1. Policy and Charging Application
  2. Policy DRA Overview
  3. Policy DRA Functions
  4. Diameter Request Message Processing

Diameter Request Message Processing

Diameter Request messages from Policy clients (PCEF, BBERF, AF, and DPI/MOS) arrive at Policy DRA routed by the DSR Diameter Routing Function based on a prioritized list of Application Routing Rules. The Application Routing Rules are configured for the Policy DRA functionality based on the information in the Diameter Request message: Application ID, Command-Code, Destination-Realm and Host, and Origin-Realm and Host.

After receiving a Diameter Request, the Policy DRA retrieves and examines the relevant AVPs contained in the message. The Policy DRA-relevant AVPs vary depending on the Diameter interface on which a Diameter message is carried.

By retrieving and examining the contents of the relevant AVPs, the Policy DRA determines:
  • The type of the Diameter Request: initiation, update, or termination
  • The type of interface over which the Request message is carried and whether the session over this interface is binding-capable or binding-dependent.

    A session over a binding-capable interface will be eligible to establish a binding to a PCRF, while a session over a binding-dependent interface will rely on an existing binding to a PCRF but cannot create a new binding by itself.

  • The subscriber’s IDs from the appropriate AVPs (Subscription-ID AVP, Framed-IP-Address AVP, and Framed-IPv6-Prefix AVP)
  • The Origin-Host and Realm AVPs, and Destination-Host and Realm AVPs.
  • The access point name (APN) from which the request was received.
  • Session-Id AVPs

The Policy DRA will use the information to query the SBR database for binding and session status of the subscriber whose IDs are included in the Diameter Request message.