Provisioning and Management of Additional QoS Flows
The PCF can create, modify, or delete multiple GBR and non-GBR PCC rules.
The following scenarios are possible:
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Multiple non-GBR and GBR PCC rules are activated during PDU session establishment. In this case:
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The SMF creates the QoS flow according to the QoS flow binding principle as described in the QoS Management section.
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On the N4 interface, the UL and DL PDRs are created for each PCC rule that is associated with all the flows. For flow-level QoS enforcement, the SMF creates QERs with the MFBR and GFBR (for GBR flows) values and associates it with each PDR of a flow.
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On the N1 interface, the "QoS Flow Description" attribute in the PDU SESSION ESTABLISHMENT ACCEPT message contains the QFI and MFBR, GFBR, and 5Qi values. The packet filters associated with each QoS rule are sent on the N1 interface in the "Authorized QoS Rules" attribute.
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Different types of packet filters are supported on both the N4 and the N1 interfaces. This list includes:
Packet filter component type identifier Bits 8 7 6 5 4 3 2 1 0 0 0 0 0 0 0 1 Match-all type 0 0 0 1 0 0 0 0 IPv4 remote address type 0 0 0 1 0 0 0 1 IPv4 local address type 0 0 1 0 0 0 0 1 IPv6 remote address/prefix length type 0 0 1 0 0 0 1 1 IPv6 local address/prefix length type 0 0 1 1 0 0 0 0 Protocol identifier/Next header type 0 1 0 0 0 0 0 0 Single local port type 0 1 0 0 0 0 0 1 Local port range type 0 1 0 1 0 0 0 0 Single remote port type 0 1 0 1 0 0 0 1 Remote port range type
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On the N2 interface, the PDU Session Resource Setup Transfer Request IE contains the "QoS flow level QoS parameters" (5Qi, ARP, and so on) and QFIs for each of the flows. The "GBR QoS Flow Information" field of the IE contains the MFBR and GFBR of the GBR flows.
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Modification of PCC rules after PDU session establishment. In this case, the following scenarios are observed:
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Modification, addition, and removal of packet filters of one or more PCC rules:
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In this case, the SDF filters of the PDR on the N4 interface are changed by invoking N4 session modification.
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The SMF initiates N1N2MessageTransfer towards the AMF with "Authorized QoS Rules" attribute in PDU SESSION MODIFICATION COMMAND message in N1 interface. The rule operation code in this attribute is one of the following:
0 1 1 Modify existing QoS rule and add packet filters 1 0 0 Modify existing QoS rule and replace all packet filters 1 0 1 Modify existing QoS rule and delete packet filter
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Change in QoS associated with one or more PCC rules:
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The SMF performs QoS flow binding evaluation which in turn results in the following operations:
1. Addition of a new QoS flow results in change of QFI on the N4 interface for some of the PDRs.
2. Movement of a PCC rule from one QoS flow to another QoS flow. In this case, the PDR/QER of impacted PCC rules are modified to update the QFI.
3. Removal of a QoS flow when the last PCC rule in that flow is moved to a different QoS flow. In this case, the PDR/QER of impacted PCC rules are modified to update the QFI.
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In the preceding cases, on the N1 interface the Authorized QoS Rules and Authorized QoS Descriptors are sent with the operation code as one of the following:
0 0 1 Create new QoS flow description 0 1 0 Delete existing QoS flow description 0 1 1 Modify existing QoS flow description
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On the N2 interface, QoS Flow Level QoS parameters of the PDU Session Resource Modify Request transfer IE carry the modified GFBR, MFBR, 5Qi and so on. For any flow removal, the QoS Flow to re-lease List is included in this IE.
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PCC rule removal:
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In this case, the SMF removes all the PDRs associated with a QoS flow on the N4 interface.
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On the N1 interface, the Authorized QoS Rules and Authorized QoS Descriptors are sent with the operation code as one of the following:
0 1 0 Delete existing QoS flow description
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On the N2 interface, the PDU Session Resource Modify Request transfer IE carries the QoS Flow to release List.
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