integrated IPS features, and external network modules called NM-CIDS. As the NM-CIDS uses the same code base as IPS Sensor, all the troubleshooting techniques pertaining to Sensor discussed in Chapter 14, "Troubleshooting Cisco Intrusion Prevention System," are applied here with some minor exceptions (for example, the inline feature of IPS that is supported on IPS Sensor is not supported on NM-CIDS). Hence, this chapter does not repeat the troubleshooting information on IPS operations that are performed on NM-CIDS. Instead the chapter focuses on configuration and troubleshooting of the Cisco IOS Router and NM-CIDS configuration issues. The chapter concludes with Best Practices specifically for NM-CIDS.