PCRF uses which command on Gx to install rules?

Q. PCRF uses which command on Gx to install rules?

a) UDR
b) STR
c) RAR
d) Charging Rule Install (CCR U)


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:arrow_right: Correct answer: Letter d.

On the Gx interface, the PCRF communicates with the PCEF (e.g., PGW) using Diameter messages. To install or modify policy and charging rules, it uses the Credit-Control Request Update (CCR-U) command.

This message enables the PCRF to send dynamic policy rules, such as QoS parameters, gating controls, or charging rules, to be enforced by the PCEF.

CCR-U is part of the Diameter Credit-Control Application (DCCA) and is essential for real-time policy control and charging in IMS and LTE networks.

Q. PCRF uses which command on Gx to install rules?

a) :x: UDR
→ Incorrect. UDR (User Data Request) is used on the Sd or Ud interface (from PCRF to UDRF or HSS), not on Gx.

b) :x: STR
→ Incorrect. Session Termination Request (STR) is used on the Cx or Rx interface for IMS sessions, not for rule installation.

c) :x: RAR
→ Incorrect. Re-Auth Request (RAR) is used on Rx (between PCRF and AF) or Gy, not for rule installs on Gx.

d) :white_check_mark: Charging Rule Install (CCR U)
→ Correct. CCR-U is the update request from PCRF to install, modify, or remove PCC rules via the Gx interface. CCR Update delivers PCC rules with TFT and QoS.