Graceful Stop the Existing PDN Procedure Call Flow
This section describes the Graceful Stop the Existing PDN Procedure call flow.

Step |
Description |
---|---|
1 |
The Initial Attach process is completed with the already established three PDNs. The PGW sends the Create Bearer Request to the S5-GTPC-EP. |
2 |
The S5-GTCP-EP forwards the Create Bearer Request for PDN1 to the cnSGW. |
3 |
The cnSGW forwards the Sx Modify Request for PDN1 to the PFCP-EP. The cnSGW waits for the Sx Modify Response for PDN1. |
4 |
The PFCP-EP sends the Sx Modify Request for PDN1 to the UPF. |
5 |
The UPF sends the Sx Modify Response for PDN1 to the PFCP-EP. |
6 |
The PFCP-EP sends the Sx Modify Response for PDN1 to the cnSGW. |
7 |
The cnSGW sends the Create Bearer Request for PDN1 to the S11-GTPC-EP. |
8 |
The S11-GTPC-EP forwards the Create Bearer Request for PDN1 to the MME. |
9 |
The PGW sends the Delete Bearer Request for PDN1 to the S5-GTPC-EP. |
10 |
The S5-GTPC-EP forwards the Delete Bearer Request for PDN1 to the cnSGW. The cnSGW waits for the MME response and the cnSGW receives the Delete Bearer Request for PDN1. When collision is detected for PDN1, stop the old transaction T1 for PDN1. |
11 |
The cnSGW sends the Sx Modify Request (async) to the PFCP-EP. |
12 |
The cnSGWcnSGW sends the Create Bearer Response with cause No-Resource-Available for PDN1 to the S5-GTPC-EP. |
13 |
The cnSGW sends the Sx Modify Request for DBR to the PFCP-EP. |
14 |
The PFCP-EP forwards the Sx Modify Request for CBR to the UPF. |
15 |
The PFCP-EP forwards the Sx Modify Request for DBR to the UPF. |
16 |
The S5-GTPC-EP sends the Create Bearer Response with cause No. |
17 |
The UPF sends the Sx Modify Response for CBR to the PFCP-EP. The PFCP-EP discards this response. |
18 |
The UPF sends the Sx Modify Response for DBR to the PFCP-EP. |
19 |
The PFCP-EP forwards the Sx Modify Response for DBR to the cnSGW. |
20 |
The cnSGW sends the Delete Bearer Request for PDN1 to the S11-GTPC-EP. |
21 |
The S11-GTPc-EP forwards the Delete Bearer Request for PDN1 to the MME. |
22 |
The MME sends the Delete Bearer Response for PDN1 to the S11-GTPC-EP. |
23 |
The S11-GTCP-EP forwards the Delete Bearer Response for PDN1 to the cnSGW. |
24 |
The cnSGW sends the Sx Delete Request for PDN1 to the PFCP-EP. |
25 |
The PFCP-EP forwards the Sx Delete Request for PDN1 to the UPF. |
26 |
The UPF sends the Sx Delete Response for PDN1 to the PFCP-EP. |
27 |
The PFCP-EP forwards the Sx Delete Response for PDN1 to the cnSGW. |
28 |
The cnSGW sends the Delete Bearer Response for PDN1 to the S5-GTPC-EP. |
29 |
The S5-GTPC-EP forwards the Delete Bearer Response for PDN1 to the PGW. |