E-UTRAN PDN Modification with S-GW Change
The following figure shows the call flow for PDN modification with S-GW change.
| Step | Description | ||
|---|---|---|---|
| 1 |
As part of the call creation at the new S-GW, the MME sends the Create Session Request to the new S-GW. |
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| 2 |
The new S-GW responds with the Create Session Response to MME. |
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3 |
MME sends Modify Bearer Request to new S-GW. |
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4 |
The new S-GW forwards Modify Bearer Request to SMF. |
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5 |
SMF sends Session Modification Request with Query URR to UPF based on event triggers.
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6 |
UPF responds with the N4: PCRF Session Modification Response with Gy and RADIUS URR to SMF based on the Gy and RADIUS configuration, which can be enabled or disabled. |
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7 |
SMF responds with Modify Bearer Response to new S-GW. |
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8 |
New S-GW forwards Modify Bearer Response to MME. |
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9 |
As part of Call deletion at the old S-GW, MME sends Delete Session Request to the new S-GW. |
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10 |
SMF sends CCR-U to OCS and Accounting Request (Interim) to AAA. |
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11 |
Old S-GW sends Delete Session Response to MME. |
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12 |
OCS and AAA respond to SMF with CCA-U and interim Accounting Response respectively. |
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13 |
SMF sends PCRF Session Modification Request with update URR to UPF. |
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14 |
UPF responds to SMF with PCRF Session Modification Response. |
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15 |
SMF sends CCR-U towards PCRF if event trigger is armed.
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16 |
PCRF responds to SMF with CCA-U. |
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17 |
SMF sends PCRF Session Modification Request with Update QER to UPF. |
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18 |
SMF sends PCRF Session Modification Response to UPF. |