ClearPass Policy Manager (CPPM) uses various methods to classify endpoints, and one of them is TCP fingerprinting, which involves analyzing TCP/IP packets to identify the type of device or operating system sending them. To utilize TCP fingerprinting capabilities, network traffic needs to be accessible to the CPPM. This can be done by mirroring traffic to CPPM's span port from a device that can see the traffic, like a core routing switch. This approach allows CPPM to observe the TCP characteristics of devices as they communicate over the network, enabling it to make more accurate decisions for device classification.