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PCRF Rx AAR message related Query

+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.


posted May 30, 2015 by Pdk

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2 Answers

+2 votes
Best answer

When AAR message will come from AF to PCRF it will have Media-Component-Description. Under MCD, Media-Sub-Component-Description will be there and it will have info related to flows. You can extract the flow information from there and pass it on to PGW in Charging-Rule-Install.
If it is a voice bearer, as per my understanding there should be 2 Media-Sub-Component-Description. Hence there will be 2 Charging Rule Install. Both will have uplink and downlink filters which can be extracted and sent to PGW in 2 Charging Rules.


answer May 30, 2015 by Peeyush Sharma
Hi Peeyush,
Thanks a lot  , with your help now the basic Rx and Gx works fine. Both the attach and the Dedicated bearer setup test pass :) . But there are minor corrections needed.

The issue is in our current design, the SIP(IMS) stores the dedicated bearer Id for the SIP(IMS) instance. But I donot see this AVP in anywhere which I can use to indicate this info back to IMS from PGW or PCRF.

Any inputs on this is very much appreciated.

0 votes

Can you please let me know what is the difference between the TFT which Rx_AAR sends to PCRF and PCRF to PGW (which you answered above ) and the TFT info which Gateway sends to MME in Create Bearer Request and Update Bearer Request.?

with regards,

answer Dec 6, 2018 by Polisetty Bhanu
Its a very old thread, ask a fresh question?
Bhanu, basically PCRF picks up filters from AAR which it receives from AF. It just binds them to rules after applying the necessary policies which might have been defined in the PCRF like QoS. Here on Gx or Rx interface you can simply refer them as packet filters.
However, in CBR/UBR we have set of filters (called as TFT). Here we send the remote node IP only towards SGW/MME (as UE is already aware of its IP).

Hope that helps.
Similar Questions
+2 votes

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?

+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.

+2 votes

PGW sending a USU of 0 in CCR Updates after the first USU in first CCA Update was sent correctly. GSU from PCRF is 10Mb.

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