S1 Handover SGW Relocation with Bearer Context Marked for Removal Call Flow

This section describes the S1 handover SGW relocation with bearer context marked for removal call flow.

S1 Handover SGW Relocation with Bearer Context Marked for Removal Call Flow
S1 Handover SGW Relocation with Bearer Context Marked for Removal Call Flow Description

Step

Description

1

GTPC-EP ingress receives Create Session Request from MME with the following:

  • OI flag unset

  • MME Control TEID

  • PGW Control TEID

  • Bearer context to create (EBI:5, PGW Data TEID, EBI:6, 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 allocates TEID.

5

SGW service reads UPF cache and performs UPF selection.

6

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

10

SGW forwards Sx Session Establishment Response to GTPC-EP ingress.

11

Session updated at CDL. Transaction S-T1 completed.

12

GTPC-EP ingress sends Create Session Response to MME.

13

GTPC-EP ingress receives Modify Bearer Req with the following:

  • Updated eNodeB FTEID with new Bearer Contexts (here EBI 5) and removed (here EBI 6).

14

GTPC-EP forwards Modify Bearer Req to SGW.

15

Create a new transaction S-T2.

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

  • Updated downlink FAR and uplink PDR (Apply Action as DROP for Bearer 2).

16

PFCP-EP forwards Sx Session Modification Req forwarded to UPF.

17

UPF sends Sx Modification Response to PFCP-EP

18

PFCP-EP forwards Sx Modification Response to SGW service POD.

19

SGW service POD sends Modify Bearer Req 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

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

23

SGW service POD forwards Create Session Response to GTPC-EP ingress with cause Accepted for both Bearer Contexts.

24

Session updated at CDL. Transaction S-T2 completed.

25

GTPC-EP ingress sends Modify Bearer Response to MME.

26

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

27

MME receives Delete Session Response.

Call cleared in old SGW.

28

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

29

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

30

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

31

GTPC-EP forwards Delete Bearer Command to PGW.

32

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

33

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

34

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

35

GTPC-EP ingress sends Delete Bearer request to MME.

36

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

37

GTPC-EP ingress receives Delete Bearer response and sends to SGW service POD.

38

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

39

GTPC-EP forwards Delete Bearer Response to PGW.