CPA is a DSR Application that is responsible for routing Diameter accounting (Rf) messages that are being exchanged between clients (CTFs) and servers (CDFs).
CPA enables load balancing of ACR-Start and ACR-Event messages across CDFs. CPA also sets the preferred CDF value in the Charging SBR. The preferred CDF is used for the duration of the Rf accounting session. CPA updates the preferred CDF in the event of a CDF failover.
CPA is also responsible for triggering Message Copy. Message Copy allows ACR-Start or ACR-Event messages that match a configured rule to be copied to a Diameter Application Server (DAS). Message Copy can be disabled without impacting the other functions of CPA.