X2 Handover SGW Relocation with Bearer Context Marked for Removal Call Flow

This section describes the X2 handover SGW relocation with bearer context marked for removal call flow.

X2 Handover SGW Relocation with Bearer Context Marked for Removal Call Flow
X2 Handover SGW Relocation with Bearer Context Marked for Removal Call Flow Description

Step

Description

1

GTPC-EP ingress receives Create Session Req with the following:

  • OI flag set

  • MME Control TEID

  • PGW Control TEID

  • new Bearer Contexts to create (EBI:5, eNodeB Data TEID and PGW Data TEID)

  • Bearer context to delete (EBI: 6)

Establishes new transaction at GTPC-EP.

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 allocates TEID.

5

SGW service POD 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 EBI 5 and as Drop EBI 6)/CTEs.

7

PFCP-EP forwards Sx Session Establishment Req 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 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 sends Create Session Response to GTPC-EP ingress with cause Accepted for both Bearer Contexts.

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.

18

MME receives Delete Session Response. Call cleared in old SGW.

19

GTPC-EP ingress receives Delete Bearer Command for Bearer Context from MME to delete (EBI 6).

20

SGW service POD receives Delete Bearer Command from GTPC-EP ingress.

21

SGW service POD forwards Delete Bearer Command to GTPC-EP.

22

GTPC-EP forwards Delete Bearer Command to PGW.

23

PGW responds with Delete Bearer Request (EBI 6) to GTPC-EP.

24

GTPC-EP forwards Delete Bearer Request to SGW service POD.

25

SGW service POD processes Delete Bearer Request and sends to GTPC-EP.

26

GTPC-EP ingress forwards Delete Bearer request to MME.

27

MME responds with the Delete Bearer Response to GTPC-EP ingress.

28

GTPC-EP ingress forwards Delete Bearer Response to SGW service POD.

29

SGW service POD processes Delete Bearer Response and sends to GTPC-EP.

30

GTPC-EP forwards Delete Bearer Response to PGW.