Create Session Request Call Flow

This section describes the Create Session Request call flow.

Create Session Request (Context Replacement – Single or Multi-PDN subscriber) Call Flow
Create Session Request (Context Replacement – Single or Multi-PDN subscriber) Call Flow Description

Step

Description

1

MME sends Create Session Request with C-TEID as zero to GTPC-EP ingress.

2

GTPC-EP ingress forwards the Create Session Request to SGW-SVC.

Following actions takes place:

  • App Infra invokes the GetKey() method, which locates and loads the existing subscribers using Primary Key: IMSI.

  • Performs Sx Session Deletion Request for all PDNs using ASYNC IPC

  • Performs Resource Management Request (IdReq: IdReqType_ID_REQ_REL) using SYNC IPC

3, 5

The SGW service pod sends the Delete Session Request for PDN 1 - N to PFCP-EP.

4, 6

PFCP-EP forwards Delete Session Request for PDN 1 - N to UPF.

7, 9

PFCP-EP receives Delete Session Response for PDN 1 to N from UPF.

8, 10

PFCP-EP forwards Delete Session Response for PDN 1 - N to SGW service pod.

11

SGW service pod sends Resource Management Request to RMMgr with request ID-type as Request REL.

12

SGW service pod receives Resource Management Response from RMMgr with Req ID-type as REQ REL.

The SGW service pod performs following:

  • Removes all session CDL keys (Using RemoveAllSessionKeys(txn))

  • Removes affinity Key (Using RemoveSubscriberAllKey())

  • Cleans up the local database (Subscriber/PDN)

Note

You can ignore unhandled events for the Deletion Response from UPF.