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.