D.2 Binding Mechanisms

29.2133GPPPolicy and charging control signalling flows and Quality of Service (QoS) parameter mappingRelease 17TS

Depending on the bearer control mode, bearer binding can be executed either by PCRF, PCEF or both PCRF and PCEF.

– For “UE-only” IP-CAN bearer establishment mode, the PCRF performs bearer binding.

– For “UE/NW” IP-CAN bearer establishment mode, the PCRF performs the binding of the PCC rules for user controlled services while the PCEF performs the binding of the PCC rules for the network controlled services.

If the PCEF performs the bearer binding, the PCRF shall follow the procedures as described in clause 5.4 with the exceptions described in this subclause.

If the Bearer Binding function is located at the PCEF, the PCEF shall check the QCI and ARP indicated by the PCC Rule(s) and bind the PCC rule with an IP-CAN bearer that has the same QCI and Evolved ARP (if this is supported by the SGSN).

If there is no suitable PDP-Context to accommodate a PCC rule when PCEF performs the bearer binding, the PCEF shall initiate the establishment of PDP-Contexts as specified in 3GPP TS 23.060 [3].

The PCEF shall not combine PCC rules with different ARP to the same bearer. If the Evolved ARP parameter is not supported by the SGSN, the PCEF shall map the Evolved ARP to Rel-99 ARP as specified in clause B.3.3.3 of 3GPP TS 29.212 [9].

NOTE: If Evolved ARP is not supported by the SGSN then this enables a modification of the PDP context ARP without impacting the bearer binding after relocation to a SGSN that supports Evolved ARP.

If the Bearer Binding function is located at the PCRF, the PCRF shall compare the TFT(s) of all IP-CAN bearer(s) within the IP-CAN session received via PCEF from the UE with the existing service data flow filter information. The PCRF shall indicate to the PCEF the IP-CAN bearer within the IP-CAN session where the PCC Rules shall be installed, modified or removed. This is done including the Bearer-Identifier AVP together with the associated PCC Rules within the corresponding RAR and/or CCA commands.

– When the PCRF does not require additional filter information coming from the UE in order to decide on bearer binding, the PCRF shall supply the PCC rules to be installed over the Gx interface to the PCEF within a RAR command.

– Otherwise, the PCRF shall wait for the PCEF requesting a policy decision for the establishment of a new IP-CAN bearer or the modification of an existing one within a CCR command over the Gx interface.

– When the PCEF reports the bearer event, it shall include within the CCR command a bearer reference together with the new or modified TFT information, the QCI and associated bitrates for new or modified PDP-Contexts.