MME-initiated Deletion Call Flow
This section explains the processing of MME-initiated dedicated bearer deletion call flow when the procedure SLA timer expires. Upon the expiry of procedure SLA timer for Delete Bearer Command (DBC), the SMF sends Delete Bearer Failure Indication.
Note | The SMF uses procedure SLA configuration for S5 or S2b interface based on the RAT type. |
The following figure depicts the dedicated bearer deletion call flow initiated by MME upon receipt of Delete Bearer Command.

The following table describes the processing performed at each stage when the SLA timer expires:
Timeline or Slice availability |
Request or Event |
Stage - Failure |
Timeout due to Transaction SLA |
---|---|---|---|
Procedure SLA as configured |
Delete Bearer Command |
Idle |
Send Delete Bearer Failure Indication |
Procedure SLA as configured |
PCF update request |
Send Delete Bearer Failure Indication |
|
Procedure SLA as configured |
First N4 Modification Request |
Async DBR Sync N4 to remove tunnels for the deleted rules. Perform sync procedure to avoid loss of usage reports which the UPF sends N4 modification response for the deleted flows. |
|
Procedure SLA as configured |
Delete Bearer Request |
Sync N4 to remove tunnels for the deleted rules. Perform sync procedure to avoid loss of usage reports which the UPF sends N4 modification response for the deleted flows. |
|
Procedure SLA as configured |
Second N4 Modify Request |
Treat as procedure success. Then, update PDU context. |
|
Procedure SLA as configured |
Charging Update Request |
Treat as procedure success. Then, update PDU context. |