4.23.16 Handover of a PDU Session procedure between 3GPP and untrusted non-3GPP access

23.5023GPPProcedures for the 5G System (5GS)Release 18TS

4.23.16.1 Handover of a PDU Session procedure from untrusted non-3GPP to 3GPP access (non-roaming and roaming with local breakout)

The following impacts are applicable to clause 4.9.2.1 when a PDU Session is handover from untrusted non-3GPP to 3GPP access (non-roaming and roaming with local breakout):

– Step2: The UE performs a PDU Session Establishment procedure with the PDU Session ID of the PDU Session to be moved as specified clause 4.23.5.1 and an I-SMF and an I-UPF may be selected and inserted for this PDU. If I-SMF is selected, in the Nsmf_PDUSession_Create Response the SMF shall include all QoS information for the QoS Flow(s) applicable to the PDU Session for the target access so that when sending the PDU Session Establishment Accept, within the N1 SM container and in the N2 SM information, the I-SMF can include all QoS information (e.g. QoS Rule(s) in N1 SM container, QFI(s) and QoS Profile(s) in N2 SM information) for the QoS Flow(s).

4.23.16.2 Handover of a PDU Session procedure from 3GPP to untrusted non-3GPP access (non-roaming and roaming with local breakout)

When a PDU Session is handover from 3GPP access with an I-SMF to untrusted non-3GPP access (non-roaming and roaming with local breakout), the following steps take place:

1) Step 1 of clause 4.9.2.2.

2) Step 2 of clause 4.9.2.2.

3) The step 3 in clause 4.9.2.4.2 is executed involving I-SMF instead of V-SMF, with following differences:

– Figure 4.3.4.3-1 step 14 involving I-SMF instead of V-SMF.

– Figure 4.3.4.3-1 step 16a: The SMF invokes Nsmf_PDUSession_StatusNotify (Release) indicating the release is due to a PDU Session Handover out of the I-SMF.

– Figure 4.3.4.3-1 step 16b: the I-SMF invoke the Nsmf_PDUSession_SMContexStatusNotify (Release) indicating the Release is due to a PDU Session Handover out of the I-SMF: the AMF determines that only the SMcontext with the I-SMF is to be released but that the PDU Session is not released.

The steps 2 to 3 above shall be repeated for all PDU Sessions to be moved from 3GPP access to untrusted non-3GPP access.

4.23.16.3 Handover of a PDU Session procedure from untrusted non-3GPP to 3GPP access (home routed roaming)

4.23.16.3.1 The target AMF is in the PLMN of the N3IWF

The following impacts are applicable to clause 4.9.2.3.1 when a PDU Session is handover from untrusted non-3GPP to 3GPP access (home routed roaming) and target AMF is in the PLMN of the N3IWF:

– Step2: The UE performs a PDU Session Establishment procedure with the PDU Session ID of the PDU Session to be moved as specified clause 4.23.5.1. A different V-SMF and a different V-UPF may be selected for the PDU Session.

If a new V-SMF is selected, in the Nsmf_PDUSession_Create Response the H-SMF shall include all QoS information for the QoS Flow(s) applicable to the PDU Session for the target access so that when sending the PDU Session Establishment Accept, within the N1 SM container and in the N2 SM information, the V-SMF can include all QoS information (e.g. QoS Rule(s) in N1 SM container, QFI(s) and QoS Profile(s) in N2 SM information) for the QoS Flow(s) acceptable according to VPLMN policies.

– (additional) Step 4: If a new V-SMF and a new V-UPF are selected for the PDU Session, the step 3a and 14 in clause 4.3.4.3 are performed to release the resource in the old V-SMF and old V-UPF.

The steps 2 to 4 shall be repeated for all PDU Sessions to be moved from to untrusted non-3GPP access to 3GPP access.