X2 Handover SGW Relocation to CN-SGW (Multi PDN) Call Flow
This section describes the X2 handover SGW relocation to CN-SGW (Multi PDN) to cnSGW-C call flow.

Step |
Description |
---|---|
1, 2 |
MME sends Create Session Req for both PDNs to GTPC-EP ingress with the following:
Establishes new transactions at GTPC-EP ingress. |
3, 4 |
SGW service POD receives Create Session Req for both PDNs from PFCP-EP ingress. Collision resolver added Create Session Req for PDN 2 in queue. |
5 |
Create a new transaction S-T1 for Create Session Req for PDN1 Validate CSReq. |
6 |
NodeMgr allocates TEID. |
7 |
SGW service POD reads UPF Cache and performs UPF selection. |
8 |
PFCP-EP receives Sx Session Establishment Req from SGW service POD for PDN 1 with the following:
|
9 |
PFCP-EP forwards Sx Session Establishment Req for PDN 1 to UPF. |
10 |
UPF sends Sx Session Establishment Response for PDN 1 to PFCP-EP with Created CTEs. |
11 |
PFCP-EP forwards Sx Session Establishment Response for PDN 1 to SGW service POD. |
12 |
SGW service POD sends Modify Bearer Req for PDN 1 to GTPC-EP with the following:
|
13 |
GTPC-EP forwards Modify Bearer Req for PDN 1 to PGW. |
14 |
PGW sends Modify Bearer Response for PDN 1 to GTPC-EP. |
15 |
GTPC-EP forwards Modify Bearer Response for PDN 1 to SGW service POD. |
16 |
SGW service forwards Create Session Response for PDN 1 to GTPC-EP ingress. |
17 |
Session updated at CDL. Transaction S-T1 completed. Collision resolver schedules Create Session Req for PDN 2 from queue. |
18 |
GTPC-EP ingress forwards Create Session Response for PDN 1 to MME. |
19 - 27 |
Repeat steps from 8 to 16 for PDN2. |
28 |
Session updated at CDL. Transaction S-T2 completed. |
29 |
GTPC-EP ingress forwards Create Session Response for PDN 2 to MME. |
30 - 33 |
MME sends Delete Session Request for both PDNs with SI=1 to old SGW and receives Delete Session Response. Call cleared in old SGW. |