PDU Session Establishment Call Flow

This section describes the PDU session establishment procedure involving a request for Always-on PDU session initiation in the Create Session Request.

The following figure illustrates the PDU Session Establishment call flow.

PDU Session Establishment Call Flow


PDU Session Establishment Call Flow Description
Step Description
1

If the UE requests to establish an always-on PDU session, the UE includes an "Always-on PDU Session Requested" IE in the PDU Session Establishment Request message.

2

The SMF checks the DNN profile to determine whether the always-on support is enabled.

3

The SMF includes an "Always-on PDU Session Indication" IE in the PDU Session Establishment Accept message if one of the following is true:

  • "Always-on PDU Session Indication" is sent with value as "enabled" if the always-on configuration is enabled under the DNN profile.

  • "Always-on PDU Session Indication" is sent with value as "disabled" when the "Always-on PDU Session Request" IE is received and configuration is disabled.

4

The SMF does not include an "Always-on PDU Session Indication" only when both these conditions are true:

  • If the UE did not send an "Always-on PDU Session Requested" IE.

  • If the always-on configuration is disabled in the DNN profile.