Inter and Intra MME Handover and S1 SGW Relocation with Less Number of Bearer Context Call Flow

This section describes the inter and intra MME handover and S1 SGW relocation with less number of bearer context call flow.

Inter and Intra MME Handover and S1 SGW Relocation with Less Number of Bearer Context Call Flow
Inter and Intra MME Handover and S1 SGW Relocation with Less Number of Bearer Context Call Flow Description

Step

Description

1

Established NEW MME session with the default bearer EBI 5 and dedicated bearer 6.

New MME receives Create Session Request for S1 SGW Relocation with Default bearer EBI 5 and dedicated bearer 6.

New MME sends Modify Bearer Request to GTPC-EP ingress with the following:

  • New MME Control TEID

  • New Bearer Contexts to create

  • EBI5

  • eNodeB Data TEID

2

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

3

SGW service POD sends Delete Bearer Command with EBI 6 to GTPC-EP.

4

GTPC-EP forwards Delete Bearer Command to PGW.

5

SGW service POD sends Sx Mod Req to PFCP-EP with Remove DL Traffic Endpoint and Remove UL Traffic Endpoint for Bearer 2.

6

PFCP-EP forwards Sx Mod Req to UPF.

7

UPF sends Sx Mod Response to PFCP-EP.

8

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

9

SGW service POD sends Modify Bearer Response to GTPC-EP ingress with the following:

  • Bearer Contexts EBI 5 to modify with cause as Accepted

10

Updated session to CDL.

11

GTPC-EP ingress sends Modify Bearer Response to New MME.

12

PGW sends Delete Bearer Request to GTPC-EP.

13

SGW service POD receives Delete Bearer Request with EBI6 from PGW as Delete Bearer Command handled as separate procedure.

14

SGW service POD responds with Delete Bearer Response with cause as Context Not Found to GTPC-EP.

15

GTPC-EP forwards Delete Bearer Response to PGW.

Note
  • Sx Modify Request message along with Remove DL traffic Endpoint and Remove UL traffic Endpoint is sent as don’t confirm message in Legacy CUPS. Sx Modify for MBReq message follows Sx Modify Request and sent to UPF.

  • UPF receives the following messages in cnSGW-C.

    • Single Sx Modify Request message for MB Request

    • Remove DL traffic Endpoint

    • Remove UL traffic Endpoint