Feature Description
The Message Interactions feature provides the capability to receive and process the messages from different peers (UPF, MME, and PGW), and performs the priority resolution.
The following are the examples of message interaction scenarios and priorities:
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The Modify Bearer Request (MBR) and Update Bearer Request (UBR) received for the same PDN1 waits for the Sx Modify Response from UPF. The UBR is processed after the MBR is completed. In this scenario, the UBR process is suspended until the MBR is processed.
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The UBR1 received for the PDN1 while processing a Release Access Bearer (RAB) for the same PDN1. The UBR is processed after the RAB is completed. In this scenario, the UBR1 process is suspended when the RAB procedure is in progress.
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The existing PDN procedure is stopped when the disconnect procedure (Delete Session Request (DSR), Delete Bearer Request (DBR), or Clear Sub) is sent for the same PDN. For example, cnSGW-C receives the DSR for the PDN when the CBR1 and UBR1 procedures are in progress for the same PDN1. The DSR processing is started, and CBR1 and UBR1 processing is stalled. For more information, see the Graceful Stop the Existing PDN Procedure Call Flow call flow.
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The existing UE procedure (RAB or DDN) is stopped when the disconnect procedure (DSR, DBR, or Clear Sub) for the PDN is received. For example, cnSGW-C receives the DBR for the PDN while processing the RAB or DDN. The DBR procedure is started, and the RAB or DDN procedure is stopped.
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The incoming procedure for the PDN is stopped when the disconnect procedure (DSR, DBR, or Clear Sub) for the same PDN is in progress. For example, the UBR receives the PDN when sending the DSR for the same PDN. The UBR procedure is stopped, and the DSR procedure continues.
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The new incoming UE procedure is stopped when processing the disconnect procedure (DSR, DBR, or Clear Sub) for the same PDN. For example, the RAB received for the PDN1 when processing the multi-PDN call DSR for the same PDN1. The RAB procedure is stopped and rescheduled after the DSR for PDN1 gets completed.
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The CBR and the UBR message handling are stopped when the initial attach procedure is in progress.
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Optimization of the double delete handling. For example, the cnSGW-C receives the DSR from MME and DBR in the PGW, for which the DBR Sx modify step is pending toward the UPF. The DBR signaling is not initiated toward the S11 interface.
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The processing of the low priority procedures is stopped when the high priority procedure is received on the same bearer. For example, cnSGW-C receives the DBR for the PDN on a dedicated bearer while processing UBR on the same bearer. The DBR handling procedure is started, and the processing of the existing UBR procedure on the same bearer is stopped.