Cisco Identity Services Engine (ISE) uses various probes to collect attributes of connected endpoints, such as device type, operating system, IP address, MAC address, and so on. These attributes are used to profile the endpoints and assign them to appropriate identity groups and policies. Two of the probes that can be configured to gather attributes of connected endpoints using Cisco ISE are RADIUS and DHCP.

RADIUS probe: The RADIUS probe collects attributes from the RADIUS packets that are exchanged between the network access devices (NADs) and the ISE Policy Service Nodes (PSNs) during the authentication and authorization process. The RADIUS probe can extract attributes such as username, calling-station-ID, NAS-IP-address, NAS-port-type, service-type, and so on. The RADIUS probe can also collect attributes from the RADIUS accounting packets that are sent by the NADs to the ISE PSNs after the session is established. The RADIUS probe can extract attributes such as session-ID, framed-IP-address, acct-session-time, and so on. The RADIUS probe is enabled by default and does not require any additional configuration on the NADs or the ISE PSNs.

DHCP probe: The DHCP probe collects attributes from the DHCP packets that are exchanged between the endpoints and the DHCP server during the IP address assignment process. The DHCP probe can extract attributes such as hostname, vendor-class-identifier, client-identifier, parameter-request-list, and so on. The DHCP probe can also collect attributes from the DHCP relay packets that are forwarded by the NADs to the ISE PSNs. The DHCP probe can extract attributes such as relay-agent-information and subscriber-ID. The DHCP probe requires some configuration on the NADs and the ISE PSNs. The NADs must be configured to relay or copy the DHCP packets to the ISE PSNs, and the ISE PSNs must be configured to receive the DHCP packets on a specific interface.

https://www.cisco.com/c/en/us/td/docs/security/ise/2-4/admin_guide/b_ISE_admin_guide_24/m_assetvisibility_endpointprofiler.html

https://www.cisco.com/c/en/us/td/docs/security/ise/2-2/admin_guide/b_ise_admin_guide_22/b_ise_admin_guide_22_chapter_00.html