Inter-SGW Handover on 4G RAT for 5G Capable Devices Call Flow
This section describes the Inter-SGW Handover on 4G RAT for 5G Capable Devices call flow.

Step |
Description |
---|---|
1 |
Established UPF association with control planes. UPF sends Sx Association Req/Rep to destination cnSGW-C. |
2 |
UPF sends Sx Association Req/Rep to SMF. |
3 |
4G call connected between cnSGW-C-source and SMF. MME selects cnSGW-C-Destination for the SGW handover. MME sends Create Session Req with PGW-Ctrl-TEID to cnSGW-C-Destination. |
4 |
cnSGW-C extracts same associated UPF ID from PGW-Ctrl-TEID. cnSGW-C-Destination sends Sx Establishment Req (SXA) to UPF. |
5 |
cnSGW-C-Destination receives Sx Establishment Rsp (SXA) from UPF. |
6 |
cnSGW-C-Destination sends Create Session Response to MME. |
7 |
cnSGW-C-Destination receives Modify Bearer Request from MME. |
8 |
cnSGW-C-Destination sends Sx Establishment Req-N4 to UPF. |
9 |
cnSGW-C-Destination receives Sx Establishment Rsp-N4 from UPF. |
10 |
cnSGW-C-Destination sends Modify Bearer Request to SMF. |
11 |
cnSGW-C-Destination receives Modify Bearer Response from SMF. |
12 |
cnSGW-C-Destination forwards Modify Bearer Request to MME. |