PDR (Packet Detection Rules) are a set of rules that enable the PGW to identify each packet belongs to which application or service. The PDR may be configured on the PGW, or it may be sent from the PCRF to the PGW as part of the PCC rules.

The PGW use PDRs to identify each packet belongs to which application or service based on the source/destination IP address, the transport protocol (UDP/TCP), and the application protocol.