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.

Inter-SGW Handover on 4G RAT for 5G Capable Devices Call Flow
Inter-SGW Handover on 4G RAT for 5G Capable Devices Call Flow Description

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.