Hi , I will split the answer into two parts
1. If we see TFT-Packet-Filter-Information AVP
TFT-Packet-Filter-Information ::= < AVP Header: 1013 >
[ Precedence ]
[ TFT-Filter ]
[ ToS-Traffic-Class ]
[ Security-Parameter-Index ]
[ Flow-Label ]
[ Flow-Direction ]
*[ AVP ] Major AVP is TFT-Filter and Precedence. As we know TFT-Filter AVP it contains the flow filter for one TFT packet filter. Which basically contains Source IP Address, Destination IP Address,Source and Destination Port,Protocol Type,Direction, Action.
The Precedence AVP is used within the TFT-Packet-Filter-Information AVP to indicate the evaluation precedence of the Traffic Mapping Information filters as received from the UE.
2. Within the Charging Rule Definition AVP, the Precedence AVP determines the order, in which service data flow templates consisting of service data flow filters are applied at service data flow detection at the PCEF. For PCC rules with an application detection filter, the Precedence AVP only determines which PCC rule is applicable for the detected application for the enforcement of QoS, for charging control, for reporting of application start and stop and for usage monitoring. A PCC rule with the Precedence AVP with lower value shall be applied before a PCC rule with the Precedence AVP with higher value.
So in CCA message from PCRF we will get the Charging-Rule-Install AVP which contains Charging-Rule-Definition AVP and it has Precedence AVP which will determine the service data flow(SDF) filter that needs to be applied at service data flow detection or TFT-Filter precedence evaluation.
For more details please refer: http://www.etsi.org/deliver/etsi_ts/129200_129299/129212/12.09.00_60/ts_129212v120900p.pdf Please refer the Charging-Rule-Definition AVP,TFT-Packet-Filter-Information AVP, Precedence AVP
