5G to EPS Handover Using N26 Interface – cnSGW-C and SMF Separate Node Call Flow

This section describes the 5G to EPS Handover Using N26 Interface – cnSGW-C and SMF Separate Node call flow.

5G to EPS Handover Using N26 Interface – cnSGW-C and SMF Separate Node Call Flow
5G to EPS Handover Using N26 Interface – cnSGW-C and SMF Separate Node Call Flow Description

Step

Description

1

cnSGW-C selects associated same UPF.

cnSGW-C receives Sx Establishment Request with User-plane ID from UPF/UP.

2

cnSGW-C sends Sx Establishment Response from UPF/UP.

3

UPF/UP sends Sx Association Request with User-plane ID to SMF.

4

SMF sends Sx Association Response to UPF/UP.

5

cnSGW-C sends Relocation Request to MME on interface N26.

6

MME sends Create Session Request to cnSGW-C with SMF and PGW-ctrl-TEID information.

7

cnSGW-C selects associated same UPF.

cnSGW-C sends Sx Establishment Req (SXA) to UPF/UP.

8

cnSGW-C receives Sx Establishment Rsp (SXA) from UPF/UP.

9

cnSGW-C sends Create Session response to MME.

10

MME sends Modify Bearer Request to cnSGW-C.

11

cnSGW-C sends Sx Modify Req (SXA) to UPF/UP.

12

cnSGW-C receives Sx Modify Rsp (SXA) from UPF/UP.

13

cnSGW-C sends Modify Bearer Request to SMF.

14

SMF sends Sx Modify Request – N4 to UPF/UP.

15

SMF receives Sx Modify Response from UPF/UP.

16

cnSGW-C receives Modify Bearer Response to SMF.

17

cnSGW-C forwards Modify Bearer Response to MME.