TAU X2 Handover SGW Relocation to cnSGW-C Call Flow

This section describes the TAU X2 handover SGW telocation to cnSGW-C call flow.

TAU X2 Handover SGW Relocation to cnSGW-C Call Flow
TAU X2 Handover SGW Relocation to cnSGW-C Call Flow Description

Step

Description

1

MME sends Create session Req to GTPC-EP ingress with the following:

  • OI flag set

  • MME Control TEID

  • PGW Control TEID

  • PGW Data TEID

Establishes new transaction at GTPC-EP ingress.

2

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

3

SGW service POD receives Create Session Req.

Create a new transaction S-T1.

4

Validate CSReq.

NodeMgr performs TEID allocation.

5

SGW service reads UPF Cache and performs UPF selection.

6

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

  • Uplink and downlink Create PDRs/FARs(ApplyAction as Forward for the uplink FAR)/CTEs.

7

PFCP-EP forwards Sx Session Establishment Req to UPF.

8

PFCP-EP receives Sx Session Establishment Response from UPF.

9

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

10

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

11

GTPC-EP forwards Modify Bearer Request to PGW.

12

GTPC-EP receives Modify Bearer Response from PGW.

13

GTPC-EP forwards Modify Bearer Response to SGW service POD.

14

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

15

Session updated at CDL. Transaction S-T1 completed.

16

GTPC-EP ingress forwards Create Session Response to MME.

17

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

Call cleared in old SGW.