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Information on the PCRF, mainly the Sp, Rx and Gx interface.

+3 votes

Looking for the information related to PCRF.

Another specific question. When the PCRF decides on a QOS and sends across to P-GW. P-GW might not have got any info related to Dedicated bearer to be established earlier. So how does it map this newly sent QOS for the new dedicated bearer to the one it requested by P-CSCF.

I am trying to understand, how to map the QOS info sent by PCRF to the "dedicated bearer request by the P-CSCF. Can PCRF on sending the QOS, also create the new dedicated bearer id, which is sent back to P-CSCF ?

Any info regarding with is very helpful.

posted Nov 15, 2014 by Pdk

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1 Answer

+1 vote
Best answer


Bearer binding in EPC is done by PDN-GW. When AAR is sent by P-CSCF to PCRF, based on the Media-Component PCRF sends RAR message to PDN-GW(after evaluating policies for service or subscriber).

PDN-GW then does the bearer binding based on the QCI and ARP values. If there is an existing bearer which has the same QCI & ARP values then the rule is applied to the same bearer otherwise a new bearer is created.

In case of EPC LTE bearer id not sent by PCRF when the resource allocation is done by it, it is called network initiated resource allocation.

It is the duty of PDN-GW to do the traffic shaping and QoS management of the packet filters.

Hope that helps.

P.S. You can read about more about in 29.212 and 29.214 3gpp specs

Peeyush Sharma

answer Nov 16, 2014 by Peeyush Sharma
Sorry for the confusion. I meant per subscriber , what all information needs to be stored ?
Gimme some time i'll try to get back by tomorrow..

Meanwhile what i remember is like
Billing Cycle date could be there
Threshold Quota
Service based Quota
Services that are supported for the subscriber are few things that could be there
Thankyou for the quick replies ..take your pbm at all,
Hi   Nice explanation.  For volte call how pcrf linked to P Gw . Wht is the key element to map .
Similar Questions
+3 votes

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)

+1 vote

Looking at interoperability issues.
The CCRequest message sent from PGW to PCRF during attach. Does the CCA sent back from PCRF to PGW needs to have TFT info?

+4 votes


I have been able to write a standalone basic PCRF code in our software.

I had also written them using the Gx and RX interfaces (i.e using the diameter protocol). There was no time to test this feature.

Now I find flaws in my design regarding the Diameter while testing.

Initially the SIP (i.e ike IMS) was sending the request to PGW to create the voice bearer. Now my initial implemetation of Rx i thought the TFT was calculated in the SIP and sent across in the RX, but now when revisiting the code, i feel, that there was no such parameter to pass this info to the PCRF from SIP.

Now my doubt is, how this info related to TFT is being passed across to PCRF. Is it through the "Flows".
If so how to get the TFT in the PCRF to send back to PGW...I have missed this part of the design as i was looking more into the QOS..

Any help is greatly appreciated.


+1 vote

Hi all,

We have complexity linked to Gy and Gx interfaces.

Let's say that we have two rules configured as static on PGW with :

Rule1= Reports RatingGroup1
Rule2= Reports RatingGroup2

When PCRF install Rule 1 on Gx, the ratingGroup reported by PGW to OCS is RatingGroup1
When PCRF uninstal Rule1 then install Rule2, the ratingGroup reported by PGW remain RatingGroup1 till a Gy trigger is reached (revalidation time, GSU consumption...).
Then the problem on our system is that when PCRF change the rules on Gx interface the PGW keep reporting the old rating group on Gy interface ie: Gx change do not lead to a Gy change similtanously. I m wondering if there is a standard behaviour for such a use case?

Thanks a lot