PDU Session Establishment Call Flow

This section describes the call flow of the PDU session establishment.

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’ in the PDU Session Establishment Accept message if any 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 '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 always-on configuration is disabled in the DNN profile.