PCRF-Initiated RAR / CCAU
The following figure shows the call flow for E-UTRAN Network Credit Control Answer Update (CCAU) or Re-Authorization Request (RAR) initiated Update Bearer Request (UBR).

Step | Description | ||
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1 |
PCRF sends RAR to SMF or CCAU to SMF with modified Default Bearer Qos and/or APN AMBR change. |
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2 |
SMF sends Update Bearer Request to S-GW with updated Default Bearer Qos and/or updated APN AMBR. |
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3 |
SGW sends the Update Bearer Request to MME. |
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4 |
MME sends the Update Bearer Response to S-GW. |
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5 |
SGW sends the Update Bearer Response to SMF. |
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6 |
SMF sends N4 PFCP Session Modification Request to the UPF to update the Bearer level information (if default bearer Qos is changed) and/or APN AMBR QER (if APN AMBR is changed). |
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7 |
UPF sends N4 PFCP Session Modification response to SMF. |