S1 Handover SGW Relocation to cnSGW-C Call Flow

This section describes the S1 handover SGW Relocation to cnSGW-C call flow.

S1 Handover SGW Relocation to cnSGW-C Call Flow
S1 Handover SGW Relocation to cnSGW-C Call Flow Description

Step

Description

1

MME sends Create Session Request message to GTPC-EP ingress with the following:

  • OI flag unset

  • MME Control TEID

  • PGW Control TEID

  • PGW Data TEID

Establishes new transaction at GTPC-EP ingress.

2

SGW service POD receives Create Session Request.

3

Create a new transaction S-T1.

4

Validate Create Session Req.

5

NodeMgr allocates TEID.

SGW service reads the UPF cache and performs UPF selection.

6

PFCP-EP receives Sx Session Establishment Request from SGW service POD with the following:

  • Uplink and downlink Create PDRs/FARs (Apply Action as Forward)/CTEs

7

PFCP-EP forwards Sx Session Establishment Request to UPF

8

PFCP-EP receives Sx Session Establishment Response from UPF with Created CTEs.

9

SGW service POD receives Sx Session Establishment Response from PFCP-EP.

10

SGW service POD forwards Create Session Response to GTPC-EP ingress.

11

Updated session at CDL. Transaction S-T1 completed.

12

GTPC-EP ingress forwards Create Session Response to MME.

13

GTPC-EP ingress receives Modify Bearer Req with updated eNodB FTEID from MME.

14

GTPC-EP ingress forwards Modify Bearer Req to SGW service POD.

Creates new transaction-T2.

15

PFCP-EP receives Sx Mod Req from SGW service POD with the updated downlink FAR and uplink PDR.

16

PFCP-EP forwards Sx Mod Req to UPF.

17

PFCP-EP receives Sx Mod Response from UPF.

18

SGW receives Sx Mod Response from PFCP-EP.

19

SGW service POD sends Modify Bearer Request with updated S5 SGW Control TEID and S5 SGW Data TEID to GTPC-EP.

20

GTPC-EP forwards Modify Bearer Request to PGW.

21

GTPC-EP receives Modify Bearer Response from PGW.

22

SGW service POD receives Modify Bearer Response from GTPC-EP.

23

GTPC-EP ingress receives Modify Bearer Response from SGW service POD.

24

Session updated at CDL. Transaction S-T2 completed.

25

GTPC-EP ingress forwards Modify Bearer Response to MME.

26

MME sends Delete Session Request with SI=1 to old SGW and receives Delete Session Response.

Call cleared in old SGW.