PCRF Rx AAR message related Query

Question

Hello,

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.

thanks
pdk

Answer 1

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.

Regards,
Peeyush

Comments

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.

thanks
pdk

Answer 2

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,
BHANU PRAKASH.

Comments

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.