How does PGW maintains QoS for various services ?

Question

PGW uses TFT's to differentiate the incoming data but if anyone explains more indepth it will be helpful.

Answer 1

From Bart:

It's pre-defined like.

Operator knows how he would like to treat Facebook, YouTube or whatever. Operator is making decision.

Then this whatever they want/need is implemented in a DPI. The DPIC works closely with PCEF which enforces needed QoS.

To the whole picture may contain the PCRF also. Then the logic is.
Detect the flow thanks to pre-configured filters, report it to PCRF, PCRF will contact PCEF with set of rules it would like to apply over specific traffic.