Question about Gx over Gy interface in Diameter

Question

3GPP 29.210 section 6 talks about Gx over Gy application. My question is about the use case, i.e. in what practical scenario one will require to have Gx over Gy support.

Answer 1

Both are interfaces have for different purposes. Gx interface is used between PGW/PCEF and PCRF for PCC(Policy and charging rules). PCRF generates PCC rules and send the generated PCC rules towards PGW/PCEF to enforce the PCC rules at PGW for an User. Gy interface is between PGW/PCEF to OCS(online charging system). Gy interface is used to transfer data uses report from PGW/PCEF to OCS. So both the interfaces used to achieve different objectives.

Comments

Thanks Vimal.
29.210 talks about the Gx over Gy application but could not understand the use case. Interface Gx and Gy these two are different and used for different purpose but I am not clear about this section (Section 6.2) what is it talking about.

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Salil, 29.210 is explicitly obsoleted, but for all practical purposes, I think it is dead. Even the application Id is different (16777224, new id is xx238).

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Thanks Ratna.

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This is obviously rather for 3GPP standardization body. However, background was in the very beginning of Gx/Gy specification (Release 6) to allow a simple solution, i.e. by letting the OCS to control some PCC stuff, i.e. including QoS bearer modification (e.g. Fair Usage Policy use case). No extra Gx/PCRF etc. were needed in this case. This option as standards solution was immediately ceased in further 3GPP releases as PCC got more complex (Gx, PCRF functions, LTE concepts, etc.).

Answer 2

As I understand there is no special use cases.
When credit authorization(Gy) and charging rule provision(Gx) are required simultaneously, then it will use Gx over Gy application such that it will avoid signalling load on Network. If we do not use this mechanism then we have to send Gx and Gy message separately.

Comments

Yes when we use the same endpoint for both PCRF and OCS functinality in same box, in this case we can use the Gx over Gy it will reduce signalling load over network.