Why Gxc interface (PCRF-SGW) is needed when we have Gx interface(PCRF-PGW)?

Question

I am trying to handle all the error scenarios seen while testing the Gx with the third party. As of now I had coded for just the successful scenarios.

I am looking for some of inputs on these error scenarios and how to proceed and exit gracefully (rather than crashing the code)

• Dynamic rule config with wrong parameters., PGW sends CCR with the CCR type=TERMINATION_REQUEST. How can PCRF respond (just log error and comeout ?)

• Static rule config with the "wrong rule name". When the PCRF sends CCA-I with the wrong rule name, PGW sends CCR-U with the Charging Rule Report with the "Rule-Failure-Code" as "Unknown Rule Name". In this case remove those rules and continue OR just comeout with just logging error)

Answer 1

I'm not quite sure but I'll tell you about my experience. A lot of operator uses SAE-GW instead S-GW and P-GW separated. This architecture can avoid to use Gxc interface using only Gx. However, if you have to use S-GW separated for geographical purposes or if you use P-GW separated by applications, you use Gxc for QoS treatment. The Gxc interface is only applicable in the S5 PMIP variant and, in this case, S-GW acts as BBERF.

I extracted this paragraph from https://sites.google.com/site/amitsciscozone/home/lte-notes/pcc-architecture

The PCC rule needs to be mapped to a particular IP-CAN bearer to ensure the packets receive the appropriate QoS treatment. The association between PCC rule and a bearer is referred to as bearer binding. The bearer binding is done by the Bearer Binding Function (BBF). The BBF is located either in the PCEF (if GTP is used as the protocol on S5/S8 interface aka. on-path model) or the BBERF (if Mobile IP is used as the protocol on S5/S8 interface aka. off-path model).
When the PCRF sends new or modified PCC rules to the PCEF or BBERF (depending upon the location of BBF), the BBF evaluates whether it is possible to use one of the existing IP-CAN bearers and initiate IP-CAN Bearer Modification procedure or initiate a new IP-CAN Bearer Establishment procedure. The binding is created between the Service Data Flow(s) and the IP-CAN bearer which has the same QoS Class Identifier (QCI - applies to user plane) and Allocation and Retention Priority (ARP - applies to control plane).

Comments

It was my answer :)

---

Thanks for answering and helping people :)